【作者】 刘少武；

【导师】 张智；

【作者基本信息】 重庆大学 ， 市政工程， 2010， 博士

【摘要】 三峡成库后,因水流减小导致水体自净能力的减弱,氮磷过量排放引起的库区富营养化问题越来越严峻,尤其在前年无锡太湖蓝藻事件,更引起人们对三峡库区氮磷过量排放的担忧,对库区污水进行深度除磷脱氮的要求越来越迫切。CAST工艺(CyclicActivated Sludge Technology)作为SBR一种新的变型工艺,具有良好的脱氮除磷功能,又由于其占地面积较小、无需初沉池和二沉池、基建及运行费用低,比较适合三峡库区地少和运行经费紧张的特点,同时CAST工艺由于设置生物选择池限制丝状菌的生长,操作自动化程度高、劳动强度低等优点,近年来在我国特别是三峡库区的应用越来越广泛。虽然CAST工艺的研究很多,但其生产性试验的研究尚处于初步阶段,本课题针对TN平均约60mg/L的高氮城市进水CAST工艺,对其污泥培养驯化、工艺调试、优化运行控制全程和运行过程中生化系统中微生物变化等进行了系统而深入的研究。在2008年,对CAST工艺去除CODCr、TN、NH3-N等污染物的特性进行了研究,并就生产中出现的问题进行了分析。通过对影响CAST工艺运行关键性参数进行调整,对影响因素的不同作用规律进行了系统研究,寻找适合李家沱污水处理厂水质水量的冬季低温期和常温期最佳运行模式。在对2008年各种运行数据分析的前提下,重点对影响脱氮的因素及规律进行了分析,提出适合李家沱污水处理厂将来水量增大脱氮压力增加的运行模式。在2009年的实验中对脱氮过程ORP的变化规律、影响因素和指示作用以及微生物与脱氮的关系等进行了初步的研究。在实验工程中采用了五种运行模式来研究CAST工艺,即A:进水0.5h—进水/曝气1.5h—沉淀1h—滗水1h;B(初步设计采用模式):进水/曝气2h—沉淀1h—滗水1h;C:进水/曝气2h—微曝1h—沉淀1h—滗水1h;D:进水1h—曝气2h—沉淀2h—滗水1h;E:进水/曝气3h—沉淀2h—滗水1h。根据近一年的实际运行情况,选定C模式:进水/曝气2h—微曝1h—沉淀1h—滗水1h为冬季低温期运行模式,对DO、MLSS等运行参数进行了优化,主曝阶段DO控制在3.0~4.0mg/L,微曝阶段DO控制在0.5mg/L以下,污泥龄控制为15~20d,MLSS值控制在4000~6000mg/L,污泥回流比约30%时,系统可取得最好的脱氮效果,此时脱氮率基本在75%左右。选定了B模式(设计模式):进水/曝气2h—沉淀1h—滗水1h为常温期运行模式,并通过实验确定MLSS、DO等运行参数,DO控制2.0~3.0mg/L,MLSS值控制在4000~5000mg/L,相应的污泥龄为14~16d,污泥回流比为20%时系统处理效果最优。通过近2年的实验研究,发现CAST工艺采用不同的运行模式时,处理效果显著不同;在对CAST工艺实际运行管理中,应首先摸清实际进水情况,根据实际进水水质合理选定运行模式和各项控制参数,重视进水中因工业废水进入产生的高氮和低C:N现象带来的脱氮压力;在实际设计中,为取得较好的脱氮效果,建议氮负荷率取值不应高过0.04gN/gMLSS.d;污泥龄控制在15～20d左右。目前,李家沱污水处理厂进行较少,负荷不高,未来水量增大会带来严重脱氮压力,因此本课题进行了强化同步硝化反硝化试验,提出了DO水平梯级控制的概念。运用DO梯级控制,合理选择运行参数,CODCr、BOD5等污染物可以得到稳定有效的去除效率,而TN的去除率也提高了10%~15%左右,出水TN浓度基本在15mg/L以下,TN出水平均在11mg/L左右,达到或接近《城镇污水处理厂污染物排放标准》(GB18918-2002)一级A标准。ORP作为运行控制参数之一,在脱氮过程中越来越显示其作用,为此,在2009年进行ORP与脱氮效果的初步研究,寻找和探索了CAST工艺中厌氧区和主反应区ORP与CODCr、NH3-N、硝态氮等物质浓度的关系。研究ORP值随进水水质变化而变化,但ORP的变化有一定的规律,在厌氧区ORP和CODCr、NH3-N的浓度乘积与硝态氮浓度的比值的对数线性相关性较好R2=0.9146,在主反应区曝气阶段ORP值与LnDO相关性系数为R2=0.8708。污水处理装置中起污水净化作用的主要是各种细菌,微生物与细菌之间存在相互依赖的功能关系,微型动物的群落结构在很大程度上反应细菌群落结构,因此,微生物可以指示污水处理效果的好坏。通过对CAST工艺微生物特别是纤毛虫种类、数量的变化和对应的出水理化参数的Pearson相关性分析的研究证明:有肋楯纤虫、龙骨漫游虫、小口钟虫为微生物的优势种;纤毛虫中优势种属与出水的理化参数呈一定的相关性,相关程度随种属的不同而异。更多还原

