Gresham is expecting more stringent ammonia requirements when they renew their discharge permit in 2012. Because Gresham’s permit levels are based on pH of the water, their engineer initially proposed a $400,000 CO2 injection system to manage the pH instead of actually trying to remove the ammonia. After learning of WCS’s Bio-Dome systems, and the associated potential cost savings of implementing Bio-Domes over the CO2 system, the community requested a pilot study.
Solution & Results
Because Gresham has year round ammonia requirements, it was agreed that they should conduct a pilot study over the course of an entire winter. WCS constructed a pilot unit in an insulated 20’ cargo container which contained a 1,500 gallon open top tank and a single Bio-Dome dome in the tank. The pilot study began in October 2010, and is expected to run through spring of 2011. The graph below shows performance to-date.
Art Bahr has really taken ownership of this pilot test and has provided valuable feedback on how we can improve the pilot unit, which we are incorporating into our other pilot units. Art was interviewed by NPR for a program called Living On Earth. To hear first hand Art’s impressions of the Bio-Domes please visit:
Additionally, WCS recently provided Gresham with a proposal for a full scale system of 54 domes, for which Gresham is in the process of submitting a facilities plan amendment to include the Bio-Domes in their 2013 wastewater plant upgrade.