Indirect Potable Reuse Research Articles

Pretreatment for potable reuse: Enhancing the biological removal of 1,4-dioxane from landfill leachate through cometabolism with tetrahydrofuran.

1,4-Dioxane is a probable human carcinogen and a persistent aquatic contaminant. Cometabolic biodegradation of 1,4-dioxane is a promising low-cost and effective treatment technology; however, further demonstration is needed for treating landfill leachate. This technology was tested in two full-scale moving bed biofilm reactors (MBBRs) treating raw landfill leachate with tetrahydrofuran selected as the cometabolite. The raw leachate contained on average 82 μg/L of 1,4-dioxane and before testing the MBBRs removed an average of 38% and 42% of 1,4-dioxane, respectively. First, tetrahydrofuran was added to MBBR 1, and 1,4-dioxane removal was improved to an average of 73%, with the control MBBR removing an average of 37% of 1,4-dioxane. During this period, an optimal dose of 2mg/L of tetrahydrofuran was identified. Tetrahydrofuran was then fed to both MBBRs, where the 1,4-dioxane removal was on average 73% and 80%. Cometabolic treatment at the landfill significantly reduced the concentration of 1,4-dioxane received from the landfill at a downstream wastewater treatment and indirect potable reuse facility, reducing the load of 1,4-dioxane from 44% to 24% after the study. PRACTITIONER POINTS: Cometabolic degradation of leachate 1,4-dioxane with THF in MBBRs is a feasible treatment technology and a low-cost technique when retrofitting existing biological treatment facilities. The MBBRs can be operated at a range of temperatures, require no operational changes beyond THF addition, and operate best at a mass ratio of THF to 1,4-dioxane of 24. Source control of 1,4-dioxane significantly reduces the concentration of 1,4-dioxane in downstream wastewater treatment plants and potable reuse facilities.

Comparison of treatment trains for indirect potable reuse and use of quantitative microbial risk assessment (QMRA) to evaluate reliability of pathogen removal: Zoo Miami case study

Wastewater and reclaimed water contain various microorganisms such as bacteria, viruses, and protozoa that can cause waterborne diseases in humans and animals. Zoos and animal conservation parks utilize reclaimed water for various purposes which may contain pathogens harmful to human and animal health. The goal of this study was to assess the treatment performance of two treatment trains for indirect potable reuse (IPR) and perform quantitative microbial risk assessment (QMRA) to evaluate the reliability of pathogen removal at a proposed advanced water treatment facility at the Zoo Miami. A review of advanced treatment and disinfection technologies relevant for reclaimed water production and pathogen removal was conducted as a part of this study. DPRisk was used to perform QMRA for four reference pathogens selected as model organisms for two IPR treatment trains (TT1 and TT2). Public health risk estimates for pathogens including Adenovirus, Cryptosporidium, Giardia, and enteric viruses indicated that the risk of infection was below the EPA's target daily threshold of 2.7 × 10−7 and annual risk threshold of 10−4 without failure analysis. With failure analysis, both treatment trains met the daily risk goals for each of the reference pathogens approximately 99 % of the time. Adenovirus demonstrated the highest probability of infection with a mean annual risk of infection for TT1 of 6.65 × 10−9 in the absence of failures but reached a maximum of 7.34 × 10−2 with failure analysis. TT2 resulted in higher risk estimates compared to TT1 with a mean annual risk of infection of 2.10 × 10−8 without failure and a maximum of 8.37 × 10−2 with failure analysis. The results of the failure analysis demonstrate the benefit of treatment redundancy in potable reuse system design and highlight the importance of online process monitoring to rapidly identify off-spec or treatment failure events to protect public health. With this information, stakeholders can better understand treatment requirements and microbiological risks to inform potable reuse planning, design, and risk management.

Long-Term Statistical Process Monitoring of an Ultrafiltration Water Treatment Process.

As water treatment technology has improved, the amount of available process data has substantially increased, making real-time, data-driven fault detection a reality. One shortcoming of the fault detection literature is that methods are usually evaluated by comparing their performance on hand-picked, short-term case studies, which yields no insight into long-term performance. In this work, we first evaluate multiple statistical and machine learning approaches for detrending process data. Then, we evaluate the performance of a PCA-based fault detection approach, applied to the detrended data, to monitor influent water quality, filtrate quality, and membrane fouling of an ultrafiltration membrane system for indirect potable reuse. Based on two short case studies, the adaptive lasso detrending method is selected, and the performance of the multivariate approach is evaluated over more than a year. The method is tested for different sets of three critical tuning parameters, and we find that for long-term, autonomous monitoring to be successful, these parameters should be carefully evaluated. However, in comparison with industry standards of simpler, univariate monitoring or daily pressure decay tests, multivariate monitoring produces substantial benefits in long-term testing.

