Article

Sieving wastewater - Cellulose recovery, economic and energy evaluation

September 2012
Water Research 47(1)

DOI:10.1016/j.watres.2012.08.023

Source
PubMed

Authors:

Guido Breuer

Wageningen University & Research

E. Klaversma

Show all 5 authorsHide

Application of fine-mesh sieves (<0.35 mm) as pretreatment for municipal biological wastewater treatment gives an opportunity to recover resources and increase sustainability of wastewater treatment processes. Sieves are traditionally used for single stage mechanical treatment (typical mesh of 0.35 mm) or in combination with an MBR (typical mesh >0.7 mm). When sieves with a mesh of 0.35 mm are used on raw sewage we observed that cellulose fibres mainly originating from toilet paper are removed efficiently from the influent with a high recovery and purity. The application of sieves as pretreatment for conventional activated sludge processes has been evaluated based on pilot plant research at three WWTPs in the Netherlands. With sieving applied to the dry weather flow only the overall energy usage of the WWTP including sludge treatment can be decreased by at least 40% with a payback time of 7 years.

Removal of toilet paper fibers from residential wastewater: a life cycle assessment

Article

Full-text available

Jun 2023
ENVIRON SCI POLLUT R

Toilet paper has been reported as one of the major insoluble pollutant components in the influent of wastewater treatment plants. Toilet paper fibers contribute to a large production of sewage sludge, resulting in a high treatment cost and high energy consumption. To find energy-efficient, cost-effective, and environment-friendly technologies for fiber removal and resource recovery from wastewater, a life-cycle assessment (LCA) was performed to analyze the wastewater treatment processes, including a sieving process for removing and recovering suspended solids before the biodegradation units. Based on the LCA results, it was estimated that the sieve screening process saved 8.57% of energy consumption. The construction phase of sieving consumed 1.31% energy cost compared with the operation phase. Environmental impact analysis showed that sieving reduced the impacts of climate change, human toxicity, fossil depletion, and particulate matter formation, which reduced the total normalized environmental impacts by 9.46%. The life-cycle analysis of the removal of toilet paper fibers from wastewater revealed the need to use more efficient methods to enhance the recovery of cellulose fibers.

Influence of Cellulose on the Anoxic Treatment of Domestic Wastewater in Septic Tanks: Statistical Analysis of the Chemical and Physico-Chemical Parameters

Article

Full-text available

May 2023

Cellulose is a very common polymer in domestic wastewater (WW), representing a not negligible part of the organic substance contained in sewage. To date, many studies have highlighted the feasibility of reusing this compound in several ways (e.g., building sector, wastewater treatment, energy production, etc.) after its separation from domestic WW. However, studies about the impact of the absence of cellulose on the chemical and physico-chemical parameters of a biological process are still lacking. In this work, two pilot-scale plants were used to simulate an anoxic treatment of WW in septic tanks, with and without cellulose (CWW and NCWW, respectively), for three months. The results of the monitoring highlighted that T, pH, and electrical conductivity (EC) remained almost constants, in both cases. The Spearman correlation coefficients (SCC) for turbidity (TUR), total suspended solids (TSS), and color (COL) indicated a higher removal in the case of CWW (65%, 66%, and 56%, respectively). Organic substance and nitrogen forms showed a similar behavior with and without cellulose, but in the case of CWW, N-NH3 was highly negatively correlated with TUR (SCC: −0.54), TSS (−0.49), and COL (−0.39). A biological denitrification process was highlighted in both cases. Despite these differences, when statistically analyzing the trends of the chemical and physico-chemical parameters for CWW and NCWW, a significant difference due to the absence of cellulose was excluded. These results will be useful to the scientific community, as they exclude that the operational parameters of anoxic treatments and the effectiveness on pollutants removal can be affected in the case of preliminary cellulose separation from domestic WW for recovery/reuse purposes.

Hydrolysis of particulate organic matter originated from municipal wastewater treated under aerobic and anaerobic conditions

Thesis

Full-text available

Nov 2021

Alondra Alvarado

The hydrolysis of particulate organic matter (POM) originated from municipal wastewater is considered a limiting factor in biological systems. The mechanics and limiting factors involved in the hydrolysis process are not well understood. Therefore, the goal of this work was to characterize the hydrolysis products formed during the hydrolysis of POM originated from municipal wastewater under aerobic and anaerobic conditions. The biodegradability of the hydrolysis products was determined based on the nominal molecular weight (MW) and UV response by using the size exclusion chromatography coupled with online carbon and UV (254 nm) detection (SEC-OCD-UV) method together with standard sum parameters. The experimental set-up used in the aerobic experiments allowed a parallel observation of the formation and utilization of the hydrolyzed POM. The chromatographic results showed accumulation of the high molecular weight (HMW) organic products (nominal MW > 20.000 g/mol) within the first three days indicating that bacteria needed this time to grow and develop the necessary enzymes to degrade the HMW organic products, which were mostly depleted after 13 d. The volatile suspended solids (VSS) removal after 13 d was around 70 %. The chromatographic results of the anaerobic hydrolysis experiments showed accumulation of the low MW organic products (nominal MW: 150 - 1550 g/mol) within the first 2 and 4 d at pH 7 ± 0.2 and pH 6 ± 0.2, respectively. It was determined that changes of pH (i.e., 7 and 6) did not affect the hydrolysis rate but the kind of volatile fatty acids (VFA) produced and their further utilization rate. The VSS removal after 24 d was around 60 %. The bacteria growth dynamics and the extracellular polymeric substances (EPS) formation were visualized under aerobic and anaerobic conditions by using confocal laser scanning microscopy images. The findings of this work significantly extended the fundamental understanding of the aerobic and anaerobic hydrolysis of POM. The SEC-OCD-UV effectively characterized the hydrolysis products providing detailed insight into the hydrolysis process.

Physico-chemical characteristics and biodegradability of primary effluent and particulate matter removed by microscreens

Article

Full-text available

Mar 2023
WATER ENVIRON RES

In this study, the physical, chemical, and biological characteristics of raw wastewater were compared with the liquid and solid streams generated by a primary clarifier (PC), a rotating belt filter (RBF, 350 μm), and a drum filter (DF, 60 μm) and series (SER) combination of an RBF with a PC or a DF using pilot‐scale primary treatment units. The RBF removed about 36% of the influent total suspended solids. The DF and PC yielded an influent total suspended solid removal of 47% to 55% in both individual (parallel) and SER configurations. The size fractionation and chemical characterizations of the liquid fractions indicated a significant change in the wastewater composition in both filter configurations with no variation in the biodegradability of liquid fractions. The solids recovered by RBF had a higher total solids (TS) concentration and a higher volatile solids (VS) content (0.92 g VS/g TS) than that of DF and PC treatments (0.58 to 0.84 g VS/g TS). DF and PC sludge demonstrated a higher biodegradability rate (k 1 ; 0.11 d ⁻¹ < k 1 < 0.20 d ⁻¹ ) than solids recovered by RBF (0.09 d ⁻¹ ). The retained solids in the SER configuration demonstrated a significantly lower theoretical biochemical methane potential than the parallel configuration, likely due to the presence of smaller particles with a significantly higher ratio of particulate chemical oxygen demand over volatile suspended solids (1.86 to 2.40 g chemical oxygen demand/g volatile suspended solids). These results indicated that the physical, chemical, and biological characteristics of liquid and solids from different filter configurations are required to determine design criteria to upgrade or retrofit water resource recovery facilities using an RBF or a DF. Practitioner Points A rotating belt filter (RBF) removed less solids than a drum filter (DF) or a primary clarifier (PC). A series configuration of an RBF with either a DF or PC resulted in an effluent with a lower proportion of slowly biodegradable organic matter than in a parallel configuration. Solids from an RBF, a DF, or a PC had similar theoretical biochemical methane potential.

Recovery of Cellulose, Extracellular Polymeric Substances and Microplastics from Sewage Sludge: A Review

Article

Full-text available

Oct 2022

Wastewater treatment plants are considered to be not only as treatment facilities, but also essential elements of the circular economy. Wastewater treatment plants can be essential chains of the circular economy cycle. Despite this, sewage sludge management and utilization are mostly limited to biodegradation and further agricultural uses or incineration. The recovery of valuable products is mainly limited to nitrogen and phosphorus compounds. Fewer analyses focus on generating, recovering, and removing various polymers from sewage sludge, such as cellulose or extracellular polymeric substances (EPS). On the other hand, sewage sludge also contains polymeric pollutants, such as microplastics. The recovery and use of biopolymers is significant considering the problems connected with the presence and effects of artificial polymers (microplastics) in the environment. Despite the technical possibilities, not many technical scale installations are operated. Law regulations should make some incentives to develop the technologies and sell the recovered polymers in the market not as waste material, but as a valuable product. This paper presents state-of-the-art technologies for selected polymers’ recovery from sludge, including technical parameters of the processes and possible applications of recovered products, but it also considers the possibility of microplastics’ removal from this waste material.

