Enhancing energy recovery from Wastewater Treatment Plant sludge through carbonization

Abstract

The Wastewater Treatment Plant (WWTP) uses a dewatering machine to separate sludge from water. The resulting sludge is used as raw material for Refuse Derived Fuel (RDF), while the separated water is treated in the subsequent WWTP unit. However, the sludge from the WWTP is currently only processed into briquettes as per policy and then disposed of in landfills. Our investigation centers on the effects of carbonization temperature on sludge characteristics in a dewatering unit. Initial analysis revealed that 1-day-old sludge possesses a high moisture content (87.72 %) and a low calorific value (3.44 MJ/kg). Carbonization at 300 °C significantly enhanced the sludge's calorific value to 12,504 MJ/kg, reduced its moisture content to 60.72 %, and increased its carbon percentage to 22.76 %, indicating a direct correlation between carbonization temperature and both energy recovery and carbon content. Comparative analysis showed sludge carbonized at lower temperatures (200 °C and 100 °C) yielded lower carbon percentages (22.23 % and 21.66 %, respectively) and energy values, underscoring the efficiency of higher temperature carbonization in optimizing energy recovery.. This research contributes to developing sustainable organic waste recycling practices and supports achieving Sustainable Development Goals 11 and 12 targets. This research promotes sustainable development by improving sludge utilization from WWTPs as a raw material for energy production rather than being directly disposed of in landfills. This study provides insight into the potential for energy recovery from organic waste, technology, and policy's role in achieving a circular economy.