STUDY ON COLLABORATIVE TREATMENT SOLUTIONS OF KITCHEN WASTE IN SEWAGE PLANTS

The treatment of municipal organic solid waste is a key factor in the construction of zero waste city in China. Aiming at the comprehensive treatment needs of kitchen waste (350 t/d), manure residue (50 t/d), garden greening waste (80 t/d) and sludge (300 t/d), this study designed five kinds of technical solutions for water-solid collaborative treatment on the limited reserved land of sewage treatment plants. Several technologies were used, including high-temperature aerobic drying/fermentation + RDF/organic fertilizer preparation, anaerobic fermentation to extract commercial carbon sources, and wet air oxidation technology. In addition, five methods were evaluated in terms of energy consumption, economy, carbon emission reduction, and sewage plant capacity. The results show that it is economically feasible to use high-temperature aerobic drying/fermentation + RDF/organic fertilizer preparation to treat kitchen waste and manure. If the heat of water or tailwater in a sewage plant is recovered by a water source heat pump, the total power consumption can be reduced by 25%~30%, the operating cost by 3%~5%, and carbon emission by 10%~18%, which reflects the energy saving advantage of the water-solid collaborative solution. Combined with anaerobic fermentation to extract carbon sources, it can further reduce the operating cost and increase the carbon emission reduction effect. After the introduction of green waste treatment, the operating cost can be reduced to 403 yuan/ton, and the carbon emission reduction can be increased to 98.5 t CO₂-eq/d, which is the best solution available at present. The wet oxidation technology solution is significantly superior to other solutions in terms of operating cost and carbon reduction effect and can be developed as an alternative technology in the future.