STUDY ON BIOENERGY AND FERTILIZER RECOVERY THROUGH ANAEROBIC DIGESTION METHOD

Abstract

Anaerobic digestion (AD) is a microbiological process whereby organic matter is de-composed in the absence of oxygen. Anaerobic digestion of organic waste provides many benefits. This includes the generation of renewable energy, a reduction of greenhouse gases and a reduced dependency on fossil fuels. In the bid to looking out for an alternative source of energy to reduce over dependent on the fossil fuel, this work investigated into the production of biogas and potential for fertilizer from waste using anaerobic digestion system. Poultry waste was used in co-digestion with sawdust in varying proportions in ratios 1:1 2:1 and 1:2 (poultry waste: sawdust). The resulting production of biogas gave 990cm³, 850cm³ and 450cm³ respectively. Digesting only the poultry waste also yielded 390cm³ volume of biogas. The digestate was collected to recover the embedded fertilizer components in it. The fertilizer components include Nitrogen (N), Phosphorous (P), and Potassium (K). After the analysis of the digests, the cumulative NPK recovered was 14.48g, 9.94g, 7.29g and 6.46g for 100%, 75%, 50%, and 25% poultry waste digestion respectively. The hydraulic retention time of the various mixtures was noted and varied between 7 to 15 days. Utilization of saw dust from the environment to generate gas reduces environmental pollution caused by burning and improved local/rural economies.