Caetano C Dorea

• Ph.D. (if you want to get in touch send me an email)
• Professor (Associate) at University of Victoria

Groundwater is heavily exploited for a variety of uses. Depending on their structure, the wells from which water is extracted can act as an entry point/gateway for a variety of microbiological contaminants, which can cause numerous adverse health effects. This study aimed to identify the microorganisms present in the groundwater in the Western Amaz...

Discharge of excreta into the environment and the use of decentralized sanitation technologies, such as septic tanks, pit latrines and ecological sanitation variants (i.e., container-based sanitation), contribute to greenhouse gas (GHG) emissions but have remained poorly quantified. The purpose of this analysis was to investigate the impacts that m...

To monitor safely managed drinking water services, an increasing number of countries have integrated water quality testing for Escherichia coli into nationally-representative household surveys such as the Multiple Indicator Cluster Surveys (MICS). However, plastic waste generated during such water quality testing programs, mostly through the use of...

Chlorine is a widely used water disinfectant in humanitarian emergency water supply. However, its effective application can be limited by the uncertainty in initial dose determination. The target free chlorine residual in water should achieve both health objectives and aesthetic considerations, but the varying field conditions and changing source w...

The concentration of chlorine in water declines as it reacts with various substances, causing decay of the residual free chlorine until its total consumption. In light of the typical characteristics of the water from protected dug wells and tube wells, this study aimed to evaluate the decay kinetics of free chlorine in the water of alternative indi...

The red mud (RM) has been used as an alternative low-cost adsorbent to remove trace elements, with the adsorption onto sodalite surface described as the main removal mechanism for trace elements. However, recent studies have shown that precipitation might be of great importance for some trace metals removal using natural and thermal activated RM. T...

Lack of access to safe drinking water on premises remains widespread in low- and middle-income countries. Interventions to improve access to safe water at the point of collection are essential, but water safety at the point of consumption is also an important consideration. This research aimed to 1) improve understanding of household practices in c...

Background: Conventional septic tank (ST) systems are an important and relatively low-cost type of decentralized on-site sanitation infrastructure. Although ST systems are one of the most applied decentralized sanitation technologies globally, limited research has been performed to identify the type and degree of biodegradation mechanisms present w...

Streams and rivers convey freshwater from lands to the oceans, transporting various organic particles, minerals, and living organisms. Microbial communities are key components of freshwater food webs and take up, utilize, and transform this material. However, there are still important gaps in our understanding of the dynamic of these organisms alon...

Billions of people globally gained access to improved drinking water sources and sanitation in the last decades, following effort towards achieving the Millennium Development Goals. Global progress remains a general indicator as it is unclear if access is equitable across groups of the population. Agenda 2030 calling for `leaving no one behind', th...

Efforts to control of unwanted disinfection by-products (DBPs) can be hindered by the relatively low-frequency data that is generated from DBP monitoring for regulatory purposes. Differential UV absorbance (DUVA) has the potential to overcome some of these difficulties as a relatively simple and low-cost technique for the estimation of regulated DB...

In a recent contribution by Curry et al. (2020), a field-derived assessment of a reportedly common pretreatment technique to reduce turbidities of biosand filter (BSF) feed water was reported. Their results demonstrated that despite alum pretreatment achieving lower settled turbidity values relative to control filters, such intervention led to sign...

Monitoring access to drinking water is complex, especially in settings where on-premises water supply is not available. Although self-reported data are generally used to estimate coverage of access, the relationship between self-reported time travelled and true time travelled is not well known in the context of water fetching. Further, water fetchi...

The occurrence and the fate of 18 ozonation by-products (OBPs) (17 different aldehydes and bromate) were studied over one year in two Canadian drinking water systems. This is the first and only study reporting the occurrence of all these non-halogenated aldehydes (NON-HALs) and haloacetaldehydes (HALs) simultaneously, based on the multi-point monit...

Safely managed drinking water services (SMDWS) is the service ladder used for the Sustainable Development Goal (SDG) monitoring of drinking water and expands on the Millennium Development Goal metric (“improved water source”) with three additional criteria, namely: availability when needed, accessibility on premises, and safety (free from faecal an...

Free chlorination is a widely employed disinfection method in humanitarian water provision due to its many advantages. However, its effective application is hindered by the challenge in determining adequate initial doses to achieve free chlorine residuals that satisfy both health and aesthetic requirements. Current guidelines show varying recommend...

