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Evaluating the Sustainability of Ceramic Filters for Point-of-Use Drinking Water Treatment
Abstract
This study evaluates the social, economic, and environmental sustainability of ceramic filters impregnated with silver nano-particles for point-of-use (POU) drinking water treatment in developing countries. The functional unit for this analysis was the amount of water consumed by a typical household over ten years (37,960 L), as delivered by either the POU technology or a centralized water treatment and distribution system. Results indicate that the ceramic filters are 3-6 times more cost-effective than the centralized water system for reduction of waterborne diarrheal illness among the general population and children under five. The ceramic filters also exhibit better environmental performance for four of five evaluated life cycle impacts: energy use, water use, global warming potential, and particulate matter emissions (PM10). For smog formation potential, the centralized system is preferable to the ceramic filter POU technology. This convergence of social, economic, environmental criteria offers clear indication that the ceramic filter POU technology is a more sustainable choice for drinking water treatment in developing countries than the centralized treatment systems that have been widely adopted in industrialized countries.
... 1 While centralized water treatment plants (WTPs) provide safe drinking water to over 94% of households in North America and Europe, they are often not a suitable option for rural communities living in developing countries. [1][2][3] The intensive capital investment required for the installation, management and maintenance of centralized WTPs often renders them impractical for the target communities. Moreover, the recontamination of WTPs' piped drinking water during distribution in developing countries has been highlighted as a concern for final water consumption. ...
... Moreover, the recontamination of WTPs' piped drinking water during distribution in developing countries has been highlighted as a concern for final water consumption. 2 This raises the need for decentralized point-of-use (POU) water treatment technologies that are effective, robust, reliable, affordable and user-friendly. 4 Ceramic water filters (CWFs) are one appealing option amongst POU water treatment technologies. ...
... Moreover, CWFs were found to be a sustainable solution in comparison with centralized WTPs in developing countries, as they are reported to reduce diarrheal diseases by an average of 71% amongst children under five, while WTPs' treated water reduced diarrheal incidents by an average of 26% due to subsequent recontamination. 2 As such this is predicated on proper use of CWFs, which may be challenging in some communities or situations. ...
BACKGROUND
Point‐of‐use filtration units often incorporate silver as a disinfection aid. However, system performance and robustness may be increased by considering co‐application of additional transition metal nanoparticles (NPs) to support treated water disinfection. In this paper, the use of silver (Ag), zinc (Zn) and copper (Cu) NPs as disinfectants within drinking water applications was explored. Disinfection efficiency against E. coli was investigated over 72 h in batch‐phase experiments using NP concentrations within or lower than drinking water limits. Concentration ranges of the NPs were from 0 to 200 μg L⁻¹, reflecting typical concentration reports for Ag in similar applications. Samples were examined with respect to pH and two water types. The effect of co‐application of NPs was assessed for potential synergy using the Bliss model, which compares individual treatment performance to combined treatment results.
RESULTS
Disinfection efficacy when applying NPs individually was Ag > Cu > Zn with, for instance, complete removal (≥3 log) of E. coli observed with 50 ppb Ag at 24 h, 1 log removal by Cu and no removal achieved with application of Zn. The Bliss model analysis demonstrated the co‐application of NPs resulted in synergistic behavior with the combinations. Zn‐containing combinations (Ag–Zn and Cu–Zn) were significantly more synergistic than the Ag–Cu combination.
CONCLUSIONS
Low‐level (0–200 ppb) concentrations of Ag, Cu and Zn demonstrated effective bacterial control and disinfection for E. coli under various water quality scenarios. In particular, co‐application of transition metal NPs increased system robustness and synergy, demonstrating potential for disinfection with water treatment applications. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).
... While centralized treatment is often considered the gold standard, POU technology is frequently utilized for its cost-effectiveness and relative lack of barriers. Perhaps its primary advantage is economic: POU treatments are almost six times more cost-effective than centralized treatments (Ren et al. 2013). POU interventions require relatively little planning and construction in comparison with centralized treatments (Elimelech 2006), offer flexibility if population growth occurs (Elimelech 2006), and are more effective at reaching rural areas (Montgomery & Elimelech 2007;Peter-Varbanets et al. 2009). ...
... Although centralized treatment systems facilitate monitoring and enforcement of water quality standards, meeting such standards requires meticulous maintenance of the whole treatment and distribution infrastructure; if maintenance or public confidence is lacking, POU treatment may play a role (Wu et al. 2021). Furthermore, the use of POU technology may stimulate the local economy, as local economies in lower-income countries may have the capacity to produce the POU technology themselves (Montgomery & Elimelech 2007;Ren et al. 2013). ...
... Many studies have shown POU filter technology has not held up as well over multiple years in community settings, with high proportions of filters out of use due to disrepair or missing parts (Brown et al. 2009;Kohlitz et al. 2013;Sisson et al. 2013). This points to the need for accessible and affordable repairs and/or replacements of filters, whether through in-country manufacturing of filters and parts or promoting local distribution of replacement parts and repairs (Lantagne et al. 2006;Ren et al. 2013)there is currently no such situation for the Sawyer PointOne filter in Liberia. ...
In Liberia, access to safe water is not universal, and waterborne diseases like diarrhea run rampant. As part of a larger border-to-border clean water project in Liberia, hollow membrane fiber filters were distributed to households in remote and/or small villages across Liberia. While filter efficacy has been demonstrated in the laboratory, studies of filter efficacy in real-world settings yield more mixed results. Intervention efficacy in Liberia was evaluated by assessing (1) user ability to correctly filter and backwash and (2) filter functioning at follow-up visits approximately 2 and 8 weeks post-intervention. Ultimately, the results supported the efficacy of this intervention. At arrival of both follow-ups, over 95% of filters were functioning properly and the majority of issues were resolved during visits. This supported the short-term durability of the filters and the importance of follow-up visits for repairs. Furthermore, the vast majority of households were able to correctly demonstrate filtering and backwashing: 88.47% at the first follow-up and 91.79% at the second. This slight increase may indicate the value of follow-up visits as educational tools. The widescale distribution of point-of-use filters as a mechanism for clean water should include on-going education and affordable filter repair and replacement opportunities.
HIGHLIGHTS
Describes a border-to-border clean water filtration intervention in Liberia.;
Results demonstrate that point-of-use filters are easy to use.;
Results demonstrate high rates of filter durability in the short-term.;
... 2−6 These filters are manufactured using locally available raw materials (i.e., clay and organic combustible materials) with added Ag and are cost-effective in comparison with a centralized water treatment. 7,8 However, there are some issues associated with ceramic filters, including difficulties in maintaining a high flow rate over an extended service period, insufficient removal of diverse water pollutants (e.g., toxic metals), and the need for firing (at up to ∼1000°C for several hours). The firing may cause smog and particulate matter emissions, especially when using low-quality fuels in firing kilns. ...
... Scenario 3 (CER) represents the typical ceramic filter raw materials and the firing process reported earlier. 7,9 For a detailed description of LCA, see the text and Table S3 in Supporting Information. ...
... The CWF is a low-cost technology for drinking water treatment that, similarly to BSF, makes use of physical and chemical processes to remove different contaminants from the water, especially microorganisms. Commonly it is made of a terracotta structure containing a microporous filtering region, they may or may not be impregnated with colloidal silver [49][50][51]. When the filtering region is not part of the filter wall, a filtering component, also called "a candle", is incorporated into the CWF [52]. ...
... When the filtering region is not part of the filter wall, a filtering component, also called "a candle", is incorporated into the CWF [52]. CWF have been widely demonstrated as effective [53][54][55], sustainable [50,56] and socially acceptable [51,57], capable of significantly reducing the risk of diarrhea when promoted as a household drinking water treatment technology [58][59][60][61]. ...
In a world where the consequences of inequalities in access to safe drinking water persist, Household Drinking Water Treatment Technologies (HDWT) remains the most readily available and promising alternative solution to prevent waterborne diseases. While successful cases of combating waterborne diseases with HDWT have been documented, there are also reports of failures in reducing water-related illnesses. Understanding the reasons behind these inconsistent results is crucial. This work aimed to identify and critically discuss barriers, enablers, and technology delivery strategies for HDWT-based interventions to improve drinking water safety. Data from 147 articles covering Solar Disinfection, Chlorination, Flocculation-Disinfection, BioSand Filter, and Ceramic Water Filter were extracted from a total of 11,982 systematically retrieved records. Among the identified factors, 77 barriers and 76 enablers were distributed across different domains: psychosocial (37.7, 47.4%), promotion (22.1, 26.3%), technology (28.6, 10.5%), economic (9.1, 14.5%), and environmental (2.6, 1.3%) for barriers and enablers, respectively. Technology delivery strategies primarily included water education and technology promotion, training for technology usage, provision of HDWT through donation or promotional sale, donation of safe water storage, technical assistance, and the use of a diarrhea control diary. All barriers and enablers affect the initial adoption, regular, and sustained use of HDWT and should be considered when planning and implementing interventions. The health impacts of interventions decreased over time since HDWT adoption. Adequate user training, HDWT donation, and high compliance are important predictors of success for HDWT-based interventions. In general, identifying and exploring the listed enablers can help overcome many of the reported limitations.
... These POU systems often utilize simple, affordable treatment technologies that seek to provide the basic level of prevention of waterborne diseases. Few investigations have studied the utilization of POU systems as a means of upgrading existing centralized treatment systems (Brown et al., 2017;Ren et al., 2013). Brown et al. (2017) found that POU systems can augment the centralized treatment for the reduction of lead and copper, which have leached into the drinking water from the distribution pipe network. ...
... However, the study was focused on treatment capacity and did not investigate its environmental, economic, or public health impacts. Ren et al. (2013) compared POU systems' environmental and human health implications with a centralized upgrade alternative for turbidity and microorganism removal. They found that the POU scenario resulted in a lower cumulative energy demand (CED) and global warming potential (GWP). ...
Per- and polyfluoroalkyl substances (PFAS) chemicals are a growing threat to public health and safety. This study seeks to compare the life cycle environ- mental, economic, and human health performances of centralized and point- of-use (POU) systems used to upgrade existing drinking water treatment facili- ties for enhanced PFAS removal, using Merrimack, NH as a testbed. Out of all studied system upgrade scenarios, a POU scenario that combines granular acti- vated carbon and ion exchange filters has the lowest environmental and human health impacts and relatively low economic impact. Despite all drink- ing water taps in the house being protected, the centralized scenario does not perform the best in terms of the health impacts because of its relatively low perfluorooctane sulfonate removal efficiency. This suggests a potential tra- deoff between protecting the highest number of taps and achieving the highest removal efficiency at limited taps as two water treatment objectives.
... The sustainability of ceramic filters was systematically and quantitatively evaluated by Ren et al. 50 Their results suggested that POU ceramic filters may be representative of a sustainable water treatment technology in developing countries. Specifically, in comparison to a centralized water system, the use of ceramic filters can be six times more cost-effective for developing countries and can reduce environmental impact (e.g., global warming potential, water use) by up to ∼75%. ...
... Specifically, in comparison to a centralized water system, the use of ceramic filters can be six times more cost-effective for developing countries and can reduce environmental impact (e.g., global warming potential, water use) by up to ∼75%. 50 The environmental impact and footprint of ceramic filters may be further improved with advances in filter fabrication processes with cost reductions and the use of environmentally benign materials (e.g., recycled paper fiber). Furthermore, several previous studies reported the use of surface coated ceramic materials for the removal of viruses and heavy metals. ...
