Evaluation of the possibility of utilization of sewage sludge from a wastewater treatment plant – case study.

The starting point for the research discussed in this study was the assumption that sewage sludge generated by wastewater treatment plants (WWTP) should be treated as a valuable raw material in the Circular Economy. Hence, the results of the research are part of the search for the best technological solutions aimed at achieving the maximum possible efficiency of sludge management in WWTP. The research was carried out on the example of a sewage treatment plant in Minsk (the capital of Belarus), where the dominant technology is still the storage of sewage sludge, and annually more than 5 million tons of sludge accumulates, which represents a significant hazard to the environment. The research takes into account the real economic, environmental, economic and social conditions in this country. As an alternative to the current technology, which is no longer recommended in EU countries, the effectiveness of three technological solutions was analyzed: (1) thermophilic digestion option with the production of biogas and subsequent combustion of the fermented sludge in the territory of treatment facilities, (2) high-temperature drying followed by the use of sludge in cement production and (3) production of fertilizers (soil-improving additives). A comparative analysis of these technologies was performed by the ranking method using weighting indicators (significance factors). The methodology takes into account technical, economic, environmental and social criteria. As a result of the evaluation, it was found that the most effective technology for the management of sewage sludge of the WWTP in Minsk is the technology of drying and then using the sludge as an alternative fuel in cement production. This technology provides, among others waste-free utilization of the entire volume of sewage sludge generated in Minsk, and also gives opportunities to create new jobs in the area of production of alternative fuel from sewage sludge. [ABSTRACT FROM AUTHOR]