食品工业废水处理中混合液悬浮固体浓度对膜生物反应器效率的影响研究

研究了在处理食品工业废水时,混合液悬浮固体的浓度(MLSS)对正在运行的膜生物反应器的影响。膜生物反应器主要由活性污泥和中空纤维微滤膜组成。两个实验过程分别在低MLSS浓度和高MLSS浓度情况下进行。由悬浮固体(99.95%)、浊度(NTU)(99.34%)和CODcr(95.4%)的去除率可知,低MLSS浓度的实验过程达到了更高的处理效果。用MBR处理食品工业废水,出水水质稳定。     

膜生物反应器处理油脂废水的研究

采用膜生物反应器对油脂废水进行强化处理.试验结果表明:膜生物反应器对油脂废水中的化学需氧量(COD)、油、总有机碳(TOC)、氨氮和生化需氧量(BOD5)的平均去除率分别为85.2％、93.8％、88.4％、51.3％和97.5％,相应的平均出水含量为233.6、310.1、95.7、3.9 mg/L和22.6 mg/L;氨氮和BOD5达到国家污水综合排放一级标准(GB 18918-2002).在考察膜通量对膜污染的潜势中发现,随着膜通量的提高,跨膜压差(TMP)增加的较快,通过将膜通量降低到8 LMH以下,TMP得以稳定,维持在2～6 kPa之间.     

Anaerobic fluidized bed membrane bioreactor for wastewater treatment

Anaerobic membrane bioreactors have potential for energy-efficient treatment of domestic and other wastewaters, membrane fouling being a major hurdle to application. It was found that fouling can be controlled if membranes are placed directly in contact with the granular activated carbon (GAC) in an anaerobic fluidized bed bioreactor (AFMBR) used here for post-treatment of effluent from another anaerobic reactor treating dilute wastewater. A 120-d continuous-feed evaluation was conducted using this two-stage anaerobic treatment system operated at 35 °C and fed a synthetic wastewater with chemical oxygen demand (COD) averaging 513 mg/L. The first-stage was a similar fluidized-bed bioreactor without membranes (AFBR), operated at 2.0-2.8 h hydraulic retention time (HRT), and was followed by the above AFMBR, operating at 2.2 h HRT. Successful membrane cleaning was practiced twice. After the second cleaning and membrane flux set at 10 L/m(2)/h, transmembrane pressure increased linearly from 0.075 to only 0.1 bar during the final 40 d of operation. COD removals were 88% and 87% in the respective reactors and 99% overall, with permeate COD of 7 ± 4 mg/L. Total energy required for fluidization for both reactors combined was 0.058 kWh/m(3), which could be satisfied by using only 30% of the gaseous methane energy produced. That of the AFMBR alone was 0.028 kWh/m(3), which is significantly less than reported for other submerged membrane bioreactors with gas sparging for fouling control.     

MBR工艺处理印染废水的研究进展

纺织是高能耗、高污染行业,印染废水对我国环境影响巨大.近几十年,众多学者对印染废水的处理技术进行了大量研究.其中,膜生物反应器(M B R)由于占地面积小、出水水质好、污泥浓度高、污泥产率低等被用作处理印染废水的首选工艺之一.梳理了MBR工艺处理印染废水的研究文献,总结亟需解决的难题.     

The effects of intermittent aeration on the characteristics of bio-cake layers in a membrane bioreactor

The effects of a sequencing variation for dissolved oxygen (DO) concentrations on the membrane permeability in a submerged membrane bioreactor (MBR) were studied. An MBR was continuously operated under alternating DO conditions, e.g., 36 h of an aerobic phase, followed by 36 h of an anoxic phase. The rate of increase in transmembrane pressure (TMP) in the anoxic phase was always steeper than that in the aerobic phase, indicating that the fouling rate was higher in the anoxic than in the aerobic condition. Regardless of the phases, the rate of TMP increase became steeper as the cycles were repeated. However, this trend became less important as the cycle numbers increased. Even in identical microbial communities, the number of colloidal particles and soluble extracellular polymeric substances (EPS) in the bulk solution were increased during the anoxic condition, which caused a reduction in the porosity of the bio-cake. During analysis of the bio-cake profile along the cake depth, the temporal variation of the bio-cake structure was attributed to the temporal change in the number of colloidal particles as well as the change in compression forces acting on the bio-cake. The influence of the latter was found to be more important than that of the former, which was verified by comparing the various structures of bio-cake formed in differing DO environments.     

