Potable Water Reuse Research Articles

Microbial Treatment Targets for Potable and Nonpotable Water Reuse – A Comprehensive Update and Harmonization

Microbial Treatment Targets for Potable and Nonpotable Water Reuse – A Comprehensive Update and Harmonization

Regulating the Hydrophilicity of Hyper-Cross-Linked Polymers via Thermal Oxidation for Atmospheric Water Harvesting.

We explore the thermal oxidation of hyper-cross-linked polymers to enhance their hydrophilicity and efficacy in atmospheric water harvesting. Comprehensive chemical and physical characterizations are used to confirm the successful incorporation of polar oxygen moieties and the preservation of porosity upon thermal treatment. Newly introduced oxygen-based functional groups significantly improve water sorption properties, increasing total water uptake capacities by up to 400% and shifting water uptake onsets to significantly lower relative humidity. We also investigate the regeneration of oxidized hyper-cross-linked polymers after water sorption to probe their potential for multiple water harvesting cycles and reuse. Our findings outline a simple and cost-effective postsynthetic modification route for optimizing porous organic polymers for more sustainable and efficient atmospheric water harvesting.

What is the Difference between Conventional Drinking Water, Potable Reuse Water, and Nonpotable Reuse Water? A Microbiome Perspective.

As water reuse applications expand, there is a need for more comprehensive means to assess water quality. Microbiome analysis could provide the ability to supplement fecal indicators and pathogen profiling toward defining a "healthy" drinking water microbiota while also providing insight into the impact of treatment and distribution. Here, we utilized 16S rRNA gene amplicon sequencing to identify signature features in the composition of microbiota across a wide spectrum of water types (potable conventional, potable reuse, and nonpotable reuse). A clear distinction was found in the composition of microbiota as a function of intended water use (e.g., potable vs nonpotable) across a very broad range of U.S. water systems at both the point of compliance (Betadisper p > 0.01; ANOSIM p < 0.01, r-stat = 0.71) and point of use (Betadisper p > 0.01; ANOSIM p < 0.01, r-stat = 0.41). Core and discriminatory analysis further served in identifying distinct differences between potable and nonpotable water microbiomes. Taxa were identified at both the phylum (Desulfobacterota, Patescibacteria, and Myxococcota) and genus (Aeromonas and NS11.12_marine_group) levels that effectively discriminated between potable and nonpotable waters, with the most discriminatory taxa being core/abundant in nonpotable waters (with few exceptions, such as Ralstonia being abundant in potable conventional waters). The approach and findings open the door to the possibility of microbial community signature profiling as a water quality monitoring approach for assessing efficacy of treatments and suitability of water for intended use/reuse application.

Produced Water from the Oil and Gas Industry as a Resource—South Kuwait as a Case Study

Produced Water (PW) represents the largest waste stream in the oil and gas industry. As a water resource and as a source of valuable minerals such as alkali salts, it is has been highly under-valued, especially in hyper-arid regions. The beneficial use of PW ranges from water reinjection to elevated oil recovery from reservoirs with almost instantaneous returns, to the extraction of minerals from PW, which involves a number of different processes and setups. The economic value of PW-derived end products offers alternative revenue sources, with market fluctuations and conditions different from those of the hydrocarbon market. The end products of water and industrial salt support local industries such as agriculture, reflecting positively on the gross domestic product (GDP). Furthermore, resource extraction from PW of the oil and gas industry helps countries augment their circular economy. In this regard, the economic feasibility of three scenarios—the use of PW for oil recovery, the use of PW as an alternate source of water and industrial salt, and a hybrid process of both—is explored. The results show that there is great potential for water reuse in Enhanced Oil Recovery operations, as well as in the reduction in freshwater consumption for oil- and gas-extraction operations in the state of Kuwait by up to 4.8 percent when PW generated by SK oilfields is considered, and by 42 percent if PW from all oilfields in Kuwait is reused in the same manner.

Control of Aromatic Disinfection Byproducts in Potable Reuse Water by the UV222/H2O2 vs UV254/H2O2 Advanced Oxidation Processes.

