Continuous Enzymatic Prehydrolysis Treatment of High-Fat Wastewater

A lipolytic fermented solid was produced by solid-state fermentation of Rhizopus micro-sporus CPQBA 312-07 DRM on a mixture of sugarcane bagasse and sunflower seed meal and used, in a packed-bed bioreactor, to pretreat a high-fat wastewater from a meat and sausage processing factory located in Sao Jose dos Pinhais, State of Parana, Brazil. With a hydraulic residence time of 24 h, this pretreatment not only reduced the wastewater's oil and grease content by up to 96 %, but also increased its 5-day biochemical oxygen demand to chemical oxygen demand ([BOD.sub.5]/COD) ratio. This ratio was only 0.19 in the raw wastewater, indicating poor biodegradability, but increased to 0.55 in the pretreated wastewater, indicating that it had a sufficiently high biodegradability to be sent to a traditional anaerobic digestion or activated sludge process. After 96 days of operation of the packed bed, a microbiological analysis showed that R. microsporus was still present and viable in the fermented solid. Our work shows that a continuous packed-bed bioreactor containing fermented solid produced by R. microsporus has good potential for the treatment of high-fat wastewater. Key words: enzymatic hydrolysis, lipases, Rhizopus microsporus, high-fat wastewater, packed--bed bioreactor