Production and Utilization of a Novel Solid Enzymatic Preparation Produced by Penicillium restrictum in Activated Sludge Systems Treating Wastewater with High Levels of Oil and Grease

Abstract

The efficiency of a solid enzymatic preparation (SEP), produced through solid-state fermentation by the fungus Penicillium restrictum with waste from the babassu oil industry, was evaluated in a pretreatment stage of a dairy effluent. A range of oil and grease (O&G) contents in the effluent were tested (400, 600, and 800 mg O&G/L). Two parallel activated sludge systems were operated continuously with a hydraulic retention time of 20 h during a 240-day period, one of which treated raw effluent (Control) and the other of which treated enzymaticaly prehydrolyzed effluent (Test). In the trials with 800 mg O&G/L in the delivered effluent, a significantly improved waste treatment outcome was obtained with the Test bioreactor than the Control bioreactor, including chemical oxygen demand removal (13% higher), O&G accumulation in flocs (40% lower), biomass concentration (1.7 times higher), degradation constant (4.7 times higher), and specific oxygen uptake rate (1.3 times higher). Only the Test bioreactor attained parameters within the discharge standards required by the local environmental legislation for treated effluent. The employment of enzymatic pools produced by solid-state fermentation (known as SEP) from low-cost industrial wastes may represent an important contribution as an adjuvant in the aerobic biological treatment of dairy effluents with high O&G contents.