【作者】 鹿雯；

【导师】 胡开林；

【作者基本信息】 昆明理工大学 ， 环境工程， 2007， 硕士

【摘要】 随着生活污水和工业废水处理率的提高,污泥的产量日益增多。由于污泥含水率极高,脱水性能差,使得污泥后续处理的费用急剧增加,因此,如何提高污泥的脱水性能,减小污泥的体积,降低污泥后续处理的费用已成为一个重要的研究课题。通过物理、化学或生物的方法对污泥进行预处理,可以改变污泥絮体的物理性质和化学组成,破坏污泥胶体结构,减小污泥与水的亲和性,从而改善污泥的脱水性能。添加化学药剂作为化学调理方法的一种,由于操作简单,费用低而被广泛采用。目前使用的污泥调理剂,几乎都是阳离子型高分子絮凝剂,由于其具有吸附架桥和电中和作用,可以达到良好的固液分离效果。本试验主要是以移除污泥絮体中的水分为主要目的,使用十六烷基三甲基溴化铵(CTMAB)和四甲基溴化铵(TMAB)两种同属季铵盐的阳离子表面活性剂对活性污泥进行调理,研究阳离子表面活性剂对活性污泥脱水性能的影响及其改善。阳离子表面活性剂是由疏水基通过共价键与带正电荷的亲水基相连的表面活性剂,通常阳离子表面活性剂的疏水基由烃基构成,亲水基由含氮、磷、硫等原子的可携带正电荷的基团构成。CTMAB含有一条较长的疏水链,而TMAB的疏水链较短,它们的作用原理可以通过Laplace-young方程来解释。将阳离子表面活性剂投加到活性污泥系统中,一方面可以降低气/液界面张力,增大固/液界面接触角;另一方面可以增大毛细半径,减小毛细吸水压力,从而改善活性污泥的脱水性能。阳离子表面活性剂主要通过吸附架桥作用和电中和作用来改善固液分离效果,并利用自身分子的长疏水链来增强污泥絮体表面的疏水性,减少结合水的含量。试验数据表明,在同样的投加量下,CTMAB比TMAB能更有效地改善污泥的脱水性能。与TMAB相比,投加约为泥样干质量25%的CTMAB可以释出更多污泥胞外聚合物总量,约为231mg/L;污泥毛细吸水时间(capillary sop time,CST)可缩短为73s左右,离心后污泥上清液浊度降至15.9,离心后污泥含水率为73.2%;当TMAB和CTMAB的投加量＞15%时,真空抽滤后,污泥比阻达到易脱水范围;但TMAB和CTMAB对污泥沉降性能的改善不是非常明显。在试验过程中还对污泥进行了风险评价和资源化利用研究,对未调理和调理过的污泥进行有机物、病原体和污泥菌落等指标的讨论;同时对污泥上清液进行COD,BOD测定,以说明调理后污泥的性质和再利用的可能性。试验数据表明:当TMAB的投加量依次增加,污泥的COD不断减小,由初始的1356mg/L依次减小为1267mg/L、1154mg/L、1049mg/L、891mg/L、775mg/L、734mg/L;当投加CTMAB时,污泥的COD由初始的1356mg/L依次减小为1247mg/L、1084mg/L、957mg/L、837mg/L、734mg/L、623mg/L;同时污泥上清液BOD与COD的比值不断增大,当TMAB的投加量增至30%时,比值由初始的0.4增加到0.55;当CTMAB的投加量增至30%时,比值由初始的0.40增加到0.59。表明两种阳离子表面活性剂在改变污泥上清液COD和BOD值的同时,也提高了其生化性,有益于上清液的生化处理;但是污泥对病原体的吸引力没有达到要求,直接资源化利用对环境有一定的危害。更多还原

