延缓膜生物反应器膜污染的技术措施探讨

膜生物反应器(MBR)是膜分离技术和污水生物处理技术有机结合产生的一种新型污水处理工艺,与传统污水处理工艺相比具有很多优点,但膜污染是限制膜生物反应器广泛应用的关键因素.介绍了膜污染的定义,系统论述了膜污染的研究进展,着重从改良膜的性质,改善污泥混合液的特性和优化膜分离操作条件3个方面介绍了国内外有效延缓膜污染的技术措施.     

MBR法处理洗涤废水

应用膜生物反应器(MBR)处理洗涤废水,在反应器中当水温为30～33℃,DO为2～4 mg/L,pH为6.3～7.1,MLSS为4000～8100mg/L,污泥沉降比为77%～97%,SRT为90 d,HRT为2.2 h,24 h连续曝气的情况下,经MBR处理后出水COD_(Cr)为12～64 mg/L,去除率大于80%;NH_3—N为0.3～3.4 mg/L,去除率大于80%;浊度为0.3NTU,去除率大于99%。试验证明MBR法工艺处理洗涤废水简单、基建费用低、占地面积小、便于管理,处理后水质较稳定,抗冲击负荷能力强,处理效率高。     

膜生物反应器在我国的研究进展

膜生物反应器 (MBR)是通过膜强化生化反应的污水处理新技术。综述了该技术在国内的研究进展 ,指出MBR工艺具有污染物去除效果好 ,污泥产率低的优点 ,分析了影响MBR处理效果的相关因素     

一体式膜-生物反应器污水处理特性及膜污染机理研究

本文介绍了一体式膜 生物反应器处理生活污水和含难降解有机物废水的试验研究 ,取得了以下主要结果 :(1 )采用一体式膜 生物反应器处理实际生活污水 ,系统地考察了不同ＳＲＴ和ＨＲＴ对污染物去除效果的影响。结果表明 ,一体式膜 生物反应器在不同的ＳＲＴ和ＨＲＴ下均表现出良好的污染物去除效果和运行的稳定性。但在长ＳＲＴ的条件下 ,生物反应器内出现了微生物代谢产物的积累。污泥龄过短时 ,反应器料液会对膜过滤造成极其不利的影响。(2 )对生物反应器微生物和混合液特性的研究表明 ,随着污泥龄的增长 ,生物反应器内的污泥活性有降低的…     

膜生物反应器的污泥特性和膜污染研究

对中试规模的缺氧—好氧—膜生物反应器(A/O—MBR)处理城市污水进行研究,并对好氧池内活性污泥的特性和膜污染后期的影响因素进行了分析。试验结果表明:污泥浓度(MLSS)对CODCr、氨氮等各指标的处理效果均有影响。与传统活性污泥工艺相比,膜生物反应器污泥负荷小、表观产泥率低。     

MBR—RO工艺深度处理煤化工废水试验研究

采用膜生物反应器(MBR)—反渗透(RO)组合工艺深度处理煤化工废水,结果表明,原水经MBR系统处理后,可有效去除废水中的COD、NH3—N、浊度和SS,去除率分别达72.6%、85.4%、98.8%和100%。MBR系统出水进入RO系统进行深度处理,硬度的去除率和除盐率分别达到87.7%和95.3%,同时可进一步除去剩余浊度和COD。系统出水水质满足《工业循环冷却水处理设计规范》(GB 50050—2007)中再生水水质指标的要求。同时,根据现场中试结果,提出了煤化工废水的膜组件和生物段的设计、运行参数及布置方案。     

膜生物反应器在生活污水回用与污泥减量中的试验研究

围绕着生活污水回用和污泥减量这两个问题,以MBR 作为核心生物处理工艺,通过与厌氧单元和臭氧化单元联用,进行了对生活污水和污泥合并处理的研究。MBR与厌氧反应器联合在不排泥情形下运行3个月, 系统对COD、NH3-N、TN均保持了较高的平均去除率。通过将原水水量的30%引入厌氧反应器为反硝化脱氮和厌氧     

生物膜-膜生物反应器处理生活污水的试验研究

采用生物膜-膜生物反应器处理生活污水.结果表明在DO,pH等因素控制得当的情况下,系统对COD,NH3-N和TN的平均去除率分别为92.82%,93.04%和88.93%,同时获得了0.156 gSS/gCOD的剩余污泥产率.试验期间还对膜通量的变化情况进行了考察,在小试的基础上提出了延缓膜污染的措施.     

