【作者】 郑莉；

【导师】 孙水裕；

【作者基本信息】 广东工业大学 ， 应用化学， 2012， 博士

【摘要】 随着城市污水处理量的进一步增加,必将会产生更大量的生活污泥,生活污泥的有效处理与处置已成为城市污水处理厂急需解决的一大难题,研究开发生活污泥处理新技术是目前国内外环保界关注的一个热点。本文针对生活污泥处理中存在的问题,有效利用超声波的特性,将超声波预处理技术与污泥缺氧／好氧消化工艺相结合,通过实验室小试和中试试验研究,考察了超声波预处理对污泥缺氧／好氧消化的影响；在此基础上,研究了超声波-缺氧／好氧消化工艺实现污泥减量化的机理；最后在广州某城市污水处理厂现场,进行了污泥超声波—缺氧／好氧消化工艺示范工程的应用研究。本文首先研究了超声波溶胞前后对污泥理化和生化性质的影响。研究结果表明,声能密度对超声波预处理污泥效果影响最显著,最佳的超声预处理参数组合为：超声频率28kHz,声能密度0.15W/mL,超声时间10min。此外,研究还发现不同浓度的污泥,对应的最佳超声组合参数也有所不同。其次通过实验室小试和中试试验,研究了超声波预处理对污泥缺氧／好氧消化的影响。小试试验结果表明,超声波-缺氧／好氧消化工艺最佳的停留时间为12d；中试试验结果表明,引入超声处理后,大大缩短了污泥的稳定时间,显著提高了污泥的消化效率,污泥消化12d就已经达到了稳定标准,比对照污泥缩短了8d；经过25d的消化后,TSS、VSS、TN的去除率分别达到38.32%,50.48%和40.5%,比对照污泥分别提高了6.72%,8.52%和4.69%。然后通过实验室中试对比试验,研究了污泥超声波-缺氧／好氧消化对传统好氧消化的比较优势。研究结果表明,经过25d的消化后,超声波-缺氧／好氧消化污泥TSS和VSS的去除率分别达到了35.77%和50.02%,比好氧消化污泥分别提高了3.90%和8.99%；超声波-缺氧／好氧消化污泥稳定时间比好氧消化污泥缩短了近6d；超声波-缺氧／好氧消化污泥的TN去除率为40.8%,远高于传统好氧消化,并且超声波-缺氧／好氧消化污泥上清液中氨氮和硝态氮浓度却远低于传统好氧消化,因而降低了上清液回流氨氮和硝态氮对污水处理系统的负荷压力。在工艺条件试验研究的基础上,利用生化分析法和分子生物学方法,从物质转化、能量的传递以及反应器内微生物群落结构的演替等方面阐述了超声波-缺氧／好氧消化工艺实现污泥减量化机理。生化分析研究结果表明,超声波加快了EPS和蛋白质溶出,促进了有机物降解,提高了蛋白酶与脱氢酶活性；同时超声污泥ATP的含量比对照污泥要低,能量在超声污泥中耗散的速度比对照污泥快,因此,超声污泥的TSS和VSS降解比对照污泥要快,超声污泥的TSS和VSS去除率大于对照污泥。分子生物学的研究结果表明,在污泥超声波-缺氧／好氧消化反应器运行期间,微生物群落结构和氨氧化细菌群落结构均发生动态演替。微生物群落结构DGGE图谱的优势菌种中,发现了4株在活性污泥消化过程中起着重要作用的芽孢杆菌(Bacillus),它们加快了超声污泥的TSS和VSS降解。氨氧化细菌DGGE图谱的优势菌种中,发现了6株反硝化菌,它们对提高反应器脱氮效率具有重要作用,其中3株菌属于假单胞杆菌属(Pseudomonas),1株菌属于德氏食酸菌属(Acidovorax),2株菌属于伯克氏菌属(Burkholderia)。因此,超声波促进了硝化与反硝化作用,超声污泥的TN去除率高。Real-time PCR结果表明,AOB数量先减少后增加,且AOB数量与氨氮的浓度有关,高浓度氨氮有助于AOB数量的增加。此外,AOB数量的增加可促进氮去除率的提高。此外,还通过绿色荧光蛋白菌(GFP)表征溶菌特性的手段,从细胞转化的角度阐述了超声波-缺氧／好氧消化的反应机理。研究结果表明,超声波-缺氧／好氧消化过程中的好氧期污泥上清液对荧光菌胞内GFP的释放具有明显的促进作用；该时期的污泥上清液具有显著的溶菌作用,污泥上清液具有的溶菌活性可能主要来自于污泥胞外水解酶。在实验室工艺条件和机理研究的基础上,将超声波-缺氧／好氧污泥消化工艺应用于污水处理厂现场,考察了该工艺的污泥减量化实际效果。工程连续运行3个月以上,污泥TSS去除率和VSS去除率分别达到36%和50%,总氮的去除率达40%。污泥上清液中氨氮、硝酸盐、亚硝酸盐和TP的含量较低,相应的氮负荷和磷负荷也较低,回流返回的氮磷量不会影响污水处理厂出水水质。超声波-缺氧／好氧污泥消化费用为0.324-0.389元/m3污水,比传统好氧消化的要高,但其优点在于节省占地面积,停留时间更短,处理效果更好。本研究结果为生活污泥超声波-缺氧／好氧消化工艺技术的推广应用提供了重要的理论基础和实践依据。更多还原

