EPA has already treated the roughly 14 million gallons of wastewater left at the Twin Street site with a hydrogen peroxide solution to kill the bacteria that emits the hydrogen sulfide gas at the source of the stench.
Last week, EPA advised citizens the odor may periodically heighten as it was necessary to turn on aerators in one of the three basins onsite to allow for breakdown of bacteria in the water. However, federal on-scene coordinator Jason Booth said they have now decided against using the aerators.
“After considering the odor caused by turning on the aerators in the smaller basin, we have decided to not turn on the aerators in that basin at this time, but to treat the oxygen-depleted smaller basin with hydrogen peroxide,” Booth said.
Oxygen is needed in the basins to break down certain bacteria like nitrates and ammonia that must be lowered to safely discharge the materials into Shirtee Creek, which is the ultimate goal once the wastewater is fully treated.
“This will enable the smaller basin to increase its oxygen level while minimizing the off-gassing of hydrogen sulfide,” Booth said.
Further maintaining a commitment to minimize the odor, which has long been a complaint of citizens near the facility and throughout the city, Booth said he requested and received a real-time air monitoring system. The same monitoring system was used during the initial emergency response phase when EPA first arrived at the site last October.
“The instruments will be placed along the fence line downwind of the basins to monitor and record the air quality in real time 24/7,” he said.
EPA is still experimenting with treatment techniques for the onsite wastewater, which was largely left untreated when the now-bankrupt REEF Environmental ceased operations in late 2010. A system obtained from Birmingham-based Rain For Rent is, thus far, not treating the waste to the level required by their discharge permits from the Alabama Department of Environmental Management, Booth previously said.
“There is always a trial and error period when you do these kind of operations,” he said. “We will continue trying different configurations for treatment until we get things right.”
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