【作者】 徐功娣；

【导师】 刘宇陆；

【作者基本信息】 上海大学 ， 流体力学， 2006， 博士

【摘要】 本文针对高浓度、高色度有毒有害难降解的工业废水，利用生物流化床废水处理技术和多种厌氧—好氧组合方式的原理方法，设计了新型序批式双外循环生物流化床系统。该系统具有如下特点：（1）该系统结合了序批式操作模式和生物流化床技术的优势，是一种新型、高效的序批式生物膜反应器（SBBR），解决了已有固定床SBBR易堵塞、反应效率低等问题；（2）该流化床在不同的运行阶段，可以分别利用强制水力循环和气提式循环，实现液-固两相循环流化床及气-液-固三相循环流化床的操作，从而在同一流化床中实现了厌氧、好氧及沉降等多个过程；（3）该系统可使被处理的废水在处理过程中历经序批式厌氧—好氧过程、交替式厌氧—好氧过程以及厌氧—好氧原位降解过程的多种组合协同作用，能对包括染料在内的难溶、难降解的大分子进行更有效地吸附和分解，使厌氧分解及硝化和反硝化过程更完全；（4）该流化床采用了较轻的细小活性碳颗粒（100-120目）为载体且添加量较少，并采用循环射流的启动和流化方式，使系统更容易启动和流化，而且具有更优的生物降解性能；（5）该系统的微生物采用了悬浮生长和附着生长共存及序批式驯化的方式，生物相丰富，适应性强，具有多种降解能力；（6）合理设置的“闲置”期可以使厌氧分解、反硝化过程及色度的去除更完全，并对污泥进行减量降解及载体和生物系统再生，达到同时去除高浓度含碳有机物、去氮、脱色并减少污泥的目的。该技术系统还包括一个可以根据工艺需要产生多种不同控制模式的自动控制箱，能够对各种序批式的间歇过程进行自动地连续化操作，所以该技术在一定意义上实现了一体化处理，自动化操作，高效节能化运行，无二次污染的环保化处理目标。对系统特性的实验研究表明，该系统中气-液-固三相流化床，具有较好的充氧特性：氧总转移系数K_La（20℃）=10.78h^-1，氧的利用率较高：E_A=18.9％；系统的微生物能适应从厌氧到好氧再到厌氧过程的溶解氧（DO）环境变化；在厌氧和好氧阶段，系统内微生物量合适，生物相丰富，悬浮生长和附着生长比例适当，生物膜厚度适宜，分别为124μm和146μm。另外，本文还对运行过程中该系统的流体动力学特性进行了细致研究，主要包括两部分：一是采用粒子图像速度场仪（PIV）对液-固两相循环阶段主、副床的流场特性进行了实验研究，得到了主、副床速度分布规律及涡量分布特性，结果表明：主床x方向的轴向速度分布V_z—r_x/R是不对称的，其最大值偏向外侧（r_x/R为正）：y方向的轴向速度分布V_z—r_y/R是对称的，最大速度均在中心r_y/R=0；在不同的循环流量下，主床和副床内的涡量的分布都比较均匀，不会出现由于剪切力过大而使生物膜被破坏的情况，说明流化床结构设计合理；实验确定了最佳操作条件下主、副床的涡量范围分别是（35-45）s^-1和（10-20）s^-1。二是采用RSM湍流模型对流化床进行数值模拟计算，得到了流化床在不同入射流量下的三维速度场，与相应条件下实验结果对比均符合得比较好；模拟计算还得到了流化床在不同循环流量下的三维压强分布和湍流强度分布。本文对流化床系统流体力学特性的深入研究为此类设备的设计和工程放大提供了新的方法和基础数据。本文利用该系统对模拟印染废水进行处理，考察了厌氧阶段和好氧阶段COD_cr及NH₃-N的去除规律和效果，确定了其最佳的循环流量和气速分别为1.4m³/h和0.17m/min经过五种不同厌氧．好氧组合工艺的比较，最佳组合处理工艺为：一次性进水厌氧A（4.0h）—好氧O（4.0h）—沉淀出水D（2.0h）—闲置（2.0h），一个处理周期总计12h；该最佳组合方式处理模拟印染废水结果如下：高浓度(COD_cr1000-1200mg/L)进水，COD_cr去除率可达到90％以上，低浓度(COD_cr400-600mg/L)进水，去除率达82％；NH₃-N去除率均达60％以上；色度去除率均接近100％，该结果表明系统对含染料废水的处理效果比较理想；对最佳的运行模式下系统的主要性能参数的研究表明：反应器中DO和pH均呈周期性变化，满足多重厌氧-好氧的生化处理要求；系统中污泥量在好氧阶段结束时达到最大值4272mg/L，保证良好的处理效果，在闲置期结束时又减到最少，从而大大降低了污泥排放量；该系统进水pH值在6.0～8.5范围内，温度在18～30℃范围内，有机负荷在1.4～5.4（kgCOD/m³·d）之间，碳氮比大于5时，NH₃-N的去除率基本不受影响，经过30个周期以上的运行，均能达到规定的排放标准，进一步验证了该系统的有效性和稳定性。更多还原