Indicator and pathogenic virus removal in bench scale soil aquifer treatment

The demonstration of enteric virus removal for indirect potable reuse of advanced purified water is necessary to ensure safe water reclamation practices. This study evaluated the efficacy of soil treatment in reducing concentrations of Pepper Mild Mottle Virus (PMMoV), Hepatitis A (HAV), and Norovirus (NoV) gene markers through bench scale unsaturated soil columns. Three different infiltration rates were evaluated to determine their impact on viral gene marker removal. The concentrations of viral markers in the column influent and effluent samples were measured through RNA extraction and then RT-qPCR, and the log reduction values (LRVs) were calculated to quantify the effectiveness of removal across the columns. The LRVs achieved for PMMoV were 2.80 ± 0.36, 2.91 ± 0.48, and 2.72 ± 0.32 for infiltration rates of 4.9 mm/h, 9.4 mm/h, and 14.0 mm/h, respectively. A one-way ANOVA indicated no statistically significant differences in LRVs among the various infiltration rates (p-value = 0.329). All samples measured for HAV were below the detection limit both in the influent and effluent of the soil columns. While NoV GI and GII markers were measurable in the soil column influent, they were removed to below the detection limit in the effluent. The use of half the Limit-of-Detection (LoD) for effluent values enabled the estimation of log removals, which were calculated as 1.42 ± 0.07, 1.64 ± 0.29, and 1.74 ± 0.18 for NoV GI and 1.14 ± 0.19, 1.58 ± 0.21, and 1.87 ± 0.41 for NoV GII at infiltration rates of 4.9 mm/h, 9.4 mm/h, and 14.0 mm/h. This highlights the efficacy of soil treatment in reducing virus gene marker concentrations at various infiltration rates, and that spreading basins employed for reclaimed water recharge to ground water aquifers are an effective method for reducing the presence of viral contaminants in indirect potable reuse systems.

Process benefits of ozone/BAC as pretreatment to membrane-based advanced treatment for direct potable reuse

ABSTRACT The state of California, USA, has developed regulations for projects that want to pursue direct potable reuse. One of the most significant requirements is that the treatment train must include ozone and biological activated carbon (ozone/BAC) as pretreatment to a membrane-based treatment train. Ozone/BAC mitigates chemical peaks and diversifies the removal mechanisms of low molecular weight compounds likely to persist in advanced treated water. This paper will present the process benefits of ozone/BAC as pretreatment to the membrane-based treatment train based on testing at a 3,785 m3/d demonstration facility in San Diego, California, USA. One of the most significant benefits of ozone/BAC pretreatment is the improved water quality that benefits not only the product water produced for potable consumption but also the residual stream that is generated with the implementation of the RO process, commonly known as RO concentrate. This improved water quality originates from TOC reduction which is achieved through a combination of chemical oxidation with ozonation and biological growth in the BAC process that results in reduced operating pressures and chemical use for the membrane systems. These process benefits were quantified to develop an overall water cost comparison between a DPR and an indirect potable reuse train.

To what extent do water reuse treatments reduce antibiotic resistance indicators? A comparison of two full-scale systems

