Energy integration in wastewater treatment plants by anaerobic digestion of urban waste: A process design and simulation study

Abstract

7 The process simulation performed in the present study was aimed to investigate 8 energetically self-sufficient wastewater treatment plant of 500,000 population equivalents. 9 To implement this, three different scenarios were evaluated using computational tools 10 named GPS-X® and SuperPro®. They were designed based on municipal wastes recovery 11 to energy generation and its utilisation within the facility. An anaerobic/anoxic/oxic process 12 for biological treatment of wastewater was considered and mesophilic anaerobic digestion 13 of: scenario 1) primary sludge (PS) with waste activated sludge (WAS), scenario 2) PS with 14 thermally hydrolysed WAS and scenario 3) PS with WAS and organic fractions derived 15 from municipal solid waste. The results from scenario 1 and scenario 2 showed only 16 enough thermal energy to meet their demand (they reach only 44 and 52% of electrical self-17 sufficiency, respectively), while positive net thermal and electrical energy result in scenario18 3 from co-digestion of sewage sludge and the organic fraction of municipal solid waste. 19 The main limitation of tools used, is their lack of sensitivity to economies of scale, and 20 their dependence on real data used for process design to obtain more accurate results.