Ceramic filters are widely used for sustainable point-of-use water treatment in developing countries. It remains a great challenge, however, for ceramic filters to simultaneously achieve high flow rate and effective bacterial removal. In this work, we reported the use of recycled paper fiber (greenfiber) as combustible material for the development of effective and fast-flow ceramic filters and compared their performance to filters that were fabricated using starch and rice husk, two common combustible materials used in previous studies. The clean ceramic filters made using 15% greenfiber achieved > 4 log removal of bacteria (>99.99% removal) and an equivalent flow rate of 5.9 L/h (37.5 L/m²-h); the filters made using 20% greenfiber exhibited a fast flow rate of 13.9 L/h (87.1 L/m²-h) while maintaining a log microbial removal efficiency of >2 (> 99% removal of bacterial cells). The two flow rates were ~100% and > 300% higher than the flow rates of mainline ceramic filters currently in use. The filters were characterized using mercury intrusion porosimetry, scanning electron microscopy, X-ray fluorescence analysis and Fourier transform infrared spectroscopy. Our results suggested that the pore size distribution pattern played critical roles in the microbial removal efficiency. A mathematical framework was developed to provide a semi-quantitative analysis of the relationship between filter bacterial removal efficiency and pore size distribution.
... Ag-NPs impregnated in porous ceramic filters for point-of-use (POU) water treatment are a promising option for expanding access to clean water, especially in rural areas. Several studies have demonstrated the effectiveness of this technology in filtering and sterilizing water [39][40][41][42]. It has been shown that the addition of Ag-NPs to ceramic filters using different methodologies (painting and immersion) improves the performance of the filters and provides them with the ability to remove Escherichia coli in the range of 97-100% [42]. ...
Water purification has become a significant challenge in the last decades due to the increase of
pollutants present in water sources. Inorganic contaminants, as well as organic compounds, have
received special attention due to their impact on human health and the environment. The presence
of these species in aquatic ambient is increasing within the last few years due to industrialization
and population growth. For this reason, it is necessary to create an environment of human
conscience and develop methodologies for protecting and remediating the ambient. In this sense,
the development of novel technologies is emerging. Nanotechnology appears as a recourse for the
development of new nanomaterials, which could be implemented in different methodologies for
environmental remediation and especially for water purification. In this chapter, an overview of the
most novel nanomaterials based on inorganic nanoparticles and bio-based nanocomposites was
reviewed, and their methodology of synthesis, characteristics, and properties for water remediation
was exhausted analyzed due to give knowledge in terms of their impact on environmental
remediation.
... For instance, the cost to provide functional ceramic water filters to a typical household for 10 years is $63 (assuming a functional life of 3.5 years). On the other hand, the cost to provide a centralized water system for the same time period is approximately $221 per household (Qian et al., 2013;Ren et al., 2013). As a result, ceramic water filters are less expensive and easily commercialized to local people in most developing nations including Tanzania. ...
Water safety concerns are increasing tremendously as a result of the rising
population and environmental pollution. As a result, viable water treatment
approaches need to be designed to meet the water consumption demands of
the population, particularly in developing countries. The recent technological
advances in water treatment and purification are well articulated in this
review. The efficiency of the materials used for purification and their affordability
for people living in rural and remote settlements in various parts of the
world have been discussed. Water treatment techniques prior to the rapid
advancement of science and technology included a variety of strategies such as
coagulation/flocculation, filtration, disinfection, flotation and pH correction.
The use of nanotechnology in water treatment and purification has modernized
the purification process. Therefore, efficient removal of microbes such as
bacteria and viruses are exquisitely accomplished. These technologies may
include membrane filtration, ultraviolet irradiation, advanced oxidation ionexchange
and biological filtration technologies. Thus, nanotechnology allows
for the fabrication of less expensive systems, allowing even low-income people
to benefit from it. Most developing countries find these technologies particularly
valuable because access to clean and safe water for drinking and residential
needs is critical. This is because access to municipal water supplies is also
difficult.
... Hence, compared to nanotechnology uses in the fields of health and electronics, not much advancement has been made. According to numerous areas based on bench-scale, full-scale, and pilot investigations, the use of nanotechnology in drinking water treatment and contaminant remediation appears promising (Ren et al. 2013;Mellor et al. 2015). ...
The rapid increases in industrialization and populations are significant sources of water contamination. The speed with which contamination of groundwater and surface water occurs is becoming a serious problem and posing a significant obstacle for water stakeholders. Heavy metals, organic, and inorganic contaminants in the form of suspended and dissolved materials are just a few of the contaminants that can be found in drinking water. One of the most common contaminants in the water is fluoride, which is responsible for numerous toxic diseases. Different traditional techniques, for example, coagulation, ion exchange, absorption, and membrane filtrations are being used to dispose of fluoride from water. However, nanomaterials such as magnetic nanoparticles (NPs) are very efficient, reliable, cost-effective, and stable materials to replace traditional water treatment techniques. There has been an increase in interest in the application of nanoma-terials to the purification of drinking water over the past few decades. The use of magnetic NPs, such as metal and metal oxide NPs, to remove fluoride ions and organic matter from water is highlighted in this review article. Also, this section also discusses the properties, benefits and drawbacks, and difficulties of utilizing magnetic NPs in the process of purifying drinking water.
... More and more companies are involved in activities in the field of sustainable development. The concept of sustainable development is based on the coexistence of three factors: economic, social, and environmental (Ren et al., 2013). The subject literature (Munasinghe, Cruz, 1994) views the social concept of sustainable development as being people-oriented, those who are in the organization, and interest groups outside the organization. ...
... El filtro de olla cerámica está conformado por una olla en forma de maceta con capacidad entre 8 y 10 litros y por lo general impregnada con plata coloidal; la olla se ubica en un recipiente plástico en el cual se almacena el agua filtrada (Centre for Affordable Water and Sanitation Tecnology [CAWST], 2018). Este sistema de tratamiento es considerado más rentable y ambientalmente sostenible comparado con los sistemas de tratamiento de agua centralizados (Ren, Colosi, & Smith, 2013). ...
La Organización Mundial de la Salud (OMS) propone el tratamiento doméstico del agua como un medio efectivo que contribuye en gran medida al mejoramiento de la calidad del agua en las zonas rurales. El propósito de este estudio fue evaluar la eficiencia de remoción de dos sistemas de tratamiento doméstico del agua que corresponden al filtro de olla cerámica y filtro de vela cerámica bajo dos condiciones de mantenimiento. Se empleó agua natural proveniente del pozo subterráneo de la Universidad de Boyacá. Los parámetros evaluados fueron la turbiedad, coliformes totales, E.coli, pH, conductividad, color y la tasa de filtración. El tiempo de evaluación fue de 46 días, cada filtro fue alimentado diariamente con un volumen de 7,5 l. Los resultados mostraron que en los días de las actividades de limpieza se generaban picos en la turbiedad; los filtros sin mantenimiento mantuvieron un efluente con menores valores de este parámetro con respecto a los sistemas con mantenimiento. Adicionalmente, se comprobó la eficiencia de estos sistemas para la remoción E.coli. La variación de la tasa de filtración influye significativamente en el grado de sostenibilidad de los sistemas, siendo el mantenimiento uno de los factores incidentes, por tal razón se recomienda que se debe realizar semanalmente, siendo este un mantenimiento preventivo para evitar la colmatación de los poros en ambos sistemas de filtración.
... The bactericidal action of the silver is directly proportional to the quantity of the agent applied on the CWF (Oyanedel-Craver and Smith, 2008) and the holding of the bactericide in the filter (Ren et al., 2013). Inspite of the success of the ability of CWFs to remove microbes by reducing their pore sizes and coating them with silver nitrate 30 solution, the leaching of the silver and the compromise between flow rate and pore size, presents health risks. ...
Ceramic water filters (CWFs) are globally employed as point-of-use water treatment technology.
There is no comprehensive explanation of the function of CWFs in terms of biological and
physicochemical correction. Therefore, understanding the chemical characteristics of the CWFs can
serve as the basis for the description of the filter’s effectiveness. An efficiency model of the CWF is
very crucial for the setting of standard parameters for the acceptance or otherwise of the filters. This
study developed an efficiency model for CWF by considering both the chemical characteristics and
mechanical behaviour of three filters: ball filter (BF+AC), candle filter (CF) and pot filter (PFcs). To
achieve that, the elemental and mineral oxide compositions of the selected CWFs were analysed with
x-ray fluorescence method. The filtrate from CWFs for three water sources were analysed for
physicochemical, metal ion removability and microbial correction. Water Quality Index (WQI) scores
were computed using physicochemical parameters of the filtrates to rank the effectiveness of the
filters. Also, the flow rate of the CWFs were estimated and the adsorptioncharacteristics of the
selected CWFs were assessed. To statistically set the optimum conditions for an efficient CWF, an
optimisation experiment was conducted. From the results, the major mineral oxide compositions of
all CWFs were alumina (Al2O3) and silica (SiO2). Also, the CWFs ability to reduce total coliform in
water samples was BF+AC>CF>PFcs for the “more turbid water” (MTW) sample. Therefore BF+AC
was more effective in total coliform removability for surface water compared to other CWFs.
Furthermore, it was observed that the BF+AC was more efficient in the physicochemical correction
of all water samples ‘less turbid water’ (LTW) and MTW compared to the selected CWFs. Also, WQI
score for filtrate from CWFs were in the order BF+AC>CF>PFcs of effectiveness. The adsorption
characteristics of the CWFs in the study fitted the pseudo-second-order kinetic and Freundlich
isotherm models. Thermodynamic (∆G°, ∆H° and ∆S°) and kinetic study of the adsorption behaviour
of the compositions of the CWFs indicated that the process of sorption between the Cu2+ ions and
CWFs was chemisorption while the thermodynamic properties suggest the process was favourable,
feasible, spontaneous and endothermic in nature. From the experimental results, an efficiency model
of CWF was developed and the model developed considered the chemical characteristics and
mechanical properties of the CWF. To statistically optimise the efficiency of the CWF, optimum
conditions as selected were Rf (1.7-2.1 L/h), KD (0-0.4 kg/L), TB (0-5 NTU), pH (6-8.5) and TC (0-
1) which gave predicted values for WQI in the range of 3.74-11.76 for Tap water (TP) and 18.5 to
25.96 for MTW. This implied that when a CWF obeys the above optimum values and gives a
computed WQI <25, the filter is efficient and subsequently could be accepted by users. Therefore, it
is proposed that the method could be adopted for the standardisation of CWFs in the country.
... In the drinking water industry, we cannot achieve a "zero risk" scenario by removing 100% of a contaminant from drinking water; therefore, solutions need to remove a sufficient amount of the contaminant (i.e., below a regulatory standard such as a maximum contaminant level [MCL]) to protect public health while also considering environmental impact and economic cost. Previous studies of POU/POE devices in comparison to centralized systems have largely focused on one of these three elements examined in isolation, primarily public health protection from microbial contaminants (Abbaszadegan et al., 1997;Momba et al., 2009;Ren et al., 2013;Siwila, 2019), or upfront cost to a community (USEPA, 2006b;Speth et al., 2020) and do not include community engagement and SDWA compliance considerations for POU/POE devices (Bixler et al., 2021) and therefore may generate results that are not community specific. ...
Small drinking water systems in the United States often suffer from repeated Safe Drinking Water Act water quality violations that necessitate upgrades to the existing centralized systems to achieve compliance. Community water systems (CWSs) need to evaluate the tradeoffs between public health, environmental and economic impacts when choosing these system improvements. This study developed the input and output components of a triple‐bottom‐line methodology to compare two alternatives: (1) installing a centralized treatment upgrade or (2) a point‐of‐use/point‐of‐entry device over a 30‐year period, using a health exposure assessment specific contaminants, life cycle analysis of environmental impacts improvement, and life cycle costing to account for the useful life of components and the number of households served by a CWS. We present recommendations and considerations for future usage of the triple‐bottom‐line approach methodology.