印染废水膜生物反应器的设计及应用

对膜生物反应器处理印染废水工艺进行改进,采用水解酸化+膜生物反应器组合工艺,并在膜生物反应器中引入填料,设计了一套日处理量5 m3的印染废水处理设备,针对某印染厂废水连续运行3个月。结果显示,在设计运行条件下,COD基本保持在80 mg/L以下,COD去除率达95%左右;色度去除率可达90%左右;出水SS和浊度接近于0,pH值为7.0～8.5,主要指标符合《渭河水系(陕西段)污水综合排放标准》(DB 61-234—2006)一级标准。     

Characterization of cake layer in submerged membrane bioreactor

Cake layer formation on the membrane surface has been a major challenge in the operation of membrane bioreactors (MBRs). In this study, the cake layer formation mechanism in an MBR used for synthetic wastewater treatment was investigated. The major components of cake layer were systematically examined by particle size analyzer (PSA), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), X-ray fluorescence (XRF), energy-diffusive X-ray analyzer (EDX), and Fourier transform infrared (FTIR) spectroscopy. The results indicate that the small particles in sludge suspension had a strong deposit tendency on the membrane surface. The SEM and CLSM analysis exhibited that bacterial clusters and polysaccharides were significant contributors to membrane fouling. The main components of biopolymers were identified as proteins and polysaccharide materials by the FTIR. The examination by EDX and XRF demonstrated that Mg, Al, Ca, Si, and Fe were the major inorganic elements in fouling cake. Furthermore, the results suggest that bridging between deposited biopolymers and inorganic compounds could enhance the compactness of fouling layer. During the operation of MBRs, the biopolymers and inorganic elements in the bioreactor should be controlled to minimize membrane fouling.     

Partial nitrification of ammonium-rich wastewater as pretreatment for anaerobic ammonium oxidation (Anammox) using membrane aeration bioreactor

A lab-scale membrane aeration bioreactor (MBR) system was developed for treating synthetic ammonium-rich wastewater to yield an appropriate NO(2)(-)/NH(4)(+) mixture as a pretreatment for anaerobic ammonium oxidation (Anammox). The effluent with a suitable NO(2)(-)/NH(4)(+) ratio (1:1 to 1:1.3) was obtained in 24 h using the developed MBR system under suitable conditions. Additionally, the control of bulk dissolved oxygen (DO) level under a desired condition (anoxic condition) was easier and more economical than traditional aeration systems. An optimal initial alkalinity of 1500 mg CaCO(3)l(-1) was necessary for achieving 50% partial nitrification of wastewater with an initial ammonium concentration of 510 mg NH(4)-N l(-1) within 24 h. Furthermore, there is no need for pH adjustment by adding a base or an acid throughout the reaction if the initial alkalinity is appropriately controlled. Both the appropriate NO(2)(-)/NH(4)(+) ratio and the low DO level make this MBR system an ideal system for Anammox.     

Hospital wastewater treatment by membrane bioreactor: performance and efficiency for organic micropollutant elimination

A pilot-scale membrane bioreactor (MBR) was installed and operated for one year at a Swiss hospital. It was fed an influent directly from the hospital's sanitary collection system. To study the efficiency of micropollutant elimination in raw hospital wastewater that comprises a complex matrix with micropollutant concentrations ranging from low ng/L to low mg/L, an automated online SPE-HPLC-MS/MS analytical method was developed. Among the 68 target analytes were the following: 56 pharmaceuticals (antibiotics, antimycotics, antivirals, iodinated X-ray contrast media, antiinflamatory, cytostatics, diuretics, beta blockers, anesthetics, analgesics, antiepileptics, antidepressants, and others), 10 metabolites, and 2 corrosion inhibitors. The MBR influent contained the majority of those target analytes. The micropollutant elimination efficiency was assessed through continuous flow-proportional sampling of the MBR influent and continuous time-proportional sampling of the MBR effluent. An overall load elimination of all pharmaceuticals and metabolites in the MBR was 22%, as over 80% of the load was due to persistent iodinated contrast media. No inhibition by antibacterial agents or disinfectants from the hospital was observed in the MBR. The hospital wastewater was found to be a dynamic system in which conjugates of pharmaceuticals deconjugate and biological transformation products are formed, which in some cases are pharmaceuticals themselves.     

