A method for treating residual sludge after biological treatment of wastewater

Abstract

The invention provides a method for treating surplus sludge produced after biological treatment of wastewater. By adding a ferrous sulfate solution, a sodium persulfate solution or a potassium persulfate solution, and industrial coal ash, the sludge is treated to obtain a filter cake and a filter liquor. Compared with the prior art, adding divalent ferric salt and heating synergize to stimulate the persulfate to produce a free sulfate radical having a strong oxidizing property, the free sulfate radical is used to efficiently break a microbial cell in the sludge, then the microorganism is inactivated, the adhesive action with an extracellular polymeric substance is remarkably weakened, the extracellular polymeric substance is then stripped, the bond-state water is released, and the structure and the surface hydrophobicity of the sludge flocculant are changed; after the industrial coal ash is added, the permeability of the filter cake is improved, and the filter cake can play the role of a filter aid. According to the method, the specific resistance of the sludge is as low as (0.2-0.5)*108S<2> / g, the moisture content of the dehydrated filter cake is as low as 40-60%, the secondary pollution caused by common flocculants like polyacrylamide is reduced, the operating cost for the dehydration of the sludge is lowered, original processing equipment can be used to implement the method without any transformation, the operation is convenient, and the dehydrated sludge is directly backfilled or is used to produce a ceramsite or building material.

Description

technical field [0001] The invention relates to a treatment method for excess sludge, in particular to a treatment method for excess sludge after biological treatment of wastewater. Background technique [0002] In recent years, the rapid development of my country's sewage treatment work has largely alleviated the crisis of water pollution in my country. However, the activated sludge process and derivative processes are the most widely used biological treatment technologies for wastewater treatment. The biggest drawback is the generation of a large amount of surplus sludge. As wastewater treatment standards become more and more stringent, the output of excess sludge has also increased significantly, and the accompanying sludge pollution has become increasingly prominent, which has aroused great concern from all walks of life. At present, after anaerobic / aerobic digestion of excess sludge, organic polymers such as polyferric sulfate, polyaluminum chloride, and polyacrylamide ...

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Problems solved by technology

Li Juan et al. (Environmental Science, Vol. 30, No. 2, 2009, 475-479) found that the extracellular polymers of activated sludge could be effectively decomposed by Fenton reagent, and the average particle size of sludge particles was significantly reduced after oxidation treatment. , the uniformity is improved, the inorganic degree and hydrophobicity of the sludge are improved, and the solid content of the mud cake after dehydration is increased, which is conducive to the reduction and resource utilization of the sludge. However, practice shows that Fenton and similar processes treat sludge High cost hinders the engineering application of this technology

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