Wastewater Reclamation System Research Articles

A pilot-scale wastewater reclamation system based on direct descending filtration and chlorine disinfection

The development of cost-effective technologies for treating and disinfecting wastewater to a level that makes it economically valuable, environmentally sustainable, and health-safe for reuse is of utmost importance. In this study, a direct descending filtration pilot unit was designed, assembled, and tested within a municipal wastewater treatment plant to produce nonpotable reclaimed wastewater. Bench-scale tests were performed to define the optimum coagulant type and dosage (Poly aluminium chloride, 15 mg L−1). The pilot plant performed best at a filtration rate of 15 m h−1 in a bed of commercial building silica sand with an average particle size of 0.93 mm, resulting in a net production of 0.103 m3 h−1 of treated water. The removal efficiencies for apparent color, E. coli, turbidity and total suspended solids were 86.8 ± 2.3%, 86.8 ± 3.6%, 76.9 ± 6.9% and 68.7%, respectively. After a final stage of chlorine disinfection, the E. coli removal was higher than 99.7%. All the resulting parameters were within the recommended standards for nonpotable uses, such as landscape irrigation, dust and fire control, soil compaction, and street cleaning.

Feasibility of membrane distillation process for potable water reuse: A barrier for dissolved organic matters and pharmaceuticals

In this study, the feasibility of the membrane distillation (MD) process as a wastewater reclamation system for portable reuse was investigated. The flux was stably maintained at about 20 L/m2h (LMH) at ΔT 30 °C, compared to higher flux at ΔT 50 °C, which showed a rapid decrease in the flux due to severe fouling. MD produced excellent quality of potable water satisfied the drinking water standards of Korea from effluent of sewage treatment plant (ESTP). The fractions of the hydrophobic OC (HOC) and chromatographic DOC (CDOC) from LC-OCD analysis was firstly suggested to understand different organic transport during the MD process. The transport of organic matters across the MD membrane mitigated at low operation temperature and the transported organics in all the tested waters were mostly volatile low molecular weight organics, aromatic amino acids. All of thirteen selected pharmaceuticals were completely removed by MD, regardless of their properties. In order to retard the membrane fouling of the MD process, coagulation and filtration pre-treatments were applied. The pre-treatment process coupled MD process could successfully remove impurities including NH4-N without severe membrane fouling. Moreover, coagulation pretreatment reduced transport of ammonia due to decrease in pH.

Application of safety and reliability analysis in wastewater reclamation system

With the development of the world water resources situation, the reuse of wastewater will be one of the essential measures for solving water resources' problems and implementing practical and sustainable use of water resources. Wastewater reclamation risks have received considerable attention in all worlds, but research in this area is minimal, and a unified understanding and evaluation method has not yet been formed. Therefore, based on the system theory process analysis (STPA) method and hazard analysis and critical control point (HACCP) theory, this paper expounds on the concept of the safety and reliability of the wastewater reclamation system. Through the application of analysis methods, this paper proposes a verification method for the safety of the wastewater reclamation system and a reliability evaluation system for the wastewater reclamation system. Besides, the next research direction is further to improve the analysis model and evaluation index system to provide technical support for the construction of a safe, reliable, and economical wastewater recovery system.

Antibiotic resistome associated with microbial communities in an integrated wastewater reclamation system

Antibiotic resistome is a raising concern around the world, especially considering treated wastewater for reclamation. A wastewater reclamation system (WWRS), composed by a treatment system (TS) and a reclaimed system (RS) with supplementation from the treated effluent and considered as an integrated system of treatment and reclamation, was selected in this study. High-throughput qPCR (HT-qPCR) was applied to profile 283 antibiotic resistance genes (ARGs) and 12 mobile genetic elements (MGEs) in the WWRS. A total of 251 ARG and 12 MGE subtypes were detected in the WWRS. The TS exhibited good performance for the removal of ARGs with the number, relative and absolute abundances of ARGs largely decreased (99.07% removal efficiency) in the final effluent, which might be ascribed to biosolid sedimentation. Enhancement of biosolids removal contributed the lessening of ARGs. In the RS, high quality effluent significantly reduced the number and abundance of ARGs along the flow to downstream. MGEs were less reduced in the treated effluent than that of the influent (R2 = −0.16, p > 0.05), and exhibited close connections with ARGs. Arcobacter, Cloacibacterium, Cyanobacteria, Acinetobacter, Flavobacterium and Dechloromonas were the relatively abundant genera in the WWRS, and exhibited significantly correlations with ARGs. Microbial communities and MGEs contributed 65.64% to the changes of ARGs. These two factors may be the main drivers of ARG proliferation in the WWRS. Thus, attention should be paid to MGEs and those abundant genera when considering treated wastewater for reclamation.