Desalination of mixed tannery effluent with membrane bioreactor and reverse osmosis treatment

A limiting factor for the reuse and recycling of treated tannery wastewater for irrigation and other uses is the high salt content, which persists even after conventional treatment. Reverse osmosis (RO) membrane treatment has been shown to significantly reduce the salt contents of tannery effluents. However, the high organic content of tannery effluent leads to rapid scaling and biofouling of RO membranes with a consequent reduction in flux rates and performance. Membrane bioreactors (MBR) have been shown to be highly effective in the removal of organic pollutants and suspended solids from tannery effluent. This research investigated the use of a combined MBR and RO treatment process to treat tannery effluents to an acceptable level for irrigation purposes. The MBR was operated at 17-20 h retention time, at a F/M ratio of 0.52 kg COD x kg SS(-1) x day(-1) and a volumetric loading rate of 3.28 kg COD x m(-3) x day(-1). This treatment reduced the COD, BOD, and ammonia concentrations of the effluent by 90-100%. The MBR was shown to be an excellent pretreatment prior to RO technology, due to the high removal efficiency of organic compounds and suspended solids, with average concentrations of 344 mg x L(-1) COD and 20 mg x L(-1) BOD achieved in the permeate. RO treatment reduced the salt content of the MBR permeate by up to 97.1%. The results of the research demonstrated that the MBR system developed was appropriate for the treatment of tannery effluents and, in combination with the RO treatment, reduced the salt content to acceptable levels for irrigation. The MBR pretreatment reduced bio-fouling and scaling of subsequent RO treatment and improved the overall performance of the RO unit. It is believed that this is the first investigation of a combined MBR and RO treatment for tannery effluents. This research provided data for an outline design of a full-scale MBR and RO plant with a treatment capacity of 5000 m3 per day for mixed tannery effluents.     

Characteristics of a self-forming dynamic membrane coupled with a bioreactor for municipal wastewater treatment

A self-forming dynamic membrane (SFDM) method that used the biomass layer formed on a coarse mesh to effect solid-liquid separation was proposed. A 100-microm Dacron mesh material was used to make the SFDM modules. A SFDM coupled bioreactor (SFDMBR) was tested to treat actual municipal wastewater, and the performance and mechanisms of the SFDM were investigated. The SFDMBR worked by gravity filtration, and the water head drop was generally <5 cm. The effluent suspended solid concentrations were undetectable in most cases, and the COD and NH3 N removal efficiencies averaged 84.2% and 98.03%, respectively. An aeration in situ was adequate for cleaning the clogged modules, and the SFDM was readily and quickly re-formed. The biomass layer of the SFDM consisted of a cake layer and a gel layer. The gel layer had structures like conventional membranes and acted the key role in the SFDM. The permeability of the used mesh attached to the gel layer could be improved because the gel layer made the filtration surface more hydrophilic.     

浸没式膜生物反应器协同活性炭处理海产养殖废水效果

该文结合海产养殖废水的盐度效应特点,开展了浸没式膜生物反应器(membrane bioreactor,MBR)协同粉末活性炭(powder activated carbon,PAC)处理含盐废水的试验。考察了投加PAC对于MBR污染物去除性能及膜污染的影响;盐度变化过程中(0~35 g/L)MBR对化学需氧量(chemical oxygen demand , COD)、氨氮(ammonia nitrogen,NH+4-N)、亚硝酸盐氮(nitrite nitrogen,NO₂-N)处理效果;以及含盐废水长期作用下微生物性能、膜通量、絮体粒径的变化情况。重点分析0~5 g/L的盐度变化,本体溶液中的溶解性有机物(soluble microbile products,SMP)和污泥絮体中胞外聚合物(extracellular polymeric substances,EPS)组成及含量的变化情况。结果表明:MBR PAC对COD的去除效率比MBR高7.3%,对NH+4-N、NO₂-N去除的稳定性优于MBR;两工艺条件下膜通量随盐度变化呈现类似的趋势,即敏感期衰减,稳定期得到一定程度的恢复。养殖废水长期作用下,MBR PAC膜通量是MBR的1.5倍,MBR PAC的污泥粒径相对于MBR增加了52 μm。盐度变化过程中,PAC由于其吸附性能及絮凝能力,能吸附本体溶液中的溶解性微生物代谢产物,相对于MBR,蛋白质的含量减少了34.0%。MBR PAC适用于海产养殖废水的处理。     

厌氧与曝气处理制革废水的CODcr

对不同工段的皮革废水进行厌氧处理,测定CODcr含量;对无铬的浸酸废水和含铬的浸酸废水进行曝气厌氧组合处理,测定CODcr。结果表明:硫化物含量稍高的废水,如浸灰废水,厌氧细菌作用的初始时间更长,但是CODcr去除率比较高,本身易产生微生物的软化废水CODcr去除率也高。而铬盐对厌氧处理来说没有明显的抑制作用,对于曝气处理来说,CODcr初期下降速度比较快,到一定程度后,CODcr不再有明显的下降。通过先曝气再厌氧和先厌氧再曝气的对比试验,发现前者优点显著,处理速度快,CODcr去除率更高。     

Discharge of three benzotriazole corrosion inhibitors with municipal wastewater and improvements by membrane bioreactor treatment and ozonation

