A pilot scale anoxic/oxic membrane bioreactor(A/O MBR) for woolen mill dyeing wastewater treatment

A pilot scale(10 m 3/d) anoxic/oxic membrane bioreactor(A/O MBR) was tested for dyeing wastewater treatment of woolen mill without wasting sludge in 125 days operation. Results showed that the effluent quality was excellent, i.e. effluent COD less than 25 mg/L, BOD 5 under 5 mg/L, turbidity lower than 0 65 NTU, and colour less than 30 DT, and met with the reuse water standard of China. The removal rates of COD, BOD 5, colour, and turbidity were 92 4%, 98 4%, 74% and 98 9%, respectively. Constant flux operation mode was carried out in this study, and backwash was effective for reducing membrane fouling and maintaining constant flux. Membrane fouling had heavy impact on energy consumption. More attention should be paid on pipe selection and design for the sidestream MBR system, too.

Simultaneous nitrogen and phosphor removal in an aerobic submerged membrane bioreactor

Simultaneous nitrification and denitrification （SND） effect and phosphor removal were investigated in a one-staged aerobic submerged membrane bioreactor on pilot-scale with mixed liquor suspended solids （MLSS） 19--20 g/L. The effects of DO concentration, sludge floc size distribution on SND were studied. Test results suggested that SND was successfully performed in the membrane bioreactor （MBR） and about 70% total nitrogen removal efficiency was achieved when DO concentration was set to 0.2-- 0.3 mg/L. The main mechanisms governing SND were the suitable sludge floc size and the low DO concentration which was caused by low oxygen transfer rate with such a high MLSS concentration in the MBR. In the meantime, phosphor removal was also studied with polymer ferric sulfate （PFS） addition and 14 mg/L dosage of PFS was proper for the MBR to remove phosphor. PFS addition also benefited the MBR operation owing to its reduction of extracellular polymer substances （EPS） of mixed liquor.

Improvement of antifouling characteristics in a bioreactor of polypropylene microporous membrane by the adsorption of Tween 20

Surface modification by physical adsorption of Tween 20 was accomplished on polypropylene microporous membranes （PPMMs）. Attenuated total reflection-Fourier transform infrared spectroscopy （ATR/FT-IR） and field emission scanning electron microscope （FE- SEM） were used to characterize the chemical and morphological changes on the membrane surfaces. Water contact angles and relative pure water fluxes were measured. The data showed that the hydrophilic performance for the modified membranes increased with the increase in the adsorption amount of Tween 20 onto the surface or into the pores of polypropylene microporous membranes. To test the antifouling property of the membranes by the adsorption of Tween 20 in a membrane bioreactor （MBR）, filtration for active sludge was performed using synthetic wastewater. With the help of the data of water fluxes and the FE-SEM photos of the modified PPMMs before or after operating in a MBR for about 12 d, the PPMMs with monolayer adsorption of Tween 20 showed higher remained flux and stronger antifouling ability than unmodified membrane and other modification membranes studied.

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）.

Removal of Di-2-Ethyl Hexyl Phthalates by Membrane Bioreactor

A lab scale membrane bioreactor system was built to investigate the removal of Di-2-Ethyl Hexyl Phthalates (DEHP) in wastewater under variation of three runs: two hydraulic retention time (HRT) 24 and 36 hours in addition to two biomass: concentrated and light sludge. Solid phase extraction (SPE) followed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) was applied to quantitatively identify DEHP in wastewater samples. Membrane bioreactor was built and operated to investigate DEHP removal. Higher HRT removed DEHP more efficiently than lower HRT. The concentrated MLSS could achieve higher removal efficiency than the lighter MLSS at the same HRT value. The performance of MBR in removing DEHP, TOC and COD from wastewater with a maximum removal efficiency were 29%, 85%, and 98%, respectively. Mass balance of DEHP in the system indicated that a majority was removed by adsorption process rather than filtration or microbiological process.