Fecal Source Tracking in A Wastewater Treatment and Reclamation System Using Multiple Waterborne Gastroenteritis Viruses.

Gastroenteritis viruses in wastewater reclamation systems can pose a major threat to public health. In this study, multiple gastroenteritis viruses were detected from wastewater to estimate the viral contamination sources in a wastewater treatment and reclamation system installed in a suburb of Xi’an city, China. Reverse transcription plus nested or semi-nested PCR, followed by sequencing and phylogenetic analysis, were used for detection and genotyping of noroviruses and rotaviruses. As a result, 91.7% (22/24) of raw sewage samples, 70.8% (17/24) of the wastewater samples treated by anaerobic/anoxic/oxic (A2O) process and 62.5% (15/24) of lake water samples were positive for at least one of target gastroenteritis viruses while all samples collected from membrane bioreactor effluent after free chlorine disinfection were negative. Sequence analyses of the PCR products revealed that epidemiologically minor strains of norovirus GI (GI/14) and GII (GII/13) were frequently detected in the system. Considering virus concentration in the disinfected MBR effluent which is used as the source of lake water is below the detection limit, these results indicate that artificial lake may be contaminated from sources other than the wastewater reclamation system, which may include aerosols, and there is a possible norovirus infection risk by exposure through reclaimed water usage and by onshore winds transporting aerosols containing norovirus.

Fate of antibiotic resistance genes in reclaimed water reuse system with integrated membrane process

The fate of antibiotic resistance genes (ARGs) in reclaimed water reuse system with integrated membrane process (IMR) was firstly investigated. Results indicated that ARGs, class 1 integrons (intI1) and 16S rRNA gene could be reduced efficiently in the IMR system. The absolute abundance of all detected ARGs in the reuse water after reverse osmosis (RO) filtration of the IMR system was 4.03 × 104 copies/mL, which was about 2–3 orders of magnitude lower than that in the raw influent of the wastewater treatment plants (WWTPs). Maximum removal efficiency of the detected genes was up to 3.8 log removal values. Daily flux of the summation of all selected ARGs in the IMR system decreased sharply to (1.02 ± 1.37) ×1014 copies/day, which was 1–3 orders of magnitude lower than that in the activated sludge system (CAS) system. The strong clustering based on ordination analysis separated the reuse water from other water samples in the WWTPs. Network analysis revealed the existence of potential multi-antibiotic resistant bacteria. The potential multi-antibiotic resistant bacteria, including Clostridium and Defluviicoccus, could be removed effectively by microfiltration and RO filtration. These findings suggested that the IMR system was efficient to remove ARGs and potential multi-antibiotic resistant bacteria in the wastewater reclamation system.

Evaluation of potential environmental benefits from seawater toilet flushing

Water scarcity has become a global issue that has forced many communities to seek alternative water resources. The majority of water on the earth's surface comes from the sea. Seawater has the potential to mitigate water stress after proper treatment. In Hong Kong, seawater has been used directly for toilet flushing for more than 50 years and the seawater toilet flushing (SWTF) system serves 80% of the residents. However, its environmental feasibility remains unknown. This study is a pioneer evaluating the environmental performances of the SWTF system by comparing SWTF with other alternative water resources including desalinated seawater, desalinated wastewater effluent, centralized wastewater reclamation and on-site greywater reclamation systems, while the conventional long-distance imported water scenario is set as the baseline for comparison. This evaluation is first conducted in the Southern District and North New Territory in Hong Kong, demonstrating SWTF is significantly more environmentally-friendly than other alternative water resources, which is the only alternative water resource application approach with environmental impacts comparable with the conventional long-distance imported water scenario. On the contrary, other alternative water resources application approaches would result in additional environmental impacts. Seaside distances and effective population density are two major geographical impact factors effecting the environmental impacts of different water systems in these two districts. The benefits obtained from SWTF in fourteen cities in South China are further investigated. It is confirmed that SWTF can significantly relieve water stress with the lowest environmental impacts comparing with other alternative options in these cities if alternative water resources must be applied for domestic usage. However, the assessment from different aspects should be further conducted to compare these alternative water resources.

