The Columbus WWTP was receiving an overload of grease from restaurants. Some of the grease was traveling only 150 yards before discharging directly into the WWTP. Because of the grease received at the plant, there was little settling occurring in the 30-minute settling tanks, despite personnel maintaining a low mixed liquor in the aeration basin. The plant was hauling off up to seven loads of sludge per month.
In April 2010, BioCOPE began treating with FERI to reduce the amount of grease and eliminate its associated problems. By breaking down grease, BioCOPE decreased the food in the WWTP available for filamentous bacteria. This minimized problems caused by filamentous bacteria, such as cross-bridging and bulking in the clarifier, resulting in better settling and a clearer supernatant discharge.
After treatment, the 30-minute settling test improved from only settling to 950 ml to settling down to 600 ml. The plant was able to maintain the 600 ml settling results while it increased the MLSS to 6,000 mg/L in the aeration basin. During treatment, the plant has reduced its sludge wasting from the aeration basin an average of 33.6%.