【作者】 邹鹏；

【导师】 宋碧玉；

【作者基本信息】 武汉大学 ， 环境工程， 2005， 硕士

【摘要】 我国的城市污水和工业废水处理率逐渐提高,在此过程会产生的大量的污泥。由于污泥中含有大量的水,可达总重量的95～99%,导致污泥有巨大的容积,这给污泥的后续处理带来很大困难。所以,只要对其中的水分进行很好的处理,那将大大提高了对污泥的处理能力。但活性污泥的脱水性能很差,因而给它的处理和处置带来了很多问题。用化学药物对污泥进行预处理,能提高污泥的脱水性能,在随后的机械脱水中更好脱水。 现在很多污水处理厂处理浓缩污泥现在多采用聚丙烯酰胺(PAM),聚合氯化铝(PAC)等人工合成的絮凝剂。但这些絮凝剂有毒性、难降解,对环境和人体都会有很大危害,而天然高分子壳聚糖无毒、对人体无危害,且易降解,无二次污染。 本文主要研究的是壳聚糖絮凝剂对污泥脱水性能的影响。污泥脱水性能主要采用污泥比阻来衡量。将壳聚糖与氯化铝、阳离子聚丙烯酰胺调理后的污泥脱水性能作比较。并将壳聚糖与氯化铝复合,用两段法应用于污泥调理,研究这种复合絮凝剂的脱水性能。得到的主要结论如下: 实验条件下,壳聚糖的最佳投加量为污泥干重的2.0%,污泥比阻降低了93.7%,含水率为70.8%; 壳聚糖与氯化铝相比,投加量少,污泥脱水性能好;壳聚糖投加10g/l,污泥最小比阻达到0.69×10~8s~2/g;氯化铝需投加35g/l,污泥最小比阻才能达到1.87×10~8s~2/g。与阳离子聚丙烯酰胺相比在后者实验投加量范围内效果相当,而在此范围外,壳聚糖有能力达到更好的效果。阳离子聚丙烯酰胺投加0.2g/l,污泥最小比阻达到1.82×10~8s~2/g。 壳聚糖的用量、分子量、脱乙酰度、pH值对其调理效果有不同程度上的影响。研究表明,壳聚糖在pH值为6-8效果最好。 壳聚糖与氯化铝复合使用时,先加入氯化铝,再加入壳聚糖的效果比先更多还原

【Abstract】 As the rate of municipal wastewater treatment going up in our country, the amount of sludge produced in the treatment process increase a lot. Since the sludge contain larege proportion of water,about 95-99%, resulting in enlarged sewage volume,which bring too much trouble when disposing sludge, bring a number of problems in process of treating the sludge. Accordingly getting rid of the containing water will greatly decrease the sludge amount and enormously increase the ability of sludge proposal afterwards.Normally, due to its bad dewateringability, the sludge is difficult to be dewatered. Therefore, increasing the dewateringability of sludge is very important. Employing the chemical coagulants to pretreating the sludge can greatly increase the sludge dewater ability and then make the sludge lose a great deal liquid in the subsequent mechanical dewatering processs.At present, many sewage plants adopt PAM、PAC etc, to conditioning the sludge. These man-made coagulants have the venomousness and are difficult to decomposing, harm to environment and human health. Macromolecular Chitosan flocculant is nontoxic, and harmless to human health, easy to decomposing,and does not cause secondary pollution besides.This paper provides a study concerning the effect of Chitosan （CTS） flocculant to sludge dewater ability. Dewaterability was mainly evaluated by specific resistance to filtration （SRF）. Sludge dewatering behaviors conditioned with CTS, cation polyacrylamine （CPAM） and AlCl₃ coagulants were compared. Effects of pH,chitosan characteristics such as molecular weight, degree of deacetylation and dosage have been studied. As following, CTS composite flocculants （with AlCl₃） were also used in sludge conditioning of two stages. The sludge dewater ability is studied with this composite flocculants. The main conclusions of this study are as follows.Under the experimental condition, the optimum dosage rate for CTS was2.0% of dry solids in the sludge feed, while SRF was reduced by 93.7% and moisture content of cake was 70.8%.It was found that the sludge conditioned with CTS has better dewaterability than that with AICI3 and the dosage of CTS is less than AICI3. The similar result was obtained when CPAM was employed in the range of experimental dosage. The better result could be achieved with CTS out of this range.pH, chitosan characteristics such as molecular weight, degree of deacetylation and dosage have taken parts in sludge conditioning to different points. The literature review finds that the optimum condition is pH 6-8.As CTS is employed together with AICI3, the dewaterability was improved better in the case of that when AICI3 was followed by CTS. CTS composite flocculants was found to be more effective than single flocculant in sludge conditioning.更多还原