Toilet paper and food waste in UASB reactors: A contribution to reducing the amount of conventional solid waste disposal

Article

Feb 2022
Environ Qual Manag

The release of toilet paper (TP) and food waste (FW) in domestic sewage is a common practice in developed countries. Nevertheless, this practice has started to be used in developing countries where anaerobic digestion is applied. Therefore, this work aimed at evaluating the influence of the presence of TP and FW on the anaerobic digestion process in UASB reactors. During the experiment, two UASB reactors (8L) were fed with synthetic domestic sewage with the addition of toilet paper (TPR) and food waste (FWR) residues, respectively. In the first stage of the experiment (S‐I), the reactors operated with an organic load of 0.97 kg COD.m –3 .d –1 (TPR) and 0.96 kgCOD.m –3 .d –1 (FWR) and, in the second stage (S‐II), the quantities were increased to 1.58 kgCOD.m –3 .d –1 (TPR) and 1.35 kgCOD.m –3 .d –1 (FWR). In the experimental period of 110 days, the parameters total and filtered COD, series of solids, pH, alkalinity, and VFA were monitored. The mean removal of total COD was of 79±1% (S‐I) and 75±1% (S‐II) for TPR, and of 81±2% (S‐I) and 76±1% (S‐II) for FWR. Regarding VSS, the mean removal was of 94 ± 2% (S‐I) and 97 ± 1% (S‐II) for TPR, and of 95 ± 3% (S‐I) and 96 ± 1% (S‐II) for FWR. The VFA/TA ratio increased from S‐I (0.03 for TPR and FWR) to S‐II (0.17 to TPR and 0.10 to FWR), responding to the organic load increases, but still in the range of process stability. The added toilet paper or food waste were efficiently removed in both stages, reaching removals higher than 75%. In general, both reactors presented a good performance for the anaerobic process even under changes in organic load and influent composition. This experiment showed the feasibility of the combined treatment of TP or FW with domestic sewage in UASB reactors.

Cellulosic materials recovery from municipal wastewater: from treatment plants to the market

Chapter

Jan 2022

An urban biorefinery can involve the recovery of cellulosic materials as a starting point, representing a good example of resource recovery in the circular economy concept. Cellulose recovery from municipal wastewater maintains previous practices, only the focus is shifted from the removal to the recovery point. Rotating belt filters (RBFs) with fine-mesh sieves (microsieving <500 µm) can be efficiently used to recover cellulose fibers during primary treatment. By designing the sieving process of RBF, the downstream water quality, as well as the energy and resource recovery, can be improved. This chapter focuses on the fundamental principles, conceptual design, and pilot-/full-scale application of cellulosic materials recovery from municipal wastewater. Moreover, based on real experiences, valorization alternatives for the recovered cellulose in different sectors are presented. Lastly, economic and environmental benefits of integrating microsieving process to a wastewater treatment scheme are assessed together with possible bottlenecks and challenges of adopting this technology and products in the industry.

A method to remove cellulose from rich organic samples to analyse microplastics

Article

Dec 2021
J CLEAN PROD

Knowing the amount of microplastics that currently reach wastewater is extremely important today. Furthermore, carrying out a good quantification and detection of the type of plastic provides valuable information. However, the wastewater is loaded, in addition to a high concentration of organic matter, with a high concentration of cellulose at the treatment plant influent, which seriously hinders detection, quantification and classification of microplastics. The abundance of cellulose materials makes them possible to become false positives for microplastics. Numerous studies on the analysis of microplastics in different matrices show how to remove organic matter from samples, but there are very few studies on the removal of cellulose, which is also found in the samples and hinders their analysis. This study offers a method that combines, for the analysis of microplastics, the already known advanced oxidation treatments for the elimination of organic matter with the novel cellulose removal treatment of the samples with the aim of reducing the amount of cellulose in the influent samples of conventional wastewater treatment plants. To remove the cellulose, 40 mL of a solution of urea 8%, sodium hydroxide 8% and thiourea 6.5% (by weight) were added for every 100 mg of dry sample. The beakers were placed in the freezer at minus 20 °C for 40 min and were then placed in agitation until they reached room temperature. After that, the samples were passed through a 53 μm mesh sieve. They were washed 15 times with 30 mL of ultra-pure water. The method is called UTS because of the acronym of its reagents (Urea/Thiourea/Sodium Hydroxide). By using the UTS method it is possible to reduce almost completely the cellulose residues from the influent sewage, and sludge samples by 97.6% in a second UTS treatment and 98.2% in a third UTS treatment. In all cases analysed, the microplastics were identified as high density polyethylene (HDPE) with correlation indices higher than 0.97, which shows that the treatment is harmless for this type of plastic material. The UTS method in combination with the WPO is an efficient and effective method for the analysis of microplastics in different matrices where cellulose and organic matter may cause possible interferences.

Kinetics of aerobic cellulose degradation in raw municipal wastewater

Article

Aug 2021
SCI TOTAL ENVIRON

Cellulose contributes approximately one third of the influent suspended solids to wastewater treatment plants and is a key target for resource recovery. This study investigated the temperature impact on biological aerobic degradation of cellulose in laboratory-scale sequencing batch reactors (SBR) at four different temperatures (10–33 °C) and two different solids retention times (SRT) of 15 days and 3 days. The degradation efficiency of cellulose was observed to increase with temperature and was slightly dependent on SRT (80%–90% at an SRT of 15 days, and 78%–85% at an SRT of 3 days). Hydrolysis followed 1st order kinetics, rather than the biomass dependent Contois kinetics (default in the activated sludge models), with a hydrolysis coefficient at 20 °C of 1.14 ± 0.01 day⁻¹.

Opportunities for resource recovery from Latvian municipal sewage sludge

Article

Full-text available

Sep 2023

Sewage sludge is a type of waste that has high health and environmental risks associated with its reuse. Moreover, sludge has been neglected in global circular economy targets because it is generated in considerably lower quantities than municipal solid waste. At the same time, European Union's transition towards circular economy has set the need to reduce the amount of waste and to promote the production of secondary raw materials. Many countries have developed national strategies for sludge management to reach their sustainability goals. In Latvia, the current sludge management approaches include land application, composting and anaerobic digestion which all utilize sludge as an organic fertilizer. As an alternative to current management practices, resource recovery is put forward as a solution that is in agreement with EU policy. Carbohydrates (including cellulose), proteins and lipids were selected as candidates for energy and materials recovery from sludge. For the first time, this study demonstrates a comprehensive assessment of Latvian municipal sewage sludge composition and offers the theoretical yields of secondary resources on a yearly basis. Primary, secondary, and anaerobically digested sludge from 13 wastewater treatment plants (WWTPs) in Latvia was characterized in this study. The most abundant sludge type – secondary sludge – contained 18.5% proteins, 9.8% lipids and 2.6% cellulose per TS. On a yearly basis, secondary sludge from all Latvian WWTPs could provide 2530 t proteins, corresponding to 750 t protein-based fertilizer. Primary sludge contained 23.9% proteins, 9.1% lipids and 7.1% cellulose per TS. Primary sludge could provide 763 t/a carbohydrates, including 545 t/a cellulose. The currently available secondary and digested sludge would yield 727 t bioethanol, corresponding to 4.0% of the national biofuel consumption. This work applies the concept of resource recovery to the Latvian wastewater sector and shows the potential of simultaneously addressing waste and wastewater management issues.

Positive effects of lignocellulose on the formation and stability of aerobic granular sludge

Article

Full-text available

Aug 2023

Introduction Lignocellulose is one of the major components of particulate organic matter in sewage, which has a significant influence on biological wastewater treatment process. However, the effect of lignocellulose on aerobic granular sludge (AGS) system is still unknown. Methods In this study, two reactors were operated over 5 months to investigate the effect of lignocellulose on granulation process, structure stability and pollutants removal of AGS. Results and discussion The results indicated that lignocellulose not only promoted the secretion of tightly bound polysaccharide in extracellular polymeric substances, but also acted as skeletons within granules, thereby facilitating AGS formation, and enhancing structural strength. Lignocellulose imposed little effect on the removal efficiency of pollutants, with more than 95, 99, and 92% of COD, NH 4 ⁺ -N, and PO 4 ³⁻ -P were removed in both reactors. However, it did exhibit a noticeable influence on pollutants conversion processes. This might be due to that the presence of lignocellulose promoted the enrichment of functional microorganisms, including Candidatus_Accumulibacter , Candidatus_Competibacter , Nitrosomonas , and Nitrospira , etc. These findings might provide valuable insights into the control strategy of lignocellulose in practical AGS systems.