Water reuse is an essential strategy for reducing water demand from conventional sources, alleviating water stress, and promoting sustainability, but understanding the effectiveness of associated treatment processes as barriers to the spread of antibiotic resistance is an important consideration to protecting human health. We comprehensively evaluated the reduction of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) in two field-operational water reuse systems with distinct treatment trains, one producing water for indirect potable reuse (ozone/biologically-active carbon/granular activated carbon) and the other for non-potable reuse (denitrification-filtration/chlorination) using metagenomic sequencing and culture. Relative abundances of total ARGs/clinically-relevant ARGs and cultured ARB were reduced by several logs during primary and secondary stages of wastewater treatment, but to a lesser extent during the tertiary water reuse treatments. In particular, ozonation tended to enrich multi-drug ARGs. The effect of chlorination was facility-dependent, increasing the relative abundance of ARGs when following biologically-active carbon filters, but generally providing a benefit in reduced bacterial numbers and ecological and human health resistome risk scores. Relative abundances of total ARGs and resistome risk scores were lowest in aquifer samples, although resistant Escherichia coli and Klebsiella pneumoniae were occasionally detected in the monitoring well 3-days downgradient from injection, but not 6-months downgradient. Resistant E. coli and Pseudomonas aeruginosa were occasionally detected in the nonpotable reuse distribution system, along with increased levels of multidrug, sulfonamide, phenicol, and aminoglycoside ARGs. This study illuminates specific vulnerabilities of water reuse systems to persistence, selection, and growth of ARGs and ARB and emphasizes the role of multiple treatment barriers, including aquifers and distribution systems.

Per- and poly-fluoroalkyl substances removal in multi-barrier advanced water purification system for indirect potable reuse.

The study evaluated the removal efficacy of per- and poly-fluoroalkyl substances (PFAS) across various advanced water treatment (AWT) processes in a field-scale AWT train using secondary effluent samples from a full-scale water reclamation facility (WRF). Samples collected from April to October 2020 revealed PFCAs as the dominant PFAS compounds in the WRF secondary effluent, with PFPeA having the highest average concentration and PFSAs in notably lower amounts. Temporal fluctuations in total PFAS concentrations peaked in September 2020, which may reflect the seasonality in PFAS discharges related to applications like AFFFs and pesticides. In assessing AWT processes, coagulation-flocculation-clarification-filtration system showed no notable PFAS reduction, while ozonation resulted in elevated PFBS and PFBA concentrations. Biological activated carbon (BAC) filtration effectively removed long-chain PFAS like PFOS and PFHxS but saw increased concentrations of short-chain PFAS post-treatment. Granular activated carbon (GAC) filtration was the most effective treatment, reducing all PFSAs below the detection limits and significantly decreasing most PFCAs, though short-chain PFCAs persisted. UV treatment did not remove short-chain PFCAs such as PFBA, PFPeA, and PFHxA. The findings highlight the efficacy of AWT processes like GAC in PFAS reduction for potable reuse, but also underscore the challenge presented by short-chain PFAS, emphasizing the need for tailored treatment strategies. PRACTITIONER POINTS: Secondary effluents showed higher concentrations of PFCAs compared to PFSAs. Advanced water treatment effectively removes long-chain PFAS but not short-chain. Ozonation may contribute to formation of short-chain PFAS. BAC is less effective on short-chain PFAS, requiring further GAC treatment.

Micropoluentes no reúso potável de água: revisão dos documentos orientadores e plantas em operação ao redor do mundo

ABSTRACT The presence of micropollutants in effluents leads to an increased concern regarding the application of recycled water for direct and indirect potable reuse (DPR and IPR, respectively). The study presents a review (last 5 years) of guiding documents and operating plants of potable reuse (PR) globally, focusing on micropollutants. The guiding documents were found through an integrative literature review, while the operating plants were found in a systematic review. The study contemplated 19 regulatory documents, of which 7 address DPR and IPR jointly, 10 only IPR, and 2 only DPR. Standards for micropollutants are defined only in documents regulating IPR. Regarding plants in operation, 38 units were presented, of which 6 are DPR and 32 IPR. Some compounds presented more concern: 1,4-dioxane, 17-β-estradiol, gemfibrozil, perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), sucralose, and triclosan. It is of concern to note the absence of specific standards for micropollutants in DPR regulations. This gap highlights the importance of establishing rigorous guidelines that consider the effects of micropollutants; the study provides a state-of-the-art overview that can guide the advancement of regional regulatory frameworks for the institutionalization of PR worldwide.