Effect of components in activated sludge liquor on membranefouling in a submerged membrane bioreactor

By a membrane bioreactor with a settle tank in long-term operation and batch experiments, the effects of floes, soluble microorganism products （SMPs） and metal ions in activated sludge liquor on membrane fouling were investigated. The results showed that foulants absorbed each other and formed a fouling layer as a ＂second membrane＂ influencing the permeability of the membrane. The ＂gel layer＂ caused by SMPs and ＂cake layer＂ by floes showed great differences in morphology by analysis of scanning electron microscope and atomic force microscope. The ＂gel layer＂ was more compact and of poor permeability. When the membrane flux was 40 L/（m^2·h）, the rate of membrane fouling caused by supernatant （0.011 MPa/h） was greater than that by sludgc liquor （0.0063 MPa/h）. SMPs played very important roles on membrane fouling. In the bulking sludge, with SMPs increasing, the rate of membrane fouling （0.0132 MPa/h） was faster. While after flocculation of the SMPs, the rate of fouling decreased to 0.0034 M Pa/h. Floes could keep holes in their overlaps. They could alleviate membrane fouling by preventing the SMPs directly attaching on membrane surface.

Start-up and contaminants removal characteristics of aerobic granules-membrane bioreactor at low temperature

In order to understand the effect of low temperature on the formation process of aerobic granules and contaminants removal characteristics,the aerobic granules-membrane bioreactor (AGS-MBR) has been started up and operated at low temperature using the carbon resource of sodium acetate. Aerobic granules cultivated in AGS-MBR possess smooth surface and compact structure in morphology as well as better settling property and higher biomass after 38 days. The average parameters of aerobic granules are: diameter 3. 1 mm,wet density 1. 041 g/mL,sludge volume index 42. 35 mL/g and settling velocity 20. 6 - 45. 2 cm/min. During the start-up of AGS-MBR,the respectively average contaminants removal efficiencies at low temperature are 91. 9% for chemical oxygen demand (COD) ,89. 2% for NH4 + -N and 86. 3% for PO43- -P,and the overgrowth of filamentous bacteria has been well controlled. In addition,the hollow fiber microfiltration (MF) membrane fouling is light and the regime membrane layer is capable of enhancing membrane filtration as well as the average growth of trans-membrane pressure (TMP) is 1. 07 kPa/d. Compared with the conventional cultivation of aerobic granules,the sludge granulation time significantly decreases from 73 days to 38 days by the application of microfiltration membrane at low temperature.

Diatomite Precoated Nonwoven Membrane Bioreactor for Domestic Wastewater Reclamation

Nonwoven was selected as filtration materials in submerged membrane bioreactor( MBR) for domestic wastewater reclamation. For its hydrophobic membrane surface,diatomite was precoated on nonwoven to improve membrane hydrophilicity. In the precoating stage,diatomite dynamic membrane could be formed on10 μm polyethylene nonwoven surface efficiently and effluent turbidity could be below 5 nephelometric turbidity units( NTU).The MBR system was operated steadily under gravity flow and scanning electron microscope( SEM) analysis showed that nonwoven membrane was only partially fouled at the membrane flux of 5 L/( m2·h). Average removal efficiencies of chemical oxygen demand( COD) and NH +4-N were above 86 % and 50 %,respectively. The effluent turbidity and chromaticity were below 5 NTU and 25°,respectively. Those results could meet the requirements for wastewater reuse.

Fouling Characteristics and Prevention Techniques for Membrane Bioreactor

Membrane fouling is the main problem of membrane bioreactors (MBR), which seriously influ- ences its wastewater treatment effect and running. The characteristics of microbiology and hydrodynamics concerning membrane fouling were investigated and the measure was put forward for optimum operation of MBR. The measure is that 1) the parameters of activated sludge concentration (X) and membrane flux should be lower than the critical values of X and membrane flux respectively, and 2) the activated sludge should be discharged periodically. The experimental results show that the combination backwashing of gas and perme- ated effluent is better than single gas backwashing or single permeated effluent backwashing. This technique can remove the cake layer deposited on the membrane surface, decrease the membrane fouling, and recover the membrane flux effectively. So it is effective for prevention of membrane fouling.

