Indirect Potable Water Reuse Research Articles

Need for Direct and Indirect Potable Water Reuse Specifications

The need for more efficient use of water from all of its sources has become axiomatic, and it is a critical issue in many water‐short areas. Wastewater is a valuable commodity that can be processed, and its components can be completely reused for a variety of purposes including as a source of highly treated water for human consumption. Indirect potable reuse implies that reclaimed water is returned to the environment before being sourced for water supply. Direct potable reuse involves the delivery of highly treated reclaimed water (with or without retention in an engineered storage buffer) to a drinking water plant or distribution system.

The socio-technology of engineering sustainability

Despite the social goals of sustainable development, including the alleviation of poverty, sustainable engineering approaches have been largely limited to technical measures, promoting engineers as purely technical experts. By under-emphasising social factors, this limits opportunities for engineers to address the full spectrum of challenges posed by the sustainable development model. We explain this in terms of the dominant policy response to environmental problems, known as ecological modernisation, which conscripts engineers into reinforcing false boundaries between technology and society. In contrast to the technical focus of engineering under a framework of ecological modernisation, we suggest that engineering can, in fact, be usefully seen as a hybrid socio-technical profession that breaks these boundaries. This point is underlined by the case-study of indirect potable water reuse, demonstrating that the acknowledgement of hybridity can be used to improve engineers' relationships with the societies they serve, and enhance the contribution of the profession to sustainable development.

Salinity reduction and energy conservation in direct and indirect potable water reuse

Water scarcity combined with population growth and climate change, especially in semi-arid and arid regions like Australia, Western United States, and the Middle East, has increased the need for water conservation. Water reclamation and reuse have become an important source of water to conserve and extend water supplies. With the advancement of technologies, indirect potable water reuse (IPWR) and direct potable water reuse (DPWR) have been developed as methods for producing high-quality recycled water for potable use. In this research salinity removal and energy conservation associated with IPWR and DPWR were modeled using the system dynamics software Stella. The water/wastewater system of the Las Vegas Valley, Nevada, USA, which discharges into the Colorado River, was used as an example system augmented with reverse osmosis (RO) membranes. The results show that IPWR and DPWR reduce salinity discharge to the Colorado River. The TDS load is reduced to 0.85 and 1.02 million kg/day for DPWR and IPWR systems compared to 2.33 million kg/day by the year 2035. DPWR can also save about 50% of the energy cost of pumping water. However, one drawback with these systems is the approximately 5% loss of water in the brine of the membranes.

Carbon and Energy Footprint Analysis of an Advanced Oxidation Process for Removing NDMA in Indirect Potable Water Reuse Operations

Carbon and Energy Footprint Analysis of an Advanced Oxidation Process for Removing NDMA in Indirect Potable Water Reuse Operations

Carbon and Energy Footprint Analysis of an Advanced Oxidation Process for Removing NDMA in Indirect Potable Water Reuse Operations

Carbon and Energy Footprint Analysis of an Advanced Oxidation Process for Removing NDMA in Indirect Potable Water Reuse Operations

Combining MBR and NF/RO membrane filtration for the removal of trace organics in indirect potable water reuse applications

The aim of this study was to demonstrate the complementarities of combining membrane bioreactor (MBR) treatment with nanofiltration (NF) or reverse osmosis (RO) membrane filtration for the removal of trace organic contaminants for potential indirect potable water recycling applications. Four commercially available NF/RO membranes, namely NF270, NF90, BW30 and ESPA2, were selected for this investigation. Challenge tests were conducted with 40 trace organic compounds at concentrations of approximately 2 μg/L in initial wastewater solutions using a laboratory scale MBR system and a cross-flow NF/RO rig. The results suggest that the MBR system effectively removes hydrophobic and biodegradable trace organic compounds. The adsorption of these hydrophobic compounds onto the MBR mixed liquor suspended solids (MLSS) leads to an extended retention time in the biological reactor, thereby enhancing their removal. The remaining, mostly hydrophilic, trace organic compounds were shown to be effectively removed by NF/RO membranes. The combination of MBR and a low pressure RO membrane resulted in more than 95% removal or removal to below the analytical detection limit of all 40 trace organic compounds investigated in this study. The results also suggest that NF/RO membrane fouling could be mitigated by appropriate membrane selection. Despite a relatively high initial permeate flux, negligible flow rate decline was observed with an NF membrane and a low pressure RO membrane over more than 25 h of filtration, possibly due to the smooth surfaces of these two particular membranes.

