Characterization of Biogas Production from Anaerobic Digestion of Animal & Plant Wastes
Abstract
The negative impact of the increased use of fossil fuels for energy generation and consumption has reached a global dimension and can no longer be over looked. All efforts are now being geared towards an alternative source of energy, renewable in nature and more environmental friendly in use. This study investigates the production of biogas – a renewable energy from the anaerobic digestion of three different types of biodegradable wastes (Cassava peelings and poultry droppings, Beans waste and poultry droppings, Cassava peelings and beans wastes) as an alternative to fossil fuels for energy consumption. The study was carried out using a 0.1m3 capacity biogas digester constructed to investigate the anaerobic digestion in generating biogas. The experiment was batch operated and daily gas yield from the plant was monitored for 24 days. During this period, many operation factors were monitored to determine the effect each of them has on the biogas generation. These factors monitored are temperature changes, Pressure changes, pH changes, changes in alkality, Cassava peelings and poultry dropping generated the highest maximum biogas of 0.035m2 /kg/day at a PH value of 7.35 on the 19th day. This was followed by poultry droppings and beans mixture. Cassava peelings and beans waste had the least volume of biogas. This treatise assets that biogas is not only a renewable energy source but has a dual function of waste management in the course of its production.
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Introduction
Three major challenges to any nation and the world in general today are rise in energy need of the citizens, waste management and problems arising from environmental degradation such as green house effect, deforestation, desertification, flooding, global warming etc. These aforementioned problems are directly or indirectly linked to the use of energy sourced from fossils. The singular solution to these problems is seeking alternative sources of renewable and environmental friendly energy like biogas.
Biogas is a mixture of colourless, flammable gas obtained by the anaerobic digestion of plant based organic waste material [1]. Biogas is typically composed of 50-70% Methane, 30-40% carbon dioxide and traces of other gases [2]. In Nigeria, there are abundant of wastes arising from the domestic and agricultural sources of which the potential has not been tapped [3,4]. A look around every city in Nigeria shows enormous dumps every here and there of wastes lining up everywhere and polluting the environment. These could be re-cycled and used in biogas production.
Anaerobic biodegradation of cellulose materials is a biological process, the end product of which are a methane-rich gas called biogas and spent slurry of fertilizer vale. It is a process by which organic materials such as straw, weeds, human or animal excrements, garbage, sludge, domestic sewage and organic liquid wastes from factories etc are degraded by huge amount of various microbes of different functions under anaerobic conditions to yield methane in the end [5]. Biogas technology has advantages which include amongst others; treated digested sludge mixed with molasses and grains is said to have high nutritional value equivalent to cowpea meal with which birds can be fed [6]. It is a process having the potential for sterilization which can reduce public health hazards from faecal pathogens and if applied to agricultural residues, a reduction in the transfer of fungal and plant pathogens from one year’s crop to the next [7]. The earlier problems mentioned infesting nations could be easily solved by the adoption and implementation of biogas technology. This has been the goal of this research work.
Conclusion
The study on the production of biogas from the digestion of mixtures of poultry droppings and cassava peelings, poultry droppings and beans waste, cassava peelings and beans waste has shown that biogas can be produced from these wastes through anaerobic digestion for biogas generation.
These wastes are readily available in our environment and can be used as source of fuel if managed well. The biogas generated contains up to 65% methane which supports combustion. It was found out that temperature fluctuations and PH are among the factors that affect biogas production and temperature ranges of 25°C–45°C also purvey mesophile thermal stage for biogas production. It has also been shown that for maximum gas generation, experimentation with various mixes is very important. Results show that mixing of nitrogen rich and carbon rich wastes at a presumed ratio produce more gas than nitrogen – nitrogen or carbon – carbon rich wastes.
Finally, embarking on anaerobic biodegradation process on environmental pollutants for biogas production will not only lead to clean and safer environment but also reduce the use and much dependence on fossil fuels whose by-products are deforestation, desertification, erosion, global warming and flooding.