Inorganic nitrogen removal of toilet wastewater with an airlift external circulation membrane bioreactor

Removal of inorganic nitrogen （inorganic-N） from toilet wastewater, using a pilot-scale airlift external circulation membrane bioreactor （AEC-MBR） was studied. The results showed that the use of AEC-MBR with limited addition of alkaline reagents and volumetric loading rates of inorganic-N of 0.19-0.40 kg inorganic-N/（m^3·d） helped achieve the desired nitrification and denitrification. Furthermore, the effects of pH and dissolved oxygen （DO） on inorganic-N removal were examined. Under the condition of MLSS at 1.56-2.35 g/L, BODs/ammonia nitrogen （NH4＋-N） at 1.0, pH at 7.0-7.5, and DO at 1.0-2.0 mg/L, the removal efficiencies of NH4^＋-N and inorganic-N were 91.5% and 70.0%, respectively, in the AEC-MBR. The cost of addition of alkaline reagent was approximately 0.5-1.5 RMB yuan/m^3, and the energy consumption was approximately 0.72 kWh/m^3 at the flux of 8 L/（m^2-h）.

Experimental and Numerical Study of Gas-Liquid Flow in a Sectionalized External-Loop Airlift Reactor

The external loop airlift reactor(ELALR)is widely used for gasliquid reactions.It’s advantage of good heat and mass transfer rates compared to conventional bubble column reactors.In the case of fermentation application where a medium is highly viscous and coalescing in nature,internal in riser helps in the improvement of the interfacial area as well as in the reduction of liquidphase back mixing.The computational fluid dynamic(CFD)as a tool is used to design and scaleup of sectionalized external loop airlift reactor.The present work deals with computational fluid dynamics(CFD)techniques and experimental measurement of a gas holdup,liquid circulation velocity,liquid axial velocity,Sauter mean bubble diameter over a broad range of superficial gas velocity 0.0024≤UG≤0.0168 m s 1.The correlation has been made for bubble size distribution with specific power consumption for different plate configurations.The effects of an internal on different mass transfer models have been completed to assess their suitability.The predicted local mass transfer coefficient has been found higher in the sectionalized external loop airlift reactor than the conventional ELALR.

Effects of temperature,pH and O_(2) on the removal of hydrogen sulfide from biogas by external biological desulfurization in a full scale fixed-bed trickling bioreactor(FBTB)

Hydrogen sulfide(H_(2)S)is a critical component of biogas formed under anaerobic conditions by sulfur and sulfate reducing bacteria from animal manure and renewable energy crops.H_(2)S causes high corrosion in equipment,has a negative environmental impact,inhibits the biogas formation process and is furthermore odorous and toxic.Although several methods for internal and external desulfurization found their way into practice and had been explored at laboratory scale,no data were available on the performance of such methods in full scale practice,especially for an external fixed-bed trickling bioreactor(FBTB).The effects of temperature,pH and air ratio on H_(2)S removal efficiency(RE)were studied.The study was conducted at a research biogas plant with a given output of 96 m^(3) biogas per hour,and an H_(2)S concentration ranging between 500 ppm and 600 ppm(1 ppm=1 cm^(3)/m^(3))on average.The FBTB column has been designed to hold a packing volume of 2.21 m^(3) at a gas retention time of 84 seconds being loaded at an average of 32.88 g H_(2)S/(m^(3)·h).The highest H_(2)S RE of 98% was found at temperatures between 30℃ and 40℃.A major decline in RE to 21%-45%was observed at temperatures from 5℃ to 25℃.The results clearly showed a temperature optimum range for sulfate reducing bacteria.The results reveal that RE is little affected by different pH values and air ratios.During the experimental period,the practical suitability of the FBTB system could be proved while avoiding the disadvantages of internal biological desulfurization methods.