Applying Surrogates and Indicators to Assess Removal Efficiency of Trace Organic Chemicals during Chemical Oxidation of Wastewaters

To respond to concerns associated with wastewater-derived contaminants water utilities are looking for new approaches for monitoring trace organic chemicals in conventional and advanced water treatment processes. This study examines the use of a combination of surrogate parameters and indicator compounds tailored to monitor the removal efficiency of advanced oxidation processes employed by treatment plants engaged in indirect potable water reuse programs. Potential surrogate parameters and indicator compounds, identified by reviewing previous publications and classified by their structural properties, were tested in pilot- and full-scale treatment systems. Dilantin, DEET, meprobamate, and iopromide are good indicators to assess optimized oxidation conditions while ozonating tertiary-treated wastewaters. UVA reduction, ozone byproduct formation, such as simple organic acids, and ozone exposure correlated with "sweet spot" compounds, where ozone exposure correlated with trace organic removal across five tertiary-treated wastewaters. Findings indicate that the proposed framework can serve as a conservative monitoring approach for advanced oxidation processes as well as other indirect potable reuse processes to ensure proper removal of identified and unidentified wastewater-derived organic contaminants, to detect failures in system performance, and is protective of public health.

Toilet to Tap: Making a Case for Indirect Potable Reuse

This article discusses negative public opinion about indirect potable water reuse, efforts at obtaining public approval by the Orange County Water District of Southern California, the water treatment process at Orange County's state‐of‐the‐art water reclamation facility referred to as the Advanced Water Purification Facility, and the obvious choice of using indirect potable water reuse to meet the earth's future water needs.

Removal of trace organic contaminants by submerged membrane bioreactors

Laboratory scale experiments were conducted to investigate the removal mechanisms of trace organic contaminants using a submerged MBR system. The system was equipped with a Zenon ZW-1 membrane module. Bisphenol A and sulfamethoxazole were selected as model trace organics representing endocrine disrupting chemicals (EDCs) and pharmaceutically active compounds (PhACs), respectively. Results obtained from this study demonstrate an excellent performance of MBRs regarding basic water quality parameters such as turbidity, TOC and TN. However, removal efficiency of specific trace organic contaminants was found strongly dependent on their physicochemical properties. Approximately 90% removal of bisphenol A was recorded, while under the same condition, the removal efficiency of sulfamethoxazole was only about 50%. Both biodegradation and adsorption to the sludge were thought to be responsible for the removal of bisphenol A, which is a relatively hydrophobic organic compound. In contrast, the latter mechanism was absent for sulfamethoxazole as this compound is rather hydrophilic. Results reported here indicate that it may be possible to predict the removal efficiency of trace organic contaminants by a submerged MBR system based on their physicochemical properties. This would lead to better selection of subsequent complementary treatment processes prior to indirect potable water reuse.

The socio-technology of indirect potable water reuse

Public acceptability is widely acknowledged as a key factor in the success of indirect potable water reuse (IPR) schemes. Social research has provided useful insights into the factors that influence public attitudes to IPR and guidelines for engaging the public. Recent IPR developments in Australia demonstrate that clear democratic processes for decision making are yet to be devised. The distinction between technology and society which underpins work in this field does not adequately reflect the nature of IPR and limits possibilities for more robust decision making processes. IPR is not simply a technology to be accepted or rejected by society. IPR is a complex socio-technology which cannot exist unless its technologies become embedded in social, institutional, infrastructural and ecological networks. Reconsidering IPR as a complex socio-technology provides a new grounding for devising processes and institutions for decision making. Based on the formulations of Bruno Latour for bringing the sciences into democracy such processes will include four main tasks: 1) Perplexity—identifying propositions to be taken into account; 2) Consultation—evaluating the strength of the propositions; 3) Hierarchy—ordering the propositions into relative merit and importance; and 4) Institution—stabilising the outcomes through appropriate institutions.

Viability of a low-pressure nanofilter in treating recycled water for water reuse applications: A pilot-scale study

The purpose of this study was to investigate the potential of a low-pressure nanofiltration (NF) membrane for treating recycled water for indirect potable water reuse applications. In particular, the tradeoffs in choosing low-pressure NF over reverse osmosis (RO) were investigated including whether or not significantly lowering operating pressures/costs would result in diminished permeate water quality. A NF membrane (Dow/Filmtec NF-4040) with high permeate productivity was selected for pilot-scale testing over a period of 1200 h at a water reuse facility employing conventional RO membranes for treating tertiary treated wastewater effluent prior to aquifer recharge. The novel application of an NF membrane in treating wastewater effluent for water reuse applications permitted a comprehensive screening of NF permeate water quality and allowed for the investigation of trace organic contaminant rejection on pilot scale with environmentally relevant feed water concentrations. Results from pilot-scale testing highlighted the selectivity of NF membranes in removing organic solutes present in wastewater effluents at the parts-per-trillion level. While operating pressures were by a factor of 2–3 lower than conventional RO membranes, and bulk and trace organic rejection generally exceeded 90 percent, not surprisingly, the rejection of monovalent ions such as nitrate was poor. The poor-to-moderate rejection of monovalent ions, however, resulted in lowered brine stream total dissolved solids concentration and sodium adsorption ratio as compared with the brine stream of conventional RO membranes, which may be beneficial for brine disposal strategies.