【Abstract】 With the increase of sewage load, a larger number of municipal sewage sludge was produced inevitably. Treatment and disposal of sewage sludge becomes a difficult problem to wastewater treatment plants. At present, studies focus on developing a new technology for treatment of sewage sludge. In view of the problem of treatment and disposal of excess sludge, using characteristics of ultrasond effectivily, ultrasonic pretreatment was combined with sludge anoxic/aerobic digestion process. With small and pilot scale texts in laboratory, the effects of ultrasonic pretreatment on aerobic/anoxic digestion process were investigated and mechanisms of sludge reduction were discussed. Finally, demonstration project using this ultrasonic-aerobic/anoxic digestion process to treat sludge was also carried out in one of wastewater treatment plant in Guangzhou.In this paper, the effects of ultrasonic pretreatment on sludge physical and biological characteristics were firstly studied. The results indicated that the optimal conditions of ultrasonic pretreatment were as follows:ultrasonic frequency of 28 kHz, ultrasonic intensity of 0.15 W/mL, and ultrasonic treatment time of 10 min. In addtion, it was found from our study that different sludge concentrations corresponded to different optimal ultrasonic pretreatment conditions.Then the influences of ultrasonic pretreatment on aerobic/anoxic digestion process were investigated with small and pilot scale texts in laboratory. The results of small scale texts indicated that, the optimal sludge retention time is 12 d; the results of pilot scale texts showed that stability time of sludge was shortened greatly and digestion efficiency was markedly improved by ultrasonic pretreatment. The stability time of sludge with ultrasononic pretreatment was 12 d, which was shortened by 8 d compared to that of sludge with control treatment. After digestion time of 25d, TSS, VSS and TN removal efficiency reached to 38.32%,50.48% and 40.5%, respectively, which was increased by 6.72%,8.52% and 4.69%, respectively, compared to the control.Contrastive pilot scale experiments of ultrasonic-aerobic/anoxic digestion and conventional aerobic digestion were conducted. The results showed that, TSS and VSS removal efficiency of ultrasonic-aerobic/anoxic digestion achieved to 35.77% and 50.02%. which were increased by 3.90% and 8.99%, respectively, after digestion time of 25d. The digestion time for ultrasonic-aerobic/anoxic digestion was shortened by 6 d compared to conventional aerobic digestion. TN removal efficiency of ultrasonic-aerobic/anoxic digestion was 40.8%, which was much higher than that of aerobic digestion. Furthermore, ammonia and nitrate concentration in sludge supernatant of ultrasonic-aerobic/anoxic digestion were lower than that of aerobic digestion, so that the pressure of circumfluence to wastewater treatment plant was reduced.Based on the study of laboratory operation conditions, biochemical analysis and molecular biological research method were adopted to investigate the mechanisms of sludge reduction, from substance transformation, energy transmission and succession of microbial community structure, etc. The results of biochemical analysis revealed that ultrasonic pretreatment accelerated the solubilisation of the EPS and protein and enhanced enzymatic activities. At the same time, the ATP concentration in ultrasonic sludge was lower than that of the control, energy transmission in ultrasonic sludge was faster, resulting in the removal efficiency of TSS and VSS in ultrasonic sludge was markedly improved.The study of molecular biology showed that microbial and ammonia-oxidizing bacterial community structure changed in different operation process, which could reflect the dynamic succession of microbial and ammonia-oxidizing bacterial community. The sequencing indicated that 4 of predominant species in DGGE profiles of microbial communities are belonged to Bacillus, which playing an important role in sludge digestion. TSS and VSS of ultrasonic sludge were degradated faster. Among the predominant species of ammonia-oxidizing bacterial communities throught the operation,6 are denitrifiers, which playing an important role in improving the efficiency of nitrogen removal.3 of them are belonged to Pseudomonas,1 is belonged to Acidovorax,2 are belonged to Burkholderia. Pseudomonas, Acidovorax and Burkholderia. Nitrification and denitrification were improved by ultrasonic pretreatment, resulting in TN removal efficiency of ultrasonic-aerobic/anoxic digestion was higher. Real-time PCR revealed that the copy number of AOB decreased at the beginning, and then increased, which were associated with concentration of ammonia, higher ammonia content favors the growth of ammonia oxidizers in the reactor. In addition, high quantity of AOB populations can improve the efficiency of nitrogen removal.Furthermore, the mechanisms of sludge reduction were described through characterizing the process of cell lysis during ultrasonic- aerobic/anoxic digestion using green fluorescent protein.The results indicated that the sludge supernatants from aerobic phase promoted the releasing of the intracelluar GFP and the cell lysis capability of the sludge supernatant in ultrasonic-aerobic/anoxic digestion might be related to the hydrolytic enzymes secreted from the sludge.On the basis of study of laboratory operation conditions and mechanisms of sludge reduction, this ultrasonic-aerobic/anoxic digestion process was applied to treat the sludge in wastewater treatment plant, investigated the the effects of this technology on sludge reduction. The operation was carried out for 3 months, TSS, VSS and TN removal efficiency achieved to 36%,50% and 40%. Ammonia, nitrate, nitrite and TP content in sludge supernatant are very low, the corresponding loads of nitrogen and phosphorus pressure to wastewater treatment plant are reduced, so that nitrogen and phosphorus can’t influence the effluent quality. The cost of ultrasonic-aerobic/anoxic digestion is 0.324-0.389 yuan/m3 wastewater, which is higher than that of aerobic digestion. However, the novel process established in this study has the features of less site area, shorter sludge retention time, more effective treatment efficiency, and so on.This research provided theoretical and practical basis for the popularization and application of the ultrasonic-aerobic/anoxic digestion technology.更多还原