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China 's urban sewage and industrial wastewater treatment rate gradually improve in this process will generate a large amount of sludge . Because the sludge contains large amounts of water, up to 95 ~ 99% of the total weight of the resulting sludge is a huge volume , the subsequent processing of the sludge very difficult . Therefore, as long as a good deal wherein moisture , it will greatly enhance the capacity of the sludge . Activated sludge dewatering performance is poor , and thus brought a lot of problems to its treatment and disposal . The sludge pretreated with chemicals , can improve sludge dewatering properties, and better in the subsequent mechanical dewatering dehydration . Many sewage treatment plant thickened sludge is the use of polypropylene amide ( PAM ) , polyaluminum chloride (PAC) and other synthetic flocculant . These flocculants toxic , biodegradable , and are very harmful to the environment and the human body will , the natural polymer chitosan is non-toxic , no harm to the human body , and prone to degradation , no secondary pollution . This paper studies the chitosan flocculant sludge dewatering performance . Sludge dewatering performance of sludge specific resistance to measure . Chitosan and aluminum chloride , cationic polyacrylamide after conditioning of the sludge dewatering performance for comparison. And chitosan with aluminum chloride complex , two-stage process used in sludge conditioning and dewatering performance study of composite flocculant . The main conclusions are as follows : Under the experimental conditions , the optimum dosage of chitosan 2.0% of the dry weight of the sludge , sludge specific resistance decreased by 93.7% , the water content was 70.8% ; chitosan and aluminum chloride compared adding less , sludge dewatering performance ; chitosan dosing 10g / l, sludge minimum specific resistance of 0.69 × 10 ~~ 8S 2 / g ; aluminum chloride required dosage of 35g / l , or sewage mud minimum specific resistance only reached 1.87 × 10 ~ 8s ~ 2 / g. And cationic polyacrylamide in the latter experiment the dosage range as compared quite effective , while outside this range , chitosan has the ability to achieve a better effect . The cationic polyacrylamide dosing 0.2g / l, sludge , a minimum specific resistance of 1.82 × 10 to 8S ~ 2 / g . Chitosan amount , molecular weight , degree of deacetylation , have varying degrees of impact on the pH value of its conditioning effect . The studies showed that chitosan at pH 6-8 best . Chitosan and aluminum chloride compound used , the first aluminum chloride was added , and then adding chitosan effect than the prior
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