【作者】 张选军；

【导师】 赵建夫； 张亚雷；

【作者基本信息】 同济大学 ， 环境科学， 2007， 博士

【摘要】 厌氧工艺是一种低能耗、投资省、污泥产量低、占地面积少的污水处理技术,在我国一些气候适合的地区,利用厌氧工艺处理城镇污水将是一项很有吸引力的技术。本课题针对城镇污水的特点开发出了低能耗的新型外循环厌氧反应器（OCAR）,通过小试试验对比研究了上流式厌氧污泥床（UASB）、厌氧膨胀颗粒污泥床（EGSB）和OCAR处理模拟城镇污水的稳定运行和冲击,重点考察了上升流速、水力停留时间、有机负荷等因素对OCAR处理效果的影响。并以中试装置进一步研究了EGSB和OCAR处理实际城镇污水的性能,详细分析了进水悬浮物（SS）、溶解氧和温度对OCAR处理城市污水的影响及微生物的变化,并采用停留时间分布（RTD）模型、弥散模型和厌氧消化1号模型（ADM1）对反应器的性能进行了分析,建立了适用于OCAR的数学模型。在小试实验中,对比研究了厌氧反应器在低温和中温启动的两种方式。出水中的COD、碱度、VFA、辅酶F₄₂₀和胞外多聚物ECPs等表明,反应器启动的快慢顺序为OCAR>EGSB>UASB。随着上升流速的提高,OCAR反应器的出水SS明显低于EGSB反应器,当上升流速为9.0 m/h时最大相差值达到58mg/L,表明OCAR通过将出水与回流水在沉淀区进行分离,成功地降低了出水SS的流失;随着停留时间的降低,OCAR、EGSB去除污染物的有机负荷量增加,当停留时间为2.08 hr时,有机负荷达到3.14 kg COD/（m³·d）,此时出水COD稳定达到城市污水二级排放标准;停留时间与有机负荷去除量的关系式为:OCAR反应器Y=0.26 Ln（x）+2.13。UASB、EGSB、OCAR处理城市污水过程中的基质降解规律可以用Monod模型来拟合。通过中试反应器,具体研究了常温下OCAR处理实际城镇污水的效果。由于城市污水的波动性大,OCAR反应器在采用穿孔管布水系统时处理效率不稳定,出水COD波动明显;通过改造采用了高位脉冲布水系统代替了穿孔管布水系统进水,不仅有效的降低了进水波动对反应器运行稳定的影响,同时提高了反应器的处理效果;随着回流比的增加,EGSB和OCAR出水中SS也逐渐加大,但是OCAR出水SS比EGSB的明显要低（最大相差了66.3mg/L）,即使在回流比增大到30时,出水COD并未出现较大的波动。城市污水中的悬浮物较多,但能够有效地在OCAR反应器中被降解,不会在反应器中积累。OCAR采用了出水回流,较高的上升流速提供最佳混合条件,强化了基质的扩散、传递,同时能够保持足够的污泥量在反应器内,可以补偿温度波动对反应器运行的影响。另外由于城市污水的COD较低,抵消了低温对厌氧降解的不利影响。因此OCAR在常温下处理低浓度的城市污水时,温度的波动基本不会影响系统的运行。溶解氧与厌氧颗粒污泥的SMA具有较好的线性关系,常温下其线性关系式为:Y=-2.9885X+90.162;但是厌氧颗粒污泥由于兼性菌多包围在颗粒的外围,能够及时消耗完进水中的溶解氧,对颗粒内的产甲烷菌起到保护作用。通过对反应器污泥量平衡控制的研究表明,当反应器容积负荷Y与出水TSS（X）满足以下关系式时,才能保持反应器里污泥量平衡以维持正常的运行:Y≥X×0.8/HRT×y×η×0.7式中η为COD去除率平均值,y产率系数为,HRT为停留时间。对厌氧颗粒污泥的性质进行了研究,在中温处理高负荷柠檬酸废水IC的颗粒污泥粒径平均为1.337mm,而接种到OCAR中后,由于有机负荷和温度的降低,污泥的平均粒径30天后下降到1.106mm。颗粒污泥接种后驯化时间越长,颗粒污泥SMA值越高、产甲烷菌的活性越强;随着容积负荷的增加,颗粒污泥中辅酶F₄₂₀的量也随着增加。从中温处理柠檬酸废水的IC厌氧反应器取得接种污泥微生物种属为15个,经过在常温处理城市污水的外循环反应器驯化后,有9个种属被淘汰,并新生出6个种属。在10℃、20℃、30℃的不同温度下运行,厌氧颗粒污泥的微生物群落结构和种群数量存在明显的演替过程,其PCR-DGGE图谱相似性系数Cs在53.5%～74.5%,温度相差越大,Cs越小。采用RTD模型对比分析了EGSB和OCAR的水力学特性,离散数D和死区百分率表明,在高的上升流速时,EGSB存在沟流现象,死区百分率升高;而OCAR由于采用了中部水回流、改进了布水系统,因此上升流速越高,离散数D越大,返混效果越好,当上升流速为9.00m/h,死区百分率减少到0.87%。采用弥散模型对不同上升流速下OCAR污泥浓度进行了模拟计算,在模拟过程中,通过纳入三相分离器分离效率（SE）的概念实现了模型对出水SS的模拟,模拟数据的标准偏差小于6%。在参考ADM1的基础上,建立了适用于OCAR的动力学模型。该模型对OCAR反应器的模拟结果的平均相对误差在10%以下,与实际运行结果基本吻合,并能真实的反映反应器的运行情况。更多还原

