Estimation of energy recovery potential of sewage sludge in India: Waste to watt approach

Sewage sludge, generated post wastewater treatment, constitutes only a small percentage of the total amount of sewage treated, however, its sustainable management is inevitable. In this study, the energy recovery potential of sewage sludge by incineration and anaerobic digestion is investigated for India. The dewatered sludge has total solid content of 25-45% whereas, the primary characteristics of sewage sludge showed significant organic content of about similar to 23-40% (dry basis). The calorific value was found to be 8-21 MJ/kg for sludge dry matter. The energy recovery potential of sewage sludge was 555 -1068 kWh/tonne on sludge dry matter basis for incineration and 315-608 kWh/tonne for anaerobic digestion. Additionally, the energy recovery potential of current sewage treatment in India was found to be similar to 15.3 x 10(5) or 8.6 x 10(5) MWh, annually for incineration and anaerobic digestion, respectively. The study had provided in depth view of sludge to be considered as energetic material and its energy recovery potential countrywide, which would not only help for give a proper direction for recovering energy but also helpful to deal with the issue of sludge management in India. (C) 2020 Elsevier Ltd. All rights reserved.