Water Reuse Applications Research Articles

A multi expert decision support tool for the evaluation of advanced wastewater treatment trains: A novel approach to improve urban sustainability

Wastewater Treatment (WWT) for water reuse applications has been accepted as a strategic solution in improving water supplies across the globe; however, there are still various challenges that should be overcome. Selection of practical solutions is then required whilst considering technical, environmental, socio-cultural, and financial factors. In this study, a multi expert decision support tool that considers a variety of evaluation criteria is proposed to provide a ranking system for competing advanced WWT technologies in terms of their performance. Two scenarios of water reuse in the contexts of Brazil and Greece are defined, and evaluation is undertaken based on opinions of water reuse experts. The results prove that the tool would successfully facilitate rigorous and methodical analysis in evaluation of WWT technologies for water reuse applications with potential for use under various sets of evaluation criteria, WWT technologies and contexts.

Electrochemical treatment for greywater reuse: effects of cell configuration on COD reduction and disinfection byproduct formation and removal

Abstract Electrochemical (EC) treatment presents a low-energy, water-reuse strategy with potential application to decentralized greywater treatment. This study focused on evaluating the impacts of cell configuration, current density, and cathode material on chemical oxygen demand (COD) removal and disinfection byproduct (DBP) formation in greywater. The formation and/or cathodic removal of active chlorine, perchlorate, haloacetic acids, and trihalomethanes were assessed during EC treatment. DBP formation was proportional to current density in undivided EC cells. Sequential anodic-cathodic treatment in divided EC cells resulted in COD removal in the catholyte and anolyte. The anodic COD removal rate (using a mixed metal-oxide anode) was greater than the cathodic removal rate employing boron-doped diamond (BDD) or graphite cathodes, but anodic and cathodic COD removal was similar when a stainless-steel cathode was used. The overall energy demand required for 50% COD removal was 24% less in the divided cells using the graphite or BDD cathodes (13 W-h L−1) compared to undivided cells (20 W-h L−1). Perchlorate formation was observed in undivided experiments (>50 μg/L), but not detected in divided experiments. While haloacetic acids (HAAs) and trihalomethanes (THMs) were generated anodically; they were removed on the cathode surface in the divided cell. These results suggest that divided configurations provide potential to mitigate DBPs in water reuse applications.

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.

Effect of pre-ozonation on nanofiltration membrane fouling during water reuse applications

Abstract The selection of appropriate purification technologies for the potable reuse of municipal wastewater effluent is an important component of water resource management. In this study, a fully automated high-pressure bench-scale membrane system was used to investigate the impact of pre-ozonation of wastewater effluent on nanofiltration (NF) fouling during reuse applications. A commercial polyamide NF membrane was employed to evaluate the impact of pre-ozonation on fouling and determine an effective specific ozone dose. The results indicated that pre-ozonation of sequencing batch reactor membrane bioreactor (SBMBR) effluent with a relatively low specific ozone dose (0.2 mg O3/mg DOC) could effectively mitigate a significant portion of fouling on the membrane compared to filtration without pre-ozonation. However, increasing the specific ozone dose to 0.4 mg O3/mg DOC did not provide a significant additional benefit. The dissolved organic carbon removal performance of the NF membrane did not show a substantial change when pre-ozonation was applied and remained relatively constant which may be due to the relatively low applied specific ozone dose. Organic fouling was suspected to be the main fouling mechanism during SBMBR filtration with NF membrane.

Microbial community characterization of ozone-biofiltration systems in drinking water and potable reuse applications

Microbial community structure in the ozone-biofiltration systems of two drinking water and two wastewater treatment facilities was characterized using 16S rRNA gene sequencing. Collectively, these datasets enabled comparisons by facility, water type (drinking water, wastewater), pre-oxidation (ozonation, chlorination), media type (anthracite, activated carbon), media depth, and backwash dynamics. Proteobacteria was the most abundant phylum in drinking water filters, whereas Bacteroidetes, Chloroflexi, Firmicutes, and Planctomycetes were differentially abundant in wastewater filters. A positive correlation was observed between media depth and relative abundance of Cyanobacteria in drinking water filters, but there was only a slight increase in one alpha diversity metric with depth in the wastewater filters. Media type had a significant effect on beta but not alpha diversity in drinking water and wastewater filters. Pre-ozonation caused a significant decrease in alpha diversity in the wastewater filters, but the effect on beta diversity was not statistically significant. An evaluation of backwash dynamics resulted in two notable observations: (1) endosymbionts such as Neochlamydia and Legionella increased in relative abundance following backwashing and (2) nitrogen-fixing Bradyrhizobium dominated the microbial community in wastewater filters operated with infrequent backwashing. Bradyrhizobium is known to generate extracellular polymeric substances (EPS), which may adversely impact biofilter performance and effluent water quality. These findings have important implications for public health and the operation and resiliency of biofiltration systems.

