Council OK’s ‘Bio Dome’ study by Rick DeClue · News · September 28, 2012
At its Sept. 17 meeting, the West Branch City Council approved a pilot study to reduce ammonia in the city’s wastewater treatment system.
The city continues to search for an alternative method to constructing a new physical plant — a much more expensive option to build which requires higher ongoing maintenance costs.
The Bio Dome, marketed by Utah-based Wastewater Compliance Systems, Inc., is a 20-foot long cargo container that is submerged in a wastewater lagoon. The unit pulls water in using forced air, then passes it through a membrane system designed to nitrify the ammonia in the water. This lowers the ammonia levels in water coming out of the lagoon. The membrane is referred to as a “fixed film bioreactor.”
The pilot study uses one Bio Dome, or Mobile Pilot Unit. According to city engineer Dave Schechinger, a fully implemented system could require as many as 100 units for the city’s lagoon, at a cost of $800,000 to $1,000,000.
The West Branch test follows a test in the Lennox Iowa Bio Dome Pilot Study last winter. West Branch will pay $750 to transport the Bio Dome from Lennox, plus pay approximately $500 per month to gather data and test the unit over the winter months.
The city is trying to be proactive. It is waiting for new, lower ammonia target levels for its wastewater treatment from the Iowa Department of Natural Resources. Past testing has shown that, like many communities that use a lagoon as part of their system, West Branch’s ammonia levels in the winter exceed acceptable levels.
A fully implemented Bio Dome system would replace the lagoons’ current diffusers, which are in need of substantial rehabilitation and maintenance, Schechinger said.
Council Member Mark Worrell asked whether the membrane simply traps the ammonia or breaks it down. Schechinger said the system breaks down the ammonia, but the membranes require periodic servicing.
Member Jim Oaks asked if the air blowers in the city’s current system would provide enough air for a full Bio Dome system. Schechinger said they probably would not.
Council member Colton Miller asked why the council was, in effect, paying for a “test drive” of a system WCS wanted to sell the city.
Oaks responded that pilots or tests were not uncommon when considering large-scale infrastructure solutions. He said the relatively small cost of the test was much better than spending a million dollars on something that did not work.
The pilot test was approved on a 4-0 vote. Council Member Dan O’Neil was absent.