Performance of wastewater reclamation systems in enteric virus removal

Analysis of virus removal by tertiary or advanced sewage treatment processes is an emerging topic due to importance of reusing water on a global level. This study aimed to monitor important human viral pathogens: the human adenovirus (HAdV), JC polyomavirus (JCV) and Species A rotaviruses (RVA) in urban sewage, secondary effluents and reclaimed water from metropolitan São Paulo (MSP), Brazil. Four large wastewater treatment plants (WWTPs) in MSP were sampled monthly during a one-year period (April 2015 to March 2016). The viruses were quantified by quantitative PCR (qPCR), and HAdV viability was tested by the integrated cell culture (ICC)-qPCR assay. WWTPs are composed of activated sludge processes and different tertiary treatments (coagulation/sedimentation, sand-anthracite filters, membrane bioreactors (MBRs)/reverse osmosis (RO) and disinfection by chlorination). Physicochemical parameters were also evaluated to verify association with density of viruses detected in different treatment stages. HAdV, JCV and RVA were consistently detected (100%) in the sewage influent samples (range: 106–108 genome copies GC/L). In the secondary effluent, HAdV was detected in 100% (48/48) of the analysed samples, JCV in 85.4% and RVA in 97.9% (range: 104–107 GC/L for all viruses tested). HAdV was the most frequently detected virus in the tertiary effluent (62.2%) (28/45), exhibiting a viability between 0 and 44% of the tested samples in the wastewater reclamation systems. The MBR/RO systems demonstrated better virus removal efficiencies (range: 2.3–2.9 log10). Temperature, pH, turbidity and total organic carbon presented association with the viral density in the reclaimed water samples. Presence of viruses in treated effluents can indicates health risks depending on uses of recovery water. Further risk assessment studies should be conducted to better assess health risks under different exposure scenarios for water recovery in urban settings.

Techno-economic evaluation and comparison of PAC-MBR and ozonation-UV revamping for organic micro-pollutants removal from urban reclaimed wastewater

The presence of sewage-borne Organic Micro-Pollutants (OMP) in Wastewater Treatment Plants (WWTP) effluents represents an increasing concern when water is reclaimed for irrigation or even indirect potable reuse. During eighteen months, an innovative hybrid water reclamation scheme based on a Membrane Biological Reactor (MBR) enhanced with Powder Activated Carbon (PAC) was operated at pilot-scale (70 m3/d) in order to compare it with state-of-the art Wastewater Reclamation System (WWRS) also revamped with a final step of ozonation-UV. Removal of persistent OMP, water quality and treatment costs were evaluated and compared for the different treatment schemes. OMP removal efficiency results for the different schemes concluded that established technologies, such as physico-chemical and filtration systems as well as MBR, do not remove significantly (>15%) the most recalcitrant compounds. The upgrading of these two systems through the addition of ozonation-UV step and PAC dosing allowed improving average recalcitrant OMP removal to 85 ± 2 and 75 ± 5%, respectively. In term of costs, PAC-MBR represents an increase of 37% of costs regarding conventional systems but presents improvements of 50% reduction in space and water quality. On the other hand, ozonation requires up to a 15% increase of foot-print; nevertheless, represents lower costs and lower carbon footprint. Ozonation-UV seems to be the best option for upgrading existing facilities, while PAC-MBR should be considered when space represents a critical limitation and produced water is reused for high water quality purposes.

