Session 22B: Resource Recovery
10:30am - 11:15am
Applied Planning for Pocatello's Biosolids Reuse and Recovery
1Stantec Consulting Services Inc., United States of America; 2City of Pocatello, ID; ,
The City of Pocatello, ID has been recovering, land applying and reusing its Class B treated biosolids for decades on nearby agricultural lands. The biosolids treatment and handling system consists of mesophilic anaerobic digestion of thickened primary and secondary sludge, followed by lagoon storage and spring/summer liquid sludge hauling to both City owned and leased land. In the last few years, local growth and associated loading to the Water Pollution Control Facility (WPFC) have increased to the point where the lagoon is often overloaded in late winter through early summer. This situation creates challenges to the operations of the WPCF as the biosolids recirculate back into the liquid stream. This solids overload results in costly and hectic lagoon dewatering efforts, sub-optimal treatment performance and increases the risk of NPDES permit violations. Faced with this challenge, coupled with the desire for long term biosolids planning, the City selected the Stantec/Keller team to address this problem as part of the 2021 Facility Plan update. To properly address the biosolids issue, the team implemented a decision-making process for both solids handling and solids reuse or disposal. The first evaluation included a decision to either expand the biosolids lagoon system or move toward solids dewatering. The second decision determined whether to continue the existing land application of liquid sludge, move to dewatered sludge land application, enhance the biosolids to a Class A through composting, or shift toward landfill application. The results are in, the decisions have been made and the City is moving forward with making the recommended improvements to provide the best solution and end use for this valuable City resource.
11:15am - 12:00pm
Novel Alternative Management of Data Center Industrial Wastewater
1J-U-B Engineers; 2City of Umatilla Oregon; , ,
Data centers offer economic drivers attractive to communities able to meet utility demands. These industries have large electrical demands to power associated computer equipment which are converted to heat and must be evacuated. Data centers using evaporative cooling require large amounts of water which is evaporated or discharged as industrial wastewater when constituent concentration or temperature prohibits continued use in cooling towers. The volume of water used, the volume of water evaporated, the volume of water discharged, and constituent concentration therein will depend on the quality of source water, climatological conditions and internal management. Water and wastewater service providers must understand the demands of data centers and plan for meeting those demands prior to agreeing to serve. In 2013, the first data center was constructed within city limits at the City of Umatilla, Oregon. After the data center became operational, industrial wastewater was discharged to the City’s wastewater treatment plant when the ambient temperature began to climb in the springtime. When the temperature reached over 100 degrees, the City experienced a 65 percent increase in wastewater flow and corresponding dilution of most influent constituent concentrations. As the industrial development continued, the City had concerns over managing projected flows from future data center expansions and began planning to meet service demand. After investigating alternatives, the City decided to pursue discharging the industrial wastewater directly to a water of the state via a national pollution discharge elimination system (NPDES) permit. The presentation will focus on the City’s experience collecting, treating, permitting and disposing of the data center industrial wastewater and associated benefits: additional irrigation water, lower fees and sustainability.