Özet:

Biogas production rate was investigated from the co-digestion of 39 kg each of food waste, cow dung and water; 39 kg each of food waste, poultry droppings and water as well as 39 kg each of food waste, fruit waste and water in 43 litres plastic digester setup. Although organic waste mix ratios with higher moisture content can influence decomposition rate, HRT and biogas yield, 1:1:1 mix ratio was used in this investigation. The total rate of biogas produced from the co-digestion of food waste with poultry droppings and water (39 kg) in the ratio of 1:1:1 was 4120 g of raw biogas and 3700 g of purified biogas within with Hydraulic Retention Time 32 days, whereas, the co-digestion of food waste with cow dung and water (39 kg) in the same 1:1:1 ratio yielded a total raw biogas of 5830 g and 4920 g of purified biogas with HRT of 35 days. However, co-digestion of food waste with fruit waster and water (39 kg) in the same ratio yielded a total raw biogas of 5010 g and purified biogas 4330 g with HRT of 33 days. Raw biogas produced from each organic feedstock was channelled through a scrubbing unit comprising distilled water and Type B silica gel. After the raw biogas had passed through the distilled water stream, its pH dropped drastically from neutral range to ultra-acidic range (7-3.2), while it also had milky color and sour taste, indicating the presence of carbonic acid (H2CO3) as a result of carbon dioxide (content in the raw biogas) dissolution in the distilled water. Color of the Type B silica gel changed from crystal pink to crystal blue, indicating the absorption of water content in the biogas by silica gel particles. Organic waste is a renewable energy resource that can offset Nigeria’s increasing demand for energy if harnessed and processed into cooking gas and organic fertilizers before disposal, in which case can also prevent Green House Gas (GHG) emissions into the atmosphere.

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