Zeolite powder addition to improve the performance of submerged gravitation-filtration membrane bioreactor

In this study, the effect of zeolite powder addition on submerged membrane bioreactor （SMBR） on membrane permeability, and the removals for COD, NH3-N, TN were investigated. Through the parallel operation of control and test systems, it was found that the zeolite powder addition could alleviate the ultra-filtration membrane fouling and enhance the membrane permeability. On the basis of experimental investigations, a concept of ＂protection coating layer＂ was proposed to illustrate the phenomenon of UF membrane fouling. In addition, the removal for COD in test system was more stable, a little higher compared to the control system. Due to the combination of nitrification and ion exchange, a more excellent removal for NH3-N in test system was obtained regardless of influent NH3-N loading rate. It was also found that a mean 25% higher TN removal took place in the test system, and ion exchange and simultaneous nitrification and de-nitrification were analyzed to be main factors. During the stable operation period, the SOURs of test zeolite powder added sludge and control activated sludge were measured to be 75 mgO2/（gMLVSS, h） and 24 mgO2/（gMLVSS, h） respectively, it meant that the zeolite powder addition could enhance the microorganism activity significantly.

Bacterial diversity in activated sludge from a consecutively aerated submerged membrane bioreactor treating domestic wastewater

The bacterial diversity of activated sludge from submerged membrane bioreactor (SMBR) was investigated. A 16S rDNA clone library was generated, and 150 clones were screened using restriction fragment length polymorphism (RFLP). Of the screened clones, almost full-length 16S rDNA sequences of 64 clones were sequenced. Phylogenetic tree was constructed with a database containing clone sequences from this study and bacterial rDNA sequences from NCBI for identification purposes. The 90.6% of the clones were a?l...

One-step Continuous Phenol Synthesis Technology via Selective Hydroxylation of Benzene over Ultrafine TS-1 in a Submerged Ceramic Membrane Reactor

A new route towards phenol production by one-step selective hydroxylation of benzene with hydrogen peroxide over ultrafine titanium silicalites-1(TS-1) in a submerged ceramic membrane reactor was developed, which can maintain the in situ removal of ultrafine catalyst particles from the reaction slurry and keep the process continuous.The effects of key operating parameters on the benzene conversion and phenol selectivity, as well as the membrane filtration resistance were examined by single factor experiments. A continuous reaction process was carried out under the obtained optimum operation conditions. Results showed that the system can be continuously and stably operated over 20 h, and the benzene conversion and phenol selectivity kept at about 4% and 91%, respectively. The ceramic membrane exhibits excellent thermal and chemical stability in the continuous reaction process.

Model Study on a Submerged Catalysis/Membrane Filtration System for Phenol Hydroxylation Catalyzed by TS-1

This ranearch is focused on the, develonment of a simnle design model of the submerged catalysis/membrane filtration （catalysis/MF） system for phenol hydroxylation over TS-1 based on the material balance of the phenol under steady state and the reported kinetic studies. Based on the developed model, the theoretical phenol Conversions at steady state could be calculated using the kinetic parameters obtained from the previous batch experiments. The theoretical conversions are in good agreement with the experimental data obtained in the submerged catalysis/MF system within relative error of ±5%. The model can be used to determine the optimal experimental conditions to carry out the phenol hydroxylation over TS-1 in the submerged catalysis/MF system.

Enhancement of the flux for polypropylene hollow fiber membrane in a submerged membrane-bioreactor by surface modification

To improve its limiting flux and antifouling characteristics in a submerged membrane-bioreactor （SMBR） for wastewater treatment, polypropylene hollow fiber microporous membrane （PPHFMM） was surface-modified by the plasma-induced immobilization of poly （N-vinyl-2-pyrrolidone） （PVP） and the plasma treatment with different gases respectively. Attenuated total reflection-Fourier transform infrared spectroscopy （FT-IR/ATR）, X-ray photoelectron spectroscopy （XPS） and field emission scanning electron microscope （FE-SEM） were used to characterize the structural and morphological changes on the membrane surface. Water contact angle was measured by the sessile drop method. It was found that the water contact angle was 128.8, 72.3, 62.7, 74.4, 79.1, 86.3, and 71.3° for the nascent, PVP-immobilized, air, 02, Ar, CO2 and H2O plasma treated PPHFMM, respectively. The SMBR was operated at fixed transmembrane pressure to determine the limiting flux for the PPHFMM before and after surface modification. Results showed that the limiting flux appeared to be 103, 159, 117, 133, 136, 121 and 152 L/（m^2· h） for the nascent, PVP-immobilized, air, O2, At, CO2 and H2O plasma treated PPHFMM, respectively. After continuous operation for about 50 h in the SMBR, the antifouling characteristics were improved to some extent.