Billions of people globally gained access to improved drinking water sources and sanitation in the last decades, following effort towards the Millennium Development Goals. Global progress remains a general indicator as it is unclear if access is equitable across groups of the population. Agenda 2030 calling for ″leaving no one behind″, there is a n...

We thank Wassenaar and colleagues for their Comment on our recent paper [1] and appreciate the opportunity to address it [...]

Enhanced coagulation can be an effective way to reduce disinfection by-product (DBP) precursor concentrations. Where turbidity is not extremely high, the natural organic matter concentration evaluated by total or dissolved organic carbon concentration or UV absorbance is known to be the most important factor for determining the adequate coagulant d...

The drying (or dewatering) of fresh feces and fecal sludge is a productive step in the management of sanitation, waste treatment, and resource recovery services. An improved understanding of fresh feces and fecal sludge drying would contribute to the development and deployment of fecal sludge management services. However, there is a lack of availab...

Young children are particularly vulnerable to the chronic sequelae of anemia, including poor nutritional status. The aim of this study was to assess intestinal parasitic-infections and nutritional status (anemia and linear growth) in preschool children living in contemporary Amazonian communities. A cross-sectional study measured children’s intesti...

There is a need for accessible and low-cost microbiological water quality testing in contexts where diarrheal illness is a major public health concern. In most cases, the quantification of Escherichia coli and other microbial indicators by conventional culture methods requires an incubation step for processed samples at specific temperatures for ba...

In a recent article by van Eekart et al. (2019) an assessment of decomposition within pit latrines measured with regard to COD reductions was reported on. Some fundamental concerns were raised with regard to a key assumption of the study. The alternative perspective that is presented here does not support study's conclusion that anaerobic processes...

Probiotic products typically take the form of oral supplements or food-based products containing microorganisms, typically bacteria. The number of bacteria present in a dose of probiotic can be several orders of magnitude lower than the label claims, and in some cases, undetectable. The objective of this study was to assess probiotic products conta...

Protists are key stone components of aquatic ecosystems, sustaining primary productivity and aquatic food webs. However, their diversity, ecology and structuring factors shaping their temporal distribution remain strongly misunderstood in freshwaters. Using high-throughput sequencing on water samples collected over 16 different months (including tw...

Background: Increasing the quantity of water available for consumption and hygiene is recognized to be among the most efficient interventions to reduce the risk of water-related infectious diseases in low and middle-income countries. Such impacts are often associated with water supply accessibility (e.g. distance or collection time) and used to ju...

Research on the development of a passive phosphorus entrapment process characterized by biofilters with active wood-based media impregnated with iron hydroxide has been conducted. Phosphorus removal was done by sorption which includes adsorption, exchange of ions and precipitation. Experiments were performed in order to investigate the effect of ni...

Low-cost aerators relying on the venturi principle to entrain air into flowing water have the notable advantage of contributing both to water mixing and oxygen transfer, making them attractive for wastewater treatment in low-resource settings. This study aimed to characterize the performance of such aerators by describing the impact of different de...

Differential UV absorbance (ΔA) is an important indicator that could allow operators and utility managers to routinely monitor disinfection by-product (DBP) concentrations, even in real-time applications, without the limitations of regulatory sampling and analyses. While determination coefficients between differential UV absorbance at a single wave...

Bacteria are key players in biogeochemical cycles and control water quality in freshwater ecosystems. Nevertheless, little is known about the identity and ecology of riverine bacteria, especially during ice‐covered periods that are often mistakenly perceived as periods with negligible biological activities. Here, we analyzed in detail the effects o...

Dewatering and drying of fecal sludge (FS) is a key treatment objective in fecal sludge management as it reduces volume (thereby reducing emptying frequency and associated transportation costs), inactivates pathogens, and is beneficial and/or necessary to resource recovery activities such as composting and combustion as fuel. However, studies on de...

The use of closed-loop sanitation systems (CLSS), or reuse-oriented sanitation systems, has increased in recent years, and such systems have been successfully implemented in many parts of the world. However, no research has explored Traditional CLSS (T-CLSS) for a long-term humanitarian situation. This study explores the strengths, weaknesses, oppo...

Differential UV absorbance (ΔA) is a promising indicator that could allow operators and utility managers to routinely monitor and manage disinfection by-product (DBP) concentrations without the limitations of regulatory sampling and analyses. So far, empirical relationships between DBP formation and ΔA at 272 nm have been proposed, but these relati...