Research has demonstrated the difficulty associated with degrading the conventional 1-2 carbon aliphatic halogenated byproducts of disinfectant reactions with organic matter [disinfection byproducts (DBPs)] within advanced oxidation process (AOP) units in potable reuse trains, but the efficacy of AOP units for treating the emerging classes of halogenated aromatic DBPs is unclear. We herein demonstrate more effective removal of 28 halogenated aromatic DBPs in the UV/H2O2 AOP at 222 nm (UV222) than in the conventional UV/H2O2 AOP at 254 nm. Direct photolysis of 28 halogenated aromatic DBPs was greatly enhanced at 222 nm with fluence-based photodecay rate constants of 4.31 × 10-4-1.53 × 10-2 cm2 mJ-1, which was mainly attributed to the higher molar absorption coefficients of halogenated aromatic DBPs at 222 nm than 254 nm. Generally, quantum yields of halogenated aromatic DBPs at both 222 and 254 nm followed the order of halophenols > halohydroxybenzaldehydes > halonitrophenols. All 28 halogenated aromatic DBPs exhibit high reactivity toward HO• with second-order rate constants ranging from 2.18 × 109 to 1.15 × 1010 M-1 s-1 determined by X-ray radiolysis. The UV fluence required to achieve 90% loss of halogenated aromatic DBPs in the UV222/H2O2 AOP was 75-95% lower than that in the UV254/H2O2 AOP, and 90% removal of most tested halogenated aromatic DBPs can be achieved in the UV222/H2O2 AOP within the UV fluence levels commonly applied in potable reuse (700-1000 mJ cm-2).

Potential water reuse pathways from a life cycle analysis perspective in the poultry industry

Achieving sustainable water use in the food industry requires a paradigm change and transforming it towards circularity by exploring opportunities for water reuse. Life Cycle Assessment can comprehensively evaluate the environmental impacts of the water management and reuse options throughout their life cycle to ensure improvement of environmental performance. Through the example of a poultry processing plant it was shown that improving wastewater treatment technology can reduce the metal depletion category by almost 30 % by cutting down chemical use by 90 %. Further mitigation of environmental damage could be achieved by either choosing technological or agricultural reuse options depending on the needs or local constraints. While the improvement is not massive since the implementation of additional technologies require further resources, the Reduce scenario (technological reuse with 50 % reduction of water consumption) compared to the direct discharge into a surface water body resulted a decrease of 11.0 % and 17.1 % in freshwater consumption and 7.6 % and 2.6 % in metal depletion units. On the contrary, irrigation is better than technological reuse with regard to human health and resource scarcity indicators. Legislative requirements and social acceptance issues might slow down the process of closing the loop in the water management of the food industry; nonetheless results show that opting for water reuse is an environmentally sound solution even in this sector.

Comparative analysis of reverse osmosis and nanofiltration for the removal of dissolved contaminants in water reuse applications

The increasing demand for drinking water has led to the adoption of unconventional water sources, such as water reuse. Reverse osmosis (RO) and nanofiltration (NF) membranes are effective barriers against trace organic contaminants in potable water reuse applications. However, the use of RO is being challenged by NF, primarily due to NF's potential to achieve similar contaminant removal as RO but with higher productivity and lower energy requirements. This study compares NF and RO membranes in terms of contaminant removal and energy consumption for potable water reuse applications. RO (BW30XFR) and dense and loose NF (NF90 and NF270) membranes were tested in bench-scale systems, and RO (TW30) and NF (NF9) membrane elements were tested in an engineering scale system utilizing UF-filtered reclaimed wastewater. The highest solute passage was observed using NF270 membrane. There was no difference between NF90 and BW30XFR in terms of divalent ion passage, but NF90's total organic carbon and monovalent ion passages were higher. Both NF90 and BW30XFR highly rejected negatively charged trace organic contaminants (TOrCs), though rejections were lower for neutral and positively charged compounds. Furthermore, all compounds were highly rejected in the engineering-scale system by NF9 and TW30. These results highlight the potential of dense NF membranes as an energy-efficient barrier for contaminant removal.

Improving water flux distribution and energy efficiency in reverse osmosis for high-recovery water reuse

Reverse osmosis (RO) is widely accepted for water reuse because it ensures clean water production. However, innovation in the RO process is necessary for water reuse to enhance its recovery while mitigating membrane fouling and reducing the increase in specific energy consumption (SEC). Therefore, circle sequence reverse osmosis (CSRO) adopts a staged design with flow reversal (FR) and a semi-batch design with a jet pump to enhance water flux distribution and energy efficiency for high-recovery water reuse. This study examined the water flux distribution and SEC of CSRO. When the distribution of water flux was compared, CSRO demonstrated a 7.7 % reduction in water flux in the front element compared to semi-batch reverse osmosis (SBRO). This reduction was attributed to advanced designs in SBRO, such as the two-stage design and an FR operation. The SEC of RO systems was also compared under high-recovery conditions. While both SBRO and CSRO achieved SEC reduction of 20–25 % or 9–18 % compared to two-stage RO depending on the feed salinity, CSRO was slightly more energy-efficient for high-saline feed. It is expected that CSRO has excellent potential for high-recovery water reuse, considering the improvement in water flux distribution and energy efficiency.