Using fluorescence surrogates to track algogenic dissolved organic matter (AOM) during growth and coagulation/flocculation processes of green algae

Tracking the variation of the algogenic organic matter (AOM) released during the proliferation of green algae and subsequent treatment processes is crucial for constructing and optimizing control strategies. In this study, the potential of the spectroscopic tool was fully explored as a surrogate of AOM upon the cultivation of green algae and subsequent coagulation/flocculation (C/F) treatment processes using ZrCl4 and Al2(SO4)3. Fluorescence excitation emission matrix coupled with parallel factor analysis (EEM-PARAFAC) identified the presence of three independent fluorescent components in AOM, including protein-like (C1), fulvic-like (C2) and humic-like components (C3). Size exclusion chromatography (SEC) revealed that C1 in AOM was composed of large-sized proteins and aromatic amino acids. The individual components exhibited their unique characteristics with respect to the dynamic changes. C1 showed the highest correlation with AOM concentrations (R2 = 0.843) upon the C/F processes. C1 could also be suggested as an optical predictor for the formation of trihalomethanes upon the C/F processes. This study sheds a light for the potential application of the protein-like component (C1) as a practical surrogate to track the evolution of AOM in water treatment or wastewater reclamation systems involving Chlorella vulgaris green algae.

Correction to: Building a low-cost domestic wastewater reclamation system using local agricultural waste in Kinmen islands, Taiwan

In the original publication of the article, the affiliations of the authors have been mentioned incorrectly. Now the correct affiliations have been provided in this correction.

The comprehensive environmental performance evaluation of wastewater reclamation systems

AbstractThis is an attempt to perform an environmental evaluation of wastewater reclamation systems as part of TC282 activity. Four treatment levels were set to evaluate the performance of the water for reuse: secondary, advanced, membrane bioreactor, and reclaimed. In this study, reclaimed treatment was determined to be the most effective in the evaluation of the efficiency of wastewater reclamation systems. The selection of an appropriate wastewater reclamation system to obtain water quality for the purpose of reuse is also important as part of the effort to minimize greenhouse gas emissions.

Techno-economic analysis of a decentralized wastewater treatment plant operating in closed-loop. A Finnish case study

The study analyzes a potential to improve the local waste and wastewater management in a Finnish community. The Lappeenranta wastewater treatment plant (WWTP) is used as a case study. Two different technological setups are considered for improving the wastewater treatment plant. These are used to construct four alternative wastewater reclamation scenarios. The mass and energy balances for the considered scenarios are developed and used as input for the profitability evaluation. The utilization of the sewage sludge from the WWTP and municipal solid waste fraction that cannot be recycled for the generation of heat and electricity at the CHP plant is investigated with the aim to improve the economic performance of the wastewater treatment facility. The studied scenarios are initially compared based on their investment and operational costs. The cost of water treatment increases significantly in the case of the investigated tertiary treatment systems: higher amounts of chemicals and electricity are needed to improve the water quality. At the same time, the study indicates that the profitability of a WWTP integrated with a CHP plant can be reasonably high in a wide range of likely price scenarios for alternative wastewater purification systems. The results of the analysis showed a significant potential for the investigated wastewater reclamation systems to improve the efficiency of solid waste and wastewater management in the community.

Comparison of methods to assess the integrity and separation efficiency of ultrafiltration membranes in wastewater reclamation processes

Membrane filtration is used in many water reuse applications, thanks to its high separation efficiency with regard to particles, bacteria, cysts and in the case of ultrafiltration even viruses. However, the separation performance of a membrane system can be affected and the permeate quality can be reduced or increased by phenomena such as membrane damage, membrane fouling or microbiological regrowth on both permeate and retentate side of the membrane. Thus, in order to guarantee a sufficiently high permeate quality, the separation efficiency of a membrane system has to be assessed sensitively, reliably and, if possible, continuously.In the here presented study, a variety of different analytical methods was tested to assess the separation efficiency of ultrafiltration membranes in a pilot-scale wastewater reclamation system. After intentionally damaging the membrane to different degrees, its integrity was monitored by pressure decay testing and permeate turbidity measurements, and by continuously monitoring the concentration of micro- and nanoparticles in the permeate stream. The microbiological permeate quality was not only assessed by plate counting, but also by flow cytometric measurements. The results showed that the membrane integrity is primarily affected by physical damaging, as detectable by pressure decay testing, while the permeate quality strongly depends on particle-membrane interactions such as formation of a fouling layer or clogging of membrane defects. Nanoparticle counting was found to be a very sensitive method to continuously monitor the membrane’s separation efficiency. Additionally, flow cytometry revealed that bacterial regrowth on the permeate side can affect the microbiological permeate quality in particular.