【Abstract】 As the rate of municipal and industrial wastewater treatment goes up,the amount of sludge produced in the treatment process increases increase.Since the sludge contain large proportiomn of water,and its dewaterability is poor,thus resulting in the increasement of cost of sludge treatment and disposal.As a result,how to enhance the dewaterability of sludge and reduce the cost of sludge treatment becomes an important research in the world.Using physical,chemical and biological methods to pretreat sludge can change the physical characterization and chemical composition of sludge flocs,destroy the sludge colloid structure and reduce the affinity between water and colllid particles,thus improving the dewaterability of sludge.The medicament conditioning becomes a common method because of simple operation and low cost.At present,the sludge conditioners are mostly cationic macromolecular flocculants which can bring about good solid-liquid separation through bridging and charge neutralization effects.According to this situation,with the purpose of removing the water in the sludge flocs,the main purpose of experiment is moving the water in the sludge flocs.Sludge was mixed by two cationic surfactants including CTMAB and TMAB which belong to quaternary ammonium salt and study the effects and improvement of cationic surfactants on the dewaterability of sludge were discussed.Cationic surfactants are chemical matters which are combined through covalent bond between hydrophobe groups and hydrophilic groups with positive charge.Generally, hydrophobe groups of cationic surfactants contained alkyl;hydrophilic groups were constituted with groups containing nitrogen,phosphorus and sulfur atoms which could take positive charge.The length of hydrophobe chain present in CTMAB was longer than that of TMAB.Their functional theory could explained through Laplace-young equation.When the activated sludge was treated with cationic surfactants,the interfacial tension between gas and liquid could be reduced and the contact antenna could be advanced;on the other hand, the sludge dewaterability was improved through heightening the capillary radius and minishing the capillary sop pressure.The cationic surfactants could improve the separated efficiency between solid and liquid through adsorbed combination and electrical nentralisaion;besides this,the hydrophobe intensity was strengthened by the long hydrophobe chain of surfactants molecule;consequently the combinative water content reduced.Experimental results indicated that CTMAB can improve dewaterabilitiy of sludge evidently rather than TMAB.The results also showed that when the additive quantity was the same.when the additive quantity of CTMAB was 25%of the dry weight of sludge,the quantity of extra-cellular polymeric substance of sludge was released more than TMAB and was about 231mg/L.Besides these,the capillary sop time(CST)of sludge can be reduced to 73s;after centrifugal effect,the turbulence of top clean liquid of sludge was reduced to 15.9 and the water content of sludge was only 73.2%;when the additive quantity of TMAB and CTMAB was more the 15%of the dry weight sludge,SRF of sludge become dewater easily after vacuum filtration;the effects of CTMAB and TMAB on the sedimentation of sludge were unevidently.During the experiment,research on risk assessment and resource utilization of sludge was carried out;in order to illuminate property of sludge and probability of recycle,the organical matters,pathogens and bacteria groups contained in original sludge and treated sludge were discussed.Experimental results indicated that with the increase of additive quantity of TMAB.The COD of sludge gradually reduced from 1356mg/L to 1267 mg/L,1154 mg/L,1049 mg/L,891 mg/L,775mg/L and 734 mg/L;when using same dosage of CTMAB,COD of sludge gradually reduced from1356 mg/L to1247 mg/L,1084 mg/L, 957 mg/L,837 mg/L,734mg/L,623mg/L;besides this,the ratio of BOD and COD of the top clean water of sludge incessantly incresced,when the additive quantity of TMAB was 30%of the dry weight of sludge,the ratio increased from 0.4 to 0.55;when the additive quantity of CTMAB was 30%of the dry weight of sludge,the ratio increased from 0.4 to 0.59.The phenomenon indicated that the two kind of surfactant not only influenced COD and BOD of top clean water of sludge,but improved the simultaneously the BOD/COD. The wastewater treatment can deal with the supernatant liquor easily.But the,effect of TMAB and CTMAB on pathogens and vector attraction in sludge didn’t accorded with the control of certain standard,so it was harm to environment if it was used as resource directly.更多还原