Initial pH Conditions Shape the Microbial Community Structure of Sewage Sludge in Batch Fermentations for the Improvement of Volatile Fatty Acid Production

Article

Full-text available

Oct 2022

Conversion of wastewater treatment plants into biorefineries is a sustainable alternative for obtaining valuable compounds, thus reducing pollutants and costs and protecting the environment and human health. Under specific operating conditions, microbial fermentative products of sewage sludge are volatile fatty acids (VFA) that can be precursors of polyhydroxyalkanoate thermoplastic polyesters. The role of various operating parameters in VFA production has yet to be elucidated. This study aimed to correlate the levels of VFA yields with prokaryotic microbiota structures of sewage sludge in two sets of batch fermentations with an initial pH of 8 and 10. The sewage sludge used to inoculate the batch fermentations was collected from a Sicilian WWTP located in Marineo (Italy) as a case study. Gas chromatography analysis revealed that initial pH 10 stimulated chemical oxygen demands (sCOD) and VFA yields (2020 mg COD/L) in comparison with initial pH 8. Characterization of the sewage sludge prokaryotic community structures—analyzed by next-generation sequencing of 16S rRNA gene amplicons—demonstrated that the improved yield of VFA paralleled the increased abundance of fermenting bacteria belonging to Proteobacteria, Bacteroidetes, Chloroflexi, and Firmicutes phyla and, conversely, the reduced abundance of VFA-degrading strains, such as archaeal methanogens.

Adopting the circular model: opportunities and challenges of transforming wastewater treatment plants into resource recovery factories in Saudi Arabia

Article

Full-text available

Sep 2022

With the ever-growing population, water, energy, and resources need to be used carefully, reused, and renewed. There is an increasing global interest in resource recovery from ‘waste’, which is driven by sustainability and environmental concerns and motivated by the potential for economic benefits. A new era in waste (water) management is being realized where wastewater treatment is becoming part of the circular economy by integrating the production of reusable water with energy and resource recovery. In this new perspective, wastewater is no longer seen as a waste to be treated with energy expenditure but rather as a valuable source of freshwater, energy, nutrients (nitrogen and phosphorous), and materials (e.g., bioplastics, cellulose fibres, and alginate). In this review paper, the conversion of wastewater treatment plants (WWTPs) into resource recovery factories (RRFs) is presented as one of the ways forward to achieve a circular economy in the water sector for the Kingdom of Saudi Arabia (KSA). The advanced technologies, some highlighted in the article, can be installed, integrated, or retrofitted into existing WWTPs to create RRFs enabling the recovery of freshwater, cellulose, alginate-like exopolymers (bio-ALE), and biogas from municipal wastewater achieving climate neutrality, decarbonization, and production of new and promising resources. The article highlights the need for modular, adaptive, and/or decentralized approaches using sustainable technologies such as aerobic granular sludge (AGS)-gravity-driven membrane (AGS-GDM), anaerobic electrochemical membrane bioreactor (AnEMBR), and anaerobic membrane bioreactor (AnMBR) for conducive localized water reuse. The increase in reuse will reduce the pressure on non-renewable water resources and decrease dependency on the energy-intensive desalination process. This article also outlines the water challenges that are arising in KSA and what are the major water research programmes/themes undertaken to address these major challenges. HIGHLIGHTS The conversion of WWTPs into RRFs for the circular economy in Saudi Arabia.; RRFs enable the recovery of freshwater and resources from municipal wastewater.; Modular, adaptive, decentralized technologies to promote water reuse.; Water reuse reduces the pressure on non-renewable water resources and dependency on desalination.; Seawater toilet flushing to reduce demand for desalination.;

Upscaled and validated technologies for the production of bio-based materials from wastewater

Chapter

Full-text available

Feb 2022

Throughout history, the first and foremost role of urban water management has been the protection of human health and the local aquatic environment. To this end, the practice of (waste-)water treatment has maintained a central focus on the removal of pollutants through dissipative pathways. Approaches like – in the case of wastewater treatment – the activated sludge process, which makes ‘hazardous things’ disappear, have benefitted our society tremendously by safeguarding human and environmental health. While conventional (waste-)water treatment is regarded as one of the greatest engineering achievements of the 20th century, these dissipative approaches will not suffice in the 21st century as we enter the era of the circular economy. A key challenge for the future of urban water management is the need to re-envision the role of water infrastructure, still holding paramount the safeguard of human and environmental health while also becoming a more proactive force for sustainable development through the recovery of resources embedded in urban water. This book aims (i) to explain the basic principles governing resource recovery from water (how much is there, really); (ii) to provide a comprehensive overview and critical assessment of the established and emerging technologies for resource recovery from water; and (iii) to put resource recovery from water in a legal, economic (including the economy of scale of recovered products), social (consumer's point of view), and environmental sustainability framework. This book serves as a powerful teaching tool at the graduate entry master level with an aim to help develop the next generation of engineers and experts and is also highly relevant for seasoned water professionals and practicing engineers. ISBN: 9781789060317 (Paperback) ISBN: 9781780409566 (eBook)

Upscaled and validated technologies for the production of bio-based materials from wastewater

Chapter

Full-text available

Feb 2022

Resource recovery from municipal wastewater: what and how much is there?

Chapter

Full-text available

Feb 2022

Chapter 1: Resource recovery from municipal wastewater: what and how much is there?

Chapter

Full-text available

Feb 2022

The link between organic matter composition and the biogas yield of full-scale sewage sludge anaerobic digestion

Article

Full-text available

Feb 2022

The principal parameters influencing anaerobic digestion (AD) of sewage sludge have been extensively studied in controlled laboratory experiments, but the effects of sludge composition on full-scale systems have received relatively little attention. Sludge samples from eight major wastewater treatment plants (WWTPs) in the UK were examined to determine the effects of sludge composition on digestion performance. The biogas yield (BY) was estimated by two different methods: (1) a standard approach based on the reduction in volatile solids (VS), and (2) a more detailed mass balance of major constituent fractions of organic matter in sludge. The results showed that BY increased significantly with the overall amount of VS contained in digester feed sludge. In terms of the effects of individual fractions, BY was significantly related to and increased with the fat and cellulose contents in raw sludge, consistent with the high calorific value of fat and the digestibilities of both substrates, relative to the other major organic components. The results demonstrated the importance of sludge composition on digester performance and strategies to maximise BY were identified, for instance, by increasing codigestion of high fat containing substrates, and by utilising fat, oil and grease collected in-sewer and at WWTP. HIGHLIGHTS Major organic fractions were determined in sewage sludge samples from eight UK wastewater treatment plants.; Biogas yield increased with total organic matter, fat and cellulose contents.; Decomposition of major organic fractions was a more reliable estimate of biogas yield than volatile solids.; Increasing fat, oil and grease supply to sludge digesters is recommended to improve the process energy balance.;

Urban Wastewater Mining for Circular Resource Recovery: Approaches and Technology Analysis

Article

Full-text available

Nov 2023

Andrea G Capodaglio

Urban areas comprise less than 1% of the Earth’s land surface, yet they host more than half the global population and are responsible for the majority of global energy use and related CO2 emissions. Urbanization is increasing the speed and local intensity of water cycle exploitation, with a large number of cities suffering from water shortage problems globally. Wastewater (used water) contains considerable amounts of embedded energy and recoverable materials. Studies and applications have demonstrated that recovering or re-capturing water, energy, and materials from wastewater is a viable endeavor, with several notable examples worldwide. Reclaiming all these resources through more widespread application of effective technological approaches could be feasible and potentially profitable, although challenging from several points of view. This paper reviews the possibilities and technical opportunities applicable to the mining of resources within the urban water cycle and discusses emerging technologies and issues pertaining to resource recovery and reuse applications. The present and future sustainability of approaches is also discussed. Since sewage management issues are not “one size fits all”, local conditions must be carefully considered when designing optimal local resource recovery solutions, which are influenced not just by technology but also by multiple economic, geographical, and social factors.

Unearthing the potential sustainability of cellulose and exploring its source, fate, and recovery

Article

Full-text available

Mar 2023

The occurrence of cellulose in wastewater is mostly due to the usage of lavatory tissue, anticipated to be about 30% of the produced domestic sewage. This makes the recovery of cellulosic substances from wastewater important as a resource valorization strategy. The cellulose recovery is highly recommended to be included in wastewater treatment plant (WWTPs), associated with the favorable environmental impression, flexible routes of application, and mature value chain. In the present review, a comprehensive map was drawn for the initial and transformational applications of cellulose in WWTPs. Typical microbial cultures found in wastewater, facilitating cellulose degradation in both aerobic and anaerobic cases were thoroughly reviewed. An outlook of commercialized technologies purposed for cellulose recovery has been provided, with prominence on rotating bed filter. The benefits of cellulose recovery from wastewater via various routes were also highlighted.

Effect of toilet tissue Paper on residential sewerage-line clogging

Article

Full-text available

Jul 2019
BIORESOURCES

Toilet paper is widely used in residences. The low biodegradability of toilet paper’s pulp fibers can cause residence sewer lines to clog, which may be due to some additives or the presence of nonwoven fiber products. In this study, the disintegration rate of toilet paper was compared against various physical factors of the toilet paper sheet. The samples were disintegrated in water at varying pH levels. In the manufacturing of toilet paper, there must be a balance between the desired softness and the necessary wet strength. Twelve commonly used brands of toilet paper were purchased locally. Physical factors of toilet paper samples such as degree of polymerization, thickness, grammage, and softness were determined. The samples were evaluated based on 9 variables using correlation and multivariate linear regression analyses. A strong positive relationship was found between the degree of disintegration of toilet tissue paper and its physical factors. These were the degree of polymerization, the grammage, thickness, and the softness. Additionally, the amount of polymers applied to toilet paper decreased the degree of softness and adversely affected the redispersion of fibers. Thus, this work supports the idea that toilet paper can contribute to clogging of residential sewerage lines.