Electro-oxidation as efficient pretreatment to minimize the membrane fouling in water reuse processes

The effluent from a wastewater treatment plant was pretreated with an electrochemical cell using boron doped diamond (BDD) electrodes in order to control the fouling of an ultrafiltration membrane. The results showed that the electrochemical pretreatment decreased 36–67% the transmembrane pressure (TMP), and consequently the membrane fouling, with increasing applied current densities. The removal of dissolved organic carbon (DOC) and turbidity by the membrane process was enhanced 40% and 41% respectively using the electro-oxidation pretreatment. The removal of DOC in the pretreatment stage correlated well with the maximum TMP reached. The application of electro-oxidation as a pretreatment stage points out to be a promising alternative to reduce the membrane fouling and increase the water quality for water reuse applications.

A novel concept to integrate energy recovery into potable water reuse treatment schemes

AbstractPotable water reuse applications can provide a safe and sustainable water supply where conventional freshwater resources are limited. The objectives of this study were fourfold: (i) to analyse existing potable water reuse applications regarding operational characteristics and energy demands, (ii) to determine the theoretical energy potential of wastewater and identify opportunities for energy recovery, (iii) to define design requirements for potable water reuse schemes that integrate energy recovery and (iv) to propose strategies for more energy efficient potable water reuse schemes. Existing potable water reuse schemes commonly utilize conventional wastewater treatment processes including biological nutrient removal followed by advanced water treatment processes. While meeting high product water quality, these treatment schemes are characterized by relatively high specific energy demands (1.18 kWh/m3). Given that the theoretical energy potential of municipal wastewater is approximately two times higher (2.52 kWh/m3), opportunities exist to integrate energy recovery strategies. We propose three alternative potable water reuse schemes that integrate energy recovery from carbon via methane and nitrogen via either the coupled aerobic–anoxic nitrous decomposition operation process or partial nitritation/anammox. Compared to conventional potable water reuse schemes, the energy requirements of these schemes can be reduced by 7–29% and the overall energy balance by 38–80%.

Health-based ingestion exposure guidelines for Vibrio cholerae: Technical basis for water reuse applications

U.S. military and allied contingency operations are increasingly occurring in locations with limited, unstable or compromised fresh water supplies. Non-potable graywater reuse is currently under assessment as a viable means to increase mission sustainability while significantly reducing the resources, logistics and attack vulnerabilities posed by transport of fresh water. Development of health-based (non-potable) exposure guidelines for the potential microbial components of graywater would provide a logical and consistent human-health basis for water reuse strategies. Such health-based strategies will support not only improved water security for contingency operations, but also sustainable military operations.Dose-response assessment of Vibrio cholerae based on adult human oral exposure data were coupled with operational water exposure scenario parameters common to numerous military activities, and then used to derive health risk-based water concentrations. The microbial risk assessment approach utilized oral human exposure V. cholerae dose studies in open literature. Selected studies focused on gastrointestinal illness associated with experimental infection by specific V. cholerae serogroups most often associated with epidemics and pandemics (O1 and O139). Nonlinear dose-response model analyses estimated V. cholerae effective doses (EDs) aligned with gastrointestinal illness severity categories characterized by diarrheal purge volume. The EDs and water exposure assumptions were used to derive Risk-Based Water Concentrations (CFU/100mL) for mission-critical illness severity levels over a range of water use activities common to military operations.Human dose-response studies, data and analyses indicate that ingestion exposures at the estimated ED1 (50CFU) are unlikely to be associated with diarrheal illness while ingestion exposures at the lower limit (200CFU) of the estimated ED10 are not expected to result in a level of diarrheal illness associated with degraded individual capability. The current analysis indicates that the estimated ED20 (approximately 1000CFU) represents initiation of a more advanced stage of diarrheal illness associated with clinical care.

