Pre-treatment of sewage sludge to enhance biogas production to generate green energy for reduction of carbon footprint in sewage treatment plant (STP)

This work elucidates the effects of pre-treatment of sewage sludge for enhancement of biogas production to generate green energy and reduction of carbon footprint in STPs. Microwave pre-treatment has been adopted for this study. Experiment works have been designed and conducted to examine the effectiveness on the disintegration of sewage sludge and biogas production of continuous and intermittent batch microwave pre-treatment at 80 W for 5 minutes and 15 minutes. The quantity of biogas produced with and without pretreatment has been evaluated and compared whereby the continuous microwave pre-treated for 5 minutes and 15 minutes enhances the anaerobic digestibility rate and biogas production by 38.5% and 11.9% respectively compared to intermittently pre-treated sewage sludge sample which only increases by 15.4% and 4.8%. The additional quantity of biogas has shown to be able to increase potential green energy to 45% from current 7% which can offset the energy usage generated by fossil fuels and reduces the CO₂ emission to generate energy from fossil fuels. The replacement of green energy has potential to reduce annual CO₂ emission by 4,329.6 ton for a modern mechanized STP for 250,000 population equivalent in urban setting.