Genetic potential for exopolysaccharide synthesis in activated sludge bacteria uncovered by genome-resolved metagenomics

Article

Dec 2022
WATER RES

A good floc formation of activated sludge (AS) is crucial for solid-liquid separation and production of clean effluent during wastewater treatment. Floc formation is partly controlled by self-produced extracellular polymeric substances (EPS) such as exopolysaccharides, proteins, and nucleic acids. Little is known about the composition, structure, and function of EPS in AS and which bacteria produce them. To address this knowledge gap for the exopolysaccharides, we took advantage of 1083 high-quality metagenome-assembled genomes (MAGs) obtained from 23 Danish wastewater treatment plants. We investigated the genomic potential for exopolysaccharide biosynthesis in bacterial species typical in AS systems based on genome mining and gene synteny analyses. Putative gene clusters associated with the biosynthesis of alginate, cellulose, curdlan, diutan, hyaluronic acids, Pel, poly-β-1,6-N-acetyl-D-glucosamine (PNAG), Psl, S88 capsular polysaccharide, salecan, succinoglycan, and xanthan were identified and linked to individual MAGs, providing a comprehensive overview of the genome-resolved potential for these exopolysaccharides in AS bacteria. The approach and results provide a starting point for a more comprehensive understanding of EPS composition in wastewater treatment systems, which may facilitate a more refined regulation of the activated sludge process for improved stability.

Energy Valorization of Fine Screenings from a Municipal Wastewater Treatment Plant

Article

Full-text available

Nov 2022

The aim of this paper was to evaluate the characteristics and the energy potential for the methane production of fine screenings collected from the primary stage of a municipal wastewater treatment plant, and assess the impact on the properties and the oxygen demand of the aqueous effluents downstream from the sieves. Commercial filter bags with sieve openings of 3000, 1250, 1000, and 300 μm were used for the collection of screenings following a measurement of their biochemical methane potential. It was revealed that solid fractions from the sieves with a large size presented a high net methane production capacity exceeding 900 mL/g VS, but the gas production rate was rather slow, requiring a long time to reach the final value. However, cumulative solid fractions containing particles with a size larger than 300 μm had a lower net methane production, about 700 mL/g VS, but with a faster rate, resulting in almost 80% of the total volume released in 30 days. Aqueous samples downstream from the sieves presented decreasing organic matter content by sieve size and reduced the requirements for aeration oxygen. The installation of fine sieves in existing municipal wastewater treatment plants, therefore, may be beneficial due to the enhancement of biogas production and a reduction in the oxygen consumption of the activated sludge process.

Application of intermittent sand and coke filters for the removal of microplastics in wastewater

Article

Oct 2022
J CLEAN PROD

In recent years, microplastics (MPs) have become one of the most severe threats to the natural environment and aquatic life. The identification of urban wastewater treatment plants as one of the main pathways for these pollutants to enter the environment have led them to be the focus of several studies. The main interests are focused on the amount of MPs that are emitted into the environment, the efficiency of removal in wastewater treatment plants in addition to how their operation and design can be improved to reduce the presence of these pollutants in the effluent. One possible solution is the application of advanced treatment technologies that allow a more thorough water treatment, such as intermittent sand filters. In this study, the efficiency in removing MPs from the effluent of an urban wastewater treatment plant of three filters with different substrates (silica sand, sand/coke and coke) was analysed by comparing the performance on the three different substrates and working at different feed water flow rates. This provided useful information of retention mechanisms that affect MPs according to their morphology and how the operating parameters can influence the filtration systems performance. Several samples were collected from wastewater, before and after the filtration treatment, to analyse the presence of MPs. The results exposed a MP removal efficiency of up to 98.3%, with values in the treated water from 0.3 to 2.4 MP L⁻¹. Among the most abundant polymers identified in the samples were polyethylene (PE), polyester (PES), polyethylene terephthalate (PET) and polypropylene (PP). Statistical analysis of the results verified that there are no significant differences between the different substrates or water flow rates object of study. Results obtained, in addition to the cost-benefit ratio, showed the filter filled with a top layer of sand and a bottom layer of coke as the best option among those studied. Experiments with laboratory-scale filters carried out without possible interferences of external and uncontrolled factors showed similar performance and MP removal efficiency to that obtained working in a real plant conditions.

Enhanced biodegradation of polylactic acid and cellulose acetate nanocomposites in wastewater: Effect of TiO2 and β-cyclodextrin

Preprint

Full-text available

Sep 2022

Currently, there is a global concern about the environmental problems related to plastic wastes. Cellulose acetate (CA) and polylactic acid (PLA) are the most frequently used biopolymers in the food packaging industry. In this work, TiO 2 nanoparticles and β-cyclodextrin (βCD) have been incorporated into nanocomposite films made of PLA and CA and then evaluated under biodegradation assays in wastewater to assess the effects of both additives on the biodegradability of films. TiO 2 nanoparticles clearly enhanced the biodegradability of CA and PLA; PLA-TiO 2 nanocomposites disappeared after 60 days, whereas plain PLA remained present after 100 days. The presence of the additives provided an exponential growth to BOD profiles. FTIR spectra showed a much faster deacetylation of CA for the nanocomposites than for the bare CA, and XRD diffractograms showed that PLA nanocomposites became more amorphous than bare PLA. The thermal resistance of CA and PLA nanocomposites substantially decreased, while plain matrices remained fairly stable up to 60 days. SEM micrographs of CA and PLA nanocomposites presented voids and larger surface erosion than the plain matrices. βCD modification of TiO 2 nanoparticles seems to have a protective effect on the biodegradation of the polymers with respect to the unmodified TiO 2 .

Valorization of wastewater to recover value-added products: A comprehensive insight and perspective on different technologies

Article

Aug 2022
ENVIRON RES

In recent years, due to rapid globalization and urbanization, the demand for fuels, energy, water and nutrients has been continuously increasing. To meet the future need of the society, wastewater is a prominent and emerging source for resource recovery. It provides an opportunity to recover valuable resources in the form of energy, fertilizers, electricity, nutrients and other products. The aim of this review is to elaborate the scientific literature on the valorization of wastewater using wide range of treatment technologies and reduce the existing knowledge gap in the field of resource recovery and water reuse. Several versatile, resilient environmental techniques/technologies such as ion exchange, bioelectrochemical, adsorption, electrodialysis, solvent extraction, etc. are employed for the extraction of value-added products from waste matrices. Since the last two decades, valuable resources such as polyhydroxyalkanoate (PHA), matrix or polymers, cellulosic fibers, syngas, biodiesel, electricity, nitrogen, phosphorus, sulfur, enzymes and a wide range of platform chemicals have been recovered from wastewater. In this review, the aspects related to the persisting global water issues, the technologies used for the recovery of different products and/or by-products, economic sustainability of the technologies and the challenges encountered during the valorization of wastewater are discussed comprehensively.

Sustainable cellulose nanomaterials for environmental remediation - Achieving clean air, water, and energy: A review

Article

Feb 2022
CARBOHYD POLYM

https://authors.elsevier.com/a/1ebaYWy0-Uq2G Environmental pollution is increasingly becoming a serious global challenge due to various pollutants. Cellulose nanomaterials (CNMs) based membranes originated from green resources and sustainable processes are expected to have great potential in environmental applications due to their nanoscale dimension, high surface area, biodegradability, and biocompatibility as well as renewable capability. To fully unlock this potential, fundamental understandings of the interplay between various tunable parameters of CNMs and the substances to be separated, are required for the rational design and fabrication of CNMs based membranes. This review highlights the recent advances in CNMs membranes for environmental remediation in achieving clean air, water, and green energy. Key parameters that dominate the performances of CNMs membranes are critically assessed. The interactions of CNMs with pollutants, molecules, and ions are analyzed and their selective transport mechanisms in different membrane separation processes are discussed. The challenges and future directions for CNMs membranes are also outlined.

Functionalization of nanocellulose applied with biological molecules for biomedical application: A review

Article

Jun 2022
CARBOHYD POLYM

Nanocellulose has great potential in the biomedical field due to its biocompatibility, large specific surface area, and customizable surface chemistry. However, due to the bioinert nature and mismatch of the mechanical strength, nanocellulose itself has no cell adhesion ability and cannot directly promote cell growth and reproduction. Recently, surface functionalization of nanocellulose has been reported as an indispensable strategy for improving its bioactivities or other physic-chemical properties. In this paper, functionalization strategies of nanocellulose based on its inherent hydroxyl, aldehyde, carboxyl, and sulfate group reactions are reviewed. Biomacromolecules, such as peptides, proteins, and DNA that are commonly used in functionalization for different biomedical applications are summarized. Prospects and ongoing challenges of nanocellulose-based biomaterials application, as well as these advanced processing technologies such as additive manufacturing, nanomanufacturing, and bio-manufacturing are also discussed. This review is supposed to serve as a guideline for the development of nanocellulose-based biomaterials in biomedical applications.