MBR/RO工艺处理垃圾渗滤液

采用外置式膜生物反应器(MBR)/反渗透(RO)工艺对成都长安垃圾填埋场的渗滤液进行处理,设计处理规模为1300m3/d,出水水质满足《生活垃圾填埋场污染控制标准》(GB16889—2008)中一般地区对渗滤液出水水质的要求。

厌氧膜生物反应器及其膜污染探析

厌氧膜生物反应器(anaerobic membrane bioreactor,An MBR)集厌氧生物技术和膜分离技术于一体,具有高负荷、低能耗、可回收沼气和高效截留等优点,在高浓度有机废水治理领域潜力巨大。然而,国内外关于An MBR的工程运行参数较为欠缺。此外,膜污染问题是阻碍该工艺应用推广的重要致因,故其一直是An MBR的研究热点。本文概述了An MBR的工艺特征以及An MBR的结构、组合方式及其特点,指出当前外置式应用较多,内置式因其特点也逐渐引起关注;综述了An MBR及其组合工艺在国内外的工程应用现状,指出该技术多在实验室阶段,且于工程化方面国内落后于国外;探析了膜污染机理及其影响因素(膜组件、污泥特性和操作条件等影响因素)关于膜污染的作用机制;并总结了一些控制膜污染的典型预防和控制措施,以期为相关研究应用提供参考。

气升循环分体式膜生物反应器再生回用厕所污水的研究

研究了分体浸没式膜生物反应器及其应用于厕所污水的再生回用 .试验结果表明 ,在入水浓度COD440～970mg/L、BOD53 0 7～ 61 2mg/L、NH3 N 5 9～ 1 1 1mg/L的情况下 ,出水水质稳定 ,平均COD <47mg/L、BOD5<8 5mg/L、NH3 N <2 0mg/L ,处理水质达到建设部颁布的生活杂用水回用标准 .研究了动力学参数污泥负荷、容积负荷和HRT对出水COD的影响 ,确定本试验较佳的污泥负荷和容积负荷分别为 0 1kg/(kg·d)和 1kg/(m3·d) ,HRT为 7～ 8h .本文对污泥浓度。

气升循环分体式MBR的CFD模拟及优化

基于计算流体力学(CFD)方法,对气升循环分体式膜生物反应器(AL EC MBR)的关键结构参数与水力学参数的相关关系进行了模拟、优化和敏感性分析.研究结果表明,增加气液混合高度和曝气元件数量可提高混合液的混合程度及膜面流速、剪切力分布的均匀性,有利于膜污染控制;曝气器位置升高会使MBR流场分布的均匀性下降;混合液黏度的增加会降低混合液循环流速,但使膜组件中气液混合流的均匀度提高.在MBR膜组件中存在着混合液流速和剪切力分布中部区域高外部区域低的不均匀性,这种不均匀性是导致膜有效利用面积降低和水处理成本升高的重要流体力学因素.

气升式陶瓷膜-生物反应器渗透通量的实验研究

为了降低陶瓷膜-生物反应器的能耗、同时提高膜的渗透通量,本文将气升式外循环引入膜-生物反应器的设计。实验条件下,搭建了气升式陶瓷膜-生物反应器装置,研究了导气管直径、气升位置、气速、气体性质等循环条件对渗透通量的影响;并在相同条件下与液体不循环的过滤相比较,证明采用气升循环可以较大提高膜的渗透通量。

带内件外循环气升式生物反应器的气含率

在上升管与下降管直径之比为6.6、罐体高径比为2.9的带内件外循环气升式生物反应器内,以羧甲基纤维素钠水溶液为模拟介质,测定了反应器内气含率与操作参数的关系,用均匀设计考察了操作参数对气含率的影响程度,结果表明通风量是影响反应器气含率的最关键因素。

外置式植物纤维床反应器与膜分离联用的丙酸发酵工艺研究

开发了一种外置式植物纤维床反应器与膜分离联用的丙酸发酵装置,将外置式植物纤维床反应器与中空纤维膜组件相连接,即可实现丙酸的多批次稳定高效生产。实验结果表明,以Propionibacterium freudenreichii CCTCC M207015为生产菌株,葡萄糖做碳源,利用该装置发酵214h(5批次),批次平均丙酸浓度达50.77g·L-1,生产效率达1.19g·L-1·h-1,菌体干重最高达33.85g·L-1,丙酸对葡萄糖转化率和丙酸占总有机酸比例分别为50.77%、79.45%(w/w),均远优于游离细胞与膜分离联用的丙酸发酵装置。

