Study on the Effect of Chemical Conditioning on the Consolidation Characteristics of Municipal Sludge in Landfill Depot

Abstract

Vacuum preloading is one of the effective methods for in-situ dewatering and reduction treatment of municipal sludge landfill, but because the consolidation coefficient of municipal sludge is 1 or 2 orders of magnitude smaller than that of sludge, the drainage consolidation technology will face the problem of vacuum for too long. In order to improve the consolidation characteristics of sludge, combined with the chemical conditioning technology in the field of water treatment, firstly, the chemical conditioner suitable for landfill sludge was selected. The effects of different conditioning combinations on sludge dewatering characteristics were studied by microscopic testing techniques (zeta potential analysis and environmental scanning electron microscope analysis) and vacuum filtration test and consolidation test. The results show that the combination of ferric chloride and calcium oxide can significantly improve the dewatering characteristics of sludge. After conditioning with 10% ferric chloride and 10% calcium oxide (relative to sludge dry base), the specific resistance of sludge is reduced from 2 × 1013m/kg to 3 × 1012m / kg, and the consolidation coefficient is 3.5-10 times higher than that of original sludge, which lays a foundation for improving the efficiency of vacuum preloading treatment. In addition, from the results of vacuum filtration test and consolidation test of sludge, it can be found that there is a good negative linear relationship between specific resistance and consolidation coefficient of sludge. Compared with the consolidation test, the vacuum filtration test is simple and easy, so it can be used as an effective means to select sludge conditioner or test the conditioning effect.