... Ceramic filters can remove turbidity, organic matter, and microbes by using the difference in size between substances trapped and pores. 18 Ren et al. 19 reported that the ceramic filters with silver nanoparticles are three to six times more cost-effective than the centralized water system to reduce waterborne diarrheal illness among the general population and children under five. However, these microfilters show no sufficient barriers for viruses having diameters down to 20 nm. ...
The sustainable development goals (SDGs), including 17 goals and 169 targets, were adopted unanimously by the United Nations General Assembly in 2015. The aims are to end poverty, protect the planet, and ensure peace, health, and prosperity of all people over the world. Toward the SDGs, human beings must effectively utilize the global resources, such as (1) oceans, seas, rivers, lakes, and so forth that supply us with water and aquatic resources; (2) land, ground, and soil where we can raise agricultural crops and livestock; (3) forests and woods that provide us with lumber and paper and convert carbon dioxide to oxygen; and (4) fossil fuel and mineral resources, which are essential to our modern lives. The use of macroporous ceramics is definitely conducive to the solutions to achieve the SDGs, because it can help solve many of the related technical issues. This review addresses macroporous ceramics primarily for filtration and purification, agriculture and fisheries industry, thermal managements, sensing devices, and constructions, which contribute to achieving SDGs.
... The study realized membrane-based technologies followed by adsorption, oxidation with nanomaterials and through the Fenton process in the decreasing order of sustainable physicochemical methods for the treatment of industrial effluents. Ren et al. evaluated the social, economic, and environmental sustainability of ceramic filters impregnated with silver nanoparticles for point-of-use (POU) drinking water treatment in developing countries (127). It focused on assessing the cultural acceptability of this treatment among its intended users, understanding the impacts of raw water quality on disinfection performance, and varying materials composition and/ or manufacturing techniques to optimize disinfection. ...
Water is essential for human survival. Hence, universal access to safe and affordable drinking water is included as one of the Sustainable Development Goals of the United Nations. With increasing global water stress and stricter revised regulations by bodies such as World Health Organization (WHO) and U.S. Environmental Protection Agency (USEPA) for safe drinking water, it is imperative to research efficient water treatment and quality monitoring technologies that are environmentally benign, affordable, and have ease of implementation. In this regard, sustainable nanomaterial-based technologies are capable of delivering real-time solutions cost-effectively using less energy by reducing ecological impact. These technologies are expected to play a significant role in water remediation including potable water treatment, sensing, wastewater desalination, and water harvesting. However, it is crucial to carefully assess the various sustainability criteria for diverse technologies before their large-scale implementation. In this chapter, we discuss a variety of emerging nanomaterial-based treatment and sensing techniques in the scientific literature and in the market, from the concepts of sustainability and their applications to assess clean water technologies using sustainability metrics. Bio-based processes look promising for the future of water purification in terms of effectiveness and environmental safety. Apart from current nanotechnological frontiers in diverse clean water applications, suggestions for future research are also provided.
... According to an economic analysis of the municipal water system, the cost of delivering centralized water for 10 years is roughly $221 per family. For the same period, the adoption of water treatment technology such as a ceramic filter costs around $63 (Ren et al. 2013). This suggests that using water technologies is more cost-effective and affordable than using municipal water treatment systems. ...
Background
Approximately 69% of population in Tanzania lacks better sanitation, while 45.6% lacks access to clean and safe water. To leverage this shortage, several technologies have been used for purifying water from various sources; however, there is still persistence of waterborne diseases.
Main body
This article reviewed the efficiency of common water filters in removing water contaminants such as Escherichia coli , fluoride, TSS, turbidity, nitrate, virus, BOD, COD, fecal coliform and color. Common water filters available in Tanzania markets include slow sand filter, ceramic filter, bone char, membrane purifier and bio sand filter. The effectiveness of each technology was evaluated in terms of its ability to remove water contaminants. Ceramic filter was found to be less expensive technology compared to the rest. Ineffectiveness of common water filters can be linked to persistence of waterborne diseases in Tanzania.
Conclusion
Ability of water filters in viral removal is of greater concern. This study suggests a ceramic filter as the best filter among all common filters available in Tanzania. Ceramic filters can be synthesized by locally available materials such as clay, saw dust, rice husk ashes and flour which make it efficient in removing all water contaminants, especially viruses.
... In some cases, the combination of these nanostructures enhanced their catalytic activity [16]. Suspended nanomaterials were mainly used as adsorbents [25], disinfectant [26][27][28], filters [29], and reactive agents [30], which offer a large index for water treatment [31,32]. Fenton, photo-Fenton, catalytic ozonation, and photocatalysis mediating heterojunctions and Z-scheme catalysts are in their deep investigation today [33][34][35][36][37]. ...
Accessibility to a clean indoor environment is still an important problem in the world. Photocatalysis based on semiconductor materials was proposed as a green solution for contaminated surfaces and domestic areas. This treatment has been considered by many researchers using diverse preparation methods. Titanium dioxide (TiO2) was extensively investigated to treat dyes and microorganisms in wastewater, indoor air and even in wild environments. TiO2 showed divergent efficacy against Gram+ and Gram- bacteria, viruses (DNA-viruses, RNA-viruses, and/or reverse transcribing viruses), algae (unicellular, microalgae…) and free-floating genomic DNA. Today, photocatalysis mediating TiO2 for pollutants removal in real settings is attracting a lot of attention. TiO2 absorbs in the UV spectral region and many techniques were adopted to red shift its absorption to the visible region such as doping, coupling with other semi-conductors or decorating it with plasmonic materials. TiO2 uses started as suspended material in aqueous media. This suspension was fast faced by the difficulty to recover the catalyst after treating water. In the present review, we present the shift from the photocatalytic activity of Ti-based catalysts/photocatalysts for the disinfection of polluted water (TiO2 in suspension) to the implementation of smart indoor surfaces (supported TiO2) presenting self-sterilizing properties. In this review, we present the general context of the water issue as raised by the United Nations 2030-agenda, we show an overview of photocatalytic materials and we try to link the reported photocatalytic mechanisms for the disinfection process. At the end of this review, we stress the advantages of using supported photocatalytic thin films and the interfacial phenomena leading to bacterial killing without sacrificing the catalyst that can be easily reused.
... [18][19][20] Such bio-sand filters are utilized, for example in households as POU devices. [184,186] Another example for commercially available POU water filters are systems from LifeStraw® or wateroam. Both systems utilize a membrane to remove pathogens from water with a high efficiency. ...
Aim of this thesis is to fundamentally and comprehensively explore functional sulfur-containing 1,3,5-benzenetrisamides (BTAs) in particular in view of the formation of supramolecular fibers and their suitability in different filtration applications, including the removal of metal nanoparticles or metal ions and bacteria from aqueous media. To improve antibacterial properties of the filtration, the functional supramolecular fibers can be equipped with silver nanoparticles. To gain sufficient mechanical stability of the filter media and to provide access to a larger filtration volume, the functional supramolecular fibers shall be incorporated in different scaffolds, such as nonwovens or granular fillings. This leads to functional supramolecular fiber composites. The properties of the formed composites shall be investigated and principally demonstrated by different adsorption and filtration experiments. The thesis is structured in three different parts. This includes (i) the synthesis and structure property relation and fundamental investigation of the self-assembly behavior of sulfur-containing 1,3,5-benzenetrisamides, (ii) the investigation of such compounds as functional shell in supramolecular core-shell structures with the ability to adsorb metal ions and (iii) the use of such multicomponent supramolecular fibers in filtration applications such as sand-supramolecular fiber composites equipped with AgNPs to remove or kill bacteria during water filtration.
... Not all water hygiene approaches in low-and-middle-income countries are equally effective, but water filtration is still among the most effective ones [39]. Filtration-based water hygiene is also very cost-efficient, increasing its interest for resource limited settings [40]. ...
Water filtration is a common strategy of water sanitation in resource-poor tropical settings. Here, we assessed the intermediate term effect of this preventive procedure including specific filter-related as well as general hygiene training on the molecular detection of enteric pathogens in stool samples from Colombian Indigenous people. From a total of 89 individuals from an Indigenous tribe called Wiwa, stool samples were assessed by real-time PCR for enteropathogenic microorganisms prior to the implementation of water filtration-based infection prevention. Three years after the onset of the preventive strategy, a follow-up assessment was performed. A significantly beneficial effect of water filtration could be shown for Ascaris spp. only (p = 0.035) and a tendency (p = 0.059) for Hymenolepis nana. No hints for effects on the gastrointestinal shedding of Giardia duodenalis, Entamoeba histolytica, Cryptosporidium spp., Campylobacter spp., Shigella spp./enteroinvasive Escherichia coli, Necator americanus, Strongyloides stercoralis, Trichuris trichiura, and Taenia spp. were seen. In conclusion, the study indicates that water filtration can only be an element of a multi-modal hygiene concept to reduce enteric pathogen carriage in inhabitants of resource-poor tropical settings in spite of tendencies of beneficial effects.
... Among filtration-based HWT methods, locallymanufactured ceramic water filters (CWFs) are durable, easy to use, and do not negatively impact water taste and odor. [8][9][10] A CWF typically consists of a 6-10 L porous 'pot' structure, through which water flows via gravity, that is suspended in a storage container fitted with a tap for dispensing treated water. 11 CWFs are manufactured by pressing a mixture of locally sourced clay and a burnout material (e.g., sawdust, rice husk) into a filter shape, drying, and then firing. ...
Locally-manufactured ceramic water filters (CWFs) remove Escherichia coli via physical screening, physicochemical mechanisms, and disinfection; performance varies across local production. It was unknown whether CWFs remove Vibrio cholerae, the (smaller and metabolically different than E. coli) bacteria causing cholera. To fill this gap, we tested hydraulic and microbiological (V. cholerae and E. coli) performance of eight different CWFs (in duplicate) produced by established factories in the laboratory for three consecutive days. Four CWFs were silver-impregnated. Across all filters, average Log Reduction Values (LRV) were 1.9-5.7 for V. cholerae and 2.9-7.0 for E. coli on day 1. V. cholerae LRVs were 5.3-5.6 for silver-impregnated filters, and 1.9-4.3 for non-impregnated filters; E. coli LRVs were 5.1-7.0 for silver-impregnated and 2.9-4.0 for non-impregnated filters. The correlation between E. coli and V. cholerae LRVs was non-linear (R²= 0.003-0.24) for silver-impregnated filters, and linear (R²= 0.23-0.81) for non-impregnated filters. Our results highlight: 1) high variability in CWF performance; 2) silver disinfection as the most critical mechanism to remove V. cholerae; 3) CWFs can be used in cholera outbreak settings to remove V. cholerae, if silver remains on the filter; and, 4) assessing filter microbiological performance with specific organisms of interest, not only reference organisms, may be necessary.
... Their manufacturing process is simple, and ceramic filters are relatively inexpensive (5-15 USD/filter) [2]. However, high-temperature firing of the filters contributes to smog formation and particulate matter emissions [3]. ...
