Production and optimization of biomethane from chicken, food, and sewage wastes: The domestic pilot biodigester performance

Abstract

Anaerobic biotechnology is promising for the recovery of biomethane from organic wastes to mitigate greenhouse gas (GHG). This study aims to evaluate the performance of a domestic pilot biodigester (DPBD) designed for methane production/optimization for use in schools and households besides pollution control. Unpretreated and pretreated chicken manure (CM), waste food, and sewage sludge (SwS) both single and at various ratios were characterised and used to assess the DPBD efficiency. At 21 days retention time, 25rpm stirring, 100 kg single untreated and pretreated substrates and in the ratios of 1:1:0, 1:1:1, 3:1:0, and 3:1:1 was digested. Scrubbing with Fe 2 O 3 chips, activated carbon and water removed H 2 S and CO 2 . The average pH of 6.8, the temperature of 25.4 °C yielded 2.7 m 3 methane from CM single pretreated substrate. The pretreated 3:1:1 produced an average of 5.94 m 3 methane at pH 6.9 and temperature 27.2 °C. Substrates produced low methane in the absence of SwS, while inclusion increased methane. The 40.81 m 3 DPBD showed a high biomethane production performance when substrates are co-digested, pretreated with NaOH, neutral pH and mixed with inoculum (SwS). DPBD exhibits the characteristic sustainability of renewable energy synthesis and reduction of compost emissions. The slurry is a rich fertiliser due to high optimum values of NPK nutrients. Kinetic and mathematical modelling of the DPBD biomethane production can be a future study.