Treatment of wastewater from biodiesel generation and its toxicity evaluation by raphidocelis subcapitata

Abstract

Biodiesel was developed to solve vast economic and environmental problems related to the use of petroleum as fuel. However, large quantities of water are necessary for biodiesel production, generating a high volume of effluent waste. Therefore, it is important to treat this wastewater in order to meet the environmental legislations according to the Brazilian Resolution Number 430/2011 (CONAMA). This work aimed to treat this effluent by coagulation/flocculation (CF) and an electrochemical advanced oxidation process. The combination of CF techniques (pH = 6.5) and electrochemical oxidation (boron doped diamond - BDD - electrode with NaCl) led to 78.5% removal of total organic carbon. The evaluation of the toxicity with Raphidocelis subcapitata indicated that the treated samples (IC5072h = 1.66%) had lower chronic toxicity when compared to raw effluent samples (IC5072h = 0.17%). This indicates that the proposed treatment was effective to decrease the organic load and reduce the environmental impact of these effluents in water bodies.