A multi-criteria decision framework for circular wastewater systems in emerging megacities of the Global South

Lima faces increasing water stress due to demographic growth, climate change and outdated water management infrastructure. Moreover, its highly centralized wastewater management system is currently unable to recover water or other resources. Hence, the primary aim of this study is to identify suitable wastewater treatment alternatives for both eutrophication mitigation and indirect potable reuse (IPR). For eutrophication mitigation, we examined MLE, Bardenpho, Step-feed, HF-MBR, and FS-MBR. For IPR, we considered secondary treatment+UF + RO + AOP or MBR + RO + AOP. These alternatives form part of a WWTP network at a district level, aiding Lima's pursuit of a circular economy approach. This perspective allows reducing environmental impacts through resource recovery, making the system more resilient to disasters and future water shortages. The methods used to assess these scenarios were Life Cycle Assessment for the environmental dimension; Life Cycle Costing for the economic perspective; and Multi-Criteria Decision Analysis to integrate both the quantitative tools aforementioned and qualitative criteria for social and techno-operational dimensions, which combined, strengthen the decision-making process. The decision-making steered towards Bardenpho for eutrophication abatement when environmental and economic criteria were prioritized or when the four criteria were equally weighted, while HF-MBR was the preferred option when techno-operational and social aspects were emphasized. In this scenario, global warming (GW) impacts ranged from 0.23 to 0.27 kg CO2eq, eutrophication mitigation varied from 6.44 to 7.29 g PO4− equivalent, and costs ranged between 0.12 and 0.17 €/m3. Conversely, HF-MBR + RO + AOP showed the best performance when IPR was sought from the outset. In the IPR scenario, GW impacts were significantly higher, at 0.46–0.51 kg CO2eq, eutrophication abatement was above 98 % and costs increased to ca. 0.44 €/m3.

Multi-target assessment of advanced oxidation processes-based strategies for indirect potable reuse of tertiary wastewater: Fate of compounds of emerging concerns, microbial and ecotoxicological parameters

Two advanced oxidation processes (AOPs), namely ozone/H2O2 and UV/H2O2, were tested at pilot scale as zero-liquid-discharge alternative treatments for the removal of microbiological (bacteria and viruses), chemical (compounds of emerging concern (CECs)) and genotoxic responses from tertiary municipal wastewater for indirect potable reuse (IPR). The AOP treated effluents were further subjected to granular activated carbon (GAC) adsorption and UV disinfection, following the concept of multiple treatment barriers. As a reference, a consolidated advanced wastewater treatment train consisting of ultrafiltration, UV disinfection, and reverse osmosis (RO) was also employed.The results showed that, for the same electrical energy applied, the ozone/H2O2 treatment was more effective than the UV/H2O2 treatment in removing CECs. Specifically, the ozone/H2O2 treatment, intensified by high pressure and high mixing, achieved an average CECs removal efficiency higher than UV/H2O2 (66.8% with respect to 18.4%). The subsequent GAC adsorption step, applied downstream the AOPs, further improved the removal efficiency of the whole treatment trains, achieving rates of 98.5% and 96.8% for the ozone/H2O2 and UV/H2O2 treatments, respectively. In contrast, the ultrafiltration step of the reference treatment train only achieved a removal percentage of 22.5%, which increased to 99% when reverse osmosis was used as the final step.Microbiological investigations showed that all three wastewater treatment lines displayed good performance in the complete removal of regulated and optional parameters according to both national and the European Directive 2020/2184. Only P. aeruginosa resulted resistant to all treatments with a higher removal by UV/H2O2 when higher UV dose was applied. In addition, E. coli STEC/VTEC and enteric viruses, were found to be completely removed in all tested treatments and no genotoxic activity was detected even after a 1000-fold concentration.The obtained results suggest that the investigated treatments are suitable for groundwater recharge to be used as a potable water source being such a procedure an IPR. The intensified ozone/H2O2 or UV/H2O2 treatments can be conveniently incorporated into a multi-barrier zero-liquid-discharge scheme, thus avoiding the management issues associated with the retentate of the conventional scheme that uses reverse osmosis. By including the chemical cost associated with using 11–12 mg/L of H2O2 in the cost calculations, the overall operational cost (energy plus chemical) required to achieve 50% average CECs removal in tertiary effluent for an hypothetical full-scale plant of 250 m3/h (or 25,000 inhabitants) was 0.183 €/m3 and 0.425 €/m3 for ozone/H2O2 and UV/H2O2 treatment train, respectively.