Geopolymers resemble conventional ceramics but can be manufactured at near-ambient temperatures. In this work, geopolymer–bentonite composite foam with silver nanoparticles was prepared and applied for water disinfection, inspired by point-of-use ceramic water filters. The inactivation efficiency against Escherichia coli and intestinal enterococci bacteria was found to be promising (0.6–2.4 and 0.3–1.4 log10 reductions, respectively) for ∼1 d. However, the inactivation efficiency against somatic coliphage viruses was poor (<0.05 log10). The geopolymer matrix did not alter the chemical water quality. Thus, the pH and the concentrations of Ag, Si, Al, and Na remained in compliance with drinking water guideline values, and the foam showed no physical disintegration. These results provide preliminary proof of concept of the suitability of geopolymer foam composites for point-of-use water disinfection.
... Although piped water is the most commonly used treated drinking water source, there has been emergence of potable point-of-use technologies (POUs). The POUs vary in complexity from the simple ceramic filters to the more complex membranebased filters (Brown et al., 2017;Fiebelkorn et al., 2012;Luoto et al., 2011;Ren et al., 2013). The simpler and cheaper POUs have been mostly adopted in the developing nations such as Africa, where provision of safe drinking water is a great challenge (Teksoy and Eleren, 2017). ...
... If not, it may be polluted through storage and transport [2] Surface water considered an essential source for water supply in many improving countries. Main problem is high focus of clay and organic compounds, suspended solids, and disease-causing microorganisms (such as parasites, viruses, and some bacteria) which can cause symptoms such as cramps, nausea, diarrhea, and provide food and shelter for pathogens [3] The essential task of any water supply treatment plant is to supply safe water, in enough quantity, degree of treatment depends on raw water type [4]. To achieve high-quality drinkable water, water must undergo a chain of treatment processes such as sedimentation, flocculation, filtration, coagulation, screening, and disinfection [5] flocculation and coagulation structures for assembling little convey into more noteworthy sums inside lift ejection penetration and sedimentation [6]. ...
A number of household treatment systems are readily available in the market. They are differing mainly in make and water purification mechanisms utilized. Most of the available household treatment devices are costly and hence there is a need to come up with cheap or affordable treatment technologies. To meet this goal, study was therefore aimed at designing and evaluating effectiveness household water treatment systems using readily available materials, and environmentally friendly such as kaolin clay, and jute fibers, and the effectiveness of these filters in decreasing physical parameters like Electrical Conductivity (E.C), Turbidity (Tur.), Total Dissolved Solids (TDS), and Total Suspended Solids (TSS). Kaolin-jute fibers filters can product sufficient cooking and drinking water for a family of small members due to their flow rates. These filters may therefore be considered for treating polluted water at household in rustic areas and places where water is taken immediately from source without treatment.
... In order to acknowledge the published body of the LCA literature on nAg-enabled consumer products, a comprehensive literature review is conducted by using an academic search engine, Web of Science Core Collection, by searching combinations of key terms including life cycle assessment, environmental impact assessment, nanosilver, nAg and silver-enabled (search query can be found in the Supplementary Information (SI) file). From this search, 15 studies are identified that performed LCAs for various nAg-enabled consumer products including textiles (Hicks et al., 2015;Hicks and Theis, 2017;Manda et al., 2015;Meyer et al., 2011;Pourzahedi et al., 2017;Walser et al., 2011), coatings (Hischier et al., 2015), medical products (Hicks et al., 2016;Pourzahedi et al., 2017;Pourzahedi and Eckelman, 2015), packaging (Zhang et al., 2017), food storage containers (Bi et al., 2018;Hicks, 2018a, 2018b), children's products (Pourzahedi et al., 2017), among others (Ren et al., 2013;Yasin and Sun, 2019). Although the majority of these studies (13 out of 15) have cradle-to-grave system boundaries (from raw materials acquisition to end-of-life), 9 of them modeled nanospecific nAg emissions using a characterization factor (CF) for ionic silver (Ag + ) (Bi et al., 2018;Hicks et al., 2016Hicks et al., , 2015Hicks and Theis, 2017;Manda et al., 2015;Pourzahedi and Eckelman, 2015;Walser et al., 2011;Hicks, 2018a, 2018b) and only 1 of them used an assumed CF for nAg from literature (Pourzahedi et al., 2017). ...
Consumption of silver nanoparticles (nAg) is increasing due to their use in various industries. A comprehensive analysis is needed to elucidate the potential environmental and human health benefits and costs of the silver-enabled consumer products. For this purpose, four commercially available silver/nanosilver enabled polyester textiles with different initial silver/nanosilver loadings (1.07-4030 μg Ag/g textile) are included in the current research and cradle-to-grave life cycle assessments (LCA) are conducted to identify hotspots associated with production and use of these products throughout their lifetimes (100 cycles). Both non nano-specific and nano-specific impacts are calculated using nano-specific ecotoxicity characterization factors for nAg, instead of the commonly utilized ionic silver (Ag +) surrogate. Additionally, four different laundering scenarios were modeled to analyze the impacts resulting from using conventional and high efficiency machines. In the majority of environmental impact categories, either polyester textile manufacturing (regardless of Ag/nAg enabling) or laundering were identified as hotspots. Non nano-specific ecotoxicity impacts ranged from 1.58 × 10 1-2.91 × 10 1 CTUe/textile (CTUe: comparative toxic units for ecosystems) and nano-specific ecotoxicity impacts ranged from 2.01 × 10 − 4-3.10 × 10 − 3 CTUe/textile for the lowest and the highest Ag/nAg containing textiles, respectively. It is also found that unless the initial silver loading per textile is significantly high (in this case 4030 μg Ag/g textile comparing to the lowest load of 1.07 μg Ag/g textile), ecotoxicity and human health impacts of released silver species would be lower than ecotoxicity and human health impacts resulting from raw materials acquisition and manufacturing of the antibacterial textiles.
... Household water treatment (HWT), which means the use of any type of method to treat drinking water at a household level, such as boiling and water filtration, can be considered as an interim solution to improve the water quality at the household level even when the water quality from its source is contaminated [8,9]. HWT can improve water quality and reduce water-related diseases, such as diarrhea, as long as the users perform it correctly and regularly [10]. ...
Understanding the determinants of household water treatment (HWT) behavior in developing countries is important to increase the rate of its regular use so that households can have safe water at home. This is especially so when the quality of the water source is not reliable. We present a hierarchical Bayesian Belief Network (BBN) model supported by statistical analysis to explore the influence of household’s socio-economic characteristics (SECs) on the HWT behavior via household’s psychological factors. The model uses eight SECs, such as mother’s and father’s education, wealth, and religion, and five RANAS psychological factors, i.e., risk, attitude, norms, ability, and self-regulation to analyse HWT behavior in a suburban area in Palu, Indonesia. Structured household interviews were conducted among 202 households. We found that mother’s education is the most important SEC that influences the regular use of HWT. An educated mother has more positive attitude towards HWT and is more confident in her ability to perform HWT. Moreover, self-regulation, especially the attempt to deal with any barrier that hinders HWT practice, is the most important psychological factor that can change irregular HWT users to regular HWT users. Hence, this paper recommends to HWT-program implementers to identify potential barriers and discuss potential solutions with the target group in order to increase the probability of the target group being a regular HWT user.
... Silver-impregnated ceramic water filters can be more cost effective, exhibit lower environmental impacts (e.g., energy consumption and global warming potential), and show more potential for quality of life improvement than centralized water treatment and distribution systems. 21 The second technology is a silver-impregnated ceramic tablet (MadiDrop™, Silivhere Technologies, Inc., Charlottesville, VA). 22,23 When the ceramic tablet is placed in a household water storage container, silver diffuses through the porous ceramic into the water at a release rate that is effective for continual disinfection of waterborne pathogens while remaining below the silver drinking water standard. ...
Enteric infections early in life have been associated with poor linear growth among children in low-resource settings. Point-of-use water treatment technologies provide effective and low-cost solutions to reduce exposure to enteropathogens from drinking water, but it is unknown whether the use of these technologies translates to improvements in child growth. We conducted a community-based randomized controlled trial of two water treatment technologies to estimate their effects on child growth in Limpopo, South Africa. We randomized 404 households with a child younger than 3 years to receive a silver-impregnated ceramic water filter, a silver-impregnated ceramic tablet, a safe-storage water container alone, or no intervention, and these households were followed up quarterly for 2 years. We estimated the effects of the interventions on linear and ponderal growth, enteric infections assessed by quantitative molecular diagnostics, and diarrhea prevalence. The silver-impregnated ceramic water filters and tablets consistently achieved approximately 1.2 and 3 log reductions, respectively, in total coliform bacteria in drinking water samples. However, the filters and tablets were not associated with differences in height (height-for-age z-score differences compared with no intervention: 0.06, 95% CI: -0.29, 0.40, and 0.00, 95% CI: -0.35, 0.35, respectively). There were also no effects of the interventions on weight, diarrhea prevalence, or enteric infections. Despite their effectiveness in treating drinking water, the use of the silver-impregnated ceramic water filters and tablets did not reduce enteric infections or improve child growth. More transformative water, sanitation, and hygiene interventions that better prevent enteric infections are likely needed to improve long-term child growth outcomes.
... However, most of them cannot be easily detected and require testing to reveal whether water is contaminated or not. Thus, contaminants may result in unappealing taste or odor and staining as well as health effects [10]. Color of drinking water is a physical characteristic that cannot be noticed unless it is one of high concentration. ...
The Main aim of the present study is to manufacture "Low- Cost Water Filter" for purification water and are designed for small water capacity, using readily available material and environmentally friendly such as kaolin clay, and jute fibers. A number of household treatment systems are readily available in the market. They are differing mainly in make and water purification mechanisms utilized. Most of the available household treatment devices are costly and hence there is a need to come up with cheap or affordable treatment technologies. This research was carried out to determine the efficiency of Kaolin-jute fibers filters in improving water impurities. Types of filters that were used during this study are: Filter 1, build with mixing ratio 85% kaolin clay, and 15% jute fibers, Filter 2: 80% kaolin clay, and 20% jute fibers, Filter 3, 75% kaolin clay, and 25% jute fibers. Effectiveness of these filters in decreasing chemical parameters like Hydrogen Ion Concentration (pH), Chloride (Cl), Calcium (Ca), Total Hardness (T.H), Magnesium (Mg), Alkalinity (ALK), Sulfates (SO4), Sodium (Na), and Potassium (K), were 8.7%, 71.54%, 70.5%, 70.5%, 80.7%, 77.9%, 85.5%, 71.64%, and 69.6% respectively. Kaolin-jute fibers filters can produce enough drinking and cooking water for a family of small members due to their flow rates. These filters may be considered for treating contaminated water at household scale in rural areas and places where water is taken directly from the source without treatment.
... However, the construction and maintenance costs of such treatment and distribution systems are relatively high. In some developing countries and regions, due to economic and technical constraints, there is a lack of appropriate infrastructure and drinking water safety is difficult to guarantee (Budinova et al., 2006;Liu et al., 2019;Ren et al., 2013;Yao et al., 2020). According to the characteristics of decentralized residence in rural areas, the distributed household devices for drinking water treatment are more suitable. ...
The groundwater with high arsenic concentration is widespread, especially in many remote areas of developing countries. Arsenic existing in drinking water sources has a high risk to human health. In this study, an innovative effort to remove As(V) from water using ceramic filters functionalized with CeO2 nanocomposites (CF-CeO2) was investigated. Considering removal efficiency and flow rate, the suitable coating amount of CeO2 was determined for the production of CF-CeO2. Based on the factorial analysis, influent arsenic concentration and pH were found to be significant factors in As(V) removal. Furthermore, CF-CeO2 exhibited a good removal capability over a wide pH range and was insensitive to the change of background electrolyte concentration. In the treatment of natural water, the existence of medium and low turbidity levels facilitated As(V) removing, while the high turbidity level exhibited the opposite effect. Based on macroscopic experiments and microscopic characterizations, it was revealed that the As(V) removal mechanism by the CF-CeO2 mainly included ion-exchange and electrostatic attraction. The findings in this study provided convincing evidence for the use of CF-CeO2 as a high-efficiency, low-cost, and safe approach for water purification in the remote areas of developing countries.