Sludge ozonation and its effect on performance of submerged membrane bio-reactor

To investigate the effects of ozonation on minimizing the excess sludge and enhancing the nitrogen removal in an effluent,batch and continuous experiments in two MBRs with and without sludge ozonation (namely combined and reference run) were carried out. Through ozonation at a dose of 0.16 mg O3/mg MLVSS,53.1% of the treated MLVSS was solubilized,and soluble SCOD/TN ratio of ozonized sludge (OS) was about 8.6 due to the release of cellular nitrogen-contained materials and SCOD loss by ozone mineralization. In addition,the results of batch nitrification and denitrification tests with OS supernatant indicated that solubilized sludge could act as a reducing power for denitrification and a nitrogen source for nitrification. 40-day operation of two MBR systems demonstrated that the recirculation of OS into a bioreactor enabled the combined system have two advantages over the control one. The observed sludge yield (Yobs) was decreased from 0.13 to 0.06g MLSS/g COD,while the nitrogen removal was increased from 64.6% to 72.3%. And sludge ozonation elevated the inorganic fraction of MLSS,but did not impact sludge activities.

间歇性投加Fe(Ⅱ)控制陶瓷膜MBR膜污染的机理分析

以陶瓷膜膜生物反应器(MBR)为研究对象,考察了间歇性投加Fe(Ⅱ)对合成废水中营养物质的去除效果,并分析了膜污染的控制机理。当n_(Fe)∶n_(P)为2时,TP、TOC和TN的去除率最高,分别为99.2%、97.5%和87.2%,出水达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)中一级A标准;当nFe∶nP为1和2时,出水Fe浓度分别为0.14μmol/L和0.16μmol/L(达到中水回用标准),膜过滤时间由12 d分别延长至92 d和41 d(跨膜压差30 kPa)。间歇性投加Fe(Ⅱ)可增大污泥粒径及减少污泥混合液中有机物含量,从而提高体系的过滤性能,有效降低膜污染阻力并缓解膜污染;n_(Fe)∶n_(P)为1时,含Fe不可逆污染层的阻力较小,膜污染控制效果最好。

PAC更新率对PAC-MBR耦合处理效能及污泥特性的影响

粉末活性炭(PAC)的定期回收和补充是混合膜生物反应器(PAC-MBR)稳定运行所必需的。研究探索了不同PAC更新率对PAC-MBR中污泥过滤特性和微生物群落的影响,创新性地提出通过PAC更新来提高微生物活性,以达到提高出水效能并减缓膜污染的效果。结果表明:PAC更新对CODCr和氮的去除没有显著影响;随着PAC更新率的增加,可溶性微生物产物逐渐降低,胞外聚合物浓度逐渐增加。PAC的更新能够降低MBR系统膜污染,同时提高过滤效率。微生物活性与PAC的更新率呈正相关规律。此外,由高通量测序可知由于添加新鲜的PAC,Proteobacteria(变形菌属)、Bacteroidetes(拟杆菌属)及Nitrospira(硝化螺旋菌属)的丰度增加,保证污染物的去除,同时Proteobacteria及Bacteroidetes造成的膜污染减少。最佳PAC更新率为1.67%,能够有效缓解膜污染并增强优势细菌结构。在推动PAC-MBR广泛应用方面,PAC更新被认为是一种有前景的方法。

生物载体缓解管式膜MBR工艺中的膜污染

膜污染一直是影响膜生物反应器(MBR)工艺稳定运行的难题。试验研究了浮球填料的加入对好氧管式膜MBR工艺中膜污染的影响规律及机理。结果表明,生物载体的加入能够显著减缓膜污染。与没有生物载体的MBR相比,载体填充率达到40%时可使滤饼层阻力下降约60.7%,孔堵阻力下降约90.6%,单周期运行时间延长约83.3%。机理分析表明,载体型MBR中悬浮污泥粒度明显增大,不可逆膜污染主要组分溶解性胞外聚合物(EPS)含量显著减少,而且EPS中蛋白质相对比例增加,滤饼层与膜面间的结合程度减弱,可改善低压冲洗和化学清洗效果。