The capture technology matters: Composition of municipal wastewater solids drives complexity of microbial community structure and volatile fatty acid profile during anaerobic fermentation

Article

Full-text available

Jan 2022
SCI TOTAL ENVIRON

The production of volatile fatty acids (VFAs) represents a relevant option to valorize municipal wastewater (MWW). In this context, different capture technologies can be used to recover organic carbon from wastewater in form of solids, while pre-treatment of those solids has the potential to increase VFA production during subsequent fermentation. Our study investigates how VFA composition produced by fermentation is influenced (i) by the choice of the capture technology, as well as (ii) by the use of thermal alkaline pre-treatment (TAP). Therefore, the fermentation of solids originating from a primary settler, a micro-sieve, and a high-rate activated sludge (HRAS) system was investigated in continuous lab-scale fermenters, with and without TAP. Our study demonstrates that the capture technology strongly influences the composition of the produced solids, which in turn drives the complexity of the fermenter's microbial community and ultimately, of the VFA composition. Solids captured with the primary settler or micro-sieve consisted primarily of polysaccharides, and led to the establishment of a microbial community specialized in the degradation of complex carbohydrates. The produced VFA composition was relatively simple, with acetate and propionate accounting for >90% of the VFAs. In contrast, the HRAS system produced biomass-rich solids associated with higher protein contents. The microbial community which then developed in the fermenter was therefore more diversified and capable of converting a wider range of substrates (polysaccharides, proteins, amino acids). Ultimately, the produced VFA composition was more complex, with equal fractions of isoacids and propionate (both ~20%), while acetate remained the dominant acid (~50%). Finally, TAP did not significantly modify the VFA composition while increasing VFA yields on HRAS and sieved material by 35% and 20%, respectively. Overall, we demonstrated that the selection of the technology used to capture organic substrates from MWW governs the composition of the VFA cocktail, ultimately with implications for their further utilization.

Anaerobic Digestion for Biogas Production from Municipal Sewage Sludge: A Comparative Study between Fine Mesh Sieved Primary Sludge and Sedimented Primary Sludge

Article

Full-text available

Dec 2021

Two different types of primary sewage sludge have been used as feedstock for production of biogas through anaerobic digestion (AD): the one type was sludge from a typical primary clarifier (PC), while the other type of sludge produced by a rotating belt filter, commonly called microsieve (MS). Initially the main physicochemical characteristics of the sludges, such as total solids (TS), volatile solids (VS), VS/TS, pH and carbon to nitrogen ratio (C/N) were determined, for MS: 37.86 ± 0.08%, 83.00 ± 0.41%, 0.83 ± 0.00, 6.67 ± 0.08 and 19.68 ± 0.69, respectively, and for PC: 2.61 ± 0.08%, 78.77 ± 1.91%, 0.79 ± 0.02, 6.61 ± 0.10 and 14.46 ± 1.23, respectively. Then, calculated amounts of the sludges were inserted into airtight vials and were inoculated using anaerobic sludge. The daily biogas production was measured over a period of 30 days. PC sludge maximized the daily biogas production (44.20 mlbiogas/gvsd) 11 days after inoculation, while the MS sludge reach a peak (37.74 mlbiogas/gvsd) 14 days after inoculation. The cumulative biogas production over the 30 days of AD was in the same laver (442.29 mlbiogas/gvs for PC versus 434.73 mlbiogas/gvs for MS). However, PC sludge indicated higher daily biogas production, compared to MS sludge, while the opposite was observed for the period following the peak point. The Volatile Solids Reduction for PC and MS sludges was recorded as 46.06% and 32.39%, respectively.

Enhanced primary treatment for net energy production from sewage – The genetic clarification of substrate-acetate-methane pathway in anaerobic digestion

Article

Nov 2021
CHEM ENG J

Organic matters such as cellulose are key components in municipal sewage, and its degradation consume significant aeration energy in biological process. Pre-harvesting organic particles by chemical enhanced primary treatment (CEPT) could prevent energy consumption while increase bioenergy potential in anaerobic digestion (AD). This study provides biological proof of an “substrate-acetate-methane pathway” that may result in energy positive practice in sewage treatment. When applying CEPT sludge in AD, a stable methane yield at 0.42 m³/kg VSSin was achieved. Meanwhile, the results of mass balance suggested that for biogas conversion of CEPT sewage sludge, cellulose and protein degradation played a key factor at low organic loading operation (2 gVSS/L-day, SRT=15 days), while lipid degradation was more significant at high loading operation (3 gVSS/L-day, SRT=20 days). Microbial analysis revealed high abundance of cellulolytic bacteria, cellulosome related genes, and methanogens; and low abundance of syntrophs, suggesting effective degradation and uptake of amorphous cellulose to acetate. An unexpected result showed that cellulosome genes were identified from two high abundance species of Methanosarcina. In line with the reduced total volatile fatty acids and propionate (to 1,200 and 600 mg/L, respectively), such cellulolytic and methanogenic synergy implies unique syntrophs bypass for bioenergy production. With the combination of CEPT sludge and AD, the net energy of sewage treatment could increase from -0.36 kWh to 0.06 kWh per cubic meter wastewater treated, including reduced energy consumption in aeration process.

Influence of Substrates Concentrations on The Dynamics Of Oxygen Demand And Aeration Performance in Ideal Bioreactors

Article

Jul 2021
PROCESS SAF ENVIRON

The effect of bioreactor configurations on the dynamics of aeration modelling was investigated by incorporating three different correlations from the literature to estimate α-factors into the aeration model. Estimated air flow rates using the three correlations were then validated against experimental data obtained from pilot sequencing batch reactors (SBRs). Two identical SBRs were operated in parallel; one received raw wastewater and the other received primary treated wastewater. The validated aeration model was then used to evaluate aeration dynamics in different bioreactor configurations, both for nitrification only and nitrification/denitrification, with the three different correlations. The current study is the first to investigate the validity of the aforementioned correlations using various bioreactor configurations and to establish that the bioreactor configuration not only impacts spatial and temporal biological oxygen demands as currently understood but also oxygen transfer efficiency. The first correlation based on the real-time bioreactor soluble chemical oxygen demand (sCOD) was able to predict the temporal measured air flow rate in the pilot SBRs. The second correlation based on the influent COD overestimated the air flow rates as it considered the impact of the influent loading rates on the α-factor and overlooked the improvement in α-factor due to biodegradation. The third correlation based on MLSS concentrations underestimated the air flow rates at the beginning of the aeration cycle as it ignored the impact of influent loading rates on the α-factor and considered only the insignificant change in MLSS during the aeration cycle. In terms of bioreactor configuration, the model-based analysis showed that the first correlation is suitable for designing SBR, plug flow reactor (PFR), step-feed PFR, and completely mixed stirred reactor (CSTR) systems, and the third correlation is suitable for designing CSTRs and membrane bioreactors (MBRs), while the second correlation was not accurate in any of the reactors modelled. When nitrification was targeted, the CSTR reduced aeration energy by 44%-49% compared to the PFR, and 41% -43% when both nitrification and denitrification were targeted. Compared to the plug-flow reactor, the step-feed PFR reduced aeration energy by 9% when nitrification only was targeted. However, when pre-denitrification was added, both systems showed the same aeration energy consumption. Pre-denitrification reduced organic loadings to aeration tanks and decreased aeration energy by 22%, 11%, 15%, and 14% in PFR, CSTR, PFR step feed and MBR systems, respectively.

Highly Selective Formation of CO from Domestic Wastewater with Zero CO2 Emissions through Solar Energy Catalysis

Article

Nov 2023

Emerging Techniques for Treatment of Wastewater

Chapter

Sep 2023

Polymeric Substances Recycled from Excess Sludge in Wastewater Treatment Plant

Chapter

Sep 2023

Da-Qi Cao

Recovery of resources from wastewater, e.g., bioplastics, cellulose, metals, and phosphorus, is one of the most important research objectives in wastewater treatment. Recently, the recovery of polymeric substances from excess sludge is gaining significant research interest in future wastewater treatment technologies, which can not only enhance the dewatering performance of sludge but also promote sludge reduction. Herein, extracellular polymeric substance (EPS) and typical polysaccharide alginate as recycled materials are discussed. First, membrane recovery of alginate was discussed, including ultrafiltration (UF) concentration of sodium alginate solution, filtration coefficient and recovery rate of alginate, forward osmosis recovery with useful reverse solute diffusion, and properties of recycled materials. Second, membrane recovery and properties of EPSs were described through the role of calcium ion, microfiltration separation of polysaccharides and proteins in EPS, and removal of heavy metal ion using UF with recovery of EPSs. Finally, the surfactant-enhanced ultrasonic extraction of PSs was proposed, in which the effect of surfactant on extraction efficiency, extraction mechanisms, characteristics of PSs, and adsorption properties of lead ion were shown.

