高含固污泥厌氧消化性能及其优化

发布时间：2018-02-28 01:03

本文关键词： 污泥高固体厌氧消化沼气低温热预处理　出处：《清华大学》2015年硕士论文　论文类型：学位论文

【摘要】：厌氧消化可以实现污泥的减量化和资源化,但传统污泥厌氧消化的进泥浓度仅3~5%,这就需要较大体积的消化池,占地面积大,加热能耗高。采用高含固污泥厌氧消化,可以缩减设施体积、降低保温能耗。然而,高含固污泥黏度高,搅拌困难,再加上我国污泥有机质含量偏低,这些因素都会影响高含固污泥厌氧消化的性能。目前,高含固污泥厌氧消化性能及其影响因素还缺乏研究。针对这一实际需求,以昆明市污泥处理项目为背景,进行了高含固污泥厌氧消化实验,提出了低温热预处理优化的方法,主要研究结论如下:(1)高含固污泥厌氧消化要达到与传统厌氧消化类似的效果,需要更长的消化时间。传质困难是影响序批式高含固污泥厌氧消化性能的主要原因。搅拌不充分时,中间产物容易产生积累,游离氨是对消化系统产生抑制的关键因素。(2)逐渐提高进泥浓度,低浓度厌氧消化系统可成功过渡到高固体厌氧消化系统,并能从不稳定状态恢复到稳定状态。搅拌充分的高含固污泥厌氧消化系统中,挥发性脂肪酸浓度为200~400 mg/L,游离氨浓度低于250 mg/L,中间产物没有积累,具有与低浓度消化相当的有机质降解率和沼气产率。污泥有机质降解率与进泥有机质含量近似成正比。(3)低温热处理可以有效溶出高含固污泥中有机质,并降低污泥黏度。热处理后形成的高浓度挥发性脂肪酸和低pH不会对后续厌氧消化产生抑制。采用70°C对高含固污泥进行30 min预处理,可以有效提升消化性能。在污泥停留时间同样为22天时,沼气产率提高14.5%,有机质降解率提高9.5%;在达到同样消化效果时,污泥停留时间可以从22~30天缩短为15~22天。(4)通过能耗的分析发现高含固污泥厌氧消化的主要能耗在于搅拌,当进泥有机质含量大于40%时,大部分产能可用于发电。加70°C热预处理后,消化系统的输出能量下降5.6%,但考虑有机质降解率的提高,节约了干化系统的能耗,所以综合考虑“消化系统+干化系统”,70°C热预处理在经济上是可行的。(5)对消化污泥进行调理脱水时,有热预处理时的消化污泥需要更多的混凝剂。用三氯化铁调理比用聚丙烯酰胺调理的效果更好。消化污泥中总养分含量和重金属含量可满足园林绿化用的要求;消化污泥中无机物成分主要是二氧化硅和氧化铝,按一定比例与黏土混合后可用于制陶。
[Abstract]:Anaerobic digestion can realize sludge reduction and reuse, but the traditional sludge concentration of anaerobic digestion is only 3 ~ 5, which requires a large volume digesting pond, large area, high heating energy consumption, and high solid sludge anaerobic digestion. It can reduce the volume of facilities and reduce the energy consumption of heat preservation. However, the high solid sludge viscosity, the difficulty of stirring and the low organic matter content of sludge in China will affect the anaerobic digestion performance of high solid sludge. The anaerobic digestibility of high solid sludge and its influencing factors are still lack of research. In view of this practical demand, the anaerobic digestion experiment of high solid sludge was carried out under the background of sludge treatment project in Kunming, and the optimization method of low temperature thermal pretreatment was put forward. The main conclusions are as follows: (1) anaerobic digestion of high solid sludge should achieve a similar effect to that of traditional anaerobic digestion. It takes longer digestion time. Mass transfer difficulty is the main reason that affects the anaerobic digestion performance of sequencing batch high solid sludge. When stirring is not sufficient, the intermediate product is easy to accumulate. Free ammonia is the key factor to inhibit digestive system. The volatile fatty acid concentration is 200 ~ 400 mg / L, the free ammonia concentration is less than 250 mg / L, and the intermediate product does not accumulate. The degradation rate of sludge organic matter is approximately proportional to the content of organic matter in mud, and the low temperature heat treatment can effectively dissolve the organic matter in high solid sludge, which is equivalent to the degradation rate of organic matter and biogas production rate of biogas at low concentration. High concentration of volatile fatty acids and low pH after heat treatment did not inhibit subsequent anaerobic digestion. 70 掳C was used to pretreat high solid sludge for 30 min. When sludge retention time is 22 days, biogas yield is increased by 14.5%, organic matter degradation rate is increased by 9.5%, and the same digestibility is achieved when sludge retention time is 22 days. Sludge residence time can be shortened from 22 ~ 30 days to 1522 ~ 22 days. 4) through the analysis of energy consumption, it is found that the main energy consumption of anaerobic digestion of high solid sludge is agitation. When the organic matter content in sludge is more than 40%, most of the production capacity can be used to generate electricity. The output energy of digestive system is reduced by 5.6%, but considering the increase of organic matter degradation rate, the energy consumption of drying system is saved. Therefore, considering comprehensively that "digestive system drying system" 70 掳C thermal pretreatment is economically feasible. The digested sludge with thermal pretreatment needs more coagulants. The effect of ferric trichloride conditioning is better than that of polyacrylamide. The total nutrient and heavy metal contents in digested sludge can meet the requirements of landscaping. The inorganic components in digested sludge are mainly silicon dioxide and alumina, which can be used in ceramic making after mixing with clay in a certain proportion.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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