Mammalian Cell Genotoxicity of Potable Reuse and Conventional Drinking Waters.

Potable reuse water is increasingly part of the water supply portfolio for municipalities facing water shortages, and toxicity assays can be useful for evaluating potable reuse water quality. We examined the Chinese hamster ovary cell acute direct genotoxicity of potable reuse waters contributed by disinfection byproducts (DBPs) and anthropogenic contaminants and used the local conventional drinking waters as benchmarks for evaluating potable reuse water quality. Our results showed that treatment trains based on reverse osmosis (RO) were more effective than RO-free treatment trains for reducing the genotoxicity of influent wastewaters. RO-treated reuse waters were less genotoxic than the local tap water derived from surface water, whereas reuse waters not treated by RO were similarly genotoxic as the local drinking waters when frequent replacement of granular activated carbon limited contaminant breakthrough. The genotoxicity contributed by nonvolatile, uncharacterized DBPs and anthropogenic contaminants accounted for ≥73% of the total genotoxicity. The (semi)volatile DBPs of current research interest contributed 2-27% toward the total genotoxicity, with unregulated DBPs being more important genotoxicity drivers than regulated DBPs. Our results underscore the need to look beyond known, (semi)volatile DBPs and the importance of determining whole water toxicity when assessing the quality of disinfected waters.

Multiple barriers as an efficient treatment for removing pesticides aiming direct potable reuse: A pilot scale study

Water reuse for potable purposes can represent a realistic source supply of drinking water in areas with water scarcity. Therefore, combining conventional wastewater treatment technologies with advanced technologies is necessary to remove contaminants and obtain high-quality and safe water. In this study, the pesticides and degradation products, atrazine (ATZ), hydroxyatrazine (ATZOH), deethylatrazine (DEA), deisopropylatrazine (DIA), simazine (SMZ), ametryn (AMT), diuron (DIU), 2,4-D, fipronil (FIP), fipronil sulfide (FIP-SF) and fipronil sulfone (FIP-SN) were evaluated in effluent after membrane bioreactor (MBR), effluent after advanced treatment by multiple barriers (MBR, reverse osmosis, UV/H2O2 and activated carbon), in tap water collected in the urban region of Campinas and in the Atibaia River (water supply source from city of Campinas). The pesticide concentrations in the Atibaia River and the post-MBR effluent ranged between 1 and 434 ng L−1 and 1 and 470 ng L−1, respectively. Therefore, the Atibaia River and the post-MBR effluent had the same magnitude pesticide concentrations. In the production of potable water reuse, after the multiple barriers processes, only fipronil (1 ng L−1) and atrazine (3 ng L−1) were quantified in some of the samples. In tap water from Campinas, atrazine, ATZOH, DEA, diuron, and 2,4-D were quantified in concentrations ranging between 3 and 425 ng L−1. Therefore, when comparing drinking water obtained from conventional treatment with potable water reuse, according to the pesticides studied, it is possible to conclude that the advanced treatment used on a pilot scale is promising for use in a potable water reuse plant. However, studies involving more microbiological and chemical parameters should be conducted to classify potable water reuse as drinking water.

Investigation on pulsed-electrocoagulation process for the treatment of wet coffee processing wastewater using an aluminum electrode

The use of conventional direct current-electrocoagulation in wastewater treatment is limited by its drawbacks, which include electrode passivation, high energy consumption, and significant sludge generation. Therefore, to address these issues, pulsed-electrocoagulation (PECP) has been developed. The PECP is an advanced wastewater treatment technique that uses intermittent electrical pulses to target and break down organic compounds in wastewater. It offers several benefits, including enhanced removal of organic compounds, reduced chemical consumption, energy efficiency, treatment of complex wastewater composition, pathogen inactivation, environmental compliance, and potential for water reuse. In this research, removal efficiency of % Chemical Oxygen Demand (COD), % Color, % Turbidity, % phosphate, and %nitrate was investigated for the wet coffee processing wastewater by using PECP and the obtained results as the COD-98.75%, color-99.92%, turbidity-99.00%, phosphate-99.02%, and nitrate-98.83%, respectively. Independent variables were the major significant factors and the optimum value was investigated and obtained at pH of 7, electrolyte dosage of 0.75 g L−1, electrolysis time of 45 min, and current of 0.45 Amp. As a result, PECP with NaCl and CaCl2 as an electrolyte is an effective treatment technique for pollutant removal from wastewater. As a consequence, the specific benefits may vary depending on the system design, operational parameters, and wastewater characteristics. The pilot-scale studies and optimization are essential for assessing PECP feasibility and performance.

