The effectiveness and mechanism of combined dewatering of polyaluminum chloride pretreatment sludge
To investigate the influence of polyaluminum chloride on sludge dewatering performance and the mechanism of combining different dewatering methods to improve sludge dewatering performance,this paper carried out self-weight dehydration,centrifugal dehydration,and dialysis dehydration tests.It is found that 8%of polyaluminum chloride pretreatment combined with dialysis dehydration has the best effect.The residual moisture content of the optimally pretreated sludge reduces to 36.2%by dehydration,and its gravity water,enclosed water,enclosed water,and bound water are 81.2%,10.2%,7.3%,and 1.3%,respectively.After the sludge is pretreated with polyaluminum chloride,the spacing between the sludge particles is narrowed,the pores are reduced,there are no obvious large pores,and the structures tend to be uniform and more compact.The porosity is reduced to as low as 0.29 by using the optimal amount of polyaluminum chloride pretreatment combined with dialysis dehydration.It is speculated that polyaluminum chloride condenses the sludge into small and dense sludge particles,and this skeleton structure is conducive to the transfer of dialysis force;while free water is discharged continuously,the sludge structure continues to be closer,and promoting the transfer of dialysis force in the sludge.
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