Recycled Water Distribution Research Articles

Influence of treatment processes and disinfectants on bacterial community compositions and opportunistic pathogens in a full-scale recycled water distribution system

In this study, for the first time, a recycled water distribution system was analysed in which the inorganic nitrogen content in the recycled water was substantially minimised (<0.2 mg/L) while the total chlorine residual was maintained above 0.1 mg/L (regulatory standard). The chemical parameters and bacterial community composition of the unique full-scale recycled water treatment and distribution system were comprehensively evaluated. The application of chlorine eliminated Escherichia coli (E. coli) and largely reduced the bacterial diversity, richness, and the number of species, despite the formation of organic chloramines (>85%) having minimal disinfection abilities. The majority of the bacterial communities were proteobacteria comprising alpha-, beta-, and gamma-proteobacteria, similar to the drinking water distribution system. The gene copy numbers of total bacterial 16S ribosomal ribonucleic acid (16S rRNA) and opportunistic pathogens (OPs) were significantly decreased after the chlorination, but their populations increased with the decrease of total chlorine residual level in the distribution system. The total bacterial 16S rRNA significantly correlated with Legionella spp., Mycobacterium spp., and Pseudomonas aeruginosa. Similarly, significant correlations existed between OPs (particularly Legionella spp. and Pseudomonas aeruginosa) and iron-oxidising, manganese-oxidising, and sulphate-reducing bacterial genera. The detection of several OPs in the absence of E. coli shows that the traditional indicator used for compliance monitoring may not accurately represent the microbial water quality. This study suggests monochloramine as an alternative secondary disinfectant.

An integrated planning tool for design of recycled water distribution networks

Pipeline design of urban recycled water networks involves thousands of decisions to ensure delivery of water to multiple use locations with pipelines and pump stations correctly located, optimally sized, and compatible with existing infrastructure. Here, we introduce PRODOT, Pipeline ROuting and Design Optimization Tool, software that identifies near-minimum-cost pipeline routes; accounts for existing configurations, legal, environmental or safety concerns, and trade-offs in pipeline length, pipe installation methods, traffic congestion during construction; optimizes pump station locations, pumping energy, pipe diameters and pressure classes; and includes theoretical additional capacity of each pipe, facilitating future expansion. We illustrate the utility of PRODOT with a case study for a local utility comparing PRODOT-generated configurations to a configuration proposed by an experienced consulting firm. The comparison shows that PRODOT produces pipeline configurations similar to the consulting firm's proposal with improvements by effectively and more broadly incorporating options the consultant may not have considered.

Predicting support and likelihood of protest in relation to the use of treated stormwater with managed aquifer recharge for potable and non-potable purposes

Managed Aquifer Recharge (MAR) of stormwater has been deemed technically feasible in augmenting the total water supplies of the Adelaide region however, a major obstacle to implementation of new water schemes, particularly for potable reuse, can be gaining public acceptance and political support. The present survey of 1043 Adelaide residents addressed factors identified in the literature such as satisfaction with the quality of water, the importance of cost, perceived effectiveness of the recycled water distribution system, perceptions of community acceptance and trust in the water authorities to manage the system. The study compares three options for the use of stormwater through MAR: non-potable use through a third-pipe system, potable use whereby the water from the aquifer is pumped to a reservoir, and potable use whereby locally treated water from the aquifer is pumped into the mains system. Although respondents were positive about the reuse of stormwater via MAR for both potable and non-potable options and the likelihood of protest was less than ten percent, respondents clearly preferred the non-potable to the potable options. The results suggested a need for public education on issues such as the cost of third-pipe systems, the risks associated with the potable option with localised treatment, and the actual rate of community acceptance, which was higher than they believed. However, there was also evidence of psychological bias, which is not easily moved by the provision of information alone.

Cross-connection detection in Australian dual reticulation systems by monitoring inherent fluorescent organic matter

New housing developments are now commonly incorporating dual reticulation water systems for the redistribution of recycled water back to households for non-potable use. Within such distribution systems is the potential for cross-connections between recycled and drinking water pipelines, and a number of such events have been documented both in Australia and internationally. While many cross-connections are unlikely to present a source of health concern given the high level of recycled water treatment, they do have the potential to negatively impact public confidence in dual reticulation systems. A rapid and highly sensitive method of cross-connection detection is required to increase consumer confidence in the construction and maintenance of such recycled water distribution systems. This paper reviews a number of current and potential cross-connection detection methods, highlighting the use of fluorescence spectroscopy as a highly promising analytical tool for portable cross-connection detection.

Innovative EcoCloud™ Helps Silicon Valley Companies Adopt Sustainable Practices

South Bay Water Recycling (SBWR) is a regional recycled water distribution system serving industrial and commercial customers in the area of northern California (USA) known as "Silicon Valley." In early 2008 the City of San José, as administering agency of the San José/Santa Clara Water Pollution Control Plant, implemented a Cooling Tower Initiative to encourage recycled water use by commercial and industrial facilities. In 2009, Sustainable Silicon Valley, a non-profit organization dedicated to a sustainable future, convened a meeting of utilities, high-tech and academics to discuss how local stakeholders might collaborate to improve the sustainable use of water in Silicon Valley. Out of these discussions emerged the concept of the EcoCloud™, a coalition of private companies, public utilities, environmental organizations and academic researchers who encourage each other to adopt sustainable practices, supported by the latest social networking and data analysis tools. While the initial focus of the EcoCloud™ is to help industrial facilities use water sustainably—especially by using recycled water for cooling—its long-term goal is to support all aspects of sustainability, including energy reduction, materials management and land use. The EcoCloud™ allowed the City of San José to move from a serial marketing to a group marketing model, reaching more potential customers and connecting more facilities to the recycled water system.Inspired by the concept of industrial ecology, the EcoCloud™ is designed to be a "virtual" industrial ecosystem where industry, government and educational institutions can work together to share information about all aspects of sustainability. Although industries in the EcoCloud™ are not located next to each other, they share a common interest in reducing energy usage, conserving resources, eliminating waste, and cutting costs to improve their bottom line. Just as "cloud computing" uses the distributed power of the internet for more efficient data processing, the EcoCloud™ harnesses the power of web-based social networking tools so local business leaders and facility managers can work with industry experts, technology innovators, university researchers and government agencies to make their enterprises more sustainable and more profitable.

Decline in recycled water quality during short-term storage in open ponds

Changes were assessed in urban wastewater treatment plant (WWTP) effluent quality during short-term storage in open surface ponds. Water quality was monitored over five years at the inlets and outlets of open storage ponds located at three biological nutrient removal plants. Pond influent temperature, rainfall and sewage inflow were not found to be major factors. However, there was a trend for water temperature to be correlated negatively with nitrogenous nutrient and positively with faecal coliform values. The observed increases in faecal coliforms, nutrients and chemical oxygen demand were most likely caused through avian faecal contamination. These increases challenge the notion that pond storage has a positive or negligible effect on effluent quality. The observed one to two orders of magnitude increase in faecal coliforms may affect reuse scheme viability by limiting the range of uses under Australian water recycling guidelines. Potential improvements to short-term recycled water storage management at WWTPs could include the integration of monitoring requirements in WWTP discharge licences and recycling guidelines and the monitoring of all water quality parameters, including microbiological ones, at the point of entry into the recycled water distribution system, after WWTP storage, rather than directly post-disinfection.

Maximize your Recycled Water Distribution through Technical Customer Service

Maximize your Recycled Water Distribution through Technical Customer ServiceThe Inland Empire Utilities Agency (IEUA), a municipal water district in southern California, provides high quality recycled water for landscape, agricultural, and industrial uses. Two industrial customers, an electrical power generating station and a textile dyeing company, required special efforts to address their recycled water quality needs. The electrical power generating station faced the...Author(s)Jeff NoelteChris BerchBen PakTom LovePatrick SheildsSourceProceedings of the Water Environment FederationSubjectSession 12: Water Reclamation and Reuse: Reclaimed Water Distribution Systems and Sustainable Water ResourcesDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2006ISSN1938-6478SICI1938-6478(20060101)2006:12L.932;1-DOI10.2175/193864706783749549Volume / Issue2006 / 12Content sourceWEFTECFirst / last page(s)932 - 937Copyright2006Word count200

Risk assessment in wastewater recycling and reuse

Wastewater recycling and reuse guidelines and/or regulations have been traditionally and exclusively based on the determination of bacterial indicators and nematode eggs presence. Nevertheless, it has been demonstrated that: (a) virus presence is not well established by bacterial indicators, (b) the viability of nematode eggs is not determined, (c) parasites' presence is not analysed, (d) behaviour of all pathogens once in the recycled water distribution systems and points of use is not known, (e) behaviour of pathogens in the environment is also not known, and (f) chemical risk is not assessed. Additionally, it is to consider that risk associated with reuse is directly related to the final contact host-pathogen, or to chemicals ingestion and contact with the human body. Consequently, future developments of laws, rules and regulations for wastewater recycling and reuse need to include: (a) more detailed biological and chemical analysis of recycled water and environment, (b) the development of tools for determining environmental impact of recycled water and by-products of recycling, (c) the establishment of tools guaranteeing a reduction of the host-pathogen contact, and (d) risk assessment and management mechanisms. Suggestions and recommendations are made on how to include all this items in the future legislative developments for wastewater recycling and reuse.

A risk model for enteric virus accumulation and release from recycled water distribution pipe biofilms

Screening-level quantitative microbial risk assessments (QMRA) undertaken to assess health risks associated with the reticulation of recycled water have identified distribution pipe biofilms and their ability to accumulate enteric and opportunistic pathogens as potential sources of public health concern. A simplistic model to assess human health risks associated with enteric virions (extracellular viruses) present in recycled water for domestic use was therefore developed. Recycled water biofilms formed on glass and stainless steel coupons in a laboratory-scale distribution system were challenged with model enteric virions (B40-8, MS-2 and FX174 bacteriophages). Approximately 1% of bacteriophages present in the adjacent bulk water was incorporated into 3 month-old biofilms and a persistent sub-population (0.01%) of the model enteric virions remained infectious in biofilms throughout an experimental period of 30 days. Significant potential for virions to accumulate within biofilms was therefore demonstrated, and indeed biofilm uptake could mask treatment failures assessed through analysis of the bulk water (infectious virions would not be detected after 1.5 km even if 10.L-1 virions present in treated effluent). Subsequent sloughing of biofilm into the bulk water phase could therefore release infective virions within mobilized aggregates of biofilm and infect susceptible consumers. During normal operating conditions (one virion in 100 L of water) sufficient virions may accumulate within distribution pipe biofilms that a 50% sloughing event could present a Pi (annual) of 1.9 × 10-4 for the consumption of 1 mL of water, exceeding the US-EPA benchmark of 10-4.