SRT对膜生物反应器出水水质的影响研究

膜生物反应器中ＭＬＶＳＳ为４０００－５０００ｍｇ／Ｌ时,ＣＯＤ的去除率可达９８％左右,ＮＨ３－Ｎ的去除率可达９９％左右。但随ＳＲＴ的继续延长,污泥 度增加,使得内源呼吸加剧和大量微生物死亡,导致上清液的ＣＯＤ上升,ＳＭＰ含量增加,出水ＣＯＤ存在波动性。同时ＳＭＰ的增加会抑制硝作用,ＮＨ３－Ｎ的去除率会略有下降,可维持在９２％左右。     

一体式厌氧平板膜生物反应器处理酒厂废水的研究

研究了容积负荷、水力停留时间对一体式厌氧平板膜生物反应器处理高浓度酒厂废水效果的影响。试验结果表明,CODCr负荷为5．2～8 kg／(m3·d),水力停留时间3～5 d时,CODCr平均去除率为95％。正常运行时的碱度与VFA的比为2．5～4．5。当CODCr负荷超过10 kg／(m3·d),系统 VFA出现累积,COD去除率下降。水力停留时间对一体式厌氧平板膜生物反应器处理效果有重要影响,水力停留时间应大于70 h。     

A/O MBR与BAF组合工艺处理垃圾渗滤液

采用A/O MBR与BAF组合工艺处理垃圾渗滤液,首先用含苯酚和氨氮模拟废水对种污泥进行预驯化处理,然后切换实际垃圾渗滤液进行通水实验,在不同的进水渗滤液稀释比条件下,系统考察A/O MBR和BAF对COD及氨氮的降解情况.研究结果表明,对于A/O MBR处理单元,当进水稀释比分别为9:1和5:1时,COD与氨氮的去除率可分别保持在90%和60%左右;而当稀释比减小到2:1时,COD与氨氮的去除率会分别减小到80%和35%左右.对BAF处理单元,A/O MBR出水中剩余的COD几乎不能被降解,而剩余的氨氮可被继续降解,其结果可使组合工艺的氨氮去除率提高到75%左右.     

Mixing characterisation of full-scale membrane bioreactors: CFD modelling with experimental validation

Membrane Bioreactors (MBRs) have been successfully used in aerobic biological wastewater treatment to solve the perennial problem of effective solids-liquid separation. The optimisation of MBRs requires knowledge of the membrane fouling, biokinetics and mixing. However, research has mainly concentrated on the fouling and biokinetics (Ng and Kim, 2007). Current methods of design for a desired flow regime within MBRs are largely based on assumptions (e.g. complete mixing of tanks) and empirical techniques (e.g. specific mixing energy). However, it is difficult to predict how sludge rheology and vessel design in full-scale installations affects hydrodynamics, hence overall performance. Computational Fluid Dynamics (CFD) provides a method for prediction of how vessel features and mixing energy usage affect the hydrodynamics. In this study, a CFD model was developed which accounts for aeration, sludge rheology and geometry (i.e. bioreactor and membrane module). This MBR CFD model was then applied to two full-scale MBRs and was successfully validated against experimental results. The effect of sludge settling and rheology was found to have a minimal impact on the bulk mixing (i.e. the residence time distribution).     

MBR工艺技术在工业废水处理的应用

文章重点阐述了MBR工艺类型、工艺优势、影响因素、运行管理、在工业废水处理中的应用,并对今后的研究方向进行了展望。     

Impact of Scaffold Micro and Macro Architecture on Schwann Cell Proliferation under Dynamic Conditions in a Rotating Wall Vessel Bioreactor