Systems analysis of metropolitan-scale reuse with effects on water supply resilience and water quality

ABSTRACT Water reuse with Advanced Water Treatment (AWT) is increasingly appealing for urban areas seeking water supply reliability. In cities facing water scarcity, how can large-scale reuse support reliability and how do reuse operations affect water quality, energy use, and water conservation? This paper presents a systems analysis of metropolitan-scale water reuse and its effects on water supply and quality. For the case study of Los Angeles County, California, USA, hydroeconomic modeling is used to evaluate reuse as a contributor to water supply given urban water conservation, drought-induced water scarcity, and costs and benefits for supply and demand. Results indicate that AWT can be a viable source of supply especially when coupled with conservation. Across modeled scenarios, reuse provides as much as 30% of regional supplies. New water reuse with AWT becomes viable when imported water availability is 50% or less of historic values. Existing indirect potable reuse operations in the county remain important. Systemwide energy intensity of operations increases with greater reuse in the absence of water conservation. Modeled influent flow rates to wastewater treatment plants resemble historical values, but extreme flow events could pose risks. The paper offers a holistic framework to evaluate water reuse as a component of urban water management.

Establishing pathogen log reduction value targets for direct potable reuse in the United States

AbstractCommunities are now turning to potable reuse to augment their water supply portfolios in response to increasing demand and climate uncertainty. One barrier to broader implementation is a lack of regulations for direct potable reuse (DPR) in some locations. An incomplete understanding of the foundation of existing DPR frameworks may be contributing to this barrier. The objective of this study was to use a publicly available quantitative microbial risk assessment (QMRA) tool—DPRisk—to explain the basis behind California's existing indirect potable reuse regulations, California's draft DPR regulations, and an Expert Panel's response to those draft regulations. Then, leveraging a robust raw wastewater pathogen dataset from the literature, DPRisk was used to justify two alternatives: one based on maximum simulated pathogen concentrations and the other based on 97.4th percentile concentrations. The latter represents an effort to seek equivalency between “raw wastewater” (i.e., California) and “treated effluent” (i.e., Texas) approaches. Using justified QMRA assumptions, the baseline log reduction value (LRV) targets were determined to be 15/11/11 (maximum) or 13/10/10 (97.4th percentile) for viruses, Giardia, and Cryptosporidium. Additionally, instead of augmenting the baseline LRVs to account for undetected treatment process failures, tolerances for off‐specification conditions (e.g., up to 3 logs for 3–12 days per year) were characterized. With this foundational knowledge, stakeholders can better understand and adopt these frameworks or use DPRisk to establish a new framework that better addresses their unique constraints, including considerations for preferred treatment paradigms and capital and operational costs.

Erratum—Evaluating the sustainability of indirect potable reuse and direct potable reuse: A southern Nevada case study

Erratum—Evaluating the sustainability of indirect potable reuse and direct potable reuse: A southern Nevada case study

Effect-based evaluation of water quality in a system of indirect reuse of wastewater for drinking water production

Indirect potable reuse of wastewater is a practice that is gaining attention, aiming to increase freshwater supplies to meet water scarcity. However, reusing effluent wastewater for drinking water production comes with a paired risk of adverse health effects, due to the potential presence of pathogenic microorganisms and hazardous micropollutants. Disinfection is an established method to reduce microbial hazards in drinking water, but it has been associated with formation of disinfection by-products (DBPs). In this study, we performed an effect-based assessment of chemical hazards in a system wherein a full-scale trial of disinfection by chlorination, of the treated wastewater was performed prior discharge to the reciepient river. The presence of bioactive pollutants was assessed along the entire treatment system, starting from incoming wastewater to finished drinking water at seven sites in and around the Llobregat River in Barcelona, Spain. Samples were collected in two campaigns, with and without applied chlorination treatment (13 mg Cl2/L) to the effluent wastewater. The water samples were analysed for cell viability, oxidative stress response (Nrf2 activity), estrogenicity, androgenicity, aryl hydrocarbon receptor (AhR) activity and activation of NFĸB (nuclear factor kappa-light-chain-enhancer of activated B cells) signaling using stably transfected mammalian cell lines. Nrf2 activity, estrogen receptor activation and AhR activation was detected in all investigated samples. Overall, removal efficiencies were high in both wastewater treatment and drinking water treatment samples for most of the studied endpoints. No increase in oxidative stress (Nrf2 activity) could be attributed to the additional chlorination treatment of the effluent wastewater. However, we found an increase in AhR activity and a reduction of ER agonistic activity after chlorination treatment of effluent wastewater. The bioactivity detected in finished drinking water was considerably lower compared to what was found in effluent wastewater. We could thus conclude that indirect reuse of treated wastewater for drinking water production can be possible without compromising drinking water quality. This study contributed important knowledge in efforts to increase the reuse of treated wastewater as a source for drinking water production.

