【作者】 李欣；

【导师】 蔡伟民；

【作者基本信息】 上海交通大学 ， 环境工程， 2009， 硕士

【摘要】 随着生活污水和工业废水处理率的提高,污泥的产量越来越大。我国污泥年产生量约为1×107吨/年,且随着废水处理要求的提高污泥产生量也逐年提高。如何提高污泥的脱水性能,减少污泥处理费用成为当今各国一个重要的研究课题。目前广泛采用的污泥脱水方法是聚电解质法,其具有絮凝沉降性能好的优点,但存在着滤饼含水率偏高等问题。因此,本文以去除污泥中水为目的,合成一类污泥调理剂,不仅考察了它们对污泥絮体结构的影响(EPS、污泥絮体粒径、表面相对疏水性及污泥絮体强度),还考察了它们对脱水指标的影响(如毛细吸水时间CST、污泥比阻SRF、污泥过滤沉降速度、污泥滤饼含水率及结合水含量)。研究主要从以下两个方面展开:(1)实验室自合成一类污泥调理剂。其在固体表面作用原理是通过降低气/液界面张力、增大固/液接触角,改变污泥表面性质从而改善污泥的脱水性能。研究发现:调理剂依靠静电引力和疏水组分间的缔合作用吸附在活性污泥表面。随着投加量的增加,污泥表面EPS不断脱落,使污泥絮体特征发生了一系列变化:絮体粒径变小、相对疏水性增加等。污泥絮体特征的变化直接导致污泥脱水指标的变化,当调理剂CSC16投加量为0.02g/g干污泥时,污泥滤饼含水率降低为73.9%,脱水效果非常明显,但实验也显示表面活性剂对污泥的过滤性能和沉淀性能没有显著的提高。(2)结合调理剂和聚电解质于污泥脱水时的优缺点,通过投加不同比例的调理剂和聚电解质对活性污泥进行脱水,并与单独投加聚电解质对比,实验发现,调理剂作用于后,污泥絮体中大量结合水被去除,聚电解质絮凝时包裹的水不再是结合水而较易被除去。两种药剂联合作用后,污泥絮体结构更致密,粒径和强度都大幅增加,过滤速度也明显提高,且当两种药剂投加量分别为0.01g/g DS和0.0075g/g DS时,污泥滤饼含水率降低至72.3%,达到了非常好的脱水效果。更多还原

【Abstract】 Currently, approximately 10,000,000 tons of sludge are produced annually in the water treatment plants of China. This amount is expected to increase significantly due to the increasing demand for better quality water. How to enhance the dewater ability of sludge and reduce the cost of sludge treatment becomes an important research interest in the world.For years, polyelectrolyte conditioning has been the most popular practice for improving the dewatering property of sludge. Despite its efficiency in sludge conditioning, there is still a large quantity of water in the flocculating constituent of activated sludge, which leads to the difficulty in further reducing the water content of dewatered sludge. Many researchers have been searching for alternatives in reducing sludge water content. With the purpose of removing the water in the sludge flocs, study their effects on the sludge flocs characteristics (such as: floc size, fractal dimension, floc strength and chemical composition of sludge flocs) and dewater ability of activated sludge (such as: CST, SRF, bound water content in sludge, settling rate, water content in filtrated cake ) study from the following two aspects:1. synthesize new type of conditioner,. The mechanism of self-synthesized conditioner can be illustrated by Laplace-Young equation, in the activated sludge system, such conditioners can decrease the surface tension between vapor/liquid interfaces, and increase the solid/liquid contact angle, and increase the capillary radius, so that they can improve the activated sludge dewater ability. Conditioners can be adsorbed on activated sludge surface depending on electrostatic attraction and hydrophobic association, changing the distribution of extracellular polymeric substances (EPS) on floc surface. With the increasing of conditioners dosage, compositions of EPS were continuously released from the sludge surface and dissolved in the solution, which resulted in a series of changes of the sludge flocs characteristics, including the reduction of flocs size and increasing of relative hydrophobic. Anyhow, all the changes for the characteristics of sludge flocs directly caused the changes of the dewatering indexes of sludge. From the experimental results it can be seen that conditioners can significantly lower the bound water in sludge and the water content in filtrated cake, but no obvious effect on improving filterability and settle ability. When the dosage of CSC16 was 0.02g/g dry sludge, the water content in sludge cake after vacuum filtration dramatically decreased to 73.9%.2. Associate with the positive effects that self-synthesized sludge conditioner and commercial polyelectrolyte acted on activated sludge, adding different doses of conditioner and polyelectrolyte in activated sludge. With contrast to adding polyelectrolyte only, the experiments show that when adding polyelectrolyte, the sludge flocs would re-flocculate with a great deal of water, but this water can be removed easily. When adding 0.01g/g DS of conditioner and 0.0075g/g DS of polyelectrolyte, the water content in the remaining sludge cake after filtration decreased to 72.3%, and the sludge is more compact and dewatered comparing to the addition of one of them single at random.更多还原