Selecting sustainable technologies for disposal of municipal sewage sludge using a multi-criterion decision-making method: A case study from China

With rapid economic development and urbanization, there has been an increased generation and discharge of municipal sewage in China, ultimately increasing the amount of sewage sludge entering the treatment facilities. Given this rising problem, finding environmentally friendly, cost-effective, and socially acceptable disposal options for the municipal sewage sludge is crucial for sustainable development. This study evaluated various sludge disposal and treatment technologies for their environmental, economic, and social sustainability and developed an assessment model using multi-criteria decision-making methods. A combined Analytic Hierarchy Process and Vlsekriterijumska Optimizacija I Kompromisno Resenje approach was used for sequencing of the alternatives and evaluation of the most sustainable disposal system based on a set of sustainability indicators. The model results were validated using the Technique for Order Performance by Similarity to Ideal Solution method. Six typical municipal sewage sludge disposal technologies in China were selected for evaluation. The results showed that municipal sewage sludge disposal through land application revealed the best performance (Q = 0.000), and proved to be the ideal choice for sustainable sludge treatment. This was followed by building materials application (Q = 0.207) and disposal through pyrolysis (Q = 0.362), while landfill showed the highest environmental impact and least overall benefit (Q = 1.000). Then, a sensitivity analysis showed that the results obtained are robust and effective, and weight changes of more than 80% indicated land application to have the best performance. Finally, the predicaments and suggestions of municipal sewage sludge land application was analyzed in China from the aspects of standard and sludge quality.