Rgwo performances of submerged membrane bioreactor treating brewery wastewater: A laboratory study

Performances of submerged membrane bioreactor （SMBR） treating brewery wastewater were investigated in this study. With little variation of COD：TN：TP ratio （100：5：1） in influent, SMBR showed high removal efficiency （ 〉 90% ） for both COD and NH4^＋ - N, and it also showed a strong resistive ability for shock organics loading rate, evidenced by no obvious fluctuation for COD in the effluent when the organics loading rate suddenly increased from 0. 27 g/（ gMLSS · d） to 0. 54 g/（ gMLSS · d）. Comparatively different with the COD removal, TN and TP removal showed a strong correlation with the growth stage of the sludge in SMBR. When the sludge was in the multiplication stage, about 45% of TN was removed and an average removal efficiency of 30% for TP was also observed. However, when the activated sludge was in the steady stage, the removal efficiency for TN decreased to about 30% , whereas, the removal efficiency for TP was very low, and sometimes even below zero. The results of GC/MS indicated that the residual organic matters in the effluent were mainly alkyl hydrocarbon with high molecular weight, and coupling with the results of electroseopic scanning, it is speculated that biomass formed at external and internal membrane fibers played an important role for the removal of small organics.

Treatment of Chinese traditional medicine wastewater in a submerged membrane bioreactor

A pilot scale test was conducted in a submerged membrane bioreactor SMBR with capacity of 10. 0 m^3/d for 120 days to treat high-strength Chinese traditional medicine wastewater. Performance of the SMBR was investigated with a sludge retention time （ TSR ） of 50 days, a hydraulic retention time （ THR ） of 8.0 h, membrane flux of 8. 0 IV（ m^2 · h） and dissolved oxygen （DO） concentration of 2. 0 - 3. 0 mg/L, respectively. It was observed that the SMBR had high capacity of COD and suspended solid （SS） removal. The influent COD concentration was fluctuated between I 000 and 5 000 mg/L, while the averaged effluent COl） concentration was only 44. 6 mg/L. The influent SS concentration was fluctuated between 1 000 and 1 600 mg/L, while little effluent SS was detected. It was found that the COD remove rate increased with mixed liquor suspended solids （MLSS） and organic loading rate （ROL）. In order to obtain good-quality effluent, the operational conditions of the SMBR were suggested as follows： the temperature was controlled above 10 ℃, MLSS about 7000 mg/L, R,L under 24. 76 kg/（ m^3 · d）, low vacuum value and constant water flux.

Submergence induced changes of molecular species in membrane lipids in Arabidopsis thaliana

The composition of membrane lipids is sensitive to environmental stresses.Submergence is a type of stress often encountered by plants.However,how the molecular species of membrane lipids respond to submergence has not yet been characterised.In this study,we used a lipidomic approach to profile the molecular species of membrane lipids in whole plants of Arabidopsis thaliana that were completely submerged for three days.The plants survived one day of submergence,after which,we found that the total membrane lipids were only subtly decreased,showing significant decreases of monogalactosyldiacylglycerol(MGDG)and phosphatidylcholine(PC)and an increase of phosphatidic acid(PA);however,the basic lipid composition was retained.In contrast,three days of submergence caused plants to die,and the membranes deteriorated via the rapid loss of 96% of lipid content together with a 229% increase in PA.The turnover of molecular species from PG and MGDG to PA indicated that submergenceinduced lipid changes occurred through PA-mediated degradation.In addition,molecular species of extraplastidic PG degraded sooner than plastidic ones,lyso-phospholipids exhibited various patterns of change,and the double-bond index(DBI)remained unchanged until membrane deterioration.Our results revealed the unique changes of membrane lipids upon submergence and suggested that the major cause of the massive lipid degradation could be anoxia.