Optimization of sampling strategy to determine pathogen removal efficacy of activated sludge treatment plant.

Large-scale wastewater schemes rely on multi-barrier approach for the production of safe and sustainable recycled water. In multi-barrier wastewater reclamation systems, conventional activated sludge process (ASP) often constitutes a major initial treatment step. The main aim of this research was to determine most appropriate sampling approach to establish pathogen removal efficacy of ASP. The results suggest that ASP is capable of reducing human adenovirus (HAdV) and polyomavirus (HPyV) by up to 3 log10. The virus removal data suggests that HAdV removal is comparable to somatic bacteriophage belonging to Microviridae family. Due to the high removal of Escherichia coli (>3 log10) and very poor correlation with the enteric virus, it is not recommended that E. coli be used as a surrogate for enteric virus removal. The results also demonstrated no statistically significant differences (t test, P>0.05) in calculated log removal values (LRVs) for HAdV, HPyV, and Microviridae from samples collected on hydraulic retention time (HRT) or simultaneous paired samples collected for influent and effluent. This indicates that a more practical approach of simultaneous sampling for influent and effluent could be used to determine pathogen removal efficiency of ASP. The results also suggest that a minimum of 10, preferably 20 samples, are required to fully capture variability in the removal of virus. In order to cover for the potential seasonal prevalence of viruses such as norovirus and rotavirus, sampling should be spread across all seasons.

Building a low-cost domestic wastewater reclamation system using local agricultural waste in Kinmen islands, Taiwan

The ongoing processes of climate change and natural resource exhaustion have an especially great impact on small islands. Kinmen is an archipelago of several islands of approximately 150 km2 in area located off the southeast coast of mainland China. Kinmen does not have an abundance of natural resources, and therefore, its development is restricted by the ecological environment and reflected in cultural fragility. After the end of military administration in 1992, Kinmen transformed into a famous tourist attraction. The rapid development of tourism has attracted a large number of tourists, but also worsens the long-standing scarcity of freshwater resources. As Kinmen is currently aiming to move toward becoming a low-carbon demonstration island, installation of a water reclamation system with a low carbon consumption would be the best choice for the islands. A wastewater reclamation system that considers local conditions and uses local materials to reduce the carbon footprint was therefore proposed in this study. To reduce the carbon footprint, the system uses local agricultural waste, including sorghum stalks and oyster shells, as filter media to construct a water purification system that can purify domestic wastewater by reclamation. The results demonstrated that the reductions in suspended solids, biochemical oxygen demand and NH4-N using this system reached 95.3, 97.0 and 99.3%, respectively, achieving the standards required for tertiary wastewater treatment. In addition, oyster shells after burning absorbed around 50% of the phosphorus in wastewater. The findings demonstrated that this low-carbon water reclamation system can achieve waste reduction, recycling wastewater to a quality suitable for irrigation.

Removal characteristics and fluctuation of norovirus in a pilot-plant by an ultrafiltration membrane for the reclamation of treated sewage

ABSTRACTWhen ultrafiltration (UF) membrane processes that are able to effectively reduce viruses are installed in a waste water reclamation system, the security of sanitation safety for water-borne diseases is essential. It is important to understand the behaviour of enteric viruses such as Adenovirus, Rotavirus and Norovirus (NV), the detection rate of which is relatively high in sewage. This study focused on the UF membrane process for the reclaimed water treatment process, and investigated the removal performance in NV type GI and GII in the UF membrane process by performing coagulation and sedimentation as the pre-treatment process in a pilot-plant by considering the concentration fluctuation of the influent. The removal ratio of GI and GII by the UF membrane process alone was 3.3 ± 0.7 Log in GI and 3.6 ± 1.0 Log in GII, and no clear difference in the removal ratio by NV species type was observed. The removal ratio of NV GII was increased by about 0.6 Log on average (4.2 ± 1.1 Log) compared with the UF membrane process only when the coagulation and sedimentation process were conducted as pre-treatment. However, there was no significant difference in the removal of NV GI by conducting the coagulation and sedimentation process.