... Later, the social, economic, and environmental sustainability of silver-impregnated ceramic water filters (CWFs) for POU drinking water treatment in developing countries were evaluated (Ren et al., 2013). The water consumption of a typical household over ten years (37960 L) was used as the functional unit, as delivered by either CWFs or centralized drinking water system. ...
... LCAs implemented for AgNPs enabled food storage containers are also popular among literature where mostly cradle-tograve results are presented (Bi et al., 2018;Hicks, 2018a, 2018b). Other examples include LCAs with various system boundaries on AgNPs enabled packaging materials (Zhang et al., 2017), coatings (Hischier et al., 2015), medical gowns (Hicks et al., 2016;Pourzahedi et al., 2017), wound dressings (Pourzahedi et al., 2017;Pourzahedi and Eckelman, 2015a), environmental applications (Ren et al., 2013), and products for children (Pourzahedi et al., 2017). Aside from product-based studies, there are LCAs conducted only for producing AgNPs with different impact assessment methodologies. ...
Considering their antimicrobial, electrical and optical properties, silver nanoparticles (AgNPs) are the most common type of engineered nanomaterials found in consumer products. AgNPs may be synthesized through multiple methods, including chemical, biological and physical techniques; however, literature suggests that the manufacturers prefer to use physical and chemical methods (85 %) rather than biological. This work presents cradle-to-gate life cycle impact assessments in order to evaluate global environmental impacts of six different AgNPs synthesis routes (two chemical and four physical) along with thirteen different inventories and a mass based functional unit of 1 kg of AgNPs. Results are then combined with the annual global AgNPs production estimates, and global environmental impact calculations are performed based on both optimistic and skeptical estimations. Since AgNPs production volumes are forecasted to increase drastically, industrial scale AgNPs syntheses are modeled and future life cycle impacts are projected using three different scale-up factors. Furthermore, given that each industry has specific preferences for properties of AgNPs (i.e. size, surface area) and those are dependent on the synthesis methods, industry based environmental impact projections are developed for industries where the majority of AgNPs are used such as textiles; coatings, paints and pigments; consumer electronics and optics; cosmetics; medical and packaging. Results show that scaling up may reduce the environmental emissions up to 90 % globally, and up to 83 % per industrial sector which suggest that the global environmental impact of AgNPs may vary significantly as a function of the synthesis method, scale, and desired product application.
... • Suspended Solids and Heavy Metals: Microplastics > 0.7μm, lead, copper, mercury, cadmium, chromium, aluminium, nickel, etc [70][71][72][73][74][75][76]. ...
Drinking water is a social determinant to disease, a powerful determinant of health and also promotes socioeconomic development,
yet public health is failing to protect the public with poor drinking water quality posing a threat to public health. Major sources of
ground and surface contamination are landfill and human sewerage. Irish Water has consecutively failed to meet safety standards
for bromate, nickel, nitrite, copper, pesticides, arsenic, fluoride, lead, trihalomethanes (THM). Regardless of where public opinion
lies in relation to the addition of hexafluorosilicic acid to drinking water as a public health measure, it is found in Irish drinking
water in illegal and unsafe amounts hence by definition poses a risk to public health. The EU Drinking Water Directive does not
contain standards for microplastics. Existing drinking water treatment and wastewater treatment processes are inadequate at
removing persistent toxic substances (PTS) from water. Bottled water can contain endocrine disrupting chemicals (EDCs), heavy
metals, pesticides, persistent toxic substances and even gastrointestinal microbes. The following review article refers to Irish
drinking public drinking water supplies however the issues reflect those of many first-world countries.
Point-of-use (POU) water disinfection technologies can be adopted to provide access to safe drinking water by treating water at the household level; however, navigating various POU disinfection technologies can be difficult. While numerous conventional POU devices exist, emerging technologies using novel materials or advanced processes have been under development and claim to be of lower cost with higher treatment capacity. However, it is unclear if these claims are substantiated and how novel technologies compare to conventional ones in terms of cost and environmental impacts when providing the same service (i.e., achieving a necessary level of disinfection for safe drinking water). This research assessed the sustainability of four different POU technologies (chlorination using sodium hypochlorite, a silver-nanoparticle-enabled ceramic water filter, ultraviolet mercury lamps, and ultraviolet light-emitting diodes). Leveraging open-source Python packages (QSDsan and EXPOsan), the cost and environmental impacts of these POU technologies were assessed using techno-economic analysis and life cycle assessment as per capita cost (USD·cap–1·yr–1) and global warming potential (kg CO2 eq·cap–1·yr–1). Impacts of water quality parameters (e.g., turbidity, hardness) were quantified for both surface water and groundwater, and uncertainty and sensitivity analyses were used to identify which assumptions influence outcomes. All technologies were further evaluated across ranges of adoption times, and contextual analysis was performed to evaluate the implications of technology deployment across the world. Results of this study can potentially provide valuable insights for decision-makers, nonprofit organizations, and future researchers in developing sustainable approaches for ensuring access to safe drinking water through POU technologies.
Diarrhoea is the second-leading cause of death in Liberia, a sub-Saharan African country of 4.8 million people, with a majority living in rural villages. Diarrhoea has often been linked with poor water quality and malnutrition. Three organisations partnered to distribute point-of-use (POU) water filters to every household in Liberia without other access to safe water, documenting the distribution of filters to 101,706 households. Each such household was surveyed at a baseline, two weeks, and eight weeks. In addition to household characteristics, the prevalence of diarrhoea was reported at each survey. Our goal was to determine the extent of the impact that POU filter use had on diarrhoea prevalence by age group, controlling for effects of water source, location, and household size. Overall, there was a 94.2% decrease in diarrhoea cases from baseline to the 8-week follow-up. We discuss the success of the intervention in decreasing diarrhoea prevalence. The filter distribution focused on reaching remote villages, and providing access to clean water where there was none before. This study confirms that community-wide access to clean drinking water can reduce diarrhoea prevalence.
Household water treatment (HWT) is a solution for households that do not have access to a safe drinking water supply. A cross-sectional study was conducted in Ende District, Province of Nusa Tenggara Timur (NTT), Indonesia. A total of 425 household respondents were interviewed and observed about the HWT practice and water storage condition and 143 household drinking water samples were collected for microbial water quality analysis. Results show that even though HWT is regularly performed, not all the water they drink has been treated. The ‘level’ of psychological factors risk, attitude, norms, ability, and self-regulation (RANAS) were high, indicating that regular HWT practice goes in hand with the underlying psychological factors. Psychological factor action planning was the most influential psychological sub-factor associated related with the frequency of drinking treated water. Drinking water is mostly stored in safe storage, but placed in a less hygienic surrounding environment. Though HWT results in better water quality, water quality was not significantly associated with HWT, drinking water handling, or storage. Finally, promoting always drinking treated water and then storing it in a safe and hygienic environment are still needed in areas where HWT is commonly practiced, so people can get the maximum health impact of HWT.
HIGHLIGHTS
High level of psychological factors related to household water treatment behavior results in the regular practice of household water treatment.;
People treat their drinking water at home but often drink untreated water when being outside the home.;
Water quality is better if treated, but there is no significant association between water quality and household water treatment or variables related to water handling and storage.;
Recycling wastewater is a legitimate need, even as drinking water, but conventional wastewater handling/treatment technologies are insufficient to produce safe water as per the need, health concerns, and rising contaminants. Recent advancements in nanotechnology claim the possibilities of novel nanomaterials for the purification of surface, ground, and wastewater affected by toxic metallic ions, organic and inorganic solutes, and microorganisms. Various studies have clearly described that those nanomaterials can successfully remove multiple pollutants in water and thus have been suitable for water and wastewater treatment. This review article emphasizes the broad spectrum of the latest innovations in nanotechnologies for water and wastewater treatment and recognizes benefits, risks, challenges, and prospects. This assessment of current advancements in nanotechnologies for water contamination remediation also covers nano-based materials such as nano-adsorbents, photocatalysts, nano-metals, and nanomembranes.
The Monograph “Strategies toward Green Deal Implementation – Water, Raw Materials & Energy” includes the selected papers that have been presented during the 2nd edition of International Conference on Strategies toward Green Deal Implementation – Water, Raw Materials & Energy.
This review critically analyzes the most recent literature on parameters affecting the performance of ceramic water filters and compares proposed standardization testing as quality control tools.
Worldwide, about one out of two people depend on groundwater resources to satisfy their drinking water needs. While groundwater typically is of higher quality than surface water, pollution and geologic conditions may require treating groundwater to meet safe water quality criteria. Herein, a critical overview is presented of water treatment technologies for rural and underserved communities in emerging economies that depend on groundwater. Given that small to medium sized rural communities in emerging economies often lack the financial resources to support technologically complex and expensive centralized public water treatment systems, the focus is on proven technologies that are sustainable and acceptable by the rural population. After an overview of the underlying treatment mechanisms and the principal groundwater contaminants targeted by the traditional, advanced, and experimental water treatment technologies, we identify the groundwater quality parameters that may impact or interfere with the technology performance. We also introduce enabling environmental factors that might govern the implementation of water treatment technologies in the target communities and a brief discussion of safe storage of water after treatment to underline the importance of protecting the water from re-contamination. Our overview is further supported by tabulated summaries of the principal (dis)advantages of each technology covered herein, including cost considerations and social acceptance. Overall, our review suggests that underserved rural communities have sustainable and affordable options for cases where the quality of local groundwater resources requires treatment.
Ceramic filters are a point-of-use (POU) technology applied for water purification in developing regions. Nano-CeO2 modified ceramic filter water purifier (CeO2–CFP) is designed to provide clean potable water and address drinking water safety issues in remote areas. To assess the impact of the entire life cycle of CeO2–CFP on the water environment, a life cycle assessment (LCA)-based water footprint framework was established. The context of remote areas was used to exemplify the calculation of the developed model under different technical scenarios. The production of CeO2–CFP in the high-tech scenario exhibited excellent environmental performance and water resource cost-effectiveness was found to be only 0.59. Raw materials (71.41%) and staff consumption (82.54%) represented the largest share of water footprint in the high-tech and low-tech scenarios, respectively. Sensitivity analysis was proceeded to identify the critical factors affecting the water footprint of CeO2–CFP system and the interactions of these significant factors were investigated. A results-based analysis was carried out in consideration of environmental, social, and economic aspects, and some recommendations for reducing water footprint of CeO2–CFP were formulated.
Across the globe, billions of people lack access to safe drinking water. Many different point-of-use (POU) technologies have been developed that significantly reduce the disease-causing pathogens found in untreated water. With many different technologies available, it can be difficult to choose which technology to implement in specific areas. Beyond the cost of each technology, the environmental impacts could bring additional harm to a community. Life cycle assessments (LCAs) are used to make comparisons across different technologies. This study uses an LCA to compare boiling water, ceramic water filters, BioSand filters and POU chlorination as treatment options in the rural community of Thohoyandou, Limpopo Province, South Africa utilizing previously published, open-access data. Global warming potential, water use, energy use, smog formation, particulate matter and land use are the studied environmental impacts. Results found that boiling had the most impact on energy use, global warming potential, smog and land use; chlorination had the greatest impact on particulate matter and water use. A cost comparison found boiling water to be most expensive at 0.053 USD per liter and chlorination to be least expensive at 0.0005 USD per liter.