【Abstract】 In this thesis, a new equipment called a Sequential Batch Bi-extemal Recycling Biological Fluidized Bed （SBBRBFB） is designed to treat the highly polluted, toxic industrial wastewater which is hard to bio-degrade. The BRBFB is designed on the basis of techno-peculiarity of biological fluidized bed and the reasonable combination of anaerobic-aerobic courses. The BRBFB process has some innovations, which include:●It is a new type of sequencing batch biofilm reactor（SBBR）, which combines both the advantages of sequencing batch reactor technology and those of the biological fluidized bed technology. The shortages of liability of being blocked and low efficiency of treatment for packed bed sequencing batch biofilm reactor are overcome in this new system.●Several different processes involving anaerobic treatment, aerobic treatment and settlement can be easily realized in this fluidized bed reactor because this system can be switched easily from solid-liquid fluidized bed recycling by hydrodynamic jet to gas-solid-liquid recycling by airlift in different process stages.●The wastewater in this fluidized bed can be well dealt by various combination of anaerobic/aerobic course including sequencing, alternate, local concurrent mode, so the large molecules like dye which are difficult to dissolve and degrade can be absorbed and decomposed more effectively.●This new system can be started up and fluidized easily and has higher biodegradation ability since the fine light activated carbon particles are adopted as carrier of the microorganism, and the recycling jet is taken to start up and fluidize the liquid-solid two phase fluid.●The microorganisms in this reactor exist and develop in both suspended and attached manners and are domesticated by sequential anaerobic/aerobic process. Therefore the system has rich microorganism, good adjustability and degradation ability to many types of waste water.●An idle period devised rationally makes the hydrolyzation- acidification and denitration more completely. The idle time can also help to reduce the residual sludge, and help the carriers and the within biofilm reproduce.●Finally, an automatic control box, which can provide manifold modes of process according to the different calling for sequencing batch, is introduced, and therefore, in some way; the targets of automation, high efficiency and no secondary pollution of waste water treatment are realized in this new system.The primary investigation of the new system shows that: the gat-liquid-solid fluidized bed possesses a good ability to absorb oxygen. The total coefficient for transferring oxygen is K_La（20℃）=10.78h^-1, and the Oxygen utilization is high （E_A=18.9%）. The microorganisms can adapt for the change of environment of dissolving oxygen from anaerobic to aerobic course. The amount of rich microorganism is appropriate and the ratios of suspended microorganism to attached ones are 21% and 28% in anaerobic and aerobic processes respectively. Besides, the thick of the biofilm are 124μm and 146μm in anaerobic and aerobic processes respectively which are appropriate for biologic treatment.The fluid dynamics in the fluidized bed have also been investigated in detail both numerically and experimentally. First, the characteristics of the velocity fields in the main bed and the auxiliary bed were measured in solid-liquid fluidized phase by the particle image velocimetry （PIV）. The Reynolds averaged velocities and vorticity in the main bed and the auxiliary bed were shown and analyzed. It is shown that axial velocity component is asymmetric with respect to the X direction（V_Z-r_x/R） and the excursion to the outside wall （+ r_x/R） of the maximal value is clearly seen, whereas the distribution of the axial velocity in the Y （V_Z-r_y/R） direction is symmetric and the maximal speed is located in the centre （r_y/R=0）. On the other hand, the vorticities in the main bed and the auxiliary bed are both uniformly distributed so that the turbulent shear stresses around the carriers are not too strong to destroy the biofilms, and this accounts for the validity of the design of the reactor. The vorticities in the main bed and the auxiliary bed are between （35-45）s^-1 and （10-20）s^-1 respectively under the situation of optimal flux of recycling （1.4m³/L）. Second, a Reynold-stress model （RSM） was used to simulate the three dimensional velocities in the main and auxiliary beds. By comparison to the experiments, it is indicated that the numerical results by RSM model agree well with experiments under any flux of recycling. The distribution of pressure and turbulence intensity were also obtained and analyzed. The numerical method used in this thesis can be used to evaluate the performance of the reactor, and to shed new light on the design of such equipment.Finally, the new system was used to treat a model waste water from a dyeing plant. The effects of the removal of COD_Cr and NH₃-N were investigated in both anaerobic and aerobic phases. It is found that the most appropriate fluxes of recycling and aeration are 1.4m³/h and 0.17m/min respectively. By the comparison of five different treatment courses, the optimization of the combined operation of the system is determined to be a 12-hour cycle including an inflow process and anaerobic digestion process （4 hr）, an aerobic aeration process （4 hr）, a settlement process （2 hr）, and a recess process including effluent discharge process （2hr）. After this optimal treatment, 90% of COD_Cr is removed for a higher concentration water (COD_Cr 1000-1200mg/L), and 82% of COD_Cr is removed for a lower concentration water (COD_Cr 400-600mg/L). The removal rate of NH₃-N is higher than 60%, and nearly 100% color is removed. These results indicate that wastewater containing dying wastewater can be well treated using SBBRBFB with proper choice of courses. Meanwhile, some other performance parameters under the optimization condition were also examined. These examinations show that the values of DO and pH in the reactor are periodic and can meet the requirement of biochemistry treatment, and the sludge in the reactor is changed from the maximum in the end of aerobic process to the minimal quantity in the end of idle process, which meet the requirement of microorganism quantity for treatment. The final residual sludge is reduced to a low level. The temperature is between 18-30℃, and the organic load is between 1.4-5.4 kgCOD/m³·d. The discharge standards can be usually met after 30 periods of running. These results further indicate that SBBRBFB and the operating strategies are well designed and working well for treating dye waste water.更多还原