一体化脱氮除磷反应器研究进展

叙述了一体化脱氮除磷反应器现状及新进展,对目前一体化脱氮除磷反应器存在的问题进行了分析。认为基于MBR反应器构型、高效脱氮除磷菌种应用及计算流体力学(CFD)优化设计的一体化脱氮除磷反应器是未来研究与开发应用的一个热点方向。一体化高效脱氮除磷反应器的创新发展与应用将为点源水污染控制、水源水质保护和污水资源化提供一种具有广阔应用前景关键实用技术,产生出良好环境效益及可观经济效益。

外循环气升式生物反应器中酯酶生产及应用

采用海藻酸钙凝胶包埋法固定根霉(Rhizopus sp.F-16)细胞,在外循环气升式生物反应器(工作体积为10L,高径比为2.9)中发酵生产酯酶.与游离细胞发酵相比,固定化细胞具有发酵时间短、产酶活力高等优点,其最适通气量为0.70m3/h,最适装液量为8.75L,发酵48h时酯酶活力达41.6U/g细胞.固定化细胞的适宜作用pH为8.0～9.0,适宜作用温度为45～50℃,其酸碱稳定性和热稳定性均比游离细胞明显增强.该固定化细胞可直接用于选择性水解外消旋乳酸乙酯生成D-乳酸,当底物的质量浓度为150g/L,反应时间为3h时乳酸乙酯的水解率达43.9%,D-乳酸的光学纯度达95.7%.固定化细胞性状稳定,可重复利用,连续降解6批乳酸乙酯的平均水解率为43.3%,D-乳酸的光学纯度平均为95.4%.

气升循环分体式MBR中H循环管水力学研究

以气升循环分体式MBR为研究对象,采用计算流体力学数值模拟方法,展开H循环管水力学条件优化研究.对H循环管的作用及H循环管管径大小的影响进行了模拟分析,并推导出H循环管循环流速U的计算公式.结果表明,H循环管对于气升循环分体式MBR具有必要性;膜单元与生物单元之间的循环流量随H循环管管径增大而增大,而当D/L(H循环管管径/膜池回流口长度)=22.2%时,H循环管平均循环流速最大,循环效率较高;推导得出H循环管内流速计算公式为:U=1/n R2/3(H0/l)(Qa1/v1A1-Qa2/v2A2[])1/2.本文研究结果可为MBR水力学研究与气升循环分体式MBR研究与应用提供科学依据和参考.

Biological Nutrient Removal in a Full Scale Anoxic/Anaerobic/Aerobic/ Pre-anoxic-MBR Plant for Low C/N Ratio Municipal Wastewater Treatment

A novel full scale modified A2O （anoxic/anaerobic/aerobic/pre-anoxic）-membrane bioreactor （MBR） plant combined with the step feed strategy was operated to improve the biological nutrient removal （BNR） from low C/N ratio municipal wastewater in Southern China. Transformation of organic carbon, nitrogen and phosphorus, and membrane fouling were investigated. Experimental results for over four months demonstrated good efficiencies for chemical oxygen demand （COD） and NH4^＋-N removal, with average values higher than 84.5%and 98.1%, re-spectively. A relatively higher total nitrogen （TN） removal efficiency （52.1%） was also obtained at low C/N ratio of 3.82, contributed by the configuration modification （anoxic zone before anaerobic zone） and the step feed with a distribution ratio of 1：1. Addition of sodium acetate into the anoxic zone as the external carbon source, with a theoretical amount of 31.3 mg COD per liter in influent, enhanced denitrification and the TN removal efficiency in-creased to 74.9%. Moreover, the total phosphate （TP） removal efficiency increased by 18.0%. It is suggested that the external carbon source is needed to improve the BNR performance in treating low C/N ratio municipal waste-water in the modified A^2O-MBR process.

