Indirect Potable Use Research Articles

Integrated Water Management at the Peri-Urban Interface: A Case Study of Monterey, California

Climate change, drought, and chronic overdraft represent growing threats to the sustainability of water supplies in dry environments. The Monterey/Salinas region in California exemplifies a new era of integrated or “one water” management that is using all of the water it can get to achieve more sustainable supplies to benefit cities, agriculture, and the environment. This program is the first of its kind to reuse a variety of waters including wastewater, stormwater, food industry processing water, and agricultural drainage water. This study investigates the partnerships, projects, and innovations that shape Monterey’s integrated water network in order to better understand the challenges and opportunities facing California communities as they seek to sustainably manage peri-urban water supplies. Water reuse in the Monterey region produces substantial economic and environmental benefits, from tourism and irrigation of high-value crops to protection of groundwater and increases in environmental flows and water quality. Water resource managers in other communities can learn from Monterey’s success leveraging local needs and regional partnerships to develop effective integrated water solutions. However, key challenges remain in resolving mismatched timing between water availability and demand, funding alternative water supplies, and planning effectively under uncertainty. Opportunities exist to increase Monterey’s recycled water supply by up to 50%, but this requires investment in seasonal storage and depends on whether desalination or additional recycling forms the next chapter in the region’s water supply story. Regulatory guidance is needed on seasonal subsurface storage of tertiary-treated recycled water as distinct from potable recharge. By increasing the supply of recycled water to Monterey’s indirect potable use system, the region’s potential need for seawater desalination may be delayed as much as 30 years, resulting in cost and energy savings, and giving the opportunity to resolve present planning concerns.

Trace Organic Compound Removal from Wastewater Reverse-Osmosis Concentrate by Advanced Oxidation Processes with UV/O3/H2O2.

Advanced technologies, such as reverse osmosis (RO), allow the reuse of treated wastewater for direct or indirect potable use. However, even highly efficient RO systems produce ~10–15% highly contaminated concentrate as a byproduct. This wastewater RO concentrate (WWROC) is very rich in metal ions, nutrients, and hard-to-degrade trace organic compounds (TOrCs), such as pharmaceuticals, plasticizers, flame retardants, and detergents, which must be treated before disposal. WWROC could be up to 10 times more concentrated than secondary effluent. We examined the efficiency of several advanced oxidation processes (AOPs) on TOrC removal from a two-stage WWROC matrix in a pilot wastewater-treatment facility. WWROC ozonation or UV irradiation, with H2O2 addition, demonstrated efficient removal of TOrCs, varying between 21% and over 99% degradation, and indicating that radical oxidation (by HO·) is the dominant mechanism. However, AOPs are not sufficient to fully treat the WWROC, and thus, additional procedures are required to decrease metal ion and nutrient concentrations. Further biological treatment post-AOP is also highly important, to eliminate the degradable organic molecules obtained from the AOP.

Fit-for-purpose urban wastewater reuse: Analysis of issues and available technologies for sustainable multiple barrier approaches

A selective approach for multiple wastewater recovery is nowadays desirable and technologically feasible, to provide water at specific quality standards for each reuse objective. This “fit-for-purpose” approach to water reuse could both save water and would reduce production cost and energy demand by eliminating unnecessary treatment and long-range conveyance, as it typically aims at local reuses. The appropriate choice of technologies for such approaches is perhaps the most critical planning and design decision when evaluating systems for implementation or refurbishing. This article examines wastewater reuse goals (direct potable use, indirect potable use, non-potable uses and industrial uses) and related requirements as relevant case studies, and issues that may arise during implementation. It then proposes an overview of current conventional and advanced technologies and their possible combination to meet foreseen uses under a multiple barrier treatment (MBT) approach, which implies a sequence of complementary processes at an increasing level of protection for both conventional and emerging pollutants according to reuse goals.

