有机酸预处理对污泥深度脱水的影响研究

发布时间：2018-12-23 13:28

【摘要】：目前,污泥处理处置过程中面临的一个主要问题就是污泥经过常规调理、脱水之后,污泥的含水率仍高达80%,达不到后续处理处置要求。因此,污泥需要进一步的深度脱水。然而,常用的污泥深度脱水药剂不易降解,在解决污泥脱水的同时易带来一些其它问题。本课题从完整的污泥处理角度考虑,旨在利用有机酸的易降解优点,将其对污泥进行预处理以达到深度脱水的目的,使污泥含水率达到后续处理的要求。本课题有四部分的研究内容:第一部分是几种常见有机酸预处理污泥脱水效果对比。第二部分是有机酸预处理对泥饼重金属及上清液TOC和TN的影响。第三部分是有机酸预处理过程对污泥深度脱水的影响。第四部分是有机酸预处理对污泥深度脱水的作用机理分析。具体研究结果如下:(1)污泥经5种有机酸预处理之后,其深度脱水性能明显改善。原始污泥脱水泥饼含水率仍高达80.2%,而经过浓度为0.1mol/L-0.6mol/L的冰乙酸、乳酸、柠檬酸、草酸和酒石酸预处理,泥饼含水率降低至68.1%-75.5%。在这5种有机酸中,污泥经过0.2mol/L的草酸和酒石酸预处理后,其脱水泥饼含水率较低,分别为68.1%和68.3%。(2)有机酸预处理,在改善污泥深度脱水的同时,也能够去除污泥中部分重金属和增加上清液中的TOC和TN含量。污泥分别经0.6mol/L的酒石酸和草酸预处理后,脱水泥饼中锌去除率较高,锌的最大去除率分别达到63.1%和72.1%;上清液中的TOC含量从49.8mg/L分别增加至27280mg/L和14970mg/L,TN含量从16.5mg/L分别增加至39.5mg/L和93.1mg/L。(3)在草酸投加量为最佳投加量的条件下,改变温度、搅拌时间、搅拌速度后,污泥混合液pH值处在1.9-2.1,脱水泥饼含水率为59.2%-61.2%,温度、搅拌时间、搅拌速度对污泥的可脱水程度影响不大。随着草酸投加量的提高,污泥的沉降性能,泥饼含水率、C/N比和混合液pH值,以及上清液中的蛋白质、多糖、TOC和TN含量、C/N比变化明显。经投加量为0.34g/g DS的草酸预处理,污泥90min的沉降率从11.3%升高至40.4%,脱水泥饼含水率从73.8%降低至59.2%,脱水泥饼C/N比从6.4提高至6.9,混合液pH值从7.0降低至2.1。污泥浓度在1.5%-9.5%范围内,泥饼含水率从58.9%增大到76.3%,混合液pH值从1.7升高至4.7。(4)机理分析发现,草酸与污泥颗粒表面电荷的吸附电中和起到主要作用,改善了污泥的深度脱水性能。当草酸投加量为0g/g DS-0.57g/g DS时,混合液pH从7.0降低至1.6,而Zeta电位从-13.2mV变化为+4.1mV;d50从54.6μm降低至50.1μm。从扫描电镜图可知,与原始污泥相比,污泥经投加量为0.34g/g DS的草酸预处理后,污泥颗粒结构变得非常致密,颗粒之间距离较近,污泥表面的EPS明显减少。在草酸预处理过程中,污泥颗粒粒径的减小对污泥脱水效果的影响不大。
[Abstract]:At present, one of the main problems in the process of sludge treatment and disposal is that the water content of sludge is still as high as 80% after dewatering, which can not meet the requirement of subsequent treatment and disposal. Therefore, the sludge needs further deep dewatering. However, the commonly used deep dewatering agent is not easy to degrade, and it is easy to bring some other problems while sludge dewatering. From the point of view of complete sludge treatment, the purpose of this paper is to make use of the advantages of organic acid to pre-treat sludge to achieve the purpose of deep dewatering, and to make the moisture content of sludge reach the requirement of subsequent treatment. This paper has four parts of research content: the first part is several common organic acid pretreatment sludge dewatering effect contrast. The second part is the effect of organic acid pretreatment on heavy metal and supernatant TOC and TN in mud cake. The third part is the effect of organic acid pretreatment on deep dewatering of sludge. The fourth part is the mechanism of organic acid pretreatment on deep dewatering of sludge. The results are as follows: (1) after pretreatment with five organic acids, the deep dehydration performance of sludge is improved obviously. The moisture content of the original sludge dewatered cake was still as high as 80.2%, but after pretreatment with acetic acid, lactic acid, citric acid, oxalic acid and tartaric acid at the concentration of 0.1mol/L-0.6mol/L, the moisture content of the mud cake decreased to 68.1% -75.5%. Among the five organic acids, sludge treated with oxalic acid and tartaric acid from 0.2mol/L had a lower moisture content of decement cake, which was 68.1% and 68.3%, respectively. (2) Organic acid pretreatment improved the deep dewatering of sludge at the same time. It can also remove some heavy metals in sludge and increase the content of TOC and TN in supernatant. After the sludge was pretreated with tartaric acid and oxalic acid from 0.6mol/L, the removal rate of zinc was higher, and the maximum removal rate of zinc reached 63.1% and 72.1% respectively. The content of TOC in supernatant increased from 49.8mg/L to 27280mg/L and 14970 mg / L N from 16.5mg/L to 39.5mg/L and 93.1 mg / L respectively. (3) under the optimum dosage of oxalic acid, After changing the temperature, stirring time and stirring speed, the pH value of sludge mixture was 1.9-2.1, and the moisture content of decement cake was 59.2-61.2.The temperature, stirring time and stirring speed had little effect on the dewatering degree of sludge. With the increase of oxalic acid dosage, sludge settling performance, water content of mud cake, C / N ratio and pH value of mixed solution, and the contents of protein, polysaccharide, TOC and TN in supernatant, C / N ratio changed obviously. After pretreatment with oxalic acid (0.34g/g DS), the sedimentation rate of sludge 90min increased from 11.3% to 40.4%, the moisture content of the decement cake decreased from 73.8% to 59.2%, and the C / N ratio increased from 6.4% to 6.9%. The pH value of the mixture decreased from 7.0 to 2.1. In the range of 1.5 ~ 9.5% sludge concentration, the moisture content of mud cake increased from 58.9% to 76.3%, and the pH value of mixed solution increased from 1.7% to 4.7%. (4) Mechanism analysis showed that, The adsorption and electroneutralization of oxalic acid and surface charge of sludge particles play a major role in improving the deep dewatering performance of sludge. When the dosage of oxalic acid was 0g/g DS-0.57g/g DS, the pH of the mixture decreased from 7.0 to 1.6, while the Zeta potential changed from -13.2mV to 4.1mV / d _ (50) from 54.6 渭 m to 50.1 渭 m. Compared with the original sludge, after pretreatment with oxalic acid with the dosage of 0.34g/g DS, the granular structure of the sludge became very compact, the distance between the particles was close, and the EPS on the surface of the sludge decreased obviously. In the process of oxalic acid pretreatment, the reduction of sludge particle size has little effect on sludge dewatering effect.
【学位授予单位】：河南工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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