Recent systematic reviews have highlighted a paucity of rigorous evidence to guide water, sanitation and hygiene (WASH) interventions in humanitarian crises. In June 2017, the Research for Health in Humanitarian Crises (R2HC) programme of Elrha, convened a meeting of representatives from international response agencies, research institutions and do...

Coagulant/disinfection products (CDPs) are a point-of-use (POU) water treatment technique that can improve microbial quality, reduce turbidity, and produce a free chlorine residual (FCR), serving as a potentially effective option for decentralized water treatment in a variety of contexts, including humanitarian emergencies. A novel CDP with a sodiu...

Despite the reported achievement of the Millennium Development Goals (MDGs) with respect to drinking water, lack of access to water remains widespread worldwide. The indicator used there to measure access to water in the MDGs refers to the use of an improved water source. However, the amount of time spent in collecting water is high in countries wh...

Differential UV absorbance (ΔA) has been proposed as a method for estimating disinfection by-products (DBP) concentrations in drinking water at a lower cost and at higher frequencies than the sampling programs required by regulations. Various equations developed in laboratory settings between individual DBP concentrations and ΔA272 have been report...

Differential UV spectroscopy, defined as the difference in UV absorbance spectra before and after chlorination, has shown great potential to predict disinfection by-product (DBP) concentrations at laboratory scale. However, so far, no results have been reported on the full scale application of differential UV spectroscopy in drinking water treatmen...

We describe an inexpensive, reliable, and easily executed improvement for the extraction of DNA from SterivexTM filter units, that involves the separation of the SterivexTM filter from its casing. Our study demonstrates that our modification of the original extraction protocol significantly increased DNA yields, with an average increase of 4.1-fold...

Dewatering of faecal sludge (FS) is indispensable for adequate FS management. However, comprehensive knowledge is lacking on FS dewatering performance. This study compared the dewatering performance of FS from different countries and onsite sanitation technologies, to assess influential characteristics on dewatering, and to compare dewatering perfo...

Background Universal and equitable access to safe and affordable drinking water for all by 2030 is one target stipulated in the Sustainable Development Goals (SDGs). As of 2015, 92% of the population in Malawi did not have access to water on premises and needed to fetch it. Thus, the issue of water accessibility warrants further research, particula...

Trihalomethanes (THMs) and haloacetic acids (HAAs) are the most prevalent disinfection by-products (DBPs) in drinking water and their occurrence is regulated in several countries. However, most DBPs are not regulated, even though some may have greater toxicological relevance than regulated DBPs. Small water systems (SWS) supplied by surface waters...

This study aims to evaluate the Cr concentrations in surface water, suspended particles, and bottom sediments exposed to tannery effluent releases in the Candeias River. Cr concentrations were compared in relation to environmental thresholds imposed by United States Environmental Protection Agency (USEPA) and the Brazilian Environmental Council (CO...

Aims: There is emerging evidence that point-of-use (POU) water treatment can be effective in the improvement of microbial water quality and the decrease in diarrhoeal disease incidence in humanitarian emergencies. Coagulant/disinfection products (CDPs) have the distinct advantage of providing microbial quality improvement, turbidity reductions and...

Unlabelled: Two full-scale slow sand filters (SSFs) were sampled periodically from April until November 2011 to study the spatial and temporal structures of the bacterial communities found in the filters. To monitor global changes in the microbial communities, DNA from sand samples taken at different depths and locations within the SSFs and at dif...

This study evaluates the potential for a novel semidecentralized approach that uses coagulant disinfectant products (CDPs) for humanitarian water treatment, by testing two commercially available products (CDP-W and CDP-T). Their performances were evaluated against the relevant water quality treatment objectives (The Sphere Project) under laboratory...

BRIEFING PAPER 2190 pH is a critical parameter for faecal sludge characterisation. However, basic laboratory facilities with such instrumentation are not always available in resource limited contexts. Furthermore, the operational importance (e.g. during lime stabilisation) of this parameter warrants a method that can be applied in situ. This study...

Both employed humanitarian personnel as well as those seeking to start a career as an aid worker are often provided with or seek training on the theme of humanitarian water, sanitation, and hygiene (WASH). The objective of this study was to conduct a landscaping exercise of the available WASH-relevant training for humanitarian emergencies. An open...

This paper physically and numerically models the influence of biofilms on heavy metal removal in a gravel filter. Experimental flow columns were constructed to determine the removal of Cu, Pb and Zn by gabbro and dolomite gravel lithologies with and without natural biofilm from SuDS. Breakthrough experiments showed that, whilst abiotic gravel filte...