Evaluating water reuse applications under uncertainty: generalized intuitionistic fuzzy-based approach

Water reuse is a viable option to increase urban water supply, especially under new realities of climate change and increasing anthropogenic activities. A sustainable water reuse application should be cost-effective and have acceptable health risk to consumers. Water reuse application evaluation is complex because data acquisitions are usually associated with the problems of uncertainty, hesitancy, and parameterization. In this paper, a generalized intuitionistic fuzzy soft set (GIFSS)-based decision support framework is proposed to provide an effective approach to describe uncertainty and hesitancy in an intuitionistic fuzzy number. In addition, the modified measures of comparison and similarity are proposed to compare water reuse applications. Then, the proposed framework is applied to the City of Penticton (British Columbia, Canada) to evaluate seven water reuse applications. The evaluation results show that the applications of garden flower watering and public parks watering are the most preferred alternatives, which are consistent with the existing practice in the city. Furthermore, the results are highly affected by the generalized parameter and the weights of evaluation criteria. Both the comparison measure-based and similarity measure-based evaluations within the same GIFSS-based framework produce consistent results, indicating an applicable and efficient methodology.

Fit-for-purpose wastewater treatment: Testing to implementation of decision support tool (II)

This paper is the second in a series of two papers. In Paper I, a decision support tool (DST), FitWater, was developed for evaluating the potential of wastewater treatment (WWT) trains for various water reuse applications. In the present paper, the proposed DST has been tested and implemented. FitWater has been tested with several existing WWT plants in Canada and the USA, demonstrating FitWater's effectiveness in estimating life cycle cost (LCC), health risk, and energy use. FitWater has also been implemented in a newly planned neighbourhood in the Okanagan Valley (BC, Canada) by developing 12 alternative WWT trains for water reuse in lawn and public parks irrigation. The results show that FitWater can effectively rank WWT train alternatives based on LCC, health risk, amount of reclaimed water, energy use, and carbon emissions. Moreover, functions have been developed for the variation of unit annualized LCC and energy intensity per unit log removal of microorganisms in different treatment technologies with varying plant capacities. The functions have power relations, showing the economies of scale. FitWater can be applied to identify a cost-effective, risk-acceptable, and energy efficient wastewater treatment train with a plant capacity of 500m3/day or more. Furthermore, FitWater can be used to assess potential economic impacts of developing microbiologically stringent effluent standards. The capability of FitWater can be enhanced by including physio-chemical quality of wastewater, additional treatment technologies, and carbon emissions from wastewater decomposition processes.

Fouling reduction by UV-based pretreatment in hollow fiber ultrafiltration membranes for urban wastewater reuse

Effluent organic matter (EfOM) is the major cause of fouling in low pressure membranes processes for wastewater reuse. UV light and UV/H2O2 have been applied as pretreatment to control the fouling in ultrafiltration membranes. The results show that both pretreatments decreased 30–44% the transmembrane pressure (TMP), and consequently the membrane fouling. The removal of dissolved organic carbon (DOC) by the membrane was improved by 31% in the case of UV/H2O2 pretreatment. The turbidity removal was improved more than 30% when both UV-based pretreatments were used. The removal of SUVA, which it is a measurement of the aromaticity of the EfOM, correlated well with the maximum TMP reached so, the reduction of SUVA can be an indicator of the membrane fouling reduction in order to assess other pretreatments. The application of these pretreatments can represents important savings in the operational costs related with the membrane cleaning procedures and maintenance. So, the application of UV-based pretreatments seems to be a promising technique to reduce the membrane fouling and to increase the water quality for water reuse applications.

Cost comparison of full-scale water reclamation technologies with an emphasis on membrane bioreactors.

The paper assesses the costs of full-scale membrane bioreactors (MBRs). Capital expenditures (CAPEX) and operating expenses (OPEX) of Spanish MBR facilities have been verified and compared to activated sludge plants (CAS) using water reclamation treatment (both conventional and advanced). Spanish MBR facilities require a production of 0.6 to 1.2 kWh per m3, while extended aeration (EA) and advanced reclamation treatment require 1.2 kWh per m3. The energy represents around 40% of the OPEX in MBRs. In terms of CAPEX, the implementation costs of a CAS facility followed by conventional water reclamation treatment (physical-chemical + sand filtration + disinfection) ranged from 730 to 850 €.m-3d, and from 1,050 to 1,250 €.m-3d in the case of advanced reclamation treatment facilities (membrane filtration) with a capacity of 8,000 to 15,000 m3d-1. The MBR cost for similar capacities ranges between 700 and 960 €.m-3d. This study shows that MBRs that have been recently installed represent a cost competitive option for water reuse applications for medium and large capacities (over 10,000 m3d-1), with similar OPEX to EA and conventional water reclamation treatment. In terms of CAPEX, MBRs are cheaper than EA, followed by advanced water reclamation treatment.