Drinking water source contamination poses a great threat to human health in developing countries. Point-of-use (POU) water treatment techniques, which improve drinking water quality at the household level, offer an affordable and convenient way to obtain safe drinking water and thus can reduce the outbreaks of waterborne diseases. Ceramic water filters (CWFs), fabricated from locally sourced materials and manufactured by local labor, are one of the most socially acceptable POU water treatment technologies because of their effectiveness, low-cost and ease of use. This review concisely summarizes the critical factors that influence the performance of CWFs, including (1) CWF manufacturing process (raw material selection, firing process, silver impregnation), and (2) source water quality. Then, an in-depth discussion is presented with emphasis on key research efforts to address two major challenges of conventional CWFs, including (1) simultaneous increase of filter flow rate and bacterial removal efficiency, and (2) removal of various concerning pollutants, such as viruses and metal(loid)s. To promote the application of CWFs, future research directions can focus on: (1) investigation of pore size distribution and pore structure to achieve higher flow rates and effective pathogen removal by elucidating pathogen transport in porous ceramic and adjusting manufacture parameters; and (2) exploration of new surface modification approaches with enhanced interaction between a variety of contaminants and ceramic surfaces.
A ceramic water filter (CWF) with curved (ovoid) walls has been developed by Potters without Borders, a nonprofit that provides technical assistance to CWF factories. Here, a modified version of the USEPA testing method was used to evaluate the performance of ovoid CWFs, which have yet to be studied in the literature. Filters with/without silver nanoparticles (AgNPs) were evaluated for bacterial removal, turbidity removal, flow rate, and silver leaching. Log removal values (LRVs) for Escherichia coli for AgNP coated CWFs were 9.5–10.9 LRV while uncoated achieved 8.0–9.8 LRV. All the CWFs tested here had flow rates between 0.8 and 1.3 L h⁻¹. The turbidity of the influent was reduced by the filters throughout the general and challenge water conditions with removal of 9.1–90.9% and 99.3–99.8%, respectively. Silver-coated CWFs had a higher total effluent silver concentration compared to uncoated (coated CWFs had 74% more total silver leaching on average) and had an increased silver release during the challenge phase (35 ppb) compared to the general phase (13 ppb). The exterior wall coated with AgNPs was shown to leach silver off the ceramic using X-ray photoelectron spectroscopy, providing evidence that supports the recommendation to coat only the interior wall of CWFs with AgNPs. The procedure demonstrated utility as a reproducible performance testing technique. X-ray diffraction and mercury intrusion porosimetry were used to study the ceramic structure.
Current estimates of the global burden of disease for diarrhoea are reported and compared with previous estimates made using data collected in 1954-79 and 1980-89. A structured literature review was used to identify studies that characterized morbidity rates by prospective surveillance of stable populations and studies that characterized mortality attributable to diarrhoea through active surveillance. For children under 5 years of age in developing areas and countries, there was a median of 3.2 episodes of diarrhoea per child-year. This indicated little change from previously described incidences. Estimates of mortality revealed that 4.9 children per 1000 per year in these areas and countries died as a result of diarrhoeal illness in the first 5 years of life, a decline from the previous estimates of 13.6 and 5.6 per 1000 per year. The decrease was most pronounced in children aged under 1 year. Despite improving trends in mortality rates, diarrhoea accounted for a median of 21% of all deaths of children aged under 5 years in these areas and countries, being responsible for 2.5 million deaths per year. There has not been a concurrent decrease in morbidity rates attributable to diarrhoea. As population growth is focused in the poorest areas, the total morbidity component of the disease burden is greater than previously.
The technological performance and social acceptance of ceramic water filters impregnated with silver nanoparticles for point-of- use water treatment were investigated in the laboratory and in the field in the Guatemalan highland community of San Mateo Ixtatán. In the laboratory, filters were constructed with clay and sawdust collected from the Guatemalan community and were tested to determine the effects of percent sawdust and silver nanoparticle treatment on the transport and removal of E. coli. For ceramic filters without silver treatment, size- exclusion and/or sorption is the mechanism of removal and a lower mass-percent sawdust corresponds to greater bacteria removal. The addition of silver nanoparticles to the ceramic filters improved the performance for all mass percentages of sawdust relative to filter media without nanoparticle treatment. Filters with higher porosity achieved higher bacteria removal than those with lower porosity, suggesting an increase in burnable material percentage is advantageous, assuming structural integrity is not compromised. Subsequent to laboratory testing, ceramic filters were manufactured with local materials and labor in San Mateo Ixtatán, Guatemala, and distributed to 62 households in this peri-urban community. The study participants were randomly divided into two groups, and filters were tested periodically over 23 months or 12 months. Filtered effluent samples were tested for turbidity reduction, bacteria removal, and silver leaching. Over the course of the study, the average percent reduction in total coliforms and E. coli was 87% and 92%, respectively. The average effluent turbidity was 0.18 neph- elometric turbidity units (NTUs) and average effluent concentration of ionic silver was 0:02 mg=L (below the U.S. EPA standard of 0:1 mg=L). Filters distributed to the second study group consistently performed better than the first study group as manufacturing techniques improved and contact with researchers increased. Overall, users were satisfied with the filters, citing them as easy to use and maintain while improving water quality. The findings of this study suggest that locally manufactured ceramic filters can significantly improve the microbiological quality of water when used as a point-of-use water-treatment technology.
Waterborne pathogens present a significant threat to people living with the human immunodeficiency virus (PLWH). This study presents a randomized, controlled trial that evaluates whether a household-level ceramic water filter (CWF) intervention can improve drinking water quality and decrease days of diarrhea in PLWH in rural South Africa. Seventy-four participants were randomized in an intervention group with CWFs and a control group without filters. Participants in the CWF arm received CWFs impregnated with silver nanoparticles and associated safe-storage containers. Water and stool samples were collected at baseline and 12 months. Diarrhea incidence was self-reported weekly for 12 months. The average diarrhea rate in the control group was 0.064 days/week compared to 0.015 days/week in the intervention group (p < 0.001, Mann-Whitney). Median reduction of total coliform bacteria was 100% at enrollment and final collection. CWFs are an acceptable technology that can significantly improve the quality of household water and decrease days of diarrhea for PLWH in rural South Africa.
Abstract Safe drinking water remains inaccessible for about 1.1 billion people in the world, and the hourly toll from biological contamination of drinking water is 400 deaths of children (below age 5). This paper reviews the general guidelines for drinking water quality and the scale of the global problem. It reviews the various water disinfection technologies that may be applicable to achieve the desired quality of drinking water in developing countries. It then summarizes financing problems that deter extending access to safe drinking water to the unserved population and identifies feasible policy positions for enhancing availability of drinking water in these countries.
Diarrhoea remains a leading cause of morbidity and mortality but is difficult to measure in epidemiological studies. Challenges include the diagnosis based on self-reported symptoms, the logistical burden of intensive surveillance and the variability of diarrhoea in space, time and person.
We review current practices in sampling procedures to measure diarrhoea, and provide guidance for diarrhoea measurement across a range of study goals. Using 14 available data sets, we estimated typical design effects for clustering at household and village/ neighbourhood level, and measured the impact of adjusting for baseline variables on the precision of intervention effect estimates.
Incidence is the preferred outcome measure in aetiological studies, health services research and vaccine trials. Repeated prevalence measurements (longitudinal prevalence) are appropriate in high-mortality settings where malnutrition is common, although many repeat measures are rarely useful. Period prevalence is an inadequate outcome if an intervention affects illness duration. Adjusting point estimates for age or diarrhoea at baseline in randomized trials has little effect on the precision of estimates. Design effects in trials randomized at household level are usually <2 (range 1.0–3.2). Design effects for larger clusters (e.g. villages or neighbourhoods) vary greatly among different settings and study designs (range 0.1–25.8).
Using appropriate sampling strategies and outcome measures can improve the efficiency, validity and comparability of diarrhoea studies. Allocating large clusters in cluster randomized trials is compromized by unpredictable design effects and should be carried out only if the research question requires it.
Cost-effectiveness analysis (CEA) is increasingly important in public health decision making, including in low- and middle-income countries. The decision makers’ valuation of a unit of health gain, or ceiling ratio (λ), is important in CEA as the relative value against which acceptability is defined, although values are usually chosen arbitrarily in practice. Reference case estimates for λ are useful to promote consistency, facilitate new developments in decision analysis, compare estimates against benefit-cost ratios from other economic sectors, and explicitly inform decisions about equity in global health budgets.
The aim of this article is to discuss values for λ used in practice, including derivation based on affordability expectations (such as $US150 per disabilityadjusted life-year [DALY]), some multiple of gross national income or gross domestic product, and preference-elicitation methods, and explore the implications associated with each approach. The background to the debate is introduced, the theoretical bases of current values are reviewed, and examples are given of their application in practice. Advantages and disadvantages of each method for defining λ are outlined, followed by an exploration of methodological and policy implications.
Mortality in HIV-infected patients who have access to highly active antiretroviral therapy (ART) has declined in sub-Saharan Africa, but it is unclear how mortality compares to the non-HIV-infected population. We compared mortality rates observed in HIV-1-infected patients starting ART with non-HIV-related background mortality in four countries in sub-Saharan Africa.
Patients enrolled in antiretroviral treatment programmes in Côte d'Ivoire, Malawi, South Africa, and Zimbabwe were included. We calculated excess mortality rates and standardised mortality ratios (SMRs) with 95% confidence intervals (CIs). Expected numbers of deaths were obtained using estimates of age-, sex-, and country-specific, HIV-unrelated, mortality rates from the Global Burden of Disease project. Among 13,249 eligible patients 1,177 deaths were recorded during 14,695 person-years of follow-up. The median age was 34 y, 8,831 (67%) patients were female, and 10,811 of 12,720 patients (85%) with information on clinical stage had advanced disease when starting ART. The excess mortality rate was 17.5 (95% CI 14.5-21.1) per 100 person-years SMR in patients who started ART with a CD4 cell count of less than 25 cells/microl and World Health Organization (WHO) stage III/IV, compared to 1.00 (0.55-1.81) per 100 person-years in patients who started with 200 cells/microl or above with WHO stage I/II. The corresponding SMRs were 47.1 (39.1-56.6) and 3.44 (1.91-6.17). Among patients who started ART with 200 cells/microl or above in WHO stage I/II and survived the first year of ART, the excess mortality rate was 0.27 (0.08-0.94) per 100 person-years and the SMR was 1.14 (0.47-2.77).
Mortality of HIV-infected patients treated with combination ART in sub-Saharan Africa continues to be higher than in the general population, but for some patients excess mortality is moderate and reaches that of the general population in the second year of ART. Much of the excess mortality might be prevented by timely initiation of ART.
To determine the effectiveness of ceramic filters in reducing diarrhea, we conducted a randomized controlled trial in Zimbabwe and South Africa, in which 61 of 115 households received ceramic filters. Incidence of non-bloody and bloody diarrhea was recorded daily over 6 months using pictorial diaries for children 24-36 months of age. Poisson regression was used to compare incidence rates in intervention and control households. Adjusted for source quality, intervention household drinking water showed reduced Escherichia coli counts (relative risk, 0.67; 95% CI, 0.50-0.89). Zero E. coli were obtained for drinking water in 56.9% of intervention households. The incidence rate ratio for bloody diarrhea was 0.20 (95% CI, 0.09-0.43; P < 0.001) and for non-bloody diarrhea was 0.17 (95% CI, 0.08-0.38; P < 0.001), indicating much lower diarrhea incidence among filter users. The results suggest that ceramic filters are effective in reducing diarrheal disease incidence.