Removal of pharmaceutical compounds by submerged membrane bioreactors (MBRs)

Unintentional indirect potable water reuse, where wastewater effluent is used as a part of a downstream drinking water source, has become a great concern. In this case, a variety of organic micro-pollutants contained in wastewater effluent could create problems. Membrane bioreactors (MBRs) have gained significant popularity as an advanced wastewater treatment technology and might be effective in removing such organic micro-pollutants. Available information on the performance of MBRs regarding removal of micro-pollutants, however, is currently limited. This study examined the ability of submerged MBRs to remove pharmaceutically active compounds (PhACs). Experiments were conducted at an existing municipal wastewater treatment facility, and the performance of the MBRs was compared with that of the conventional activated sludge (CAS) process. Six acidic PhACs (clofibric acid, diclofenac, ibuprofen, ketoprofen, mefenamic acid, naproxen) and one acidic herbicide (dichloprop) were investigated. Compared with CAS, MBRs exhibited much better removal regarding ketoprofen and naproxen. With respect to the other compounds, comparable removal was observed between the two types of treatment. Removal efficiencies of the PhACs were found to be dependent on their molecular structure such as number of aromatic rings or inclusion of chlorine.

Part I. Identifying anthropogenic markers in surface waters influenced by treated effluents: a tool in potable water reuse

In potable water reuse, treated wastewater becomes part of the drinking water supply. An important question associated with this practice is whether or not the organic quality of the treated wastewater is chemically different from that of non-human impacted water. This question was addressed in a case study of indirect potable water reuse where the organic matrix of the South Platte River was analyzed upstream and downstream of the discharge of treated wastewater effluent using conventional water quality parameters combined with pyrolysis-GC/MS. Effluent-derived organic material (EfOM) was found to be more aliphatic and had higher organic nitrogen and halogen content compared to organic material derived from "natural" (non-anthropogenic) sources (NOM). Seasonal changes that resulted from the change in the contributions of aquatic and terrestrial sources were not observed in EfOM; but they were strongly observed in NOM under the control of natural processes. Using principal component and factor analyses, the pyrolysis fragments of phenol, alkyl-phenols, and acetic acid were identified as the seasonal indicators for the NOM set of samples. In contrast, benzaldehyde, benzonitrile, chlorobutanoic acid, furancarboxaldehyde, and methylfurancarboxaldehyde were identified as the indicators for wastewater inputs for the EfOM set of samples. Overall, the results from conventional water quality parameters and pyrolysis-GC/MS revealed that: (1) EfOM bears a chemical signature distinct from NOM and (2) under the conditions of this study, EfOM discharged to the South Platte River persisted and controlled organic quality at downstream points.

Rejection of neutral endocrine disrupting compounds (EDCs) and pharmaceutical active compounds (PhACs) by RO membranes

As high quality drinking water becomes scarcer, unintentional indirect potable water reuse, where wastewater effluent is used as a part of a downstream drinking water source, has become a great concern throughout the world. In this case, a variety of organic micro-pollutants contained in wastewater effluent could create problems. High pressure-driven membranes such as nanofiltration (NF) or reverse osmosis (RO) might be a powerful option to deal with such micro-pollutants, however, a lack of information on their performance is apparent. This study examined the ability of RO membranes to retain neutral (uncharged) endocrine disrupting compounds (EDCs) and pharmaceutically active compounds (PhACs). A total of 11 compounds were chosen so that a certain range of molecular weights and octanol–water distribution coefficients ( K ow) could be studied. With respect to membranes, two different materials (polyamide and cellulose acetate) were examined. Generally, the polyamide membrane exhibited a better performance in terms of the rejection of the selected compounds but the retention was not complete (57–91%). It was found that salt rejection or molecular weight cut-off (MWCO) that are often used to characterize membrane rejection properties did not provide quantitative information in terms of EDCs/PhACs rejection by NF/RO membranes. Molecular weight of the tested compounds could generally indicate the tendency of rejection for the polyamide membranes (size exclusion dominated the retention by the polyamide membrane) while polarity was better able to describe the retention trend of the tested compounds by the cellulose acetate membrane. The results obtained in this study imply that each membrane polymer material for NF/RO membranes, including ones that will be newly developed in the future, would exhibit different trends in terms of rejection of organic micro-pollutants, which is determined by physico-chemical properties of the compounds.

