RESEARCHING THE EFFICIENT SS AND COD TREATMENT IN WASTEWATER IN VIET CUONG CRAFT VILLAGES BY COAGULATION AND FLOCCULATION

Abstract

Wastewater from vermicelli produce contains high levels of organic matter with COD from 460,8 to 844, 8 mg/L; BOD5 from 209 to 325 mg/L; especially suspended solid (SS) that fluctuates from 625 mg/L to 766 mg/L). In this study, the high suspended solid value is one of the reasons that impedes biological treatment process. The purpose of this study is to find an agent in the coagulation-flocculation method that can treat SS by three coagulants: PAC (Poly Aluminium Chloride),  Aluminum Sulfate (AS) and Ferrous Sulfate Hydrate (FSH) to treat effectively SS before entering the biological treatment system. The treatment efficiency of PAC reached the highest of 98.00% with the concentration of 200 mg/L, FSH reached 80.23% with the concentration of 400 mg/L and AS was 95.84% at the concentration of 400 mg/L. pH that the factor influences the SS treatment efficiency was also studied. The results showed that the optimum pH for SS treatment with FSH, AS and PAC were 9, 7 and 7-7.5, respectively. PAC has been used as a coagulant for SS treatment of this wastewater.