Aligning monitoring of virus barriers in potable reuse with unit process treatment mechanisms and time scales: A critical review and research needs

AbstractInterest is growing in potable reuse in response to water scarcity and the desire for sustainable supplies. While potable reuse systems must control a variety of physical, chemical, and microbiological contaminants, human enteric viruses are particularly concerning and drive process performance objectives due to their often‐high occurrence in source waters, small size, potential resistance to treatment, and laborious methods to determine infectivity. This paper reviews the alignment of online monitoring practices with the mechanisms and time scales of the various barriers for enteric viruses. While there are numerous studies and reviews of individual barriers, no other review has been identified that covers operational monitoring of the entire potable reuse system. This paper also provides a critical assessment of the efficacy of current practices for operational and verification monitoring of the integrity of barriers to enteric viruses in potable reuse systems. The prevalence of human enteric viruses in wastewater and associated challenges of quantifying them through treatment are discussed within the risk management frameworks currently in use or under development for potable reuse systems. Monitoring approaches are then reviewed throughout the potable reuse water cycle. Current monitoring practices are compared with treatment process mechanisms and time scales, for the treatment barriers of biological wastewater treatment, membrane bioreactors, microfiltration/ultrafiltration, reverse osmosis, ultraviolet irradiation/advanced oxidation, ozonation, granular media/biologically active filtration, and chlorination. Monitoring and pathogen removal mechanisms are also reviewed for both environmental and engineered buffers. Implications are then discussed for future areas of research in potable reuse.

Public acceptance in direct potable water reuse: a call for incorporating responsible research and innovation

ABSTRACT As global issues such as climate change and diminishing resources become increasingly pressing, water recycling has moved into the focus. However, the successful implementation of Direct Potable Water Reuse (DPR) projects hinges on securing public acceptance, which remains challenging. This paper aims to flesh out possible reasons for the lingering public rejection of DPR. We will do so by conducting a literature review on how public acceptance is understood and what approaches are proposed to enhance it. These approaches are analyzed using Responsible Research and Innovation principles and the `opening up', `closing down' and `leaving ajar' approaches. Our research identifies an overreliance on the controversial information deficit model, closing down large parts of public engagement. We advocate for becoming more inclusive through the `leaving ajar' approach. Particularly, attention should be paid to reflexivity and responsiveness to public concerns to ensure meaningful public engagement.

Water recycling goes mainstreamPurified: How Recycled Sewage Is Transforming Our Water Peter Annin Island Press, 2023. 248 pp.

Public health and public relations are key to successful potable water reuse programs.

Potable Water Treatment and Reuse of Domestic Wastewater in the CMHC Toronto 'Healthy House'

Potable Water Treatment and Reuse of Domestic Wastewater in the CMHC Toronto 'Healthy House'

Development of high-integrity reverse osmosis membranes for enhanced removal of microorganisms

Improved integrity of reverse osmosis (RO) membranes for pathogenic microorganisms can enhance the microbiological safety of potable water reuse. This study aimed to produce a high-integrity RO membrane that is less prone to defects or failures of the polyamide skin layer. The commercial track-etched (TE) microfiltration membranes with uniform pore sizes of 0.2 μm were adopted as a robust support layer. The polyamide skin layer was successfully formed by creating a thin m-phenylenediamine (MPD) layer using a spin coater before the interfacial polymerization. The best TE-based RO membranes had a pure water permeability of 1.1 L/m2hbar and a salt rejection of 97 %. The field emission scanning electron microscopy revealed that the skin layer thickness of the TE-based membrane (approx. 31 nm) was equivalent to a commercial RO membrane. The removal of bacteria-sized particles (0.5 μm fluorescent microspheres) by the fabricated TE-based membrane (8.6-log) was greater than that by the commercial RO membrane taken out from an RO membrane element (7.8-log). Although complete removal of bacteria-sized particles was not achieved with small TE-based RO membrane coupons, this study established a viable protocol for producing a high-integrity RO membrane by forming the polyamide skin layer on the TE support layer.