Assessment of activated sludge, membrane bioreactors and vertical flow wetlands for upgrading sewage treatment works

ABSTRACTThis paper demonstrates that utilising a vertical flow (VF) wetland after a conventional activated sludge (CAS) delivers equivalent or better effluent quality to a membrane bioreactor (MBR) based on a side-by-side pilot trial. The CAS was operated under the solids retention times (SRT) of 6, 12, and 20 days, with the effluent from each pilot plant fed onto a soil aquifer treatment column to better understand their water reuse application potential. Results showed an upgraded CAS + VF system could deliver effluents with median values of 34 mgO2.L–1, 7 mg.L–1 and 1.9 mg.L–1 for organics, solids and ammonia nitrogen, respectively, which were statistically similar to those from the MBR. Water reuse standards were achieved by the upgraded system for most parameters, with the exception of total coliform removal. The upgraded system delivered superior metal removal when compared to the CAS. An economic analysis showed upgrading a CAS with a VF wetland was more favourable than investing in an MBR system for example works of 5000 and 50,000 population equivalents if the VF system was operated at hydraulic loading rates of 0.03 m.d–1 and 0.08 m.d–1, respectively. This was delivered for a tenth of the carbon footprint of the MBR treatment.

Low temperature MS2 (ATCC15597-B1) virus inactivation using a hot bubble column evaporator (HBCE)

In the treatment of household wastewater viruses are hard to eliminate. A new technique is described which tackles this major problem. The MS2 (ATCC15597-B1) virus was used as a surrogate to estimate the inactivation rates for enteric viruses by a hot (150°C) air bubble column evaporator (HBCE) system Its surface charging properties obtained by dynamic light scattering, have been studied in a range of aqueous salt solutions and secondary treated synthetic sewage water. A combination of MS2 virus surface charge properties with thermal inactivation rates, and an improved double layer plaque assay technique, allows an assessment of the efficiency of the HBCE process for virus removal in water. The system is a new energy efficient treatment for water reuse applications.

Microbial quality of reclaimed water for urban reuses: Probabilistic risk-based investigation and recommendations

Although Canada has abundant freshwater resources, many cities still experience seasonal water shortage. Supply-side and demand-side management is a core strategy to address this water shortage. Under this strategy, reclaimed water, which the Canadian public is willing to use for non-potable purposes, is an option. However, no universal guidelines exist for reclaimed water use. Despite the federal government's long-term goal to develop guidelines for many water reuse applications, guidelines have only been prescribed for reclaimed water use in toilet and urinal flushing in Canada. At the provincial level, British Columbia (BC) has promulgated guidelines for wide applications of reclaimed water but only at broad class levels. This research has investigated and proposed probabilistic risk-based recommended values for microbial quality of reclaimed water in various non-potable urban reuses. The health risk was estimated by using quantitative microbial risk assessment. Two-dimensional Monte Carlo simulations were used in the analysis to include variability and uncertainty in input data. The proposed recommended values are based on the indicator organism E. coli. The required treatment levels for reuse were also estimated. In addition, the recommended values were successfully applied to three wastewater treatment effluents in the Okanagan Valley, BC, Canada. The health risks associated with other bacterial pathogens (Campylobacter jejuni and Salmonella spp.), virus (adenovirus, norovirus, and rotavirus), and protozoa (Cryptosporidium parvum and Giardia spp.), were also estimated. The estimated risks indicate the effectiveness of the E. coli-based water quality recommended values. Sensitivity analysis shows the pathogenic E. coli ratio and morbidity are the most sensitive input parameters for all water reuses. The proposed recommended values could be further improved by using national or regional data on water exposures, disease burden per case, and the susceptibility fraction of population.

Soil aquifer treatment for wastewater treatment and reuse

Soil aquifer treatment (SAT) is a managed aquifer recharge system in which the quality of the feed water (stormwater or wastewater treatment plant effluent) is further improved during soil passage. This paper provides an overview of SAT systems for wastewater treatment and reuse, and summarises design, removal efficiencies and pre-and post-treatment options as well as cost aspects of SAT using infiltration basins. SAT is an environment-friendly and robust multi-contaminant removal system which is effective in removing pathogens, nitrogen, bulk organic matter and the majority of organic micropollutants. The contaminant removal efficiency of SAT system, however, depends on several factors including source water quality, local hydrogeological conditions and process conditions applied. The performance of SAT system can be further improved by proper site selection and appropriate design of its components including pre- and post-treatment. SAT serves as an environmental and psychological barrier for water reuse applications. It is equally attractive for developed as well as developing countries and flexible enough to allow adaptation to local requirements by combining it with conventional (above the ground) natural or engineered water and wastewater treatment technologies.