Urban water supply system optimization and planning: Bi-objective optimization and system dynamics methods

Sustainable, low-cost, environmentally conscious development is a major challenge for urban water supply systems. This study considers household and industrial water demand and establishes a bi-objective model to balance the economic and environmental cost of a three-stage urban water supply system including water production, distribution, and treatment processes. Considering different attitudes toward the increasing imbalance between water demand and supply, three hypothetical scenarios are designed based on which three sets of data on water demand and wastewater production volumes are defined. Then, a two-step method is applied to obtain solutions to decision variables (potable water use rate and wastewater untreated rate). After optimization, a system dynamics model is applied to test water supply system performance under short-, medium-, and long-term planning scenarios. Finally, the model is applied to Singapore to test its feasibility. The proposed bi-objective model provides managerial insights into the use of alternative water resources. For example, in 2020, water demand is simulated as 5.63×108m3. After optimization using the proposed model, the quantity of alternative water is 2.5×108m3 (water from the local catchment), 2.5×108m3 (imported water), 5.31×107m3 (desalinated water), 4.05×107m3 (NEWater for indirect potable use), and 8.10×107m3 (NEWater for direct non-potable use). Total water supply is 6.75×108m3, which means there is some redundancy in water supply. Further, three indexes—supply-demand ratio, economic cost, and environmental cost—help to identify the suitable planning period: the medium-term focus is the most appropriate option as it promises water adequacy for over 15 years and has lower energy costs and less negative environmental impact during the evaluation years. In addition, this study proves the influence of decision makers’ preferences on contradictory objective functions (economic cost minimization and environmental negative impact minimization). Overall, the proposed model balances a trade-off between the risk of an increasing future supply-demand imbalance and current water adequacy. Lastly, the proposed model offers a paradigm to identify a sustainable planning period.

Role of metal modified water treatment residual on removal of Escherichia coli from stormwater runoff

Extensive studies have been conducted on bioretention filter media applied in best management practices for stormwater runoff treatment. To date, more reported studies are focused on pollutants elimination such as suspended solids and nutrients. There has been limited research on pathogen removal from stormwater runoff. More focused studies on pathogen removal are therefore required if the intended stormwater is harvested for indirect potable use. In this study, water treatment residuals (WTR), a recycled biofilter media was surface-modified with metals to assess its potential for E. coli removal from stormwater runoff. To achieve this goal, four types of modified WTRs, prepared using iron, copper, platinum, and silver as antibacterial agents, were tested in parallel batch tests. After the cost-effectiveness evaluation among the four modified WTRs for bacterial removal, Fe2O3- and CuO-WTRs were shortlisted for further mechanism and stability studies. Stable antibacterial performances (E. coli log removal of 0.58 ± 0.04 and 0.90 ± 0.04, respectively) were achieved using the Fe2O3- and CuO-WTRs under intermittent synthetic and natural stormwater runoff conditions. No significant metal leaching was observed over prolonged continuous treatment. The experimental results showed the bio-adsorption onto the surface modified Fe2O3- and CuO-WTR was a key mechanism for E. coli removal followed by E. coli inactivation at solid-liquid interface caused by the antibacterial effect of metal coatings (where CuO was reported to have higher biotoxicity than Fe2O3). These findings clearly suggested the potential of CuO-modified WTR for pathogen removal in stormwater treatment practices.

Overcoming psychological resistance toward using recycled water in California

AbstractWe use data from a representative sample of adult Californians (N = 1500) to examine the relation between information and sociodemographic factors to the willingness to adopt recycled water in 10 different applications. We find that direct consumption or skin contact with recycled water stirs the strongest resistance. We conducted a randomized experiment to test how respondents would react to learning that there is large, existing, indirect potable use program in Orange County. While both messages boost support for almost all uses of recycled water, respondents still resist drinking, bathing and cooking with it. Contrary to some previous findings, the response to both information cues generally does not appear to depend upon level of education.

Singapore’s experience with reclaimed water: NEWater

NEWater, Singapore’s reclaimed water, has enabled Singapore to sustainably meet its growing water demand despite limited land for water catchment and storage. While technology provided this water reuse solution, strong political will, good governance and effective public engagement were key to Singapore’s success in supplying NEWater for indirect potable use and direct nonpotable use. A multiple-barrier process including dual-membrane filtration and UV disinfection, complemented by a strict operating philosophy and comprehensive water quality management programme, ensures reliable delivery of good-quality NEWater even as the supply capacity expands.