膜生物反应器处理避孕药废水初探

采用A/O膜生物反应器处理高氨氮、高pH、难生物降解的避孕药废水。试验结果表明,此工艺处理该类废水可行,当水力停留时间为6h,系统对COD、氨氮和总氮的去除率分别为86%、73%和75%。好氧段的溶解氧维持在4mg/L可以同时实现对有机物和氮类的去除,对COD、氨氮和总氮去除率分别达到94%、63%和64%。通过控制A/O膜生物反应器的操作条件,可实现短程硝化和反硝化,提高总氮去除率。     

生物膜─膜生物反应器处理生活污水的试验研究

采用生物膜 膜生物反应器处理生活污水。结果表明 :在DO ,pH等因素控制得当的情况下 ,系统对COD ,NH3 -N和TN的平均去除率分别为 92 82 % ,93 0 4 %和 88 93% ,同时获得了0 15 6 gSS/ gCOD的剩余污泥产率。试验期间还对膜通量的变化情况进行了考察 ,在小试的基础上提出了延缓膜污染的措施     

Evaluation of MBR effluent characteristics for reuse purposes.

One of the advantages of MBR is its excellent effluent quality, which is suitable for a wide range of reuse purposes. We investigated the characteristics of MBR effluent and evaluated them based on the Japanese guideline for the reuse of treated wastewater. As the result, MBR effluent showed qualitative coaracteristics that satisfy the requirement except chromaticity for recreational purpose. Further treatment, such as by oxone or activated carbon, will be required to remove the remaining color. MBR shows high removal efficiency of bacteria and other hazardous microorganisms such as Cryptosporidium. We investigated the removal efficiency of virus by MBR using coliphage as an alternative index. The results showed that high removal efficiency for coliphage could be obtained by MBR. The removal mechanism appears to be that coliphage are attached to the activated sludge and thus rejected by the membrane together with activated sludge particles. With regard to the endocrine disrupters, no significant differences were observed between MBR and CAS in the removal of main endocrine disrupters.     

Comparison of the behaviour of selected micropollutants in a membrane bioreactor and a conventional wastewater treatment plant.

Micropollutants as pharmaceutical active compounds (PhACs), residuals of personal care products or endocrine disrupting chemicals are of increasing interest in water pollution control. In this context the removal efficiencies of sewage treatment plants (STPs) are of importance, as their effluents are important point sources for the release of those substances into the aquatic environment. Activated sludge based wastewater treatment is the worldwide prevalently used treatment technique. In conventional plants the separation of treated wastewater and sludge occurs via sedimentation. A new development is the application of membrane technology for this separation step. The studies focus on the influence of the solids retention time (SRT) on the removal efficiency, as the SRT is the most important parameter in the design of STPs. A conventional activated sludge plant (CASP) and a membrane bioreactor (MBR) were operated at different SRTs. The substances selected are the antiepileptic carbamazepine, the analgesics diclofenac and ibuprofen, the lipid regulator bezafibrate, the polycyclic musks tonalide and galaxolide and the contraceptive 17alpha-ethinylestradiole. No significant differences in the removal efficiency were detected. Due to the absence of suspended solids in the MBR effluent, substances with high adsorption potential could be retained to slightly higher amounts.     

Membrane bioreactor (MBR) sludge inoculation in a hybrid process scheme concept to assist overloaded conventional activated sludge (CAS) process operations

This study analyzes the effect of inoculating membrane bioreactor (MBR) sludge in a parallel-operated overloaded conventional activated sludge (CAS) system. Modelling studies that showed the beneficial effect of this inoculation were confirmed though full scale tests. Total nitrogen (TN) removal in the CAS increased and higher nitrate formation rates were achieved. During MBR sludge inoculation, the TN removal in the CAS was proven to be dependent on MBR sludge loading. Special attention was given to the effect of inoculation on sludge quality. The MBR flocs, grown without selection pressure, were clearly distinct from the more compact flocs in the CAS system and also contained more filamentous bacteria. After inoculation the MBR flocs did not evolve into good-settling compact flocs, resulting in a decreasing sludge quality. During high flow conditions the effluent CAS contained more suspended solids. Sludge volume index, however, did not increase. Laboratory tests were held to determine the threshold volume of MBR sludge to be seeded into the CAS reactor. Above 16-30%, supernatant turbidity and scum formation increased markedly.     

Biomass adaptation to complex substrate degradation in membrane bioreactors: appropriated operating conditions.

The aim of this work is to analyse the biological performances of two immersed membranes bioreactors focusing on the biomass adaptation to complex substrate degradation and the performance in term of permeate quality. Two influents were selected: a synthetic complex influent (acetate/Viandox, MBR1) and a real seafood processing wastewater (surimi product, MBR2). The MBR systems were operated for long periods without any sludge extraction except for sampling. Organic matter removal, sludge production and quality of the treated wastewater were analysed and studied. COD removal efficiencies after a period of biomass adaptation were higher than 97% and 95% for the synthetic and real wastewater respectively. In both cases, the COD of the treated wastewater was lower than 50 mg.L(-1). In spite of salt concentration in the real wastewater a biomass adaptation process occurs. In the overall operational period, a 0.058 gCOD P.gCOD T(-1) and a 0.12 gCOD P.gCOD T(-1) observed sludge yields were obtained for the MBR1 and MBR2 respectively. These values are approximately 5 to 10 times lower than those measured in conventional activated sludge process. These results showed that the presence of particular and some of non-easily degradable compounds in the influent of MBR2 didn't limit the performance of MBR in term of COD removal achieved. The results have also confirmed the excellent permeate quality for water reuse from MBRs systems.     

