Biogas Development of Tea Dregs and Cow Manure: Study of CN Ratio and Pretreatment on Liquid State Anaerobic Co-Digestion

Abstract

Energy problems in Indonesia are issues that are not easy to solve. If the energy needs dominated by fossil fuel oil continue to increase without any changes in the pattern of energy use, then Indonesia's sustainability and energy security will be disrupted. Therefore, Indonesia really needs alternative energy. Biogas is an alternative energy produced from the anaerobic degradation of organic compounds and can be a substitute for natural gas and fossil fuels. Tea dregs can be used as a substrate from anaerobic co-digestion biogas production with cow dung. In general, the purpose of this study is to produce biogas from tea pulp and cow manure by anaerobic co-digestion and have a specific purpose, namely (i) Assessing the effect of pretreatment on the yield of biogas produced, (ii) Assessing the effect of pH on yield of biogas, (ii) Assessing the effect of the value of the C/N ratio on the yield of the biogas produced. This research was conducted by making variations in treatment including physical pretreatment with and without grinding (± 1 mm), biological pretreatment with and without addition of 5% v/v microbial consortium, pH controlled (addition of buffer) and uncontrolled, and ratio of C/N tea dregs (25 and 30). The biogas formation process is carried out for 2 months at room temperature with the quantitative response test results in the form of biogas volume every 2 days. Biogas production in pretreatment tea grounds gives better results than without pretreatment. Optimum biogas production is obtained at a C/N ratio 30. Comparison of C/N substrate will affect the growth of microorganisms, the microbes that play an anaerobic process need nutrients to grow and develop, in the form of carbon and nitrogen. The highest biogas accumulation produced was 73.167 ml/gTS on variable C/N ratio 30, NaOH pretreatment, microbial consortium and smooth size of tea dregs that used.