【Abstract】 After the completion of Three Gorges Reservoir, the ability of water self- purification is weaken due to water flow become slowly. The excessive emission of nitrogen and phosphorus resulted that eutrophication was more severe in the reservoir, especially, Taihu Lake have appeared cyanobacteria events in Wuxi in the year before past, which gave rise to concern about excess emissions of nitrogen and phosphorus in the Three Gorges Reservoir Area. The deep removal of nitrogen and phosphorus is more and more urgent. CAST Technology (CyclicActivated Sludge Technology), as a new variant of SBR process, has many merits, such as good function of nitrogen and phosphorus removal, smaller area, without primary sedimentation tank and secondary settling tank, low infrastructure and operating costs. so CAST process is adapt to Three Gorges reservoir area which has smaller area and short of funds. At the same time, the bio-selecting tank is set up in CAST process to limit the growth of filamentous bacteria, with high operating automation and low labor intensity. In recent years, CAST is used more and more widely in China,especially in the Three Gorges Reservoir.Although there are many researches of CAST technology, the productive experient is still at a preliminary stage.In this paper, the CAST process treatment highly influent Nitrogen, average 60mg/L, cultivation and domestication of sluge, process test, optimization of operation and microorganism changes in the system were systematically and thoroughly researched. In 2008, there had research the feature on the removal of CODCr, TN, NH3-N and other pollutants in CAST Process and analyze production problems. Through adjusting key parameters affecting CAST process, the different roles of affecting factors were systematically researched to find best operation modes that adapt to Lijiatuo WWTP in low and normal temperature periods. On the base of analysis operation datas in 2008, especially Nitrogen removal rule and affection factors analysis, a new operation mode, adapted to Lijiatuo WWTP that wastewater quantity and Nitrogen removal pressure increased in future, was brought forward. The variation, factors and indicative of ORP during nitrogen removal process and the relationship between microbes and nitrogen were preliminary studied in 2009.During CAST process test, there are five operating modes, A: Influent0.5h-Influent/Aeration1.5h—Settle1h—Decant1h; B(preliminary design pattern ): Influent/Aeration2h—Settle1h—Decant1h; C: Influent/Aeration 2h—Slight Aeration 1h —Settle 1h—Decant 1h; D: Influent 1h—Aeration 2h—Settle 2h—Decant 1h; E: Influent/Aeration 3h—Settle 2h—Decant1h.According to the actual operation of the past year, C was selected in low temperature period: Influent/Aeration 2h—Slight Aeration 1h—Settle 1h—Decant1h and DO, MLSS and other operating parameters were optimized. At the conditions that DO was controlled at 3.0 ~ 4.0mg/L in main exposure stage, below 0.5mg/L in micro-exposure stage, the sludge age was 15 ~ 20d, MLSS value was 4000 ~ 6000mg/L, the sludge recycle ratio was about 30%, the system can achieved the best nitrogen removal, about 75%. B(design pattern) was selected in normal temperature period: Influent/Aeration2h—Settle1h—Decant1h; DO, MLSS and other operating parameters were determined .At the conditions that DO was controlled at 3.0 ~ 4.0mg/L, MLSS value was 4000 ~ 5000mg/L, the sludge age was 14~16d, the sludge recycle ratio was about 20% , the system can achieved the best nitrogen removal.Base on WWTP actual operating parameters and quality of influent and effluent in 2008 ~ 2009, the following conclusions were obtained: the nitrogen removal in CAST process were significantly different at different modes of operation; in CAST process operation, it was should to compared with water quality of design and actual, attention to different operating modes with different quality to avoid nitrogen pressures caused by high percentage of industrial wastewater and high influent nitrogen concentration. In the actual design, in order to obtain better nitrogen removal, the nitrogen loading values should not be higher than 0.04gN/gMLSS.d and sludge age is about 15d.Currently, the influent is less and load is not high in Lijiatuo WWTP, increased water quantity in future will bring serious pressure of denitrification. Therefore, this topic studied on strengthening the simultaneous nitrification and denitrification,and raised the concept of DO Step-Control. Under the premise of removing pollutants such CODCr、BOD5 and so on, the results showed that nitrogen removal in DO Step-Control was more stable and effective than ordinary whether in low or normal temperature operating conditions. Denitrification rate increased by 10% ~ 15%, the effluent TN concentrations was mostly below15mg/L, TN effluent was 11mg / L or so.ORP as one of control parameters, more show its role in the nitrogen removal process. In 2009, When carry out the pilot study for researching the role of ORP making during the Nitrogen removal process, the study emphases is put on the relationship between ORP, CODCr, NH3-N and NOX-N during denitrification process in anaerobic tank and the main reaction tank . Research found that the different influent wastewater quantity, ORP values is significantly different changes. And the results indicate that influent wastewater quality makes an important role in affecting ORP. Linearity pertinency between ORP and logarithm of CODCr、NH3-N concentration product and NOX-N concentration ratio is preferable, R2=0.9146;Linearity pertinency between ORP and logarithm of DO in aeration phase of the main reaction tank, R2=0.8708.A variety of bacteria are mainly play the role of sewage purification in Sewage treatment plant, there are interdependent functional relationship between Micro- organisms and bacteria. Community structure of Microfauna Performances bacterial community structure to a large extent, so Micro-organisms can indicate good or bad effects of sewage treatment. In the CAST Process, micro-organisms, especially ciliates, Pearson correlation analysis while changes of ciliates type and quantity and the corresponding physical and chemical parameters of Drainage have been shown that : Aspidisca costata、Litonotus carinatus stokes and Vorticella microstoma Ehrenberg are dominant species of micro-organisms. here are interdependent functional relationship between Dominant species of Ciliates and physical and chemical parameters of Drainage, the different species have different degree of correlation.更多还原