Utilization of poultry, cow and kitchen wastes for biogas production: a comparative analysis
During the past two decades, developing countries and particularly Nigeria has witnessed increased level of waste generation due to population explosion, increased agricultural activities, and the growth of industries. Consequently, there is intense scrutiny of possible alternative of solid waste utilization through biogas production using organic residues, which includes poultry droppings, cattle dung, and kitchen wastes. Governments and industries are constantly on the lookout for technologies that will allow for more efficient and cost-effective waste treatment Guruswamy et al., 2003; Alvarez et al., 2006. One technology that can successfully treat the organic fraction of wastes is anaerobic digestion (Hill, 1983; Verma, 2002). It has the advantages of producing energy, yielding high quality fertilizer and also preventing transmission of disease (Koberle, 1995). Anaerobic digestion is the controlled degradation of organic waste in the absence of oxygen and the presence of anaerobic microorganisms. The digestion process is carried out using an airtight reactor tank and other equipment used for waste pretreatment and gas retrieval. The process generates a product called “biogas” that is primarily composed of methane (which can be used for cooking), carbon dioxide (which can be used for fire extinguishers), and compost products suitable as soil conditioners on farmlands (Ojolo and Bamgboye, 2005). The final effluent can be used as fertilizer on farmlands and sometimes as animal food additives. Harnessed biogas can either be processed and sold directly or used to generate energy, which can then be sold. Anaerobic digestion also produces savings by avoiding costs of synthetic fertilizers, soil conditioners and energy from other sources.