内、外置式MBR处理垃圾渗沥液的性能比较

根据内置式和外置式MBR在处理垃圾渗沥液中的工艺性能比较,通过实验表明:外置式MBR进水污泥浓度高,膜通量大,所需生化池容积小,膜的使用寿命长,易清洗维护,不易堵塞,运行稳定。并以蚌埠市垃圾填埋场渗沥液处理站工艺为例,证明了其应用外置式MBR对主要污染物质的去除率均达到了95%以上。

米糠纤维床反应器固定化发酵产丁酸的研究

将米糠作为固定化载体,构建了一种新型的外置式纤维床反应器,应用于固定化发酵产丁酸实验。以酪丁酸梭菌为发酵菌株,进行了游离细胞和固定化细胞发酵比较。结果表明:固定化细胞分批发酵丁酸生产率为0.48 g/L/h,比游离分批发酵提高了55%。进行了重复分批发酵,8个批次的丁酸浓度平均值为21.05 g/L,可以稳定多批次运行。在发酵条件一致的情况下,进行了米糠对丁酸钠的吸附模拟实验,米糠对丁酸钠的平衡吸附量可达0.084 g/g。固定化发酵后的米糠会吸附产物丁酸钠,吸附量为0.105 g/g,这有利于将反应后的米糠直接用来生产含丁酸钠的饲料添加剂。

外置式生物反应器对水库原水中总氮去除的试验

利用外置式生物反应器系统对水库Ⅰ中水的原位总氮控制开展了试验研究。结果表明,在适宜的水温下,系统稳定运行20 d后,水库中TN浓度由起始的1.93 mg/L降至0.89 mg/L,TN去除率达53.9%,水质由地表Ⅴ类水标准迅速提升至Ⅲ类水标准,TN降解效果好,时间短。台风后,系统TN去除效果恶化的内外部主要原因调查分析表明,水库库底排水破坏了水库水体的自然分层,导致脱氮环境恶化,降雨地表径流对水库TN也有一定输入,同时底部排水带走了部分反硝化菌,且低温时水库中微生物活性有所降低。该水库属于单季完全或不完全混合型,水质完全混合期不利于TN的控制。底泥的扰动能够改善脱氮环境但对TN控制不利。实际运行中应尽量避免或调整以上不利因素以确保TN去除效果。

MBR工艺处理垃圾渗滤液——以河源市七寨生活垃圾卫生填埋场工程为例

采用外置式膜生物反应器(MBR)工艺对河源市七寨生活垃圾卫生填埋场的渗滤液进行处理,设计处理规模为300 m3/d,出水水质满足《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级A标准和《生活垃圾填埋场污染控制标准》(GB 16889-2008)中一般地区渗滤液出水标准较严者的要求。

气升式外循环流化床生物反应器中成药废水处理研究

以中成药废水厌氧出水为处理对象,以传统内循环好氧流化床(反应器II)反应器做参比,对比研究了具有自主知识产权的气升式外循环流化床生物反应器(反应器I)的运行性能;并通过对反应器I投加悬浮填料,分析挂膜运行对反应器I性能强化的可能性。实验结果表明,经过60 d启动,稳定运行阶段反应器I出水COD和TN、NH4+-N的质量浓度及分别为99.8 mg/L和11.7、9.7 mg/L,去除率分别为85.6%、86.6%、87.6%,优于反应器II,可达到GB 21906-2008的要求;挂膜运行可强化反应器I运行性能,添加悬浮填料后,反应器I的出水COD和TN、NH_4^+-N的质量浓度及优于稳定运行期达14.2 mg/L和1.6、0.8 mg/L,去除率分别为8%、5.6%、5.4%。可为其后续工程化应用奠定基础。

预处理-高负荷生化反应器-外置式膜生化反应器处理垃圾中转站渗滤液的研究

采用预处理-高负荷生化反应器-外置式膜生化反应器(MBR)的组合工艺处理垃圾中转站的渗滤液。研究结果表明,利用该组合工艺处理渗滤液后,COD和BOD去除率都超过95%;出水氨氮、总氮浓度分别低于30 mg/L和50 mg/L;SS去除率超过98%,其浓度由1500 mg/L降低至20 mg/L;最后经过外置式超滤的出水水质即可达标排放。