Feasibility and simulation model of a pilot scale membrane bioreactor for wastewater treatment and reuse from Chinese traditional medicine

The lack and pollution of water resource make wastewater reuse necessary. The pilot scale long-term tests for submerged membrane bioreactor were conducted to treat the effluents of anaerobic or aerobic treatment process for the high-strength Chinese traditional medicine wastewater. This article was focused on the feasibility of the wastewater treatment and reuse at shorter hydraulic retention time （HRT） of 5.0, 3.2 and 2.13 h. MLSS growth, membrane flux, vacuum values and chemical cleaning periods were also investigated. The experimental results of treating two-phase anaerobic treatment effluent demonstrated that the CODfilt was less than 100 mg/L when the influent COD was between 500-10000 mg/L at HRT of 5.0 h, which could satisfy the normal discharged standard in China. The experimental results to treat cross flow aerobic reactor effluent demonstrated that the average value of CODfilt was 17.28 mg/L when the average value of influent COD was 192.84 mg/L at HRT of 2.13 h during 106 d, which could completely meet the normal standard for water reuse. The maximum MLSS and MLVSS reached 24000 and 14500 mg/L at HRT of 3.2 h respectively. Membrane flux had maximal resume degrees of 94.7% at vacuum value of 0.02 MPa after cleaning. Chemical cleaning periods of membrane module were 150 d. A simulation model of operational parameters was also established based on the theory of back propagation neural network and linear regression of traditional mathematical model. The simulation model showed that the optimum operational parameters were suggested as follows： HRT was 5.0 h, SRT was 100 d, the range of COD loading rate was between 10.664-20.451 kg/（m3.d）, the range of MLSS was between 7543-13694 mg/L.

Application of Submerged Ultrafiltration in Pretreatment of Flue Gas Desulfurization Wastewater

Nowadays,the zero liquid discharge of flue gas desulfurization(FGD)wastewater from coal-fired units has attracted the attention of all countries in the world.The pretreatment methods generally have the problems of high operation cost,small treatment capacity,and poor flexibility.However,the membrane method can avoid the above problems.In the current research,it has not been found that someone directly uses submerged ultrafiltration to pretreat FGD wastewater.Therefore,this paper innovatively proposed to directly use ceramic ultrafiltration membrane to treat FGD wastewater,which can ensure effluent quality and improve the flexibility of the pretreatment system.In this paper,the performance of submerged ultrafiltration membrane for the filtration of FGD wastewater from a power plant was studied to optimize the filtration performance and improve the effluent quality.The effects of operating parameters such as membrane permeate flux,aeration rate and filtration/backwashing time combination on the membrane performance were studied.The results showed that when the filtration/backwashing time combination was 15 min/30 s,with the increased in permeate flux from 55 L/(m2·h)to 100 L/(m2·h),the steady transmembrane pressure(TMP)increased from 39 kPa to 70 kPa,and the fouling rate increased significantly from 4.5 kPa/h to 7.3 kPa/h;When the aeration rate increased from 10 m3/(m2·h)to 30 m3/(m2·h),the membrane pollution was much reduced.Excessive aeration rate cannot further alleviate the membrane pollution,but also brought greater energy consumption;Increasing backwashing time can effectively inhibit the formation of gel layer on the surface of the membrane and prolong the initial stage of low-pressure operation;The rejection of suspended solids(SS)and turbidity of the equipment studied in this paper can reach more than 99%under various working conditions,which can satisfy the water quality requirements of the subsequent steps.The submerged ultrafiltration membrane was suitable for the pretreatment of FGD wastewater because it can ensure the quality of permeate under the premise of long-term operation.