Water reuse through managed aquifer recharge (MAR): assessment of regulations/guidelines and case studies

Managed aquifer recharge (MAR) with reclaimed water is an important water reuse application. As an intentional way of recharging water into aquifers, MAR can be used to address water shortages and contribute to sustainable water resources management practices. The establishment of a MAR system depends on the source of recharge water, the selection of a recharge method and site, the type of water treatment system, and the ultimate purpose of recovered water, and these components are closely related and integrated. However, at present, detailed regulations or guidelines that specifically guide MAR with reclaimed water are unavailable in most countries. The complexity of MAR systems and the lack of a sophisticated regulatory framework increase the difficulties of MAR implementation. This review provides an introduction to MAR with reclaimed water and a comparison of current worldwide water reuse regulations or guidelines, including a proposed approach for MAR implementation. An analysis of selected MAR with reclaimed water case studies was also done within the context of this proposed approach. This paper recommends the development of specific regulatory or design criteria, including a complete quantitative risk assessment framework for the evaluation and operation of MAR systems.

Editorial: Journal of Water Reuse and Desalination moves to Open Access

The Journal of Water Reuse and Desalination (JWRD) has been established since 2011, and has successfully grown in popularity as a leading publisher of scientific articles on management, sustainability and application of water reuse and desalination. In order to further increase our readership and disseminate the research outcomes more broadly, JWRD is going to become Open Access in 2017. By going Open Access, the published articles will be available free of charge to everyone who has internet access, making them available to the world rather than just the subscribers of the journal. This will increase the visibility of published articles and allow them to …

Submerged membrane filtration adsorption hybrid system for the removal of organic micropollutants from a water reclamation plant reverse osmosis concentrate

Reverse osmosis (RO) is a widespread water treatment process utilised in water reuse applications. However, the improper discharge of RO concentrate (ROC) containing organic micropollutants such as pharmaceuticals into the environment may cause potential health risks to non-target species and particularly those in aquatic environments. A study was conducted using a submerged membrane-filtration/granular activated carbon (GAC) adsorption hybrid system to remove organic micropollutants from a water treatment plant ROC by initially adding 10g GAC /L of membrane reactor volume with 10% daily GAC replacement. The percentage of dissolved organic carbon removal varied from 60% to 80% over an operation lasting 10days. Removal of organic micropollutants was almost complete for virtually all compounds. Of the 19 micropollutants tested, only two remained (the less hydrophobic DEET 27ng/L and the hydrophilic sulfamethoxazole 35ng/L) below 80% removal on day 1, while five of the most hydrophobic micropollutants were detectable in very small concentrations (<5–10ng/L) with >89%–>99% being removed. High percentages of micropollutants were removed probably because of their high hydrophobicity or they had positive or neutral charges and therefore they were electrostatically adsorbed to the negatively charged GAC.

A rapid and reliable technique for N-nitrosodimethylamine analysis in reclaimed water by HPLC-photochemical reaction-chemiluminescence

A fast and reliable analytical technique was evaluated and validated for determination of N-nitrosodimethylamine (NDMA) formation and rejection by reverse osmosis (RO) membranes in potable water reuse applications. The analytical instrument used in this study is high-performance liquid chromatography (HPLC), photochemical reaction (PR) and chemiluminescence (CL) – namely HPLC-PR-CL. Results reported here show that HPLC-PR-CL can be used to measure NDMA with a similar level of accuracy compared to conventional and more time-consuming techniques using gas chromatography and tandem mass spectrometry detection in combination with solid phase extraction. Among key residual chemicals (i.e. monochloramine, hydrogen peroxide and hypochlorite) in reclaimed wastewater, hypochlorite was the only constituent that interfered with the determination of NDMA by HPLC-PR-CL. However, hypochlorite interference was eliminated by adding ascorbic acid as a reducing agent. Direct injection of ultrafiltration (UF)-treated wastewater samples into HPLC-PR-CL also resulted in an underestimation of the NDMA concentration possibly due to interference by organic substances in the UF-treated wastewater. Accurate determination of NDMA concentrations in UF-treated wastewater was achieved by reducing the sample injection volume from 200 to 20 μL, though this increased the method detection limit from 0.2 to 2 ng/L. In contrast, no interference was observed with RO permeate. These results suggest that RO membranes could remove part of substances that interfere with the NDMA analysis by HPLC-PR-CL. In addition, RO treatment experiments demonstrated that HPLC-PR-CL was capable of evaluating near real-time variation in NDMA rejection by RO.