科研之友
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摘要
This study investigated the combined effects of chlorination with subsequent coagulation by Fe(Ⅱ) and Fe(Ⅲ) on the co-conditioning and dewatering of concentrated municipal sludge. Results indicate that preoxidation by chlorine may improve sludge dewatering, and chlorine at 200 mg?g-1 contributed to the decrease of the specific resistance to filtration (SRF) from 5.3×109 m?kg-1 to 2.0×109 m?kg-1. Fe(Ⅲ) at 30 mg?g-1 may significantly decrease the SRF from 3.5×109 m?kg-1 to 1.6×109 m?kg-1, whereas Fe(Ⅱ) shows little effect on sludge dewatering. The introduction of chlorine prior to Fe(Ⅲ) and Fe(Ⅱ) may further improve their positive effects, and SRF are respectively decreased by 40.3% and 78.3% as compared to that without prechlorination. Chlorination of sludge damages its extracellular polymeric substances (EPS) and the release of protein and polysaccharide in the sludge occurs thereafter, and the content of released protein and polysaccharide is observed to be positively correlated with the dewatering efficiency. The combined co-conditioning by chlorine and iron salts may improve the dewatering efficiency, and the synergistic effects between oxidation and coagulation are the main mechanisms.
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