Analysis of sludge management parameters resulting from the use of domestic garbage disposers

The use of domestic garbage disposers may reduce the amounts and improve the solid waste composition, by lowering putrid matter and water content and by raising the caloric potential. However, additional loading on the sewerage systems might require increased investments and operation costs of the wastewater treatment facilities. This project analyses additional amounts of solids, biosolids and process requirements connected with wastewater treatment facilities resulting from the domestic use of garbage disposers, as well as the additional production of biogas. It was found that the use of the domestic garbage disposers in 60% of the households in a given urban area, is expected to reduce the weight, volume and water content of the solid waste by 7.0%, 3.3% and 4.4% for garbage characterized by low organic content, and by 18.7%, 11.0% and 13.3% for high organic content, respectively. The additional amounts of sludge are expected to be the lowest in case of biological treatment only, 24 to 38 g/capita/day, and the highest in case of primary chemical sedimentation followed by biotreatment, 67 to 100 g/capita/day. In these conditions the energy potential from biogas obtained in anaerobic digestion of sludge from wastewater collected from the same area, will increase by 50% to 70%, depending on the wastewater treatment sequence. The investment in wastewater treatment is estimated to increase by 23% to 27% and the annual costs for operation and maintenance are expected to increase by 26% to 30%.