Selection of Advanced Oxidation Process for Indirect Potable Use Experience Transfer

Selection of Advanced Oxidation Process for Indirect Potable Use Experience Transfer

Management and treatment of landfill leachate by a system of constructed wetlands and ponds in Singapore

Lorong Halus, Singapore's first landfill leachate treatment system, consists of a pre-treatment system (8,000 m(2)), five constructed reed beds (38,000 m(2)), five polishing ponds (13,000 m(2)), an education centre and a learning trail for visitors. Eight species of wetland plants (total 160,000 plants) were selected for their ability to uptake nutrients, tolerance to low phosphorus concentrations and resistance to pest infestations. The wetland was launched in March 2011 and water quality monitoring started in April 2011. The removal efficiencies of the pre-treatment system from April 2011 to August 2012 are biochemical oxygen demand (BOD5) 57.4%; chemical oxygen demand (COD) 23.6%; total suspended solids (TSS) 55.1%; ammoniacal nitrogen (NH4-N) 76.8%; total phosphorus (TP) 33.3% and total nitrogen (TN) 60.2%. Removal efficiencies of the reed beds are BOD5 47.0%; COD 42.2%; TSS 57.0%; NH4-N 82.5%; TP 29.3% and TN 83.9%. Plant growth is generally satisfactory, but the lower than designed volume of leachate has adversely affected some sections of plants and resulted in uneven flow distribution in reed beds. The plant management programme includes improving plant regrowth by harvesting of alternate strips of plants and replanting. The treated effluent meets water quality limits for discharge to the public sewer and is subsequently treated by the NEWater treatment system, which recycles water for industrial and indirect potable use.

NEWater—multi safety barrier approach for indirect potable use

Singapore, a small island city-state depends on four sources, namely local catchment, imported water from Malaysia, desalinated water, and NEWater, to provide for its daily water consumption of about 1.36 million m3 per day. NEWater, a high grade reclaimed water, is key in achieving water sustainability through the multiplying effect of water reuse. In addition to being used for direct non-potable use (DNU) in wafer fabrication processes and other industrial processes, NEWater is being injected into surface reservoirs for indirect potable use (IPU). To ensure the safety of NEWater for IPU, PUB has adopted a multi barrier safety approach. The multi safety barrier approach starts from source and extends to taps in households in stages, namely source control; greater than 85% of wastewater from domestic source; comprehensive secondary wastewater treatment; microfiltration (MF) process, reverse osmosis (RO) process and ultra-violet (UV) disinfection in NEWater production; natural attenuation in surface reservoirs; as well as conventional water treatment process of coagulation, flocculation, sand filtration and disinfection. The approach is further enhanced by a comprehensive water quality monitoring programme that includes emerging contaminants of concern and a strict operating philosophy. The water quality test results are in turn reviewed by experts from local universities as well as overseas experts of international standing. Over the years of operations, NEWater has been found to be well within WHO Drinking Water Guidelines and USEPA Drinking Water Standards and each safety barrier has a significant role to play in ensuring the safety of NEWater for IPU.

Emerging contaminants and treatment options in water recycling for indirect potable use

Solutions to global water stress problems are urgently needed yet must be sustainable, economical and safe. The utilisation of alternative water sources like reclaimed municipal wastewater is one of the most obvious and promising options in integrated water resources management. Among the various beneficial uses of reclaimed wastewater Aquifer Recharge (AR) receives growing attention because it features advantages such as additional natural treatment, storage capacity to buffer seasonal variations of supply and demand as well as mixing with natural water bodies which promotes the acceptance of further uses, particularly indirect potable use. Major concerns about the safety of this exploitation route of an alternative water source are connected to microbial and chemical contaminants occurring in wastewater, among which are emerging trace organics like endocrine disrupters and pharmaceuticals. This paper reviews the current international debate about the relevance of emerging contaminants and technical mitigation options in water recycling for indirect potable use.

Integrated Water Resource Management — through reuse and aquifer recharge

Increased water demand from population and economic growth, environmental needs, change in rainfall, flood contamination of good quality water and over abstraction of groundwater are all factors that will continue to create water shortage problems. This paper considers alternative solutions, which conform to sustainable solution premises whilst being economically beneficial to the community. Case studies are described that demonstrate the solutions including the benefits of proven hydrogeological expertise, water resource management in very poor developing regions, cash crop production by reusing brackish municipal wastewater and aquifer recharge for saline ingress and indirect potable use.