Selecting resource recovery technologies and assessment of impacts

Chapter

Jan 2023

Resource recovery from wastewater: Technical, economic, and environmental feasibility

Chapter

Jan 2023

Value-Addition to Paper Waste

Chapter

Full-text available

Mar 2023

Increasing of Sludge Loading Rate Induces Gel Fouling in Membrane Bioreactors Treating Real Sewage

Article

Jan 2022

Risk assessment methods for water resource recovery for the production of bio-composite materials: Literature review and future research directions

Article

Dec 2022

Bio-composite materials made from resources recovered from the water cycle are the future of the holistic approach towards sustainable wastewater treatment. The raw ingredients for these materials are coming from contaminated sources such as wastewater resources, water plants from surface water etc.. Thus, different risks like human health, environmental and product quality risks need to be assessed. Existing literature was analysed regarding these risks, especially methods concerning the risk assessment in wastewater and drinking water treatment and water/wastewater-based resource recovery for reuse. The reviewed literature identified several risk assessment methods such as FMEA, FMECA, FTA, QMRA and QCRA as frequently used ones for these purposes. However, no dedicated methods were identified for the corresponding risk assessments related to bio-composite materials representing key knowledge gaps. The literature review also showed that the above identified risk assessment methods cannot be directly applied for bio-composite materials as many required input data are missing. To overcome above gaps, future research directions have been identified. These include use of qualitative risk assessment methods such as HAZOP and ETA to first identify hazards and map the risks. Once this is done, QMRA and QCRA could be used in combination with Monte Carlo analysis to assess the actual risks. However, before this can be done, additional work should be carried out to collect the missing data required for the use of these methods in the context of bio-composite materials. In addition, additional experimental work such as column leaching tests should be carried out to assess the environmental risks, in particular, looking at the release of toxic chemical compounds such as heavy metals in the aquatic environment. Finally, a list of quality requirements for bio-composite material and related products (e.g. requirements for mechanical properties, purity of raw materials, etc.) should be made, so that the related product quality risks can be assessed.

Zero pollution protocol for the recovery of cellulose from municipal sewage sludge

Article

Sep 2022

Business-as-usual municipal sewage sludge (MSS) management practices could impact significantly on public health and the environment. Administrative costs for municipal wastewater treatment plants account for more than 50 %. To reduce administrative costs, the EU has called for the reuse of waste to make it part of the circular economy. One of the options for MSS is reuse to recover bioresources. Because of toilet paper, the main component of the total solids in MSS is cellulose, which could be recovered by chemical or biological processes. Crystalline cellulose is of great use in various fields such as biomedical, pharmaceutical, mechanical and others. There are various solvents to dissolve cellulose present in renewable sources to recover. However, these solvents are not widely used at MSS. This review focuses on solvent options for MSS. It also develops an environmentally friendly protocol for the recovery of nanocellulose from primary MSS using alkali-based solvent systems.

An increase in sludge loading rate induces gel fouling in membrane bioreactors treating real sewage

Article

Sep 2022
CHEMOSPHERE

The main objective of this study was to investigate the cause of gel fouling in membrane bioreactors (MBRs) treating real sewage in terms of soluble microbial products (SMPs) and microbial aspects. Two anoxic/oxic-MBRs were operated as the control reactor (S1) and the sludge loading rate increased reactor (S2). The reactors were operated under low-temperature around 11 °C conditions. Membrane permeability substantially decreased in S2, and gel layer biofilm was formed on membrane surface. In contrast, the permeability of S1 gradually decreased and cake layer formed. When gel fouling occurred, the protein and polysaccharide of SMP in S2 were 47 and 23 mg L⁻¹, which were significantly lower than those recorded in S1 accounted for 118 and 68 mg L⁻¹, respectively. Furthermore, the total organic carbon concentration of SMPs was 24 mg L⁻¹, which was lower than the influent in S2, accounted for 62 mg L⁻¹. Finally, Campylobacteraceae which exists in sewage and uncultured OD1, dominated the gel layer biofilm in S2, unlike the cake layer biofilm in S1. These results indicated that the gel layer biofilm might be composed of influent substances, demonstrating the importance of influent decomposition in MBR for gel fouling mitigation.

Biodegradable Waste Streams

Chapter

Jul 2022

Biodegradable waste is generated either in nature, which naturally uses it to its advantage and there are no negative effects on the environment, or by human activity, in which it is necessary to regulate its generation and management. Biodegradable waste generated by human activity is any waste that undergoes aerobic or anaerobic digestion. Biodegradable waste is most often generated in agriculture, forestry, food industry, and from everyday used items that are produced by the public. It is important to sort them right at the source and then hand them over for processing to the facility that is designated for this purpose (composting plant, incinerator, anaerobic digestion technology, etc.). This will prevent the disposal of biodegradable waste in landfills, where they are a source of greenhouse gas (methane) and chemical and biological pollutants in landfill leachate.

Converting wastewater cellulose to valuable products: A techno-economic assessment

Article

Jun 2022
J CLEAN PROD

Wastewater contains about 25% of chemical oxygen demand as cellulose. The source of this cellulose is mainly toilet paper which can be recovered and converted into useful products. The recovered cellulose can be pretreated and pyrolyzed to produce biochar, bio-oil, and pyroligneous acid. A techno-economic assessment was performed on the entire value chain including the char activation process. The data on mass and energy balance and investment cost was obtained from the pilot plant developed at the sludge treatment plant in Ede, the Netherlands. The minimum selling prices estimated for each of the products while considering other co-products as revenue are respectively equal to €1.06, €0.25, and -€0.11/kg. The negative value of pyroligneous acid is due to the high revenue obtained from selling the other two co-products (biochar and bio-oil) at their assumed market prices. It indicates that the revenue obtained covers the annual capital and operating expenditure. Char activation is necessary to expand its applications and thus both physical and chemical activation were considered. The physical activation method resulted in a price higher than the market price whereas the chemical activation method is most suitable considering its high yield and assumed quality. The chemically activated char can be produced at €2.3/kg which is 42% lower than the assumed market price. However, the difference in quality would be significant due to the nature and source of the feedstock (cellulose). This value chain is promising under certain conditions and might be a promising business case to investigate for a sludge treatment facility.

Where is the greatest potential for resource recovery in wastewater treatment plants?

Article

May 2022
WATER RES

The restorative and regenerative ability of the circular economy has led to the rapid growth of this concept over the past decade, as it facilitates the broadly adopted principles of sustainable development and beyond, through restorative and regenerative actions. The water sector is poised to benefit from this transition, due to its intrinsic circularity and the resources it handles, predominantly found in wastewater, that are valuable and critical. Currently, the vast range of resource recovery technologies coupled with few industrial examples hinder strategic decision making. Resource recovery on a regional scale improves market share and mitigates investment risk, therefore, a structured approach has been developed for the selection of priority technologies to act as a guide for strategic planning. A representative UK wastewater model acts as the baseline, with multi-criteria analysis used to select resources and create an enhanced resource recovery scenario. It was found that implementing the recovery of 5 ‘priority resources’ (and technology pathways) increased nitrogen and phosphorus recovery by 68 % and 71 % respectively. Lastly, the need for a cross-cutting approach for the holistic assessment of circular solutions is discussed.

Review on the fate and recovery of cellulose in wastewater treatment

Article

Sep 2022
RESOUR CONSERV RECY

The wastewater treatment plants are transforming to water resource recovery facilities. The essence behind this transformation is to recover resources from wastewater as much as possible instead of destroying and removal. By far, a wide array of products (energy, fertilizer, etc.) in wastewater and recovery technologies have been identified. However, only a few technologies have been extrapolated into full-scale practices. Herein, cellulose is such a kind of resource originating from toilet paper and its recovery has been implemented and endorsed by research efforts in terms of environmental and economic favourability. This review aims to comprehensively map the technologies of cellulose recovery from wastewater and clarify the associated internal impact and external market potential. First, the source, fate, and transformation of cellulose in a typical WWTP (applying activated sludge) are analyzed to provide a holistic overview of the recovery potential and points. Second, cellulose recovery technologies are reviewed and summarized in a historical timeline with an emphasis on rotating belt filters. Particularly, the impacts of cellulose recovery on wastewater treatment performance and the valorization routes are introduced and discussed comprehensively to make the benefits more explicit. The third section of the review presents a discussion in terms of sustainability and some other factors/routes to manage toilet paper and cellulose. Considering the mature value chain, versatile application routes, and favorable environmental impact, cellulose recovery is highly recommended to be included in wastewater management.