Over the last decade tissue engineering has emerged as a powerful alternative to regenerate lost tissues owing to trauma or tumor. Evidence shows that Schwann cell containing scaffolds have improved performance in vivo as compared to scaffolds that depend on cellularization post implantation. However, owing to limited supply of cells from the patients themselves, several approaches have been taken to enhance cell proliferation rates to produce complete and uniform cellularization of scaffolds. The most common approach is the application of a bioreactor to enhance cell proliferation rate and therefore reduce the time needed to obtain sufficiently significant number of glial cells, prior to implantation.In this study, we show the application of a rotating wall bioreactor system for studying Schwann cell proliferation on nanofibrous spiral shaped scaffolds, prepared by solvent casting and salt leaching techniques. The scaffolds were fabricated from polycaprolactone (PCL), which has ideal mechanical properties and upon degradation does not produce acidic byproducts. The spiral scaffolds were coated with aligned or random nanofibers, produced by electrospinning, to provide a substrate that mimics the native extracellular matrix and the essential contact guidance cues.At the 4 day time point, an enhanced rate of cell proliferation was observed on the open structured nanofibrous spiral scaffolds in a rotating wall bioreactor, as compared to static culture conditions. However, the cell proliferation rate on the other contemporary scaffolds architectures such as the tubular and cylindrical scaffolds show reduced cell proliferation in the bioreactor as compared to static conditions, at the same time point. Moreover, the rotating wall bioreactor does not alter the orientation or the phenotype of the Schwann cells on the aligned nanofiber containing scaffolds, wherein, the cells remain aligned along the length of the scaffolds. Therefore, these open structured spiral scaffolds pre-cultured with Schwann cells, in bioreactors could potentially shorten the time needed for grafts for peripheral nerve regeneration.     

Performance of a compact submerged membrane sequencing batch reactor (SM-SBR) for greywater treatment

A long-term study was carried out to evaluate the performance of submerged membrane sequencing batch reactors (SM-SBR) for greywater treatment. Three pilot plants were operated in three different countries with distinct wastewaters to prove that treated greywater can be used for reuse purposes.In all plants the permeate quality fulfilled in most cases the high mandatory values of different European directives. Membrane permeability declined significantly within a period of three to four months so that recovery cleanings were necessary 3 to 4 times a year. In general, the treated greywater from an SM-SBR can be reused for irrigation or cleaning purposes. SM-SBR for greywater treatment are especially interesting in cases of space limitations where the small footprint of the system can outweigh inconveniences like frequent chemical cleanings.     

Simultaneous biodesulphurization and denitrification using an oil reservoir microbial culture: Effects of sulphide loading rate and sulphide to nitrate loading ratio

Biooxidation of sulphide under denitrifying conditions is a key process in control of souring in oil reservoirs and in treatment of gas and liquids contaminated with sulphide and nitrate. In this work, biooxidation of sulphide was studied using a representative culture originated from an oil reservoir. Effects of sulphide concentration, sulphide to nitrate molar ratio, and loading rates of sulphide and nitrate on their removal rates and composition of the end products were investigated. In the batch system sulphide removal rate passed through a maximum as sulphide concentration was increased from 2.1 to 16.3 mM, with the highest rate (2.06 mM h⁻¹) observed with 10.7 mM sulphide. Nitrate removal was coupled to sulphide oxidation and the highest removal rate was 1.05 mM h⁻¹. In the continuous bioreactors fed with 10 and 5, 15 and 7.5, and 20 and 10 mM sulphide and nitrate, cell wash-out occurred as dilution rate was increased above 0.15, 0.13 and 0.08 h⁻¹, respectively. Prior to cell wash-out linear increases in sulphide and nitrate removal rates were observed as loading rate was increased. The highest sulphide and nitrate removal rates of 2.0 and 0.92 mM h⁻¹ were obtained in the bioreactor fed with 15 mM sulphide and 7.5 mM nitrate at loading rates of 2.1 and 0.93 mM h⁻¹, respectively. Short residence times and high sulphide to nitrate ratios promoted the formation of sulphur, a desired end product for ex situ treatment of contaminated streams. Combination of long residence times and low sulphide to nitrate ratios, which favours formation of sulphate, is the suitable strategy for in situ removal of H₂S from oil reservoirs.