Study of Coagulation as a Pre-Treatment of Microalgae Removal by Sedimentation

Abstract

Microalgae can grow fast in wastewater. Several techniques have been developed to remove it, but do not provide optimal results. Chemical and electro-coagulation as a pre-treatment of sedimentation technique was examined to remove microalgae from the wastewater. The wastewater used were effluent from animal farm and slaughterhouse. Chemical coagulant used are Poly Aluminium Chloride (PAC) and ferrous sulfate, whereas for electrocoagulation iron electrode was used. The efficiency of Total Suspended Solid (TSS) removal as a measure of microalgae removal reached to 98% for slaughterhouse wastewater at pH 7 with a PAC dose of 100 mg/L, 98% for animal farm wastewater at pH 7.25 with a PAC dose of 200 mg/L, 99% for slaughterhouse wastewater at pH 6.5 with a ferrous sulfate dose of 65 mg/L and 80% for animal farm wastewater at pH 6.75 with a ferrous sulfate dose of 120 mg/L. The efficiency of TSS removal as a measure of microalgae removal reached to 79% and 49% for slaughterhouse and animal farm wastewater on the direct current of 15 volt and operation time 40 minutes. In addition to microalgae removal, chemical and electrocoagulation lead to reduction of the wastewater turbidity, color, Chemical Oxygen Demand (COD) and phosphate.