浸没式超滤膜在大型给水厂的应用与思考

浙江省某地两个大型水厂(J水厂和T水厂)的生产规模分别为2.0×10^(5)m^(3)/d和5.0×10^(5)m^(3)/d,其运行时间分别为2年和7年,均采用浸没式超滤膜为核心净水工艺。文章结合两个水厂的实际运行情况,研究和总结了两个水厂的运行管理经验,得到如下结论:膜运行方面,两水厂膜进水浑浊度日常在0.15~4.25 NTU,台风季偶有短时13.6~35.2 NTU的情况下,膜出水浑浊度一直稳定在0.1 NTU以下,2μm以上的颗粒数偶有检出;膜污染控制方面,物理清洗时两水厂均在产水中间阶段进行一次气冲清洗,可有效缓解膜污染;化学清洗时发现J水厂仅采用柠檬酸清洗效果好,T水厂采用先次氯酸钠、后柠檬酸清洗效果好;水厂设计方面,J水厂泵吸式产水整体能耗高达27 kW·h/km^(3),T水厂虹吸式产水最低能耗仅为13 kW·h/km^(3),有效降低了能耗;运行管理方面,扩大清水池容积可有效解决因清水池调蓄能力不足导致的超滤膜长时间超负荷运行的问题;同时在膜池的进水管上增设膜前加氯点,保证出水余氯质量浓度稳定在0.2 mg/L左右可有效解决藻类滋生问题。

改良Bardenpho+浸没式超滤工艺在污水处理厂的应用

华中地区某市政污水处理厂已建一、二期工程设计规模为20万m^(3)/d,出水执行《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A标准。本次三期扩建工程设计规模为20万m^(3)/d,是国内首个采用“改良Bardenpho+浸没式超滤膜”工艺的大型市政污水处理厂。2022年1月—12月,出水各项指标稳定达到一级A标准。其中,BOD_(5)、COD_(Cr)、氨氮概率值为100%、99.7%、91.7%,达到《地表水环境质量标准》(GB 3838—2002)中Ⅲ类标准,TP稳定达到地表水Ⅳ类标准。该组合工艺结合了生化处理系统和膜处理系统两者的优点,抗冲击负荷能力强、占地面积小。在用地面积很紧张、尾水提标和再生水回用需求进一步提高的大趋势下,该组合工艺因具备实现更高、更稳定的出水能力,从而在新、改、扩建市政污水处理厂中具有广阔的运用前景。

非浸没式超滤技术净化处理煤矿矿井水的试验研究

采用非浸没式超滤(NSUF)技术净化处理煤矿矿井水,从NSUF陶瓷膜的操作参数与性能、膜污染清除、超滤浓水加药絮凝以及污泥压滤脱水性能等方面进行了现场试验研究。控制超滤产水率在70%条件下,NSUF“膜面流”操作方式与在线物理清洗相结合,可以清除滤层堵塞和膜污染,使膜通量与跨膜压差得到恢复,NSUF装置实现连续稳定运行。超滤浓缩产生的30%浓水在添加PAC和PAM后,沉降比达到4.3%,澄清液返回到超滤单元。絮凝污泥通过板框压滤进行脱水处理,滤饼含水率约75%。采用三级NSUF—絮凝沉淀—污泥压滤组合工艺,系统总产水率可以达到98%。

浸没式超滤膜在某中华鲟大型科普展示水体维生系统中的工程应用

采用上向流活性炭、浸没式超滤膜以及砂滤组合工艺,循环处理某大型中华鲟展示水体。展示总水体量为10 000 m^(3),设计水体循环周期为1.5 h/次,维生系统处理规模为1.6×10^(5)m^(3)/d。经维生系统处理后,出水浊度可稳定小于0.1 NTU以下,确保科普展示的水体清澈、透明,展示效果良好,为膜技术在养殖废水处理中的应用提供工程案例支持。

碳化硅陶瓷膜在MTO化工污水回用应用的试验研究

本试验采用浸没式超滤工艺研究了碳化硅陶瓷膜对某化工厂MTO化工污水和清净废水过滤的工艺特性和效果,分析了不同水质来源对膜通量的影响以及不同膜通量下跨膜压差(TMP)、产水水质的变化关系,为同类污水回用项目的建设提供了设计参考。