In vitro bioassays to monitor complex chemical mixtures at a carbon-based indirect potable reuse plant

Potable water reuse technologies are used to treat wastewater to drinking water quality to help sustain a community's water resources. California has long led the adoption of potable water reuse technologies in the United States and more states are exploring these technologies as water resources decline. Reuse technologies also need to achieve adequate reductions in microbial and chemical contaminant risks to meet public health goals and secure public acceptance. In vitro bioassays are a useful tool for screening if reuse treatment processes adequately reduce toxicity associated with a range of chemical classes that are contaminants of concern. In this study, we used an aryl hydrocarbon receptor (AhR) and an estrogen receptor luciferase bioassay to detect the presence of dioxin-like and estrogenic compounds across a 3800 m3/d carbon-based indirect potable reuse plant that uses carbon-based treatment (SWIFT-RC). Our results demonstrate significant removal of dioxin-like compounds across the SWIFT-RC treatment train. Estrogenicity declined across the treatment train for some months but was extremely variable and low with many samples falling below the method quantification level; consequently, we were not able to reliably determine estrogenicity trends for SWIFT-RC. Comparing the bioanalytical equivalent concentrations detected in the SWIFT-RC water with established monitoring trigger levels from the state of California suggests that SWIFT-RC produced water that met the bioassay guidelines. The log total organic carbon concentration and AhR assay equivalent concentrations are weakly correlated when data across all SWIFT-RC processes are included. Overall, this research demonstrates the performance of in vitro bioassays at a demonstration-scale carbon-based IPR system and highlights both the potential utility and challenges associated with these methods for assessing system performance.

Water supply, waste assimilation, and low‐flow issues facing the Southeast Piedmont Interstate‐85 urban archipelago

AbstractRapidly growing cities along the Interstate‐85 corridor from Atlanta, GA, to Raleigh, NC, rely on small rivers for water supply and waste assimilation. These rivers share commonalities including water supply stress during droughts, seasonally low flows for wastewater dilution, increasing drought and precipitation extremes, downstream eutrophication issues, and high regional aquatic diversity. Further challenges include rapid growth; sprawl that exacerbates water quality and infrastructure issues; water infrastructure that spans numerous counties and municipalities; and large numbers of septic systems. Holistic multi‐jurisdiction cooperative water resource planning along with policy and infrastructure modifications is necessary to adapt to population growth and climate. We propose six actions to improve water infrastructure resilience: increase water‐use efficiency by municipal, industrial, agricultural, and thermoelectric power sectors; adopt indirect potable reuse or closed loop systems; allow for water sharing during droughts but regulate inter‐basin transfers to protect aquatic ecosystems; increase nutrient recovery and reduce discharges of carbon and nutrients in effluents; employ green infrastructure and better stormwater management to reduce nonpoint pollutant loadings and mitigate urban heat island effects; and apply the CRIDA framework to incorporate climate and hydrologic uncertainty into water planning.

Application of a fluorescence EEM-PARAFAC model for direct and indirect potable water reuse monitoring: Multi-stage ozone–biofiltration without reverse osmosis at Gwinnett County, Georgia, USA

Periods of drought coupled with increasing population growth have prompted increased interest in potable water reuse in Gwinnett County, Georgia, USA. However, such inland water recycling facilities are challenged with treatment approaches where reverse osmosis (RO) membrane concentrate disposal is a barrier to implementation of potable reuse. To evaluate alternative treatment processes, testing of two side-by-side pilot systems using multi-stage ozone and biological filtration without RO was conducted to compare indirect potable reuse (IPR) to direct potable reuse (DPR). Two water sources were investigated—influent from Lake Lanier for the IPR pilot, and a blend of 25 % reclaimed water mixed with lake water (75 %) for the DPR pilot. To assess the nature of organic matter removed during potable reuse, excitation–emission matrix (EEM) fluorescence spectroscopy/PARAllel FACtor (PARAFAC) analyses were examined as a fingerprinting tool. The objectives were to determine (a) if a DPR scenario, when preceded by advanced wastewater treatment, could achieve drinking water quality comparable to IPR and (b) if water quality monitoring using EEM/PARAFAC methods could predict results for DPR and IPR water quality, comparable to parameters obtained in a supplementary study that required more expensive, time-consuming, and complicated analytical techniques. Sample scores representing relative concentrations of fluorescing organic matter derived from the EEM-PARAFAC model decreased in the order of reclaimed water > lake water > DPR pilot > IPR pilot, demonstrating that EEM/PARAFAC could distinguish between DPR and IPR water quality. An assessment of a comprehensive list of individual organic compounds (reported separately) validated that blend ratios of 25 % reclaimed water, or higher mixed with lake water (75 %) did not meet primary and secondary drinking water standards. Likewise, in this study, EEM/PARAFAC analysis demonstrated the 25 % blend did not provide drinking water quality indicating this simple, inexpensive method could be used for potable reuse monitoring.

