Biogas and Organic Fertilizer from Kitchen Waste Based Biogas Plant at Tezpur University, Assam

Abstract

Cooking is one of the major energy-consuming activities in residential academic institutes including Tezpur University, Assam. Tezpur University has 12 hostels with a population of over 3000 students. With rise of prices of conventional LPG fuel and its other demerits, search for an alternative fuel system has become essential to address the economic and environmental concerns. Further, food and vegetable waste (kitchen waste) available from the kitchen of the hostels require a sustainable and environment-friendly application. An attempt has been made to study the techno-economic feasibility of utilizing kitchen wastes for generation of biofuel and bio-fertilizer in one of the hostels of Tezpur University. For this purpose, a 50 m3 floating dome-type kitchen waste-fed biogas plant has been installed in a hostel with a capacity of 400 students. The plant is fed with 130 kg kitchen waste per day after necessary screening and sorting. An average production of about 13 m3 of Biogas is obtained per day from the plant with a minimum and maximum of 6.7 and 14.9 m3, respectively. High oil content and acidic nature of kitchen waste can be inhibitory to biogas production. It is necessary to manage the right type of kitchen waste failing which, biogas production reduces. In addition to the nature of the kitchen waste, seasonal variation of temperature also affects the biogas production to a great extent. Biogas is used in the kitchen to supplement the conventional LPG thereby reducing LPG consumption (an average of 10 cylinders per month). The waste digestate coming out of the plant is also processed through a separation tank. The solid component of the digestate is converted to vermicompost, thereby, providing a scope of dual energy recovery in an economic and a more sustainable manner. Saving of up to 123 LPG cylinders per annum and a production of about 1.5 tonnes of vermicompost has been estimated from the biogas plant. Use of kitchen waste for fuel and fertilizer production with the associated environmental and economic benefits is expected to be an exemplary case for its further promotion.