Ceramic water filters have been identified as one of the most promising and accessible technologies for treating water at the household level. In a six-month trial, water filters were distributed randomly to half of the 50 participating households in a rural community in Bolivia; the remaining households continued to use customary water handling practices and served as controls. In four rounds of sampling following distribution of the filters, 100% of the 96 water samples from the filter households were free of thermotolerant coliforms compared with 15.5% of the control household samples. Diarrheal disease risk for individuals in intervention households was 70% lower than for controls (95% confidence interval [CI] = 53-80%; P < 0.001). For children less than five years old, the reduction in risk was 83% (95% CI = 51-94%; P < 0.001). These results show that affordable ceramic water filters enable low-income households to treat and maintain the microbiologic quality of their drinking water.
To assess the effectiveness of interventions to improve the microbial quality of drinking water for preventing diarrhoea.
Systematic review.
Cochrane Infectious Diseases Group's trials register, CENTRAL, Medline, Embase, LILACS; hand searching; and correspondence with experts and relevant organisations.
Randomised and quasirandomised controlled trials of interventions to improve the microbial quality of drinking water for preventing diarrhoea in adults and in children in settings with endemic disease.
Allocation concealment, blinding, losses to follow-up, type of intervention, outcome measures, and measures of effect. Pooled effect estimates were calculated within the appropriate subgroups.
33 reports from 21 countries documenting 42 comparisons were included. Variations in design, setting, and type and point of intervention, and variations in defining, assessing, calculating, and reporting outcomes limited the comparability of study results and pooling of results by meta-analysis. In general, interventions to improve the microbial quality of drinking water are effective in preventing diarrhoea. Effectiveness was not conditioned on the presence of improved water supplies or sanitation in the study setting and was not enhanced by combining the intervention with instructions on basic hygiene, a water storage vessel, or improved sanitation or water supplies--other common environmental interventions intended to prevent diarrhoea.
Interventions to improve water quality are generally effective for preventing diarrhoea in all ages and in under 5s. Significant heterogeneity among the trials suggests that the level of effectiveness may depend on a variety of conditions that research to date cannot fully explain.
Africa is one of the most water-scarce continents in the world but it is
the lack of potable water which results in diarrhoea being the leading
cause of death amongst children under the age of five in Africa (696
million children under 5 years old in Africa contract diarrhoea
resulting in 2000 deaths per day: WHO and UNICEF, 2009). Most potable
water treatment methods use bulk water treatment not suitable or
available to the majority of rural poor in Sub-Saharan Africa. One
simple but effective way of making sure that water is of good quality is
by purifying it by means of a household ceramic water filter. The making
and supply of water filters suitable for the removal of suspended
solids, pathogenic bacteria and other toxins from drinking water is
therefore critical. A micro-porous ceramic water filter with
micron-sized pores was developed using the traditional slip casting
process. This locally produced filter has the advantage of making use of
less raw materials, cost, labour, energy and expertise and being more
effective and efficient than other low cost produced filters. The filter
is fitted with a silicone tube inserted into a collapsible bag that acts
as container and protection for the filter. Enhanced flow is obtained
through this filter system. The product was tested using water
inoculated with high concentrations of different bacterial cultures as
well as with locally polluted stream water. The filter is highly
effective (log10 > 4 with 99.99% reduction efficiency) in
providing protection from bacteria and suspended solids found in natural
water. With correct cleaning and basic maintenance this filter
technology can effectively provide drinking water to rural families
affected by polluted surface water sources. This is an African solution
for the more than 340 million people in Africa without access to clean
drinking water (WHO and UNICEF, 2008).
The production of drinking water from fresh surface water involves several processes, energy consumption and chemical dosing, all having global environmental impacts. These should be considered in the choice of water treatment processes. The objective of the present study was to conduct a comparative life cycle assessment of two water treatment plants: one enhanced conventional plant and one nanofiltration plant. One existing nanofiltration plant was chosen and investigated in great detail, including its operation and construction phases. This plant is located in the northern part of the Province of Quebec and has been in operation for over 10 years. A virtual conventional plant was designed for comparative purposes. The comparative life cycle assessment was performed using SimaPro software for inventory and impact assessment phases. The study revealed very different impacts for the two plants, drawing attention to the importance of the choice of water treatment chemicals and energy source.
The production of drinking water from fresh surface water involves several processes, energy consumption and chemical dosing, all having global environmental impacts. These should be considered in the choice of water treatment processes.The objective of the present study was to conduct a comparative life cycle assessment of two water treatment plants: one enhanced conventional plant and one nanofiltration plant. One existing nanofiltration plant was chosen and investigated in great detail, including its operation and construction phases. This plant is located in the northern part of the Province of Quebec and has been in operation for over 10years. A virtual conventional plant was designed for comparative purposes. The comparative life cycle assessment was performed using SimaPro software for inventory and impact assessment phases. The study revealed very different impacts for the two plants, drawing attention to the importance of the choice of water treatment chemicals and energy source.
This study uses data from recent household surveys in 43 developing countries to describe the main dimensions of household size and composition in the developing world. Average household size varies only modestly among regions, ranging from 5.6 in the Near East/North Africa to 4.8 in Latin America. These averages are similar to levels observed in the second half of the nineteenth century in Europe and North America. About four out of five members of the household are part of the nuclear family of the head of the household. Household size is found to be positively associated with the level of fertility and the mean age at marriage, and inversely associated with the level of marital disruption. An analysis of trends and differentials in household size suggests that convergence to smaller and predominantly nuclear households is proceeding slowly in contemporary developing countries.
Background:
Enterocytozoon bieneusi and Cryptosporidium parvum cause chronic antimicrobial-resistant gastrointestinal infections in HIV-1-infected individuals. HIV-1 reverse transcriptase inhibitors delay the onset of opportunistic infections, but are not known to reverse established infections. HIV-1 protease inhibitors are more effective across a broader range of HIV-1-infected immune cells. Combination antiretroviral therapy that includes a protease inhibitor could improve immunity to E bieneusi and C parvum.
Methods:
HIV-1 infected patients with chronic microsporidiosis (five), cryptosporidiosis (three), or dual infection (one), were treated with combination therapy that included at least one HIV-1 protease inhibitor. Outcome measures were symptoms, weight, use of antidiarrhoeal and antimicrobial drugs, T-lymphocyte subsets, HIV-1 viraemia, stool microscopy, and biopsy by endoscopy.
Findings:
All patients had complete clinical responses, gained a median 15 kg in weight, and ceased all antidiarrhoeal and antimicrobial therapies. Biliary cryptosporidiosis responded in both affected patients. Neither pathogen was detected in follow-up stool microscopy (eight of eight patients) or in biopsy samples by endoscopy (five of five). Intestinal architecture returned to normal in three patients. There was a dense CD8 lymphocyte and macrophage infiltrate and staining of intraepithelial E bieneusi with interferon-gamma before and after treatment, but little staining for CD4 or B lymphocytes, interleukin 10, or HIV-1 gp41. Five patients remained symptom-free after a median 13 months follow-up. Four patients had recurrent diarrhoea at 7-13 months (one with positive stool microscopy), associated with declining CD4 counts.
Interpretation:
Combination antiretroviral therapy that includes a protease inhibitor can restore immunity to E bieneusi or C parvum in HIV-1 infected individuals, and result in complete clinical, microbiological, and histological responses. The persistent CD8 cell and macrophage infiltrate, and the rapid time to relapse in patients with declining CD4 lymphocyte counts, suggest that neither infection was eradicated.
Goal, Scope and Background
This paper discusses the merging of methodological aspects of two known methods into a hybrid on an application basis.
Water shortages are imminent due to scarce supply and increasing demand in many parts of the world. In California, this is caused primarily by population growth. As readily available water is depleted, alternatives that may have larger energy and resource requirements and, therefore, environmental impacts must be considered. In order to develop a more environmentally responsible and sustainable water supply system, these environmental implications should be incorporated into planning decisions.
Methods
Comprehensive accounting for environmental effects requires life cycle assessment (LCA), a systematic account of resource use and environmental emissions caused by extracting raw materials, manufacturing, constructing, operating, maintaining, and decommissioning the water infrastructure. In this study, a hybrid LCA approach, combining elements of process-based and economic input-output-based LCA was used to compare three supply alternatives: importing, recycling, and desalinating water. For all three options, energy use and air emissions associated with energy generation, vehicle and equipment operation, and material production were quantified for life-cycle phases and water supply functions (supply, treatment, and distribution). The Water-Energy Sustainability Tool was developed to inform water planning decisions. It was used to evaluate the systems of a Northern and a Southern California water utility.
Results and Discussion
The results showed that for the two case study utilities desalination had 2–5 times larger energy demand and caused 2–18 times more emissions than importation or recycling, due primarily to the energy-intensity of the treatment process. The operation life-cycle phase created the most energy consumption with 56% to 90% for all sources and case studies. For each water source, a different life-cycle phase dominated energy consumption. For imported water, supply contributed 56% and 86% of the results for each case study; for desalination, treatment accounted for approximately 85%; for recycled water, distribution dominated with 61% and 74% of energy use. The study calculated external costs of air pollution from all three water supply systems. These costs are borne by society, but not paid by producers. The external costs were found to be 6% of desalinated water production costs for both case studies, 8% of imported water production costs in Southern California, and 1–2% for the recycled water systems and for the Northern California utility's imported water system.
Conclusion
Recycling water was found to be more energy intensive in Northern than in Southern California, but the results for imported water were similar. While the energy demand of water recycling was found to be larger than importation in Northern California, the two alternatives were competitive in Southern California. For all alternatives in both case studies, the energy consumed by system operation dominated the results, but maintenance was also found to be significant. Energy production was found to be the largest contributor in all water provision systems, followed by materials production. The assessment of external costs revealed that the environmental effects of energy and air emissions caused by infrastructure is measurable, and in some cases, significant relative to the economic cost of water.
Recommendation and Perspective
This paper advocates the necessity of LCA in water planning, and discusses the applicability of the described model to water utilities.
A low-cost technology to treat water at the household level is the ceramic silver-impregnated pot filter (CSF). The CSF consists of a pot-shaped filter element that is placed in a plastic receptacle. The ceramic pot filter is a promising treatment system to supply safe drinking water especially to people living in rural areas. The focus of this study was to assess the sustainability of a household drinking water treatment system based on five criteria: (i) accessibility, (ii) water quality, (iii) water production, (iv) functionality, and (v) environmental footprint. The removal of Escherichia coli and protozoan (oo)cysts was found to be significant, which was supported by the reduction in diarrhoea cases observed by CSF users in a recent field study. The retention of MS2 bacteriophages as an indicator for virus removal was, however, found to be unsatisfactory. It is therefore recommended that research on virus removal by CSF continues, especially in relation to the colloidal silver application and other potential additives. The criterion of water production was shown to be the limiting factor, because it reduced substantially during treatment of surface water. The fast clogging of the CSF during the first hours of use was caused neither by inorganic nor organic fouling, but by colloidal particles. Two direct effects may be identified from the decreasing flow rate: frequent scrubbing and higher water prices. Frequent scrubbing results in a higher risk of recontamination and breakage. Based on this finding the authors recommend an optimization study to increase the initial flow rate without sacrificing the removal efficiency.
