Alternative Water Supplies in the Midwest: Reuse Roadmapping in Ohio

Introduction The Midwest region is known for its abundant water resources. Historically, this 'water wealth' has fostered a perception that alternative water sources are not worthwhile investments. Recent developments are challenging this status quo. Over the past decade, the state of Ohio has seen an influx of technology companies, particularly data centers [1], creating substantial demand for cooling water. Rapid industrial development is typically followed by community growth, further increasing demand. Climate change may also lead to drought, reducing supply [2]. Consequently, stakeholders in Ohio are considering treated wastewater (recycled water) to meet demand. Planning for recycled water systems requires collaboration among the key stakeholders involved, including utilities, technology companies, and regulators. This paper presents a case study where we applied a reuse roadmapping approach for a major Midwest city experiencing significant technology sector growth — Columbus, Ohio. Two areas were considered for recycled water: 1.A 5-mile radius around the existing Southerly Wastewater Treatment Plant (Figure 1a)[3]. 2.New Albany International Business Park — an area experiencing rapid technology development (Figure 1b)[4]. Water Demand Billing data and infrastructure planning documentation provided by utility and municipal partners, along with an analysis of publicly available development announcements, showed that existing potable water demand (<2 MGD) in the project areas were significantly lower than future estimated growth (>10 MGD) (Table 1). Water Supply and Quality Columbus An evaluation of existing infrastructure showed that recycled water supply could easily be met by treated effluent from the Southerly WWTP, a 114-mgd ADF (330-mgd peak) treatment facility that provides primary/secondary treatment and disinfection for wastewater in a large portion of the region. Water quality data provided by the City of Columbus showed that SWWTP effluent generally has low TSS (<30 mg/L), low BOD (<25 mg/L), low nitrogen (<20 mg/L TN), and low pathogen content. Therefore, it is likely that the effluent will require minimal additional treatment to meet quality requirements for non-potable use or irrigation. New Albany The City of New Albany does not have a dedicated WWTP to treat wastewater. Flow is currently collected via a series of interceptors and conveyed via trunk sewer to the Southerly WWTP nearly 30 miles south. Therefore, a sewer mining concept was considered, where sewage from a main trunk sewer is treated and distributed to users in the business park. The estimated future flow available was 5 MGD. Water quality data for sewage from the business park was unavailable since the user base is not established. Therefore, medium strength wastewater (190 mg/L BOD, 210 mg/L TSS, 40 mg/L TKN, 7 mg/L TP, 90 mg/L alkalinity, 30 mg/L sulfate, 500 mg/L TDS) was considered for this analysis. Treatment for organics and nutrients is likely required to support non-potable use or irrigation. Water Quality Requirements and Regulations Water quality requirements for recycled water are a balance between regulatory requirements and user requirements at specific facilities. Although reuse of treated wastewater for industrial uses is not currently defined in the Ohio administrative code, experiences from similar states (e.g., Virginia) suggest that this use case could be defined within existing codes describing treated wastewater irrigation (OAC 3745-42-13). A summary of projected water quality requirements was developed (Table 2)[5]. Treatment Strategy and Preliminary Cost Analysis Columbus Based on user water quality preferences and regulatory review, a tertiary treatment and disinfection system was considered to provide 20 MGD of recycled water to customers in the Southerly WWTP area. The opinion of probable construction cost for the treatment, pumping, and distribution system was >$200M, with O&M costs estimated at >$3M/year. The total estimated cost of treatment and distribution was >$3 per thousand gallons, similar to the potable water cost for commercial users in the Columbus area. New Albany Based on user water quality preferences and regulatory review, a membrane bioreactor (MBR) system with disinfection was considered to provide 5 MGD of recycled water to customers in the New Albany area (Figure 2). The opinion of probable construction cost for the 5 MGD treatment, pumping, and distribution system was >$200M, with O&M costs estimated at >$4M/year. The total estimated cost of treatment and distribution was >$10 per thousand gallons, significantly higher than commercial water rates. Conclusion This presentation synthesizes a case study from a water-rich region to inform the momentum for water recycling in the region. This study highlights the complexities of estimating water demands amidst uncertain future developments. Additionally, we explore challenges when development occurs miles away from the largest facilities capable of providing recycled water. Sewer mining was explored as an option to provide remote access. Cost advantages were apparent when demand was near existing treatment infrastructure. Collaboration with regulatory authorities, utilities, and users is critical to establish frameworks for demand estimation, regulatory review, and permitting.