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周期厌氧折流板反应器处理中药废水的运行模式及效能
Operating Manner and Performance of a Periodic Anaerobic Baffled Reactor Treating Chinese Traditional Medicine Wastewater
【作者】 刘小雷；
【导师】 任南琪；
【作者基本信息】 哈尔滨工业大学 ， 环境工程， 2007， 博士
【摘要】 既节能又产能的废水厌氧生物处理工艺符合可持续发展原则的治理废水途径,其在工业废水处理中成功应用的关键在于高效厌氧生物反应器的发展和应用。基于传统的厌氧折流板反应器(ABR)发展而来的新型高效厌氧生物反应器——周期厌氧折流板反应器(PABR)在处理实际工业废水的运行模式优化、水力学特性和微生物学特性等方向尚存空白丞待研究,为此本文采用一种4隔室PABR在三种不同的阀门切换模式和频率下处理实际中药废水,分别在进水平均有机负荷率(OLR)约为1,2,4和6kgCOD/(m3·d)的条件下运行了12,24,24和6d,水力停留时间(HRT)恒为2d。运行结果表明,无论采用何种阀门切换模式,稳定时PABR各隔室气体甲烷百分含量、pH和碱度均沿程递增,但挥发性脂肪酸(VFA)沿程递减。OLR的提升导致出水化学需氧量(COD)和VFA的增加。顺时针切换模式运行的PABR在OLR=4.38kgCOD/(m3·d)时,COD去除率可达86.36﹪,但在OLR提升至均值6kgCOD/(m3·d)后迅速酸化;不切换模式运行的PABR在OLR=6.45kgCOD/(m3·d)时,COD去除率可达92.51﹪,但气体产量过大所引起的生物固体迁移和流失导致气体产量隔室和COD去除率最大的隔室沿程向后迁移,使得前两个隔室因为累积了大量的VFA而酸化;每隔一隔室切换模式运行的PABR在OLR=6.37kgCOD/(m3·d)时,COD去除率可达92.51﹪,用于中药废水处理的长期运行具备更强的适应性和稳定性。无论切换模式、隔室流序和OLR如何,进水及各隔室上清液的分子量分布(MWD)谱图定性分析的变化趋势与它们COD浓度及去除率、甲烷产量和气体产量定量变化的趋势是一致的。水力学特性研究结果表明,PABR与其他反应器相比死区很少,这与ABR是相同的。PABR的死区分为生物死区和水力死区两部分。空反应器停留时间分布(RTD)试验中每隔一隔室切换模式运行的PABR死区最小;不切换模式运行的PABR死区最大。接种种泥后,无论OLR大小如何,其死区比较结果与空反应器比较结果相同。无论切换模式如何,生物死区成为PABR死区大小的主要贡献者,但生物死区的影响随OLR的提升而降低。在所有试验条件下,PABR的流动模式处于平推流和完全混合的“中间状态”。采用变性梯度凝胶电泳(DGGE)分析PABR内微生物群落动态变化的结果表明,无论采用何种阀门切换模式,PABR各隔室内微生物多样性及群落结构均不相同;而同一隔室在不同OLR条件下达到稳定时的群落结构和优势种群数量具有时序动态性。各隔室内部微生物群落的动态变化趋势与PABR效能的变化趋势相符。在相同的OLR提升方案下,切换模式和频率的不同对各隔室内部微生物群落结构动态变化的不同起决定性作用。
【Abstract】 The successful application of anaerobic technology, which can economize and generate energy and accords with the principles of sustainable development in approach of wastewater treatment, to the treatment of industrial wastewaters is critically dependent on the development, and use, of high rate anaerobic bioreactors. Periodic anaerobic baffled reactor (PABR), which is a novel reactor based on anaerobic baffled reactor (ABR) design concept, is required to investigate for operating manner optimization, hydrodynamic characteristics and microorganism characteristics in actual industrial wastewater treatment. Therefore, a four-compartment PABR was used to treat actual Chinese traditional medicine wastewater run in various switching manners and frequencies continuously at stable hydraulic residence time (HRT) of 2d, using a feed with average organic loading rates (OLRs) at about 1, 2, 4 and 6 kgCOD/(m3·d) for 12, 24, 24 and 6 d respectively.Operating results showed that methane percentage of biogas and pH and alkalinity increased while volatile fatty acids (VFA) concentrations decreased along the reactor at stable state whichever switching manner the PABR run in. A raised OLR lifted the chemical oxygen demand (COD) concentration and VFA concentrations in effluent. The PABR operated in an‘clockwise sequential’switching manner, of which COD removal rate was 86.36﹪at OLR =4.38kgCOD/(m3·d), soured fast after average OLR at about 6kgCOD/(m3·d). Movement and losing of solids caused by great gas production led to the compartment with both maximum gas production and maximum COD removal rate moved along the PABR run in a T=∞switching manner, of which COD removal rate was 92.51﹪at OLR=6.45kgCOD/(m3·d), leaving the two front compartments soured with cumulative VFA. The PABR operated in an‘every second’switching manner, of which COD removal rate was 92.51﹪at OLR=6.37kgCOD/(m3·d), had better adaptability and stability treating Chinese traditional medicine wastewater in the long run. The variation trend of qualitative analysis on molecular weight distribution (MWD) chromatogram of influent and of bulk liquid from each compartment was consistent with the alteration trend of COD concentration, COD removal rate, gas production and methane production in each compartment of PABR no matter what the switching manner, and the compartment sequence and the OLR were.Results from hydrodynamic characteristics research showed that the fraction of dead space in PABR was similar to that in ABR, which was low in comparison with other reactor designs. Dead space may be divided into two categories, hydraulic and biological. In RTD studies without biomass the hydraulic dead space in the PABR run in an‘every second’switching manner was the lowest while that in the PABR run in a T=∞switching manner was the highest. The same trend was obtained with the total dead space in RTD studies with biomass no matter what the OLR was. Biological dead space was the major contributor to dead space but affected decreasingly at higher OLR whichever switching manner the PABR run in. The flow patterns within the PABRs were intermediate between plug-flow and perfectly mixed under all the conditions tested.Results from denaturing gradient gel electrophoresis (DGGE) analysis of dynamic changes in microbial communities in PABR showed that microbial diversity and community structure were different between the compartments no matter which switching manner the PABR run in. Microbial community structure and dominant community amount in stable state at different OLR were temporally dynamic in one compartment. The trend of dynamic changes in microbial communities in each compartment accorded with the trend of alteration in performance of PABR. Under the same lifting of OLR, the difference in dynamic changes in microbial communities in each compartment depended on the difference in switching manner and frequency.