Changes of microbial composition during wastewater reclamation and distribution systems revealed by high-throughput sequencing analyses

This study employed 454-pyrosequencing to investigate microbial and pathogenic communities in two wastewater reclamation and distribution systems. A total of 11972 effective 16S rRNA sequences were acquired from these two reclamation systems, and then designated to relevant taxonomic ranks by using RDP classifier. The Chao index and Shannon diversity index showed that the diversities of microbial communities decreased along wastewater reclamation processes. Proteobacteria was the most dominant phylum in reclaimed water after disinfection, which accounted for 83% and 88% in two systems, respectively. Human opportunistic pathogens, including Clostridium, Escherichia, Shigella, Pseudomonas and Mycobacterium, were selected and enriched by disinfection processes. The total chlorine and nutrients (TOC, NH3-N and NO3-N) significantly affected the microbial and pathogenic communities during reclaimed water storage and distribution processes. Our results indicated that the disinfectant-resistant pathogens should be controlled in reclaimed water, since the increases in relative abundances of pathogenic bacteria after disinfection implicate the potential public health associated with reclaimed water.

Reduction of Pathogens, Indicator Bacteria, and Alternative Indicators by Wastewater Treatment and Reclamation Processes

In wastewater reclamation systems, microbiological monitoring is conducted to ensure that the users of reclaimed water are exposed to minimal risks from exposure to pathogens. Typically, utilities rely on the use of process controls to remove or inactivate pathogens. Routine monitoring of indicator organisms is conducted to evaluate overall process performance and for regulatory compliance. However, the effectiveness of individual treatment processes for removal of pathogens is dependent on process variables. This project was conducted to compare the effectiveness of biological treatment, filtration, and disinfection for removal of bacterial and viral indicators, enteric viruses, and protozoan pathogens. Six full-scale treatment facilities were each sampled a minimum of four times over a one year period. The relative impacts of loading conditions, process design, and operating parameters on the removal/inactivation of a suite of nine microbial species (bacteria, coliphages, enteric viruses, and protozoan pathogens) was evaluated. Bacterial removal was consistent for all types of biological systems, however, increased virus removal was associated with biological nutrient removal and nitrification processes. Parasite removal was highly variable. The effectiveness of filtration was impacted most by the use of upstream chemicals (either chlorine or coagulant chemicals). Chlorine disinfection was more effective in cases where ammonia levels were low (biological nutrient removal or nitrification facilities). Infectivity assays for protozoan pathogens suggest that the proportion of infective cysts or oocysts increases with increasing level of treatment. This title belongs to WERF Research Report Series ISBN: 9781843397304 (Print) ISBN: 9781780404370 (eBook)

Environmental performance of wastewater reuse systems: impact of system boundaries and external conditions.

Wastewater reclamation will be a significant part of future water management and the environmental assessment of various treatment systems to reuse wastewater has become an important research field. The secondary treatment process and sludge handling on-site are, especially, electricity demanding processes due to aeration, pumping, mixing, dewatering, etc. used for operation and are being identified as the main contributor for many environmental impacts. This study discusses how the environmental performance of reuse treatment systems may be influenced by surrounding conditions. This article illustrates and discusses the importance of factors commonly treated as externalities and as such not being included in optimization strategies of reuse systems, but that are necessary to environmentally assess wastewater reclamation systems. This is illustrated by two up-stream and downstream processes; electricity supply and the use of sludge as fertilizer commonly practiced in regions considered for wastewater reclamation. The study shows that external conditions can have a larger impact on the overall environmental performance of reuse treatment systems than internal optimizations could compensate for. These results imply that a more holistic environmental assessment of reuse schemes could provide less environmental impacts as externalities could be included in measures to reduce the overall impacts.