Comparison of membrane options for water reuse and reclamation

The reuse of effluents for irrigation and indirect potable water uses is rapidly developing as an alternative to seawater desalination. This paper explores two membrane-based options available to treat sewage for water reuse, tertiary filtration (TF) of the effluent from a conventional activated sludge (CAS) process and an integrated membrane bioreactor (MBR). These options are compared from technical, performance and cost points of view using ZeeWeed® immersed membranes. The analysis shows that an integrated MBR is less expensive than the CAS-TF option. The total life cycle costs for the treatment of sewage to a quality suitable for irrigation reuse or for feeding reverse osmosis decrease from 0.40$/m 3 to 0.20$/m 3 as plant size increases to 75,000 m 3/d. It is also shown that the incremental life cycle cost to treat sewage to indirect potable water reuse standards (i.e. by ultrafiltration and reverse osmosis) is only 39% of the cost of seawater desalination.

Factors controlling nitrosamine formation during wastewater chlorination

Recent discoveries of the formation of low levels of the potent carcinogen N-nitrosodimethylamine (NDMA) during wastewater chlorination has caused concern where indirect potable water reuse is practiced. Experiments indicate that nitrosamine formation during chlorination of wastewater is consistent with a reaction scheme involving the slow formation of a hydrazine intermediate from a secondary amine and monochloramine, followed by its rapid oxidation to the corresponding N-nitrosamine. A survey of precursors indicates that secondary amines form their corresponding N-nitrosamines to the greatest extent. However, molecules containing the secondary amine as a functional group can also form the corresponding N-nitrosamine. NDMA is the predominant N-nitrosamine found in chlorinated wastewater. However, other nitrosamines are detected. These N-nitrosamines may be important if the summed risk posed by the exposure to all N-nitrosamines is considered.

Source water impact model (SWIM) - a watershed guided approach as a new planing tool for indirect potable water reuse

The scope of this study was to develop a model to assess the impact of source water quality on reclaimed water used for indirect potable reuse. The source water impact model (SWIM) considered source water qualities, water supply distribution data, water use and the impact of wastewater treatment to calculate reclaimed water quality. It was applied for sulfate, chloride, and dissolved organic carbon (DOC) at four water reuse sites in Arizona and California. SWIM was able to differentiate between the amount of salts derived by drinking water sources and the amount added by consumers. At all sites, the magnitude of organic residuals in reclaimed water was strongly effected by the concentration of organics in corresponding water sources and effluent-derived organic matter. SWIM can be used as a tool to predict reclaimed water quality in existing or planned water reuse systems.

Wastewater reuse through dual-membrane processes: opportunities for sustainable water resources

Numerous pilot plant studies and commercial facilities operating all over the world have demonstrated the technical and economic feasibility of reclaiming municipal wastewater treatment plants (WWTP) effluent through dual-membrane treatment processes. Dual-membrane processes such as continuous microfiltration (CMF) followed by reverse osmosis (RO) are used to produce water that meets all drinking water standards. Pilot plant studies conducted in Gran Canaria (Canary Islands) at the former DEREA Center, treating the effluent from the EDAR del Sureste using CMF followed by RO or electrodialysis reversal (EDR), clearly demonstrated the high quality of the treated water. Commercial facilities producing water for irrigation, for industrial use, to recharge aquifers, or as a source for indirect potable water reuse systems are already operating at these locations: Waster Factory 21, California; West Basin Water District at El Segundo, California; Samsung General Chemicals Co., Ltd., at Daesan, Republic of Korea; Vértesi Power Plant Co., at Oroszlány, Hungary; EDAR de Tías, at Lanzarote, Canary Islands. By the end of 1999 the Scottsdale Water Campus at Scottsdale, Arizona, will produce reclaimed water for irrigation and for indirect potable water reuse. The advanced wastewater treatment (AWT) facility, using CMF and RO, will have a capacity of 38,000 m 3/d of product water.

Health Effects of Indirect Potable Water Reuse

A five‐year, multidisciplinary research project was undertaken to evaluate the effects on health of using treated wastewater for groundwater replenishment. The study focused on the Whittier Narrows Groundwater Replenishment Project in Los Angeles County, Calif., where replenishment with a mixture of imported river water, stormwater, and reclaimed wastewater has been practiced since 1962. Results of the study showed that the proportion of reclaimed water currently used for replenishment had no measurable impact on either groundwater quality or human health. Recommendations for optimization of groundwater replenishment with reclaimed water are included.