This study evaluated the effect of natural water composition onto the bactericidal and physicochemical properties of silver nanoparticles (AgNPs) stabilized with three different polymeric compounds. All the nanoparticles behaved similarly in the water conditions tested. Compared to solutions with low organic matter content and monovalent ions, lower disinfection performances of AgNPs suspensions were obtained in the following order seawater ≤ high organic matter content water ≤ high divalent cations content synthetic water. Suspension of AgNPs in seawater and water with divalent cations (Ca(2+) and Mg(2+)) formed larger AgNPs aggregates (less than 1400 nm) compared to other solutions tested (up to approximately 38 nm). The critical coagulation concentration (CCC) of AgNPs was determined to quantitatively evaluate the stability of the nanoparticle suspension in different water conditions. When the concentration of dissolved organic matter was increased from 0 mg/L to 5 mg/L, the CCC increased by a factor in the range of 2.19 ± 0.25 for all AgNPs in divalent solutions, but a smaller increase occurred, in the range of 1.54 ± 0.21 fold, when monovalent solutions were used. The concentration of ionic silver released indicated that the dissolved Ag(+) (3.6-48.2 ppb) was less than 0.5% of the total mass of Ag(0) added. At all the conditions tested, the concentration of silver ions in solution had a negligible contribution to the overall anti-bacterial performance of AgNPs. This study demonstrated that the anti-bacterial performance of AgNPs at selected natural water conditions decreases in the presence of dissolved natural organic matter or divalent ions, such as humic acid and calcium carbonate. These results may be helpful in understanding the toxicity of AgNP in various natural water conditions and in explaining the risk associated with discharging AgNP in natural aquatic systems.
The effects of improving the water supply on the incidence of diarrhoea in 1096 children from three neighbouring villages of the Kirotshe rural health district. Northern Kivu, Zaire were investigated. Two of these villages had piped water, while the third village had no such facility. Children aged under four years on registration were visited fortnightly for one year. Median diarrhoea incidence per two weeks proved to be significantly lower in the two intervention villages than in the control village. In the two intervention villages, median diarrhoea incidence per two weeks was halved in children who lived in households located less than a five-minute walk from the public standpipe, or in households using more than 50 litres of water a day. The association between diarrhoea incidence and facility use did not differ after stratification by socioeconomic variables.
These findings underscore the fact that children in households that use standpipes are exposed to a lower risk of diarrhoea. Therefore, it is important to stress that those in charge of the planning and implementation of water supply interventions investigate the access to, and use of, water amongst the target population.
The effect of piped water supply on the incidence of typhoid fever and diarrhoeal diseases in the City of Lusaka is reported. The incidence of typhoid fever and diarrhoeal diseases reduced in the City as the piped drinking water was extended to the Urban and peri Urban self-help settlements.
Enteric infectious disease (EID), defined here as bacillary dysentery, viral hepatitis A, El Tor cholera, or acute watery diarrhoea, is an important public health problem in most developing countries. This study assessed the impact on EID of providing deep-well tap water (DWTW) through household taps in rural China. For this purpose, we compared the incidence of EID in six study villages (population, 10,290) in Qidong County that had DWTW with that in six control villages (population 9397) that had only surface water. Both the bacterial counts and chemical properties of the DWTW met established hygiene standards for drinking water. The incidence of EID in the study region was 38.6% lower than in the control region; however, the introduction of DWTW supplies did not significantly affect the incidence of bacillary dysentery. These results indicate that the construction and use of DWTW systems with household taps is associated with decreased incidences of El Tor cholera, viral hepatitis A, and acute watery diarrhoea. Since high construction costs have led many authorities to question the value of DWTW, we carried out a cost-benefit analysis of the programme. The cost of constructing a DWTW system averaged US 10.50 per capita. The combined capital and operating costs of a DWTW system were US $1.46 per capita per annum over its 20-year estimated life. The benefits derived from reductions in cost of illness and savings in time to fetch water were 2.2 times the costs at present values Capital outlays were recouped in a 3.6-year payback period and the provision of DWTW proved highly beneficial in both economic and social terms.
A new disease has recently been recognised in rural Uganda. Because the major symptoms are weight loss and diarrhoea, it is known locally as slim disease. It is strongly associated with HTLV-III infection (63 out of 71 patients) and affects females nearly as frequently as males. The clinical features are similar to those of enteropathic acquired immunodeficiency syndrome as seen in neighbouring Zaire. However, the syndrome is rarely associated with Kaposi's sarcoma (KS), although KS is endemic in this area of Uganda. Slim disease occurs predominantly in the heterosexually promiscuous population and there is no clear evidence to implicate other possible means of transmission, such as by insect vectors or re-used injection needles. The site and timing of the first reported cases suggest that the disease arose in Tanzania.
A theoretical model is proposed that relates the level of ingestion of diarrhoea-causing pathogens to the frequency of diarrhoea in the community. The implications of this model are that, in poor communities with inadequate water supply and excreta disposal, reducing the level of enteric pathogen ingestion by a given amount will have a greater impact on diarrhoea mortality rates than on morbidity rates, a greater impact on the incidence rate of severe diarrhoea than on that of mild diarrhoea, and a greater impact on diarrhoea caused by pathogens having high infectious doses than on diarrhoea caused by pathogens of a low infectious dose. The impact of water supply and sanitation on diarrhoea, related infections, nutritional status, and mortality is analysed by reviewing 67 studies from 28 countries. The median reductions in diarrhoea morbidity rates are 22% from all studies and 27% from a few better-designed studies. All studies of the impact on total mortality rates show a median reduction of 21%, while the few better-designed studies give a median reduction of 30%. Improvements in water quality have less of an impact than improvements in water availability or excreta disposal.
The incidence of diarrhea, respiratory disease, and skin infections was prospectively determined after the introduction of a system which distributed unlimited quantities of high quality fresh water to each of the 150 housing units on Tupile, an island devoid of fresh water located off Panama's Caribbean coast and inhabited by 1,500 Cuna Indians. Tupile residents used 7.1 liters of water/person/day compared to the 2.3 usage rate of inhabitants on Achutupo, the control island. Despite ready availability of water in each household, Tupile residents continued to store water in contaminated vessels prior to use. Forty percent of stored water samples tested on Tupile and 45% on Achutupo were contaminated with E. coli organisms. There were 4.7 episodes/child year (E/Y) of acute diarrhea on Tupile compared with the 3.5 rate on Achutupo. The rotavirus infection rate on Tupile was 0.8 E/Y compared with 0.2 E/Y on Achutupo. Infection rates for Norwalk virus, respiratory syncytial virus and Coxsackie B 1-6 viruses were similar on both islands. Respiratory disease rates were high on both islands (2.2 E/Y on Tupile, 2.7 E/Y on Achutupo). Achutupo had much higher rates of impetigo and scabies (0.6 E/Y and 2.5 E/Y, respectively) than Tupile (0.2 E/Y and 1.4 E/Y). Provision of the water distribution system had a beneficial effect on the incidence of water-washed diseases (impetigo and scabies), but at best had no effect on diarrheal disease.
To better understand whether potent antiretroviral therapies can modify the natural history of HIV-1-associated microsporidiosis and cryptosporidiosis, the response to antimicrobial treatment of these opportunistic infections was evaluated in patients with or without antiretroviral treatment. Fifty patients with diarrhoea, all positive for Cryptosporidium parvum or Enterocytozoon bieneusi, were included in the study. Retrospective data were collected concerning demographics, clinical and microbiological characteristics of the parasitic infection, antiretroviral therapy and prophylaxis against opportunistic infections. Faecal samples were prepared using the Richie formalin-ethyl acetate method and stained using the modified Ziehl-Neelsen method for detection of Cryptosporidium parvum and Isospora belli, the modified trichrome and calcofluor white technique for detection of Enterocytozoon spp., and iodine for detection of ova, cysts or vegetative forms. Diarrhoea was defined as an abnormal increase in stool liquidity, an abnormal increase in stool frequency and a daily stool weight of more than 250 g for a period of at least 4 days. Patients treated with double antiretroviral therapy or protease inhibitors demonstrated an excellent response and a sustained therapeutic effect after follow-up (range, 5-36 months). The relapse of cryptosporidiosis in two patients who discontinued antiretroviral therapy suggests that the infection might remain in a latent stage. The resolution of the diarrhoea seems to be related to an increased CD4+ cell count rather than to the viral load. In conclusion, these data strongly support the hypothesis that combination antiretroviral therapy is able to greatly modify the course of cryptosporidiosis and microsporidiosis in patients infected with HIV-1.
We evaluated a modified WHO algorithm for the management of chronic diarrhoea in ambulatory HIV-1-infected adults that included the use of norfloxacin, metronidazole and loperamide. In a cohort of 380 HIV-1-infected adults in Nairobi, Kenya, the incidence of chronic diarrhoea was 286 cases/1000 person-years; 85% of chronic diarrhoea episodes responded completely to therapy. Although these findings appear to validate the modified WHO chronic diarrhoea algorithm, randomized controlled trials may better define the indication for antibiotics in chronic diarrhoea.
Interventions to improve water quality, particularly when deployed at the household level, are an effective means of preventing endemic diarrhoeal disease, a leading cause of mortality and morbidity. Following a national survey indicating widespread faecal contamination of drinking water in Indian cities, a point-of-use water treatment unit was developed, which combines filtration and disinfection, does not require power or water pressure and has an operating cost of Rs. 0.25 (US$0.0057) per litre. We assessed the microbiological performance of the unit in the laboratory over the full 1500 l design life of the unit's consumable components. Geometric mean reductions for the units were more than 6 logs (99.9999%) for bacteria, more than 7 logs (99.99999%) for viruses and more than 3 logs (99.9%) for the test surrogate for protozoan cysts. Geometric mean reductions exceeded levels established for microbial water purifiers. The product water was free of detectable chlorine. If these results are validated in field trials, the deployment of the unit on a wide scale among vulnerable populations may make an important contribution to public health efforts to control intractable waterborne diseases.
Cylindrical colloidal-silver-impregnated ceramic filters for household (point-of-use) water treatment were manufactured and tested for performance in the laboratory with respect to flow rate and bacteria transport. Filters were manufactured by combining clay-rich soil with water, grog (previously fired clay), and flour, pressing them into cylinders, and firing them at 900 degrees C for 8 h. The pore-size distribution of the resulting ceramic filters was quantified by mercury porosimetry. Colloidal silver was applied to filters in different quantities and ways (dipping and painting). Filters were also tested without any colloidal-silver application. Hydraulic conductivity of the filters was quantified using changing-head permeability tests. [3H]H2O water was used as a conservative tracer to quantify advection velocities and the coefficient of hydrodynamic dispersion. Escherichia coli (E. coli) was used to quantify bacterial transport through the filters. Hydraulic conductivity and pore-size distribution varied with filter composition; hydraulic conductivities were on the order of 10(-5) cm/s and more than 50% of the pores for each filter had diameters ranging from 0.02 to 15 microm. The filters removed between 97.8% and 100% of the applied bacteria; colloidal-silver treatments improved filter performance, presumably by deactivation of bacteria. The quantity of colloidal silver applied per filter was more important to bacteria removal than the method of application. Silver concentrations in effluent filter water were initially greater than 0.1 mg/L, but dropped below this value after 200 min of continuous operation. These results indicate that colloidal-silver-impregnated ceramic filters, which can be made using primarily local materials and labor, show promise as an effective and sustainable point-of-use water treatment technology for the world's poorest communities.
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Environmental Science & Technology Article dx
Environmental Science & Technology
Article
dx.doi.org/10.1021/es4026084 | Environ. Sci. Technol. 2013, 47, 11206−11213