【Abstract】 Anaerobic treatment is a technology of low energy consumption, low construction and operating costs, less sludge output and small layout area. It will be very attractive for some regions of our country, where the climate is amenable. So the subject of the paper is to develop a new type of energy saving process-the Outside Circling Anaerobic Reactor (OCAR). Through small-scale comparative study of the Up-flow Anaerobic Sludge Blanket (UASB), Expanded Granular Sludge Bed (EGSB) and OCAR treating synthetic municipal wastewater, stabilization shock of process operation were investigated, on which effects of factors such as the up-flow velocity, HRT, organic load on OCAR were focused. Characters of municipal wastewater treatment by EGSB and OCAR were studied; furthermore, effects of suspended solids (SS), dissolved oxygen and temperature on OCAR treating municipal wastewater were analyzed; also, residence time distribution (RTD) model, diffusion models and Anaerobic Digestion Model No. 1 (ADM1) were used to analyze the reactor performance.Start-up modes of low-temperature and high-temperature were studied comparatively using seeded granular sludge that has been adapted to the municipal wastewater. Analyses of COD, alkalinity, VFA, Coenzyme F420 and EPS etc indicated that the start speed were in the order of OCAR>EGSB>UASB. With the increasing of flow rate, effluent SS of OCAR was significantly lower than EGSB. When the up-flow velocity was 9.0 m/h , the value of difference reaches its biggest as 58mg/L, which indicated that through separation of effluent and recycled stream before precipitation areas, OCAR can reduce effluent SS significantly. Along with the lower residence time, organic pollutants loads of both OCAR and EGSB increases, when the residence time is 2.08 hr, the organic load reach 3.14 kg COD/(m~3·d), and the effluents meet secondary sewage discharge standards stability; relationship between the organic loading and HRT is: Y=0.26 Ln(x) + 2.13.Hours of continuous experiments showed that substrate degradation of UASB, EGSB and OCAR fit the Monod model.A pilot experiment was established in a municipal wastewater treatment plant, and actual performance of OCAR at room temperature was discussed specifically. As quality of municipal wastewater fluctuated much, The performance of OCAR pilot installations with perforated pipe water distribution system became unstable and effluent COD fluctuated obviously, the transformation used by the high pulsed water distribution system instead of perforated pipe water distribution system inundated, which not only effectively reduced effect of the flow fluctuations on the reactor operation stability, but also improved efficiency of the reactor; with increasing of reflux ratio, effluent SS of EGSB and OCAR gradually increased too. However, effluent SS of OCAR was obviously lower than that of EGSB (with the largest difference of 66.3 mg/L). Even when the reflux ratio increased to 30, effluent COD of OCAR did not change much. SS were high in the municipal wastewater, but can be effectively depredated in OCAR without accumulation in the reactor. OCAR used effluent recycle and higher up-flow rate to make better mixing conditions, strengthening the substrate diffusion and transmission; at the same time it can maintain adequate quantity of sludge in the reactor, which can compensate for the fluctuations of the temperature. As the influent COD of the municipal wastewater was low, adverse effects of low-temperature on anaerobic degradation can be offset.Therefore, temperature fluctuations will not affect the basic operation of the system of OCAR at room temperature treatment of low concentrations of municipal wastewater. DO and SMA of the anaerobic granular sludge fited a good linear relationship of Y =- 2.9885X +90.162 at room temperature; as anaerobic granular sludge has facultative bacteria buildings in the periphery of particles, with timely completion influent consumption of dissolved oxygen, it can play a protective role for particles within the methane-producing bacteria. In the media-temperature processing load IC citric acid wastewater sludge particles for the average particle size 1.337 mm, sludge average size dropped to 1.106 mm in OCAR after inoculation of 30 days, as the organic load and temperature decrease. The study of the reactor control the balance through sludge showed that only when the reactor volume load Y and effluent TSS (X) meet the following relationship, can the reactor maintain sludge balance to maintain the normal operation:In the formula,ηstands for the average removal efficiency of COD, average, y yield coefficient, HRT hydraulic retention time. The longer the granular sludge inoculated, the more SMA of the granular sludge, and the greater the methane-producing bacteria activity is; Along with the increase in volume load, Coenzyme F420 of the granular sludge increased. There were 15 microbial species in the sludge of media-temperature processing citric acid wastewater while 9 of them were eliminated, and six new species were generated from the normal temperature processing municipal wastewater treatment. After treatment at temperature of 10℃, 20℃, 30℃respectively, microbial community structure and population size of the anaerobic granular sludge marked the succession process, PCR-DGGE map similarity coefficient Cs is 53.5% - 74.5%; the greater the temperature difference, the smaller Cs is.RTD models were used to analyze the hydraulic characters of EGSB and OCAR. Discrete parameter D and the dead percentage showed that when the up-flow rate was high, EGSB existed ditch stream with increase of dead percentage; OCAR used a central return, which improved the water distribution system. The higher the velocity increases, the greater the discrete parameter D is, the better the mixed results were. When the up-flow rate rose to 9.00 m/h, the dead zone percentage decreased to 0.87%. Dispersion model was used for different velocity increased under OCAR sludge concentration of simulation, the simulation process, through the inclusion ofthree-phase separator separation efficiency (SE) to achieve the concept of the modelto simulate the effluent SS. Standard deviation of the simulation data was less than 6%.更多还原