Efficacy of simultaneous advanced oxidation and adsorption for treating municipal wastewater for indirect potable reuse

The main scope of this study was to compare the efficacy of different advanced oxidation processes (AOPs) combined with adsorption for treating secondary treated effluent of municipal wastewater in a continuous-lab-scale reactor. The results revealed enhanced removal of biological oxygen demand (BOD: C0: 14.1 and Ct: 0 mg L−1 (100%)), chemical oxygen demand (COD: C0: 40.5 and Ct: 4 mg L−1 (≤90%)), and total organic carbon (TOC: C0: 15.2 and Ct: 3.02–3.63 mg L−1 (∼80%)) by UV/PMS, O3/PMS, UV/O3/H2O2, and UV/O3/MnO2 processes followed by glass packed bed reactor (GPBR). Complete inactivation of the bacterial count was observed for all the studied processes. The GPBR showed the additional advantage of termination in the regrowth of bacterial count on the filtering medium. The gas-chromatography and mass spectrometry (GC-MS) analysis showed that AOP followed by adsorption reduced the concentrations of the by-products in the treated effluent. Overall, the synergy between AOP and adsorption improved the effluent quality to meet various indirect potable reuse (IPR) applications.

Characterization of Reverse Osmosis Reject Wastewater Generated from Sulaibiya Wastewater Treatment Plant

Sulaibiya Wastewater Treatment Plant (Kuwait) is considered as one of the largest wastewater treatment plants that use Reverse Osmosis (RO) membranes in their processes to reclaim water from municipal wastewaters for indirect potable water reuse. This result in considerable wastewater treatment brine which needs to be further investigated before discharge. Samples were collected on daily basis from the RO reject wastewater (brine wastewater) for one month and analyzed in situ and in the laboratory. The results obtained showed that the brine wastewater met the requirements of the Kuwait Environment Public Authority with the exception of biochemical oxygen demand, total dissolved solids, and total phosphate. In Kuwait, the brine wastewater is either used for deep-well injection or is discharged to the seawater. Based on the monitoring results, potential reuse options of wastewater brine include surface water discharge, sewer disposal, deep-well injection, and land application. Treatment options via evaporation ponds using membrane filters will further enhance the quality of the brine wastewater.

Combined process of chemically enhanced sedimentation and rapid filtration for urban wastewater treatment for potable reuse

ABSTRACT The objective of this study is to propose a new post-treatment of effluents from Upflow Anaerobic Sludge Blanket (UASB) using rapid filtration, aiming at the production of water for potable reuse. The final quality of the effluent produced by the treatment using gravel, sand, clinoptilolite and activated carbon associated with disinfection was evaluated by physical chemical analysis, heavy metals and persistent organic contaminants. Experiments were carried out in jar test, filter operation time, evaluation of the efficiency using peracetic acid and free chlorine as disinfectant and all results were statistically analysed. The best conditions were those using 20 mg/L of ferric chloride and natural pH of the effluent (≈ 7.0), which resulted in less reagent consumption. The use of intermediate fund discharges made it possible to obtain approximately 91% of recovered water efficiency. The effluent treated under these conditions showed DOC <2.0 mg/L, COD <1.0 mg/L, BOD <1.0 mg/L, turbidity <1.0 NTU, TSS <1.0 mg/L, ammonia <0.1 mg/L, total phosphorus <0.1 mg/L and surfactants <0.1 mg/L. The disinfection process with free chlorine and PAA allowed the total inactivation of faecal coliforms and total coliforms. The treatment using rapid filtration with disinfection by chlorine reached the appropriate level for urban, environmental, industrial and indirect potable water reuse.