Physical Chemistry Treatment of Wastewater From Biodiesel Purification

Abstract

Biodiesel, a biodegradable renewable product that obeys the carbon cycle, comes detaching more each time in the national scene due to the National Program of Production and Use of Biodiesel from the Federal Government, that stipulates a 2% obligatory addition of biodiesel to the Diesel oil starting at 2008. However the possibility of massive production of biodiesel in Brazil represents a serious threat to the drinking water sources, since one of the critical stages that guarantee the fuel quality is the laudering with water to the removal of biodiesel's by-products, such as the glycerin, the residual alcohol and the catalyst that still mixed in the renewable fuel. This water enters in the process of production not contaminated (some times also potable) and returns to the environment contaminated, presenting pH = 11, oils and greases near of 500 mg L-1, color equal to 3,000 mg L-1, turbidity equal to 905 NTU, beyond a chemical demand of oxygen equal to 16,564 mg L-1. This values are in disagreement with the Conama Resolution nº357. However after treatment it obtains pH = 6, nothing detected for oils and greases and color, 0,64 NTU for turbidity and chemical demand of oxygen equal to 5,000 mg L-1.