Process Modeling and Evaluation for Anaerobic Treatment of Vegetable Oil Refining Wastewater with High Sulfate Concentrations

The Vegetable Oil Refinery (VOR) wastewater has a high concentration of Chemical Oxygen Demand (COD) and contains large amounts of oil, grease, sulfates, and phosphates. VOR wastewater is usually treated by a combination of pretreatment for oil and grease, biological treatment, and advanced treatment. High sulfate concentration is a result of sulfuric acid addition during the acidulation process, which poses a challenge for treatment of this type of wastewater. A comparative modeling assessment was conducted for treatment alternatives for a VOR wastewater containing high COD and sulfate concentrations. Two treatment alternatives were evaluated: Covered Anaerobic Lagoon (CAL) followed by activated sludge and Sulfate reduction, Autotrophic Denitrification and Nitrification Integrated (SANI®) process. Biogas production, sulfate, nitrogen and COD removal, aeration and chemical demand, and other key parameters were compared. Process modeling and analysis indicated excessive H2S concentration in biogas. Dilution of acidulation wastewater, and pre-treatment for sulfate removal prior to biological system were investigated.