Membrane bio-reactor for textile wastewater treatment plant upgrading.

Textile industries carry out several fiber treatments using variable quantities of water, from five to forty times the fiber weight, and consequently generate large volumes of wastewater to be disposed of. Membrane Bio-reactors (MBRs) combine membrane technology with biological reactors for the treatment of wastewater: micro or ultrafiltration membranes are used for solid-liquid separation replacing the secondary settling of the traditional activated sludge system. This paper deals with the possibility of realizing a new section of one existing WWTP (activated sludge + clariflocculation + ozonation) for the treatment of treating textile wastewater to be recycled, equipped with an MBR (76 l/s as design capacity) and running in parallel with the existing one. During a 4-month experimental period, a pilot-scale MBR proved to be very effective for wastewater reclamation. On average, removal efficiency of the pilot plant (93% for COD, and over 99% for total suspended solids) was higher than the WWTP ones. Color was removed as in the WWTP. Anionic surfactants removal of pilot plant was lower than that of the WWTP (90.5 and 93.2% respectively), while the BiAS removal was higher in the pilot plant (98.2 vs. 97.1). At the end cost analysis of the proposed upgrade is reported.     

Removal of inhibitory phenolic compounds by biological activated carbon coupled membrane bioreactor.

Phenolic compounds cause problems for conventional treatments due to their toxic and inhibitory properties. This work investigated the treatability of phenolic compounds by using two membrane-bioreactor systems, namely: activated sludge coupled with MBR (AS-MBR) and biological granular activated carbon coupled with MBR (BAC-MBR). Initially, the system was fed with phenol (500 mg/L) followed by adding 2,4-dichlorophenol (2,4-DCP). Phenol, 2,4-DCP, TOC and COD removal were higher than 98.99% when the organic load ranged between 1.80 and 5.76 kg/m3.d COD. In addition to MBR system development, removal mechanisms were also investigated. Relatively low values of phenol adsorption of GAC and biomass, and high maximum substrate removal rates obtained from a biokinetic experiment, proved that the removals were mainly due to biodegradation. Analysis of sludge indicated a significant difference in the sludge characteristics of the two reactors. The high EPS content in BAC-MBR led to higher viscosity and poor sludge settling properties. The relationship between sludge properties and EPS components revealed that settleability had no direct correlation with EPS, though it was better correlated to protein/carbohydrate ratios.     

A pilot study on accelerated sludge degradation by a high-concentration membrane bioreactor coupled with sludge pretreatment.

A new sludge treatment process combining a high MLSS membrane bioreactor with sludge pretreatment techniques was studied in pilot-scale experiments. The membrane bioreactor (MBR) was adopted for high efficiency aerobic digestion. The combination of alkaline-ozone treatment of the mixed liquor in the MBR reactor accelerated the biodegradation process by enhancing biodegradability of the sludge. The hydraulic retention time (HRT) of the reactor was set as 3.1 days and the DO level was 1 mg/L on average. After 5 months of operation, the accumulative total solids reduction was more than 70%. Removal efficiency of volatile solids and non-volatile solids were 76% and 54%, respectively. It was found that a considerable portion of the non-volatile solids was dissolved into ions and then flushed out with the effluent. Also, about 41% and 28% of T-N and T-P in the raw sludge were removed although no biological nutrient removal process was adopted. The experiment was run smoothly without significant membrane fouling, even at the relatively high levels of MLSS concentration (11,000-25,000 mg/L). It is concluded that the newly proposed process can significantly increase the sludge reduction efficiency with much shorter retention times.     

Integration of performance,molecular biology and modeling to describe the activated sludge process

To study process performance and population dynamics in activated sludge, a pilot-scale Membrane Bioreactor (MBR) was installed in a municipal wastewater treatment plant (Aubergenville, France). Since no solids losses occur in the MBR effluent, the sludge residence time (SRT) can be: i) easily controlled by means of the sludge withdrawal, and ii) dissociated from the hydraulic residence time (HRT). A complete characterization of this activated sludge system was performed at three sludge ages (5, 10 and 20 days). Raw and treated wastewater quality, as well as sludge concentration, was analyzed, nucleic probe analysts was performed to determine the heterotrophic and nitrifier populations, and the results were compