Develop Management Practices to Control Potential Health Risks and Aesthetic Issues Associated with Storage and Distribution of Reclaimed Water
Type: Decision Making Tool
Year Released: 2015
Funding Partner: Singapore Public Utilities Board Total
Investment: $377,578 (Cash: $199,998, In-Kind cash and service: $177,580)
Principal Investigator: Patrick K. Jjemba, MBA, PhD American Water
Reclaimed water should be viewed as a perishable product analogous to food products with a shelf life, signifying the need for minimal water detention time in storage or distribution system (i.e., increased turnover). A rapid turnover minimizes the deterioration in water quality whereas low water turnover increases water age in the system. There is a need to tap into existing knowledge to ensure a product of reliable quality up to the point of intended use by using a best management practices (BMPs) approach. BMP guidance is distinct from regulations in various ways. Regulations are set by a regulatory agency and require compliance with certain standards containing numerical criteria. By contrast, BMP guidance is typically voluntarily implemented to prevent negative impacts or improve operations. They are considered as the “best” available and practical means of preventing a particular impact without affecting the cost or efficiency of the production, storage and distribution of reclaimed water. The study used a multi-layered approach of surveys, interviews, case studies, literature review, and an expert workshop to develop BMPs for controlling potential health and aesthetic issues associated with storage and distribution of reclaimed water.
Goals and Objectives
The study was conducted to:
- Conduct a literature review of reclaimed water storage and distribution system facility guidelines, regulations and case studies using peer reviewed and gray literature
- Document facility characteristics and practices as to collate treatment, storage, distribution and water quality information of geographically dispersed reclaimed water systems.
- Document the issues and practices associated with management of reclaimed water distribution and storage facilities;
- Conduct site visits to evaluate storage and distribution system design and management practice;
- Use the literature review, questionnaires and case studies to develop solution-oriented best management practices
- Streamline the developed BMPs through a workshop and/or interview of industry leaders; and
- Develop a report and user-friendly guidance manual for the reclaimed water industry for distribution and storage BMPs.
The problems associated with reclaimed water storage and distribution were identified at two levels: a brief online survey (sent to 341 recipients) and a more detailed phone interview of respondents (selected using an unweighted pair group method for cluster analysis) to the online survey. These responses were used to develop a quantitative score to prioritize and identify utilities most likely to provide significant information during onsite visits and sampling. The site visits also provided an opportunity to comprehensively review each facility and verify previously provided information. During site visits, samples were collected from the effluent, reservoir, and three points in the distribution system and tested onsite for free chlorine, temperature, pH, conductivity and dissolved oxygen. Water samples were shipped overnight on ice to the laboratory to determine TOC, AOC, turbidity, chlorophyll a, sulfide and Legionella spp. Critical control point (CCP) analysis was used to outline ways for the respective utility to eliminate or reduce the risk or hazards associated with reclaimed water based on their intended use. Critical limit guidelines were developed based on peer-reviewed and grey literature sources combined with prior knowledge about historical performance. To set realistic goals, setting the proposed quality targets considered the expected use of the reclaimed water. For each monitored parameter, a corrective action was also developed to ensure the CCP could be quickly corrected to ‘normal operation’ to meet the intended use of the reclaimed water. The 14 BMPs were fine-tuned by an expert panel during a 2-day workshop.
Findings and Conclusions
The multi-layered project approach used existing expertise to develop BMPs and, coupled with an extensive review of the literature, provided effective and practical solutions to storage/distribution issues. The developed BMPs addressed infrastructure, water quality, customer, operational, cost and demand/supply issues which comprised 80% of the common problems with reclaimed water storage and distribution.
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