Determinations of Optimum Pyrolysis Conditions for Producing Refuse Tea Biochar

Abstract

It has been estimated that approximately four metric tons of refuse tea is produced daily from the tea processing industries in Sri Lanka. At present refuse tea is considered as a waste product from tea processing and, dumping and composting are the common practices of disposal. Manufacturing of biochar from organic waste is an emerging technology where biochar can be used for soil applications, environmental remediation and carbon sequestration. Hence, this research aimed to determine optimum pyrolysis conditions for producing refuse tea biochar. The pyrolysis experiments were done in a small air-tied steel reactor which was kept in a muffle furnace. Initially, refuse tea was pyrolyzed at temperatures between 300 °C and 500 °C for different residence time ranging from 15 to 60 minutes. The physical and chemical characteristics of biochar such as moisture content, ash content, carbon content, volatile matter content, bulk density, pH and electrical conductivity (EC) were analyzed following the biochar quality standards proposed by International Biochar Initiatives (IBI). Results showed that the yield of biochar varied with the residence time for a given temperature treatment. The proximate analysis of produced biochar showed the fixed carbon content varied from 26%-58%, consequently, the volatile material content was very high for optimum conditions. This research revealed that refuse tea can be effectively converted to biochar between 450 to 500 °C temperatures subjected to residence time of 45 to 60 minutes.