bioaugmentation, biofilm, compliance, operations, nitrogen, nutrient removal
The wastewater treatment plant in the Town of Orange Park, Florida was challenged to meet a new discharge permit issued by the Basin Management Action Plant (BMAP) for the lower St. John’s River that was 70% lower than the plant was capable of delivering. The Town’s existing wastewater treatment facilities utilized three parallel Contact Stabilization package-type systems to treat 1 MGD and discharge approximately 76,100 pounds per year of total nitrogen into the St. John’s River. The new BMAP permit went into effect for the Town in May 2009 and limited effluent total nitrogen to an annual load of 21,998 pounds. In accordance with the new limit, the Town planned to upgrade the treatment processes to BNR systems, reconfiguring the plant into two, five-stage Bardenpho trains. In order to maintain performance during the construction activities, the Town implemented a bioaugmentation program which delivers specialized bacteria into collection system, transforming it into a pretreatment step to reduce influent load, enhance biological treatment and nitrogen removal as well as to provide operational flexibility. With bioaugmentation in place, the average daily influent CBOD loading to the plant decreased by over 50% and the effluent total nitrogen load decreased by 60% to about 25,000 lbs/year, nearly meeting the new discharge limit before the BNR upgrades were online. The WWTP underwent a number of process changes during the construction term, which is ongoing. This paper will focus on the effects of the bioaugmentation program which, combined with process modifications and operating adjustments, enabled the plant to operate at two-thirds of its former capacity while demonstrating excellent nitrogen removal and delivering improved effluent water quality. The case study addresses the challenges of upgrading the plant and the substantial operating expense savings that the Town realized by reducing air delivery to the biological treatment process and the aerobic digester as a result of the effects of bioaugmentation in the collection system.