Reduction of Color, COD, and BOD5 of Treated Leachate Using an Activated Coconut Charcoal – Fired Clay Brick System

Abstract

Removal of color from waste water by activated carbon is a common practice and studies have also been done with fired clay bricks. Nevertheless, no studies have been carried out to evaluate the removal of color by a combination of activated carbon (CC) and fired clay bricks (BR). The present study was therefore, planned to evaluate the potential of the combination of CC (activated by ZnCl2) and BR for the removal of color, chemical oxygen demand (COD) and five day biochemical oxygen demand (BOD5) of the treated leachate discharged from sanitary landfill located at Dompe, Gampaha,Sri Lanka. CC was impregnated with 0%, 5%, 10%, 15% and 20% ZnCl2 and activated in an oven at 2000C afterwards. The activated CC – BR systems were prepared in PVC pipes with the ratio of 1:0 (T1), 0:1 (T2-T6), 1:1(T7-T11), 1:3(T12-T16) and 3:1(T17-T21) BR particles and CC respectively. Leachate was filtered through the prepared systems at flow rate of 1L/hour. Color, COD, BOD5 and pH of filtrate were measured. Percentage reductions of parameters were first subjected to arcsine transformation and then to One-Way ANOVA in MINITAB 14. Tukey’s pair wise comparisons were also carried out to identify significant differences of parameters among different percentages of activated carbon. Results revealed that 20% ZnCl2 impregnated CC and BR at 1:0 system showed the highest percentage of color (>90%) and COD (>85%) reductions. CC - BR at 1: 1(CC activated by 20% ZnCl2) (T-11) and CC - BR at 3: 1(CC activated by 20% ZnCl2) (T-16) showed the highest percentage of BOD5 (more than 95%) reduction. After 5-hour filtration, 20% and 15% ZnCl2 impregnated CC and BR at 1:0 system showed pH lower than 6. The lowest pH was observed from 20% ZnCl2 impregnated CC. The study concludes that CC impregnated with high amount of ZnCl2 has a great potential to remove the color of leachate. Thus, the present study recommends the combination of 20% ZnCl2 impregnated CC: BR at 3:1 ratio as the most suitable combination for the removal of color, COD and BOD5 of the biologically treated leachate.