A set of three benzotriazole corrosion inhibitors was analyzed by liquid chromatography-mass spectrometry in wastewaters and in a partially closed water cycle in the Berlin region. Benzotriazole (BTri) and two isomers of tolyltriazole (TTri) were determined in untreated municipal wastewater with mean dissolved concentrations of 12 microg/L (BTri), 2.1 microg/L (4-TTri), and 1.3 microg/L (5-TTri). Removal in conventional activated sludge (CAS) municipal wastewater treatment ranged from 37% for BTri to insignificant removal for 4-TTri. In laboratory batch tests 5-TTri was mineralized completely and 4-TTri was mineralized to only 25%. This different behavior of the three benzotriazoles was confirmed by following the triazoles through a partially closed water cycle, into bank filtrate used for drinking water production, where BTri (0.1 microg/L) and 4-TTri (0.03 microg/ L) but no 5-TTri were detected after a travel time of several months. The environmental half-life appears to increase from 5-TTri over BTri to 4-TTri. Treatment of municipal wastewater by a lab-scale membrane bioreactor (MBR) instead of CAS improved the removal of BTri and 5-TTri but could not avoid their discharge. Almost complete removal was achieved by ozonation of the treatment plant effluent with 1 mg O3/mg DOC.     

Removal of sulfur-organic polar micropollutants in a membrane bioreactor treating industrial wastewater

While membrane bioreactors (MBR) have proven their large potential to remove bulk organic matter from municipal as well as industrial wastewater, their suitability to remove poorly degradable polar wastewater contaminants is yet unknown. However, this is an important aspect for the achievable effluent quality and in terms of wastewater reuse. We have analyzed two classes of polar sulfur-organic compounds, naphthalene sulfonates and benzothiazoles, by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS) over a period of 3 weeks in the influent and effluent of a full-scale MBR with external ultrafiltration that treats tannery wastewater. While naphthalene monosulfonates were completely removed, total naphthalene disulfonate removal was limited to about 40%, and total benzothiazoles concentration decreased for 87%. Quantitative as well as qualitative data did not indicate an adaptation to or a more complete removal of these polar aromatic compounds by the MBR as compared to literature data on conventional activated sludge treatment. While quality improvements in receiving waters for bulk organic matter are documented and the same can be anticipated for apolar particle-associated contaminants, these data provide no indication that MBR will improve the removal of polar poorly biodegradable organic pollutants.     

OCC制浆造纸废水的膜处理技术研究

运用聚醚砜超滤膜对OCC造纸废水二级生化出水进行了处理,旨在将处理后的出水回用于纸机系统。通过考察废液通量、总固形物去除率、CODcr去除率等指标,得出了OCC废水膜处理的优化工艺,即截留相对分子量1000,压力0.3MPa,温度20℃,转速200rpm,最佳透过比为95%。结果表明,在最佳操作条件下废水的通量为27.6L/（m^2·h）,总固形物（TS）从6.96g/L降低到4.32g/L,CODcr从812mg/L降低到117mg/L,阳离子需求量（CD）从1.7532meq/L降低到0.0158meq/L,色度由2381倍降低到25倍,可满足纸机水回用的要求。     

Membrane fouling of submerged membrane bioreactors: impact of mean cell residence time and the contributing factors

In this study, four bench-scale pre-anoxic submerged membrane bioreactors (MBR) were operated simultaneously at different mean cell residence times (MCRTs) (3, 5, 10, and 20 days) to systematically elucidate the contributing factors of membrane fouling. Severe membrane fouling was first observed in the 3-day followed by the 5-day MCRT MBRs. Minimal membrane fouling was detected in the 10 and 20-day MCRT MBRs. The fouling of microfiltration membrane was not controlled by mixed liquor suspended solids concentration or zeta potential of biomass. Instead, membrane fouling rate increased with increasing soluble microbial products and extracellular polymeric substances concentrations, which both increased with decreasing MCRT. Total organic carbon, protein, carbohydrate, and UV254 absorbance in the mixed liquor supernatant increased with decreasing MCRT and were consistently higher than those of the effluent. Accumulation of carbohydrates rather than proteins in the mixed liquor supernatant was found to decrease with increasing MCRT. Normalized capilliary suction time value rather than the capilliary suction time value would indicate membrane fouling potential of a mixed liquor. Image analysis of the fouled membrane using scanning electron microscope and confocal laser scanning microscope showed that biofilm formation was the cause of membrane fouling.     

污水厌氧处理过程DCS控制系统设计

在对典型的污水厌氧处理工艺分析的基础上,设计了一套基于西门子PCS7开发平台的污水厌氧处理过程DCS控制系统。采用专家前馈＋反馈控制来调节调制池污水pH值,采用比值算法来控制营养物质投加量。