Cellulose and extracellular polymer recovery from sludge

Chapter

Jan 2022

Population explosion–mediated demand has led to an unprecedented increase in the consumption of natural resources across the globe. Most of the nonrenewable natural resources have failed to meet the ever-increasing demand, resulting in a gradual widening of the supply and demand gap. Therefore, in the recent decades, the mainstream research focus has aimed at developing technological solutions to recover secondary resources from anthropogenic wastes or waste streams. This chapter discusses about the technical possibilities and the bottlenecks associated with the recovery of cellulose, polyhydroxyalkanoate (PHA), and extracellular polymeric substances (EPS) from sewage sludge. Basic resource recovery techniques involve biochemical, physicochemical, and some of the previously unexploited biological processes. The important applications of sludge-derived cellulose fibers for the production of cellulose nanocrystals and cellulose nanofibers, recovered PHA for biopolymer synthesis, and extracted EPS application as a bioflocculant, along with other diversified application prospective have also been deliberated in this chapter. The sources and extraction methods of various resources to be recovered are highlighted in this chapter that can be helpful in choosing the suitable extraction methods depending on the sources from which the secondary resources are to be recovered and the intended use of the recovered resources. The recovery of secondary resources from waste sources is a very essential practice from the global sustainability view point.

Energy and resources recovery from wastewater treatment systems

Chapter

Jan 2022

Conventional wastewater treatment plants (WWTPs) are progressively looked upon as resource recovery facilities (RRFs), reflecting the worth of energy, nutrients and other resources, besides vindicating the required effluent quality. Though, WWTPs clean wastewater and lessen water pollution; but, while doing so, they also contribute to air pollution and need energy/material input with associated emissions. However, energy recovery (e.g., biogas, heat) and resource recovery (e.g., extracellular polymers, bioplastics, cellulose fibers, nutrients) allow us to counterbalance the negative environmental impacts of wastewater treatment. Several environment friendly approaches for resource recovery from WWT system have established their utility in optimizing WWTP operation to accomplish improved effluent quality at lower costs; they also constitute a useful tool to support the transition of WWTPs into water resource recovery facilities that maximize the valorization of products recovered from the wastewater. This article critically discusses the recent developments, opportunities, market possibilities, and barriers in the resource recovery from WWTP. Wastewater can not only dampen the effects of water shortages by means of water reclamation, but it also provides the medium for energy and nutrient recovery to further offset the extraction of precious resources.

Challenges and opportunities for more efficient water use and circular wastewater management. The case of Campania Region, Italy

Article

Nov 2021
J ENVIRON MANAGE

By 2050, global demand for water is expected to increase by some 55% due to population growth and urbanization. The utilization of large amounts of freshwater in the world, generate huge volumes of wastewater of which, globally, more than 80% is discharged without treatment, thus causing impacts on aquatic ecosystems, human health and economic productivity. More sustainable practices of wastewater management are expected as a way towards circular bioeconomy (CBE) processes, whose goal is to implement closed systems promoting the systematic use of recycling, reuse and recovery of bioproducts and by-products and the reduction of waste generation. This approach, if adopted in the water and wastewater sector, can ensure environmental, economic and social benefits. The reuse of wastewater, on the one hand, reduces the volume of wastewater and the pressure on water bodies; on the other hand, the recovery of nutrients (P or N) and/or other high value bioproducts (biogas, cellulose, biopolymers) from wastewater offers numerous advantages in terms of supplying new raw bio-based materials that can be refed back to supply chains (thus substituting fossil resources) and, at the same time, producing cleaner water to be reused. Nevertheless, while in Europe many industries have demonstrated the ability to recycle and reuse water, in many regions of Italy the sustainable management of water and wastewater is not yet consolidated. In this study we explore the available technological, economic and environmental options concerning water use and wastewater treatment and we apply them to design appropriate scenarios for improved use efficiency and circular management. A comprehensive literature review of the most promising wastewater treatment processes for resources and energy valorization was conducted. The recovery of PHAs, struvite, nitrogen and algal biomass, as potential substitutes for conventional PET, phosphate and nitrogen chemical fertilizers and electricity, respectively, in addition to reusable treated water, were hypothesized and carefully discussed. Resulting scenarios are tested against the present situation of Campania Region (situated in Southern Italy) based on population and demand statistics, in order to develop strategies and policies potentially applicable locally and elsewhere.

Biological nutrient removal enhancement using fermented primary and rotating belt filter biosolids

Article

Jul 2021
SCI TOTAL ENVIRON

This research compared the impact of two primary treatment options (i.e. primary clarification and rotating belt filtration (RBF)) on biological nutrients removal (BNR) process, using sludge fermentation liquid (SFL) as a carbon source. The liquid fraction of both fermented primary and RBF sludges comparably enhanced BNR. Despite the significant contribution of the unpurified SFL to the sharp increase in nutrient levels (i.e. 47%–64% (primary effluent; PE), and 45%–53% (RBF) of the soluble nitrogen and phosphorus loads), readily biodegradable COD and volatile fatty acids (VFAs) fractions of the combined feed increased significantly (2.5–6.1 times), compared to the original feed by additional SFL. Removal efficiencies in the reactors reached 57% (total nitrogen) and 92% (total phosphorus) after addition of SFL. Effluent nitrogen and phosphorus for the two reactors were close in the range of 15 ± 6 mg N/L, and 0.5 ± 0.3 mg P/L, respectively. Kinetics studies showed denitrification rates of 1.3, and 1.13 kg NO3-N/m³.d for primary effluent and RBF effluent-fed reactors, respectively. Phosphorus release rates were 11.7 and 9.7 mg PO4-P/g VSS.h, for primary, and RBF effluents, respectively; showing 20%–22% lower rates in the RBF SFL. Incorporating experimental data into a plant-wide model for a 100 MLD plant receiving typical medium strength wastewater, showed that although primary treatment enhanced the biogas production by 96% (primary clarification) and 62% (RBF) trains; combined fermentation and anaerobic digestion was effective to enhance the biogas production by 59% on average, compared to the base scenario without primary treatment. Additionally, if primary clarification exists, then the addition of fermentation results in additional revenue of C$1890/d in the plant, considering additional revenue of C$2230/d due to VFA generation in contrast to C$340/d loss in the methane production.

Degradation of particulate organic matter ? A comparison of different model concepts

Article

Full-text available

Dec 1999

From the results of investigations at full-scale and pilot plants, it has been found that with ‘usual’ parameters the ASM1 is only valid for a small range of SRT as well as of oxic reactor section (VOX/V). To make ASM1 applicable to a wider range of SRT the very slowly biodegradable particulate organic matter has to be taken into consideration. This fraction can be interpreted as part of the ‘heterotrophic biomass’ XB,H which requires modification of the values for the ‘heterotrophic decay rate’ bH and for the fraction of XI in the influent. In order to distinguish between ‘active heterotrophic biomass’ (XB,H) and the very slowly biodegradable substrate it seems to be useful to inkoduce the latter mass fraction as a new model component (XV) into the ASM1. This extended simulation model has given reasonable results for different activated sludge systems.

Maximum Use of Resources Present in Domestic “Used Water

Article

Full-text available

Aug 2009

Environmental protection and the sustainable management of natural resources stand at the foreground of economic and technological activities worldwide. Current sewage technologies, however, deal with diluted wastes and do not focus on recovery and are therefore not sustainable. Here, the most promising methods available for the recovery of nutrients (nitrogen, phosphorus), organic material and energy from "used waters" are examined both at the decentralised and centralised level. Novel approaches for water processing, not implementing aerobic biological treatment as a core technology, are conceived and critically evaluated regarding efficiency, diffuse emissions and requisite costs. By implementing up-concentration of dilute wastewaters, the concentrated stream becomes suitable for the waste-to-energy strategy. The approach of up-concentration of municipal effluent at arrival at the water treatment plant followed by anaerobic digestion of organics and maximal reuse of the mineral nutrients and water is estimated to have a total cost of the order 0.9 euros/m(3); the latter is comparable to that of conventional aerobic treatment technologies which has little or no reuse. It is argued that in view of the fact that recovered nutrients will become of increasing economic and ecological value, this new conceptual design for the treatment of "used water" will become feasible in the next decade.

Cellulose degradation in wastewater treatment

Article

May 1975

A considerable part of the organic matter in municipal wastewater consists of cellulose fibers, and a method of studying the bacterial degradation of these fibers has been developed. Sample fibers are enclosed in an inert nylon bag and immersed in environments encountered in an activated sludge process. The amount of degradation is determined by periodically retrieving the bags and weighing them. Such experiments show that degradation of cellulose fibers results in increased oxygen consumption. Fibers that are slowly degraded because of high lignin content or slow bacterial growth play only a minor role in the oxygen balance.

Mechanische Abwasservorbehandlung auf kommunalen Membranbelebungsanlagen

Article

Jan 2008

Optimized Particle Separation in the Primary Step of Wastewater Treatment

Article

Dec 1998

Hallvard Ødegaard

Since the pollutants in wastewater to such a large extent are associated with particles, enhanced particle separation in the primary step of wastewater treatment should be aimed at. Space restrictions demand pretreatment options will a small “foot-print”. In this paper it is shown that coagulation with metal salts is very efficient but leads to excessive sludge production. It is demonstrated how the use of cationic polymers may reduce the sludge production considerably without ruining the SS-removal efficiency and also how improved flocculation, either chemically, by the addition of flocculants or physically, by improvement of settling tank design, may lead to better particle separation as well as smaller “foot-print” of the plant. As an alternative to primary settling, primary filtration in coarse, floating filters are discussed as well.