Humanitarian water treatment interventions vary from package bulk 'kits' to household (point-of-use) options. Whereas the former can be perceived to be too complex to operate, the latter, whilst relatively simple and effective, has logistical requirements that may hinder its application during relief operations. This study evaluates the potential o...

Previous laboratory-scale studies to characterise the functional microbial ecology of slow sand filters have suffered from methodological limitations that could compromise their relevance to full-scale systems. Therefore, to ascertain if laboratory-scale slow sand filters (L-SSFs) can replicate the microbial community and water quality production o...

A world of opportunities working in the international water sector A world of opportunities working in the international water sector Contents

Sustainable urban Drainage Systems (SuDS) filter drains are simple, low-cost systems utilized as a first defence to treat road runoff by employing biogeochemical processes to reduce pollutants. However, the mechanisms involved in pollution attenuation are poorly understood. This work aims to develop a better understanding of these mechanisms to fac...

Adequate water supply is a public health intervention aimed at preventing diarrhoeal diseases in relief operations. Based on humanitarian water treatment objectives in which supplied water quantities should be prioritised (whilst safeguarding minimum quality standards) an inclined plate settler (IPS) was tested. Preliminary testing revealed that th...

Enhancing the performance of slow sand filter pre-treatment with alum (i.e. direct or contact filtration) has been proposed as an alternative to overcome limitations of conventional gravel (roughing) pre-filtration. Experimental results revealed high turbidity reduction efficiencies in alum-dosed pre-filtration. However, due to the alum coagulation...

During jar tests on alum-based drinking water treatment, dissolved Al determinations on solutions coagulated at pH ≥ 6.5 were not reproducible. These determinations were performed by inductively coupled plasma mass spectrometry after syringe filtration (0.45 μm polyethersulfone membrane). In order to better define these anomalies, the filtrates wer...

The effects of temperature and pH on the water treatment performance of a point-of-use (POU) coagulant/disinfectant product were evaluated. Cold temperatures (∼5°C) reduced the bactericidal efficiency of the product with regard to Escherichia coli and total coliform log10 reductions.

Point-of-use (POU) water treatment and safe storage techniques are effective in improving microbial water quality and decreasing diarrhoeal disease incidence and have potential to be effective interventions in humanitarian emergency contexts. Coagulant/disinfection products (CDPs) can provide microbial quality improvement, turbidity reductions, and...

Biological aerobic treatment of organic waste (composting) is of primary importance, as a way of recycling organic matter into soil. Although a relatively simple and ancient process, it needs careful project and operational considerations. The process can be applied either at small scale (home composting), or at large scale (centralized composting)...

In a recent review by Loo et al. (2012) an examination of potential technologies for emergency water supply was presented alongside selection criteria for such technologies to be used by humanitarian relief agencies. Some fundamental concerns were raised with regards to their work and is presented here.

As humanitarians we must be deeply concerned about using the most effective solutions for saving lives and reducing morbidity, whilst working within reasonable cost envelopes. In this respect it is critical to place the brightest spotlight upon the practice of using bulk water treatment units (BWTU), as witnessed most recently on a massive scale in...

Adequate water supply is a public health intervention aimed at preventing diarrhoeal diseases in relief operations. Based on humanitarian water treatment objectives in which supplied water quantities should be prioritised (whilst safeguarding minimum quality standards) an inclined plate settler (IPS) prototype was tested. Preliminary testing reveal...

Turbidity tubes have been considered to be the field method of choice for drinking water quality monitoring in resource-limited contexts because of their relative simplicity and low cost in comparison with conventional (nephelometric) turbidimeters. These tubes utilise the principle of visual extinction of a submerged target for turbidity determina...

For over 200 years, slow sand filtration (SSF) has been an effective means of treating water for the control of microbiological contaminants in both small and large community water supplies. However, such systems lost popularity to rapid sand filters mainly due to smaller land requirements and less sensitivity to water quality variations. SSF is st...

The supply of adequate amounts of safe water for drinking and hygiene during natural disasters or armed conflict can be compromised and is one of the priorities in public health interventions to prevent the spread of disease. When surface waters are the only viable source, emergency water treatment kits are usually deployed by relief agencies for t...

Emergency water treatment approaches relying on coagulation vary from centralised modular and portable “kits” to “point-of-use” or “household” interventions. Typical coagulation practice in emergencies is reviewed in view of field constraints (e.g. equipment and resources) and contrasted with underlying theory and conventional water treatment proce...

