Management of fatty acid methyl ester (fame) wastewater by a combined two stage chemical recovery and coagulation process

Abstract

AbstractA two‐step treatment process for fatty acid methyl ester (FAME) wastewater was carried out at a laboratory scale and ambient temperature. In the first step, FAME was chemically recovered from the wastewater using three types of acid (H2SO4, HNO3, and HCl) at different pH values ranging from 1.0 to 8.0. Optimally, approximately 15–30 mL/L of FAME was recovered when using H2SO4 at a final wastewater pH of 1–2.5 and a reaction time of 7 min. The properties of the recovered FAME were within the acceptable ranges for both community and methyl ester standards, except for the viscosity and the quantity of methyl ester. In the second treatment step, the aqueous phase discharged from the first step was adjusted to within the favourable pH range for chemical coagulation by either Al2(SO4)3 (pH 4.5–10) or poly‐aluminum chloride (PAC; pH 2.5–7.0) by the addition of CaO, and then subjected to chemical coagulation with either Al2(SO4)3 or PAC, as appropriate dose at 0–10 g/L. Under optimum conditions, >98.3%, 97.7%, and 99.2% of COD, BOD5, and oil and grease were respectively removed using Al2(SO4)3 at 2 g/L, whilst that achieved by PAC coagulation (at 1 g/L) was slightly lower at 98.2%, 96.5%, and 98.6%, respectively. The calculated operating cost of this management system was significantly cheaper than those using conventional management procedures, but will require an additional treatment stage such as biological remediation in sedimentation ponds to reduce the pollutant levels to acceptable limits.