Effectiveness of Bacillus megaterium in pretreatment of fish slaughterhouse effluent

Abstract

The use of microorganisms to treat effluents can reduce problems caused by oils and fats in subsequent treatment stages. The present work investigates the use of a lipase-producing microorganism in the pretreatment of effluent from a fish slaughterhouse. Initial preliminary tests were performed with two microorganisms: Staphylococcus warneri and Bacillus megaterium. The following parameters were evaluated after the treatment: chemical oxygen demand (COD), oils and greases (O&G), and lipolytic activity. Bacillus megaterium provided the highest removal efficiencies for the analyzed parameters, consequently this microorganism was then used for the pretreatment of fish slaughterhouse effluent. A central composite rotational design (CCRD) was applied, with pH, temperature, and inoculum concentration as the independent variables. The response variables were lipolytic activity, COD, O&G, free fatty acids, and pH, for a reaction time of 72 h. The maximum values obtained after the treatment were lipolytic activity of 0.25 U mL− 1, COD and O&G removals of 61.11% and 85.8%, respectively, and free fatty acids production of 12.54 µmol mL− 1. The findings showed that the application of Bacillus megaterium significantly reduced the levels of oils and fats, demonstrating the potential of the enzyme for treatment of this type of effluent.