氯/紫外工艺辅助MBR出水应急脱氮

氯/紫外(Cl/UV)工艺十分适合低有机物污水的应急脱氮处理。文中研究了Cl/UV工艺辅助膜生物反应器(MBR)脱氮的效果和影响因素,并研究确立了最佳工艺参数。结果表明,Cl/UV工艺可以在相同Cl/N下,实现比折点氯化更好的脱氮效果、更低的出水余氯含量。工艺进水的pH值在6.5~8.0对处理效果没有显著影响。当进水氨氮质量浓度<12 mg/L时,采用Cl/UV工艺比折点氯化更经济,此时可以通过文中公式计算最佳Cl/N。过高的进水COD_(Cr)(>50 mg/L)会导致所需Cl/N增加,且Cl/UV工艺对COD_(Cr)的去除效果不佳。Cl/UV工艺产生的消毒副产物主要为三氯甲烷、三氯乙烷、三氯乙醛和二氯乙腈,生成量随Cl/N的增大而增大,随初始氨氮浓度和UV强度的增大而下降。

MBR膜生物技术在生活污水处理中的运用探究

MBR膜生物技术是一种污水处理工艺,最早在欧洲的发达国家被投入使用。MBR膜生物反应器的原理与传统的二沉池工艺和深度处理过滤器原理极为相似,但比传统的处理工艺拥有较多优势,且出水水质优良,是一种非常有效的生活污水处理工艺。MBR膜生物反应器具有很高的安全性、稳定性、可靠性、精确性,发展的空间是非常可观的。

某污水处理厂MBR膜生物反应器工艺分析

在科学技术的发展下,MBR工艺作为应用于污水处理中的新工艺,其充分融合生物反应器以及膜过滤技术,尽可能保障污泥量。与传统工艺相比,在出水水质完全相同的状况下,MBR工艺具备更高的容积负荷,能够充分节约生化池占地。文章围绕某污水处理厂MBR膜生物反应器工艺进行探讨,首先介绍了工艺的基本概念和应用优势,然后具体对该工艺中重要的两个部分,即A/A/O生物反应池和MBR膜池的设计展开分析,希望为相关人员带来一些参考。

MBR在污水处理与回用工艺中的应用

MBR是将生物处理与膜分离技术相结合而成的一种高效污水处理新工艺。国内外MBR工艺在城市污水处理、中水回用、高浓度生活污水处理以及垃圾渗滤液处理等方面的应用实践经验表明 ,MBR工艺具有常规污水处理工艺无法比拟的优势 。

不同MBR反应器中硝化菌群落结构的研究

采用PCR-DGGE技术研究了正常运行工况下6个不同MBR反应器中的硝酸菌和反硝化菌的群落结构.结果表明,不同的MBR反应器好氧段中硝酸菌之间的相似性较高,相似性数值为78.7%～92.1%,但环境条件、进水水质及运行参数等因素的不同导致了不同MBR反应器硝酸菌群落的差异.MBR反应器中有5种硝酸菌和3种反硝化菌,其中优势硝酸菌种以α-变形细菌(Alpha proteobacteria)、生根瘤菌(Bradyrhizobium)、维氏硝酸菌(Nitrobacter winogradskyi)为主,反硝化菌以好氧反硝化菌-产碱杆菌属(Alcaligenes)、脱氮副球菌(Paracoccus denitrificans)、红球菌属(Rhodococcus)为主,说明反应器内同时存在好氧反硝化菌,推断MBR反应器内可能同时存在多种硝化和脱氮途径.

不同DO下MBR内微生物群落结构与运行效果关系

应用A/O-MBR处理实际生活污水,考察了不同溶解氧(DO)条件下,微生物群落结构与其处理效果的对应关系.结果表明,DO浓度在0.2～4.0mg/L对COD去除效果无明显影响,COD平均去除率均在90%以上.DO浓度变化对NH4+-N去除影响较大,DO浓度下降到0.2mg/L时,NH4+-N平均去除率由99%下降到65%.通过PCR-DGGE分析,较高DO条件下(4.0,2.0mg/L)的总细菌微生物群落多样性高于较低DO条件(0.5,0.2mg/L),但其群落结构变化与与反应器的处理效果对应关系不明显;氨氧化菌的群落结构变化较明显,且在不同的DO条件下起主要作用的氨氧化菌的菌属不同,其群落变化与反应器的NH4+-N去除效果相对应,DO为2.0,0.5mg/L时氨氧化菌群落结构比较相似,此时反应系统的脱氮效果也比较好.