【作者】 李雪；

【导师】 林聪；

【作者基本信息】 中国农业大学 ， 农业生物环境与能源工程， 2015， 博士

【摘要】 随着污水处理事业快速发展产生了大量的污泥。污水厂常采用絮凝剂将污泥脱水后外运处理,但只是减量化而未实现妥善处置,“重水轻泥”现象严重。聚丙烯酰胺作为常用絮凝剂属于高分子聚合物,具有很强的生物抗性导致脱水污泥难以被生物降解利用。本研究首先筛选出对聚丙烯酰胺有降解作用的微生物。进而研究不同消化浓度下纯污泥厌氧消化过程特性确定最佳工艺参数,在此基础上,针对不同微生物、不同预处理方式、不同菌添加量以及不同消化浓度,探讨利用微生物对污泥进行预处理的厌氧消化性能优化。主要研究结果如下：筛选出对聚丙烯酰胺有降解作用的3种微生物,分别为藤黄微球菌、宛氏拟青霉和自筛本土优势功能菌。设置不同消化浓度进行污泥中温厌氧消化试验,发现污泥的产气周期较短,产气量较少。3%和4%消化浓度产气效果优于5%和2%,因此,选择3%和4%浓度进行微生物预处理污泥中温厌氧消化试验研究。预处理方式设定为预处理2天和直接添加。通过藤黄微球菌预处理,当添加菌总数为7.6×1010个时,直接添加各处理(藤黄微球菌培养1天、2天和3天)产气量比纯污泥分别提高12.27%、15.09%和21.24%。随着菌总数提高至7.6×1011个,预处理2天和直接添加效果更显著。通过宛氏拟青霉预处理,当菌总数为8.3×109个时,预处理2天和直接添加处理较纯污泥产气量分别提高19.87%和22.91%；当菌总数为7.6×1010个时,生物处理效果更显著,其中宛氏拟青霉培养4天时,预处理2天和直接添加处理较纯污泥产气量分别提高29.49%和37.59%；当菌总数提高至7.6×1011个,宛氏拟青霉培养5天时,预处理2天和直接添加处理较纯污泥产气量分别提高30.91%和79.39%。通过功能菌预处理,当菌总数为8.7×109和7.6×1010个时,预处理2天和直接添加处理较纯污泥产气量分别提高18.16%和12.50%,67.61%和44.55%。证明微生物预处理污泥能优化厌氧消化过程,促进产沼气。当污泥进料量不变而提高消化浓度时,由于产甲烷菌接种量降低,各微生物处理效果不明显,说明产甲烷菌接种对生物处理污泥厌氧消化过程非常重要,当提高消化浓度必须增大接种量,同时建议增加微生物数量。分析认为藤黄微球菌和宛氏拟青霉直接添加效果较好,功能菌预处理2天效果较好。综合比较3种微生物认为真菌宛氏拟青霉效果最好。利用产甲烷动力学模型,对3种微生物预处理污泥厌氧消化过程进行模拟时发现模型具有较高精度,R2均大于0.98。利用有效容积17L的CSTR消化罐进行微生物预处理污泥连续试验发现,经生物处理污泥能有效提高产气效率、甲烷含量以及有机物降解效果,为污泥资源化处理和沼气工程实际运行提供理论依据。更多还原

【Abstract】 With the rapid development of the construction of sewage treatment facilities, sludge is increasing its amount, as an inevitable byproduct. In order to achieve easy transportation and centralized processing, most sewage treatment plants apply flocculants to dewater the sludge, reducing its moisture content. But this method only reduces water from sludge rather than achieve stabilization of sludge. It leads to a serious phenomenon of "paying attention to water but looking down on sludge". Polyacrylamide is a commonly used flocculant. It is a high-molecular polymer, which has a very strong biological resistance, preventing sludge from microorganism. Therefore, the disposal of sludge is imperative. First of all, this study screened the microorganism which could degrade PAM. Then, the optimum technology parameters for anaerobic digestion of sludge were studied through experiments at different organic loadings. On the basis of former researches, experiments were carried out to optimize the digestive process under different kinds of microorganisms, pretreatment methods, amounts of microorganism additive and organic loading. The main results of the research are as following:Three kinds of microorganism were found for degrading PAM, including micrococcus luteus, fungus paecilomyces variotii and self-screening functional microbe. It could be found that the mesophilic anaerobic digestion experiment of dewatered sludge had short biogas production cycle and small amount of biogas product. Feed concentration of3%and4%were better than2%and5%in producing biogas. Therefore, feed concentration of3%and4%were chosen for the subsequent pretreatment researches.There are two microbial pretreatment methods:direct adding before digestion (abbreviation:DA) and2days pretreatment adding before digestion (abbreviation:2d PA). Using the micrococcus luteus pretreatment, when the total number of microorganism was7.6x1010, the biogas production of DA treatments (micrococcus luteus cultivation for one day, two days and three days) was increased by12.27%、15.09%and21.24%respectively compared with the sludge without microbial pretreatment. As the total number of microorganism increased to7.6×1011, both2d PA and DA had positive effects on biogas production. Using the paecilomyces varioti pretreatment, when the total number of microorganism was8.3×109, the biogas productions of2d PA and DA were increased by19.87%and22.91%compared with the sludge. When the total number of microorganism was7.6×1010, the effects of microbial pretreatment were better obvious, and the biogas productions of2d PA and DA (paecilomyces varioti cultivation for four day) increased by19.87%and22.91%respectively compared with the sludge. When the total number of microorganism was7.6×1011, the biogas productions of2d PA and DA (paecilomyces varioti cultivation for five day) increased by30.91%和79.39%respectively compared with the sludge. Using self-screening functional microbe pretreatment, when the total number of microorganism was8.7×109and7.6×1010, the biogas productions of2d PA and DA increased by18.16%,12.50%and67.61%,44.55%respectively compared with the sludge. These experiments proved that microbial pretreatments of dewatered sludge would optimize of anaerobic digestion process and promote biogas production. When the feed concentration rising to4%and dewatered sludge feed amount was unchanged, the effect of microbial pretreatments was not obvious because of the low inoculation proportion. It could be suggested that the inoculation of methanogens was very important for anaerobic digestion of microbial pretreatments dewatered sludge. When feed concentration was increasing, the amount of inoculation of methanogens must be enhanced. After analysis it was found that DA was better for micrococcus luteus and paecilomyces varioti. And effect of fungus paecilomyces varioti was best among the three kinds of microorganism.Using the methane production dynamic model to simulate the anaerobic digestion process for different microbial pretreatments, it could be concluded that this model could simulate the digestion process with a high accuracy, and each R2was more than0.98. Using CSTR digestion tank with effective volume of17L, continuous anaerobic digestion experiments of different microbial pretreatments were conducted. It was showed that the efficiency of biogas production, methane concentration and organic matter degradation was promoted after microbial pretreatment, which would provide the theoretical basis of biogas engineering operation for solving dewatered sludge resourceful treatment.更多还原