Pressure Filtration of Sewage Sludge with Polymer Addition

Abstract

Pressure filtration process of sewage sludge was investigated with polymer addition. A polymer additive was selected and operational conditions were determined in the preparatory experiments using the pilot filtration equipments. The sewage sludge has been dewatererd by the pressure filters with polymer and the filtered cake has been incinerated in a multiple hearth incinerator practically over two years. A comparison of polymer addition process and other inorganics addition process (ferric chloride or ferric chloride and lime) was done on the running data. The former process is inferior to the latter in the efficiency of dewatering, but superior in the incineration and flue gas cleaning processes.
Total operating cost and construction cost of the former process are lower than those of the latter. The former process is favorable to the final disposal of ash.
There is a good outlook for the control of the adding rate of polymer additive by using CST meter.