Evaluation of Leachate Quality of Anaerobic Compost Digester Treated with Distillery Spent Wash

Abstract

In Jaffna peninsula, huge amount of Palmyra (Borassus flabellifer) sap is produced seasonally and excess amount of sap is distilled through distillation process where ethanol distillery produces around 20 L of toddy distillery spent wash (TDSW) for every liter of alcohol produced, as waste water. Meanwhile management of municipal solid waste without degrading the environment is a serious issue. Hence an attempt has been made to produce compost from » D municipal solid waste with the application of TDSW which will enrich compost quality. The objective of this study was to evaluate the leachate quality from anaerobic digester. An anaerobic digester was designed and was filled with 5 kg of manually separated organic waste from municipality and 30 L of TDSW. For the control treatment, 30 L ofwater was applied instead of TDSW with 5 kg of manually separated organic waste. Leachate was collected at weekly interval for 42 days. Chemical quality parameters of fresh TDSW and leachate were analyzed. pH, electrical conductivity, total nitrogen, phosphorous, potassium, calcium and available nitrogen contents of TDSW were 2.9,43.3 mScm', 511 mgL ', 320 mgL'1, 180 mgL'1, 69.5 mgL 1 and 9 mgL'1, respectively. There were significant differences between chemical parameters of leachate from TDSW treated digester and the control except pH. The leachate from TDSW was not suitable to dispose to the free land. Leachate from TDSW treated digester showed the pH of 6.5, electrical conductivity of 115 mScm 1 with total nitrogen (660 mg/1), phosphorous (475 mg/1), potassium (380 mg/1), and available nitrogen (225 mg/1]. It showed significant levels of total solid, volatile solid, total suspended solid and volatile suspended solid compared to control. Hence recirculation of leachate to the compost digester is essential. It also enhances the level of nutrition in the compost which can be suggested as a mitigation method of disposing toxic substances to the environment.