Hillsborough Filter Pilot Project (2006)
This report summarizes research conducted at the Talifero Stormwater Research site in Hillsborough County on coagulating agents that could improve the nitrogen removal efficiency of stormwater treatment BMPs. A zeolite filter pilot plant was operated over a 216 day period to evaluate its ability to enhance nitrogen removal from stormwater. When operated at a steady filtration rate of 192 gal/ft2-day, the zeolite filter was highly effective at removing ammonia, producing an effluent ammonia nitrogen concentration of 0.07 mg/L, and removing 93% of ammonia and 32% of total inorganic nitrogen.
Abstract
A zeolite filter pilot plant was operated over a 216 day period to evaluate its ability to enhance nitrogen removal from stormwater. When operated at a steady filtration rate of 192 gal/ft2 -day, the zeolite filter was highly effective at removing ammonia, producing an effluent ammonia nitrogen concentration of 0.07 mg/L, and removing 93% of ammonia and 32% of total inorganic nitrogen. A variety of non-steady state experiments demonstrated that the zeolite filter performance was superior to a parallel sand filter under the varying conditions that are common to stormwater management systems. A storm event was simulated by applying a sudden increase in flowrate to the zeolite filter that was over 30 times greater than normal. The zeolite filter maintained a 90% or greater concentration reduction throughout the simulated storm, removed more than 99% of the applied ammonia mass, and provided superior performance to that of a parallel sand filter control. To assess ammonia removal following an extended inter-event period, the zeolite filter received no flow for 40 days and then received a storm event loading. The zeolite filter retained virtually all added ammonia mass, while ammonia nitrogen levels in the sand filter effluent were above 7 mg/L. The zeolite filter was also operated under low dissolved oxygen conditions and provided ammonia retention superior to sand. Two denitrification filters were evaluated for removal of nitrate and nitrite from zeolite filter effluent. A sulfur/limestone filter and a barley straw filter both reduced total oxidized nitrogen by 95% or more and produced effluent levels of 0.1 mg/L or less.