Enteric virus removal by municipal wastewater treatment to achieve requirements for potable reuse

Primary and secondary treatment of municipal wastewater contributes to virus removal upstream of advanced purification to produce water for potable reuse. In this study, virus occurrence by cultivable and molecular methods was measured over a 24-month period in raw wastewater influents and secondary effluents from two municipal wastewater treatment plants that together provide the recycled water source for an advanced water purification facility. Using a rank-paired, covariance-based statistical approach, virus log removal values were determined for four wastewater treatment processes that operate in parallel at the two facilities (two activated sludge processes, trickling filter process, and trickling filter/solids contactor process). The trickling filter process exhibited the lowest observed removal of cultivable enteric virus with a median removal of 1.0 log10 (or 90% removal) and a 5th percentile log removal of 0.73 (or 82%), compared to the greatest removal observed for one of the activated sludge processes (median log removal of 2.4 or 99.6% and 5th percentile of 2.1 or 99.2%). Median log removal observed for male-specific (MS) and somatic (SOM) coliphage was 1.8 (98.6% removal) and 0.5 (70%), respectively, for trickling filter and 2.9 (99.9%) and 2.0 (99%) for activated sludge. Thus, coliphage removal was fairly similar to removal observed for cultivable enteric virus. The cultivable enteric virus 5th percentile removal (0.7) from the trickling filter treatment process was proposed to the state regulator for credit towards state requirements for virus removal related to groundwater augmentation with purified recycled water. Receiving pathogen removal credits for secondary wastewater treatment would allow for an improved margin (safety factor) of credits beyond the minimum required; and in this case may also increase the number of viable future groundwater recharge sites closer to drinking water production wells by reducing the underground travel time otherwise required to obtain sufficient credits.

Methyl nitrate as a byproduct in advanced water treatment systems: Liquid chromatographic determination method and cause of formation

Neutral low-molecular-weight organics such as methyl nitrate that can readily pass through reverse osmosis (RO) membranes employed in potable water reuse facilities attract interest owing to public health considerations. In this study, a novel determination method based on high-performance liquid chromatography, online photochemical conversion to peroxynitrite, and luminol chemiluminescence detection was developed for methyl nitrate measurement in treated water. The maximum photochemical conversion efficiency of methyl nitrate to peroxynitrite was found to be 6.5% using a 222-nm excimer lamp. The calibration curve for the developed method was linear between 1.0 × 10−9 and 1.0 × 10−7 M, and the limit of detection was 0.3 nM (0.03 μg/L) given an injection volume of 200 μL. The methyl nitrate concentrations in RO permeate from reclaimed wastewater and product water after subsequent treatment by a UV/H2O2 advanced oxidation process (AOP) were 2.2 and 22.5 nM (0.17 and 1.7 μg/L), respectively. UV irradiation of RO permeate in the laboratory using a low-pressure Hg lamp confirmed the formation of methyl nitrate in the permeate in the absence of H2O2 and residual chloramines. This chemiluminescent detection method for methyl nitrate will promote a greater understanding of the origin and formation of this treatment byproduct in reclaimed wastewater.

Water quality characteristics and reuse potential using adsorption as a post-treatment option for a full-scale hydrocyclone, coagulation, flocculation, and dissolved air flotation system.

This study established a full-scale hybrid water treatment system combining a hydrocyclone, coagulation, flocculation, and dissolved air flotation unit (HCFD) and evaluated its performance in treating anthropogenically impacted lake water. The HCFD system offered the stable and efficient treatment of fluctuating influent loadings, meeting most of the highest water reclamation quality criteria except for that of organic matter. Adsorption was subsequently examined as a post-treatment process for the HCFD effluent, which has not been examined in many previous studies. As the adsorbent for the post-treatment, pine bark, a locally available agricultural waste feedstock, was modified using H2O2 to maximize its adsorption capacity. The surface modification increased its adsorption capacity for organic matter by 53-112%. The HCFD system in conjunction with the synthesized adsorbent thus demonstrated the ability to meet the highest standards for all water quality parameters, highlighting their synergistic potential for enhancement of water treatment. Liquid chromatography-organic carbon detection and Fourier transform infrared analysis were then employed to determine the mechanisms involved in the removal of specific contaminants using the HCFD system and post-adsorption unit. While the HCFD system successfully eliminated particulate and colloidal matter (e.g., phosphorous and biopolymers with a high molecular weight) using centrifugal and floating separation with the aid of two complementary polymers, the post-adsorption unit effectively adsorbed small-sized dissolved substances (e.g., low molecular weight acids and building blocks) via surface functional groups (-CH, -OH, -CH2, C=O, C=C, and C=O) using van der Waals forces, hydrogen bonding, and π-π or n-π interactions.

Measure Viruses in the Field to Demonstrate Water Reuse Safety

Available, effective methods of virus detection adequately address the risks in treating water for potable reuse.