Alum is widely used in water treatment because of its many advantages, of which its relative low cost and worldwide availability have ensured it to be the coagulant of choice for emergency water treatment. However, in certain circumstances, its use may leave an undesirable coagulant aluminium residual in the finished water. Such residuals can gener...

Increases in residual dissolved Al from alum coagulation associated with low water temperatures should be minimised to avoid problems in the distribution mains and as a precautionary approach to possible health effects of Al. Temperature-controlled jar-tests (0.1 to 17.0°C) were used to evaluate optimisation of a plant using alum coagulation at pH...

In order to ensure maximum consumer benefits (e.g. public health, livelihood), drinking water supply technologies in developing countries should be adopted taking into consideration locally available skills, resources as well as cultural and environmental settings. This paper presents case-studies from several developing countries in different geog...

Aluminium is a non-essential element for biological systems and is used in water and wastewater processes that rely on (micro)biological purification processes. The effect of Al doses ranging from 100 to 2,000μg/l on the microbial dissolved oxygen uptake (respiration) over a 24-h period was assessed. Results indicated that Al can reduce the 24-h re...

This article reports the phytoremediation efficiencies of water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nutritional conditions for Al rich wastewaters in batch type constructed wetlands (floating aquatic macrophyte-based plant treatment systems). This study was conducted for 15 weeks after 1 week acclimatization by cultu...

Batch water treatment consists of the intermittent use of settling tanks for water clarification, and is a common treatment practice during emergency relief efforts. This article presents simple improvements to coagulant dosing and water quality based on experience gained in the aftermath of the 2005 South Asian earthquake.

Aluminium, as well as turbidity and organic precursors of disinfection by-products (DBPs), were monitored along the treatment trains of three municipal systems. This monitoring was used to understand the effectiveness of the processes at the different treatment stages, as well as seasonal variations giving rise to high aluminium residual levels. So...

Emergencies can result from the effects of unpredictable natural forces or from the cruelty of conflicts. The affected population is often left vulnerable to increased health risks. The victims' exposure to these risks can be reduced by timely public health interventions. Often, one of the first basic mitigations is the provision of water for essen...

Water drawn from rivers under emergency conditions often suffers from a high turbidity. This article describes how a water clarifier was tested in Haiti, demonstrating significant improvements in water quality over an extended period of time and at a relatively high production rate.

Regrettably, it is still common to find places without access to safe drinking water due to a lack of resources or appropriate technologies to support adequate solutions. Remedial efforts will need to focus on appropriate solutions for such locations. Coagulation with Moringa spp. seeds has been proposed as a sustainable option for water treatment...

The chemical enhancement of gravel (or roughing) filtration with coagulants, i.e. direct (gravel) filtration, has been proposed as a pre-treatment alternative for slow sand filters. However, studies have frequently focused on the efficiencies of the pre-filters in terms of reduction percentages. The effectiveness of the pre-treatment on the subsequ...

The technological and human challenges faced during emergency relief efforts are discussed. The diversity of emergencies, be they natural disasters or man-made conflicts, and the varied environmental settings in which they occur determine the water treatment and supply interventions in humanitarian relief efforts. This has been observed in two fiel...

This paper reports on the performance of a multi-stage filtration (MSF) system and associated operational details two years after its handover to the local water association (Regie) in Nyabwishongwezi, Rwanda. During a short-term study period the Nyabwishongwezi Water Treatment Plant (WTP) Was monitored for turbidity, suspended solids and faecal co...

Gravel pre-filters and slow sand filters are robust and reliable unit processes with the potential for broad small community application in the developing world as they are able to provide physical and microbiological treatment. A multi-stage system comprising gravel pre-filters, slow sand filters and terminal disinfection conforms with the multipl...

Upflow gravel filters (UGF) have the characteristic of accumulating solids in the deeper portions which can facilitate its cleaning. These filters can be placed in series comprising usually a three-stage pre-treatment. Discrete units in series should improve hydraulic behaviour, resulting in a more homogeneous retention time and hence a better trea...

Microbial Fuel Cells (MFC) are devices able to convert biochemical energy (organic matter) directly into electricity where microorganisms in the anode compartment act as biocatalysts. Escherichia coli has been described for electricity production in MFCs (Park & Zeikus, 2000) and is also an important indicator of the microbiological quality of wate...