Chemical conditioning method of dehydration pretreatment of activated sludge

Abstract

The invention discloses a chemical conditioning method of the dehydration pretreatment of activated sludge, which is characterized by comprising the following steps: transferring the activated sludge with the water ratio of 90-97 percent, which is preliminarily concentrated, into a mixing vessel, adding fully-dissolved ferrous chloride solution while continuously stirring for 3-5 minutes, adding calcined lime while continuously stirring, and then filtering and dehydrating, wherein the dry basis weight ratio of the sludge, the ferrous chloride and the calcined lime is 60: 1.6-3.0: 8-15. The invention has the advantages: 1. generated odor and ammonia gas can be greatly reduced; 2. the treatment cost is lower than that of the treatment methods adopted at present; and 3. as the ferric chloride is taken as the dehydration auxiliary agent for treating the sludge, the organic matter content of the produced sludge is improved by about 10 percent compared with that of the sludge produced by taking ferric salts and calcium oxide as dehydration auxiliary agents.

Description

technical field [0001] The invention relates to environmental protection technology, in particular to a chemical conditioning method for activated sludge dehydration pretreatment. Background technique [0002] With the development of my country's economy and the acceleration of urbanization, the continuous popularization of urban sewage treatment facilities, the improvement of treatment rate and the deepening of treatment degree, the amount of sludge produced will have a large increase. In the past ten years, newly built and under design Due to investment, quality of operating personnel, technical level and other reasons in a large number of sewage treatment plants in China, the sludge treatment part is simply concentrated and dehydrated for transportation. More than 90% of the sludge in domestic sewage treatment plants has not really achieved stabilization and harmless treatment, and there is no way for final disposal. It is estimated that by 2010, the annual output of wet ...

AI Technical Summary

Problems solved by technology

However, when polyacrylamide is used as the pretreatment flocculant for sludge dewatering, the sludge dehydration efficiency is very limited. Generally, the moisture content of the sludge can only reach 75% to 85%, which will bring great impact to the next step of landfill or resource utilization. The biggest defect of using iron salts and calcium salts as filter aids in the sludge dehydration pretreatment process is that a large amount of odor and ammonia gas that are difficult to handle are generated during sludge dehydration, which is very harmful to the health of the operators and is easy to It causes pollution to the environment, and there are situations where the sludge dehydration treatment effect is unstable and the treatment cost is relatively high; while the amount of polyaluminium chloride is relatively large and expensive, resulting in high sludge dewatering treatment costs and low sludge dewatering efficiency It is difficult to achieve the level of using iron salts and calcium salts as filter aids for sludge dewatering