Sewage sludge processing and management in small and medium-sized municipal wastewater treatment plant-new technical solution

Abstract

Although sewage sludge generated by most large wastewater treatment plants is treated as waste, this ‘waste’ is both a source of energy and nutrients. Moreover, mainly in the small and medium-sized installations of municipal wastewater treatment plants is produced sewage sludge that meets the standards for soil application. Unfortunately, the overly simplified operating systems of small wastewater treatments plants cannot provide the satisfactory content of water in sewage sludge for energy recovery purposes. Therefore, new solutions for sewage sludge treatment are required. The study presents an innovative, energy effective, wastewater treatment and sewage sludge processing in one operational sequence, with significant energy consumption decrease and autothermal biomass production. Current research contains detailed technical information about the novel integrated waste water treatment plant and sewage sludge treatment installation as well as cost analysis in comparison to conventional treatments.The aim of this study was to evaluate the operation of the one prototype line for wastewater and sewage sludge treatment and the assessment of the obtained biomass and fertilizer.This new technology is a solution for small and medium-sized municipal wastewater treatment plants and is leading to change the conception of wastewater treatment process as a whole and is resolving the management of sewage sludge at the place where it is generated. In described process the sewage sludge is adequately treated by the installation apparatus and can be used in two ways: as a source of pathogen-free compost, or as a biomass and feedstock for simple thermal installation. Obtained sewage sludge can be recycled as biomass for combustion with the remaining ash acing as a plant nutrient-rich source (soil properties enhancer). Finally, in a modified wastewater treatment process, an odorless and stabilized compost or biomass for thermal energy recovery can be obtained and utilized directly at the place of origin. This alternative system allows for the systematic (and technological) adjustment of already existing, upgraded and newly-designed wastewater treatment plants. This new and innovative technology driven by assumptions about the best possible use of the resources and energy, allows for a more sustainable functioning of the treatment plant. The present study provides a significant insight into closing carbon, nitrogen, phosphorus, potassium and energy loops in wastewater treatments system.