华北地区水源置换某地表水厂工程的设计浅析

在地下水压采和水源置换的背景下,开展华北地区某地表水厂工程建设工作,探讨短流程、紧凑型水厂建设形式的设计要点。该地表水厂主要服务于周边的工业园区及居住区,设计规模为5.0×10^(4)m^(3)/d,自用水系数5%。净水厂出厂水水质符合《生活饮用水卫生标准》的要求,主体工艺采用机械混合絮凝—斜管沉淀池—浸没式超滤工艺,对设计水质下的工艺设计参数进行了分析探讨。本工程对水库水低温低浊、微污染等季节性水质变化均有很好的适用性,抗冲击负荷能力强,水质保障率高。

Removal of nitric oxide from simulated flue gas via denitrification in a hollow-fiber membrane bioreactor

A hollow-fiber membrane bioreactor （HMBR） was studied for its ability to treat nitric oxide （NO） from simulated flue gas. The HMBR was operated for 9 months and showed a maximum elimination capacity of 702 mg NO/（m2.day） with a removal efficiency of 86% （gas residence time of 30 sec, inlet NO concentration of 2680 mg/m^3, pH 8）. Varying operation parameters were tested to determine the stability and response of the HMBR. Both the inlet NO concentration and gas residence time influenced the removal of NO in the HMBR. NO elimination capacity increased with an increase in inlet NO concentration or a shortening of gas residence time. Higher removal efficiency of NO was obtained at a longer gas residence time or a lower inlet NO concentration. Microbial communities of the HMBR were sensitive to the variation in pH value and alkalescence corresponding to an optimum pH value of 8. In addition, NO elimination capacity and removal efficiency were inversely proportional to the inlet oxygen concentration. Sulfur dioxide had no great influence on elimination capacity and removal efficiency of NO. Product analysis was performed to study N20 and N2 production and confirmed that the majority of the microorganisms were denitrifying bacteria in the HMBR. Compared to other bioreactors treating NO, this study showed that the denitrifying HMBR was a good option for the removal of NO.

Effect of Intermittent Aeration on the Treatment Performance in a Submerged Membrane Bioreactor

In order to improve removal for nitrogen in a pilot-scale submerged membrane bioreactor（SMBR）,intermittent aeration was conducted,and the effect on the treatment performance under four kinds of operation condition（run 1,continuous aeration;run 2,60/60 min aeration on/off time;run 3,60/90 min aeration on/off time;run 4,60/75 min aeration on/off time） was evaluated.The results showed that depending on the specific on/off of the aeration time ratio,removal efficiency of nitrogen could be improved significantly,and the removal rates of total nitrogen（TN） under different operation conditions were 28.0%,59.5%,66.8% and 70.7%,respectively.There were no obvious differences for removal rates for CODCr and ammonia among different operation conditions.In general,intermittent aeration could be used as a feasible way to improve treatment performance for nitrogen in the SMBR.

Investigation on removal pathways of Di 2-ethyl hexyl phthalate from synthetic municipal wastewater using a submerged membrane bioreactor

Highly hydrophobic Di 2-ethyl hexyl phthalate（DEHP） is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25 days, it can be used as an efficiency indicator of wastewater treatment plant for the removal of hydrophobic emerging contaminants. In this study, the performance of submerged membrane bioreactor was monitored to understand the effect of DEHP on the growth of aerobic microorganisms. The data showed that the chemical oxygen demand（COD）and ammonia concentration were detected below 10 and 1.0 mg/L, respectively for operating conditions of hydraulic retention time（HRT） = 4 and 6 hr, sludge retention time（SRT） = 140 day and sludge concentration between 11.5 and 15.8 g volatile solid（VS）/L. The removal efficiency of DEHP under these conditions was higher and ranged between 91% and 98%. Results also showed that the removal efficiency of DEHP in biological treatment depended on the concentration of sludge, as adsorption is the main mechanism of its removal. For the submerged membrane bioreactor, the pore size is the pivotal factor for DEHP removal, since it determines the amount of soluble microbial products coming out of the process. Highly assimilated microorganisms increase the biodegradation rate, as 74% of inlet DEHP was biodegraded; however, the concentration of DEHP inside sludge was beyond the discharge limit. Understanding the fate of DEHP in membrane bioreactor,which is one of the most promising and futuristic treatment process could provide replacement for conventional processes to satisfy the future stricter regulations on emerging contaminants.