Evaluation of the efficiency of constructed wetland and activated charcoal for the treatment of slaughterhouse wastewater

Slaughterhouses in Batticaloa district usually discharge their wastewater into the nearby soil surface and water bodies without any adequate treatment, which causes serious and deleterious threat to surrounding environment. Therefore, there is a need to treat slaughterhouse wastewater before disposal is a necessity to protect public health and environment. Even though there are several techniques available for treating this wastewater, suitability and cost for the specific places are questionable. Therefore, this study was mainly focused to design, construct and evaluate the efficiency of constructed wetland and activated charcoal treatments for slaughterhouse wastewater on the parameters of chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), nitrate, phosphate, biological oxygen demand (BOD) and pH. The wetland was constructed with the layers of coir fiber, gravel, and sand with the dimension of 1m x 1m x 0.3m. Cattail (Typha latifolia) plant was used as macrophytes and activated carbon (adsorbent) was produced from coconut shell with CaCl2 (activating agents). The results revealed that the activated carbon and constructed wetland were significantly differ in their efficacy on the treatment of slaughterhouse wastewater (p>0.05). It was observed that increasing the retention time of treatment caused increase in the removal efficiency of both treatments. The maximum removal of COD, TSS, TDS, BOD5, NO3- and PO4- with constructed wetland were 77.5%, 88.7%, 71.3%, 93.3%, 68% and 85.8%, respectively while an activated charcoal reduced COD, TSS, TDS, BOD5, NO3- and PO4- as 74.8%, 92.5%, 79.9%, 92.6%, 47.4% and 67%, respectively. It is concluded that the constructed wetland has better performance than that of activated charcoal for the treatment of slaughterhouse wastewater with the special reference to nitrate, phosphate, BOD and COD. However, activated charcoal shows better performance especially for the removal of dissolved solids.