Treatment of Synthetic Wastewater Containing Propylene Glycol by a Lab Scale Fixed Bed Activated Sludge Reactor

Propylene glycol is an organic compound which has wide applications in the pharmaceutical, cosmetics, chemical, and food processing industries. Propylene glycol is readily released into surface and ground waters and the neighboring soils via industrial wastewater effluents posing many health and environmental hazards. The main purpose of this study was to determine the efficiency of fixed bed activated sludge reactor for propylene glycol removal from synthetic wastewater. The lab scale reactor consisted of a cubic Plexiglas aeration tank with a total volume of 16 liters, 12 liters for aeration and 4 liters for settling. 25% of the aeration tank was filled with media as fixed bed for the biofilm to form. To evaluate the optimum efficiency of the reactor under variable organic loadings, the organic loading was increased in two consecutive stages: first by HRT depletion, and second by increasing COD concentration. The COD removal efficiencies obtained for hydraulic retention times of 8, 6, 4 and 2 hours and at an influent COD concentration of 500 mg/L were 95.86, 95.12, 93.96, and 79.08 %, respectively. In the fallowing stages and based on the results obtained from the first stage, a constant HRT of 6 hrs and COD concentrations of 1000, 1500, 2000 and 2500 mg/L were experimented. The removal efficiencies for the above concentrations were 95.95, 88.54, 75.95, and 35.69%, respectively. The results from this study indicate that the fixed bed activated sludge bioreactor satisfactorily capable of removing propylene glycol.