Remediation of biodiesel wastewater by chemical- and electro-coagulation: AÂ comparative study

► We use acid protonation and treatment to remediate biodiesel wastewater. ► 24.3 ml/l of FAME / FFA were removed when using H2SO4 to set a final pH of 2.5 for 7 min. ► The chemical coagulation provided lower operating cost than that of electro-coagulation process. ► A better quality of wastewater was obtained by using the electro-coagulation process, except BOD.