Investigations on cellulose biodegradation in activated sludge plants

Article

Jun 2008
J APPL MICROBIOL

Cellulose is the major carbon substrate entering treatment plants for municipal waste waters. In the present investigation an attempt was made to study its degradation in activated sludge. Cellulolytic micro-organisms were enumerated in different treatment plants and at one plant they were assessed after different steps over a period of about 1 year. The degradation of cellulose contained in Nylon bags suspended in the mixed liquor was also studied and the activities of cellulase components were assayed. Finally, the concentrations of cellulose and lignin in the suspended solids taken from different treatment steps were determined. The results showed that active cellulolysis occurred in activated sludge. The degradation was mainly bacterial, although no significant enrichment of such bacteria was found in the sludge floc. Cellulase activity, however, showed an increase. Experiments with the Nylon bag indicated that 60% of the weight of cotton wool was degraded in 4–5 weeks. It was concluded that about 60% (w/w) of the cellulose entering the system could be degraded by bacteria during aerobic treatment, while 50–60% of that present in the surplus activated sludge was degraded during anaerobic sludge digestion.

Efficiency of mechanical pre-treatment on European MBR plants

Article

Jan 2009
DESALINATION

In order to ensure a stable and reliable operation of municipal MBR plants, an enhanced mechanical pre-treatment of the raw wastewater is essential. Removal of hair, fibrous material and other contraries which can lead to operational problems at the membrane modules is of particular importance. As the number of full scale applications is continuously increasing, now appropriate investigations can be carried out to determine the removal efficiency of different units (screens, sieves) or different combination of units (multi staged system). First results of such investigations on two German MBR plants were already presented [F.-B. Frechen, W. Schier and M. Wett, Water Practice & Technology, Vol. 1, No. 3, IWA Publishing, 2006, doi: 10.2166/WPT.2006057.]. In 2006, DESEE executed further investigations on another three wwtps in The Netherlands, UK and Germany. This paper summarizes the results, thus updates the information available, discusses the present findings and gives an outlook on future developments.

Water and energy as inseparable twins for sustainable solutions

Article

Jan 2011

Although the water cycle is only a minor contributor to the energy demand in society, it is a matter of good housekeeping to minimize the energy need within a sustainable water cycle. Wastewater treatment should not only be applied to purify the water, but also recover the energy present in this water, as well as to recover essential elements like nitrogen and phosphorus. From an energy analysis of the Dutch water cycle it is concluded that creating an energy neutral water cycle by using the heat content or by making use of the organic load of wastewater is within hands.

Treating municipal wastewater with the goal of resource recovery

Article

Jan 2011

A new municipal wastewater treatment flowsheet was developed with the objectives of energy sustainability, and water and nutrient recovery. Energy is derived by shunting a large fraction of the organic carbon in the wastewater to an anaerobic digestion system. Aerobic and anaerobic membrane bioreactors play a key role in energy recovery. Phosphorus and nitrogen are removed from the wastewater and recovered through physical-chemical processes. Computer modeling and simulation results together with energy balance calculations, imply the new flowsheet will result in a dramatic reduction in energy usage at lower treatment plant capital costs in comparison to conventional methods.

Experience with Guidelines for Wastewater Characterization in the Netherlands

Article

Feb 2002

In this paper experiences and results are presented with guidelines for wastewater characterisation that are standardised in The Netherlands for modelling purposes with ASM. The wastewater characterisation is based on a physical-chemical method to characterise the soluble and particulate fractions, combined with a BOD-analysis for characterising the biodegradable fraction of the influent COD. By following the guidelines, a sufficiently detailed and practical characterisation is obtained, and the results can be used for simulation studies on treatment plants for process optimisation, trouble-shooting and design assistance. At present, five years of experience is gained with the guidelines and they were used for the simulation of circa 100 treatment plants. The guidelines are evaluated as simple and easy to implement in routine analysis programs.

Evaluation and testing of fine mesh sieve technologies for primary treatment of municipal wastewater

Article

Feb 2006

Fine mesh sieve technologies were tested in full scale at several municipal wastewater treatment plants. A screening test was used to characterize wastewater and establish the design criteria for the sieves. To achieve high removal efficiencies it was crucial to operate the sieves with a filter mat. Rotating belt sieves performed best in the full-scale tests. A small dose of cationic polymer and a static flocculator ahead of a rotating belt sieve achieved excellent results on a wastewater that was originally found unsuitable for primary treatment with fine mesh sieves. Simple screw presses dewatered the sludge from the sieves to typically 25-30% total solids. Using fine mesh sieves with <500 microns openings was found to normally be the most economical process for primary treatment.

Activated sludge models ASM1, ASM2, ASM2d, and ASM3. IWA scientific and technical report no

Jan 2000

M Henze
W Gujer
T Mino
M C M Van Loosdrecht

Henze, M., Gujer, W., Mino, T., van Loosdrecht, M.C.M., 2000. Activated sludge models ASM1, ASM2, ASM2d, and ASM3. IWA scientific and technical report no. 9. IWA Publishing, London, UK.

Water and energy as inseparable twins for sustainable solutions Degradation of particulate organic matter e a comparison of different model concepts

Jan 1999
119-127

J Hofman
R Hofman-Caris
M Nederlof
J Frijns
Van Loosdrecht

Hofman, J., Hofman-Caris, R., Nederlof, M., Frijns, J., Van Loosdrecht, M., 2011. Water and energy as inseparable twins for sustainable solutions. Water Science and Technology 63 (1), 88e92. Nowak, O., Svardal, K., Franz, A., Kuhn, V., 1999. Degradation of particulate organic matter e a comparison of different model concepts. Water Science and Technology 39 (1), 119e127.

Evaluation and testing of fine mesh sieve technologies for primary treatment of municipal wastewater Efficiency of mechanical pre-treatment on European MBR plants

Jan 2006

B Rusten
W Schier
F B Frechen

Rusten, B., 2006. Evaluation and testing of fine mesh sieve technologies for primary treatment of municipal wastewater. Water Science and Technology 54 (10), 31e38. Schier, W., Frechen, F.B., 2008. Efficiency of mechanical pre-treatment on European MBR plants, In: International Conference Amsterdam Rai Netherlands, 1st and 2nd October.

Treating municipal wastewater with the goal of resource recovery Water Science and Technology 63 (1), 25e31. STOWA 2010-19. Influent fijnzeven in rwzi's, www.stowa.nl Investigations on cellulose degradation in activated sludge plants Maximum use of resources present in domestic " used water

Jan 1982
5537-5545

P M Sutton
H Melcer
O J Schraa
A P Togna
H Verachtert
K Ramasamy
M Meyers
J Bever

Sutton, P.M., Melcer, H., Schraa, O.J., Togna, A.P., 2011. Treating municipal wastewater with the goal of resource recovery. Water Science and Technology 63 (1), 25e31. STOWA 2010-19. Influent fijnzeven in rwzi's, www.stowa.nl. Verachtert, H., Ramasamy, K., Meyers, M., Bever, J., 1982. Investigations on cellulose degradation in activated sludge plants. Journal of Applied Bacteriology 52, 185e190. Verstraete, W., Van de Caveye, P., Diamantis, V., 2009. Maximum use of resources present in domestic " used water ". Bioresource Technology 100 (23), 5537e5545.

Mechanische Abwasser Vorbehandlung auf Kommunalen Membranbelebungsanlagen

Jan 1975
39-44

N Edberg
B Hofsten
F B Frechen
W Schier

Edberg, N., Hofsten, B., 1975. Cellulose degradation in wastewater treatment. Journal of the Water Pollution Control Federation 47 (5), 1011e1020. Frechen, F.B., Schier, W., 2008. Mechanische Abwasser Vorbehandlung auf Kommunalen Membranbelebungsanlagen. Korrespondenz Abwasser 55 (1), 39e44.

Evaluation and testing of fine mesh sieve technologies for primary treatment of municipal wastewater

Jan 2002
WATER SCI TECHNOL
31-38

P J Roeleveld
M C M Van Loosdrecht

Roeleveld, P.J., Van Loosdrecht, M.C.M., 2002. Experience with guidelines for wastewater characterisation in The Netherlands. Water Science and Technology 45 (6), 77e87. Rusten, B., 2006. Evaluation and testing of fine mesh sieve technologies for primary treatment of municipal wastewater. Water Science and Technology 54 (10), 31e38.

Sieving wastewater - Cellulose recovery, economic and energy evaluation

Abstract

No full-text available

Recommended publications

WATER DEMINERALIZATION BY THERMALLY REGENERABLE ION EXCHANGE.

The limits and ultimate possibilities of technology of the activated sludge process

Direct influent filtration as pretreatment step for more sustainable wastewater treatment systems

BIOLOGICAL NUTRIENT REMOVAL IN THE PHOREDOX PROCESS.