An Integrated System for Disposal of Sludges Originating from Water Softening and Sewage Treatment in Municipalities.

摘要

The objective was to explore the feasibility,both technically and economically,of developing an integrated system for the disposal of sludges originating from water softening and sewage treatment in municipalities. The proposed system consists of utilizing the water softening sludge in a beneficial use in the primary treatment process of the sewage treatment plant,then handling the resulting sludge in one disposal operation. A laboratory solids contact unit was constructed and operated on raw wastewater with lime softening sludge. The effluent from the solids contact unit was characterized and dewaterability studies were performed on the sludge retained in the unit. Both orthophosphate and total phosphorus concentrations normally present in domestic sewage can be reduced by the addition of 600milligrams of lime softening sludge per liter of raw sewage with continuous mixing. The sludge withdrawn from the primary unit can be expected to be about 3.5times that resulting from conventional settling but when the total sludge quantities are compared,the overall system results in a total sludge production only slightly larger than in separate systems. The mixture of lime softening sludge and primary sludge filtered well without filtration aids.