The Effectiveness of Poly Alumunium Chloride (PAC) on Chemical Oxygen Demand (COD) Levels of Laundry Wastewater in Batam City, Indonesia

Laundry activities produces waste water contains high pollutants such as Chemical Oxygen Demand (COD). The COD level of sample from a laundry wastewater was 541 mg/L, which over the wastewater quality standard the Indonesian Minister of Environment Regulation no 5/2014 (100 mg/L), therefore wastewater treatment was required to prevent any adverse effect. One of the parameters which is able to describe the pollutants in wastewater is COD. Wastewater treatment can be done by coagulation-flocculation process with Poly Aluminum Chloride (PAC) coagulant. The purpose of this study was to determine the efficiency of PAC in reducing COD levels in laundry wastewater. This study was a true experimental study with a pre-test post-test with control group design, used jar test to simulate the coagulation-flocculation process in a laboratory scale. PAC variations concentration were 300 mg/L, 350 mg/L, 400 mg/L, and 450 mg/L with additional samples of pretest and control. The treatments were repeated in 6 times. Kruskal Wallis test showed population of COD level difference before and after treatment (p=0.008). Mann Whitney test showed that groups which had significant difference in COD reduction were between the control group and each of PAC-treated group (p<0.05). The optimum concentration of PAC in reducing COD levels was 300 mg/L with an average effectiveness of 58.97%. The final COD levels in this study still requires further wastewater treatment before the final disposal.