Environmental impact and economic sustainability analysis of a novel anaerobic digestion waste-to-energy pilot plant in Pakistan.

A novel medium–large industrial-scale, anaerobic digestion (AD) waste-to-energy pilot plant has been investigated in terms of cost–benefit, environmental impact, and economic sustainability. This pilot plant exclusively features a multi-digester AD system induced by motorized stirring, methane purification, compression, storage and digestate–fertilizer processing systems, and subsequent electricity generation. The operational productivity and success of the pilot plant has been proven on a variety of waste feedstock substrates in the form of cow–buffalo manure and potato waste. The plant has an average energy productivity of 384 kWh/day and an annual rate of return was estimated to be 15.4%. The life cycle environmental impact analysis deliberated the significant impact potentials in terms of climate change (kg CO₂ equivalent), and fossil depletion (kg of oil equivalent) for three selected substrates: 100% cow–buffalo manure (CBM), 100% potato waste (PW), and a mixture of 75% CBM and 25% PW. The results show the climate change potential of 70 kg, 71 kg, and 149 kg and fossil depletion potential of − 2.43 kg, − 16.45 kg, and 18 kg per 2000 kg of substrate slurry, respectively. As such, the substrate of 100% CBM posed the least climate change impacts whereas 100% PW has been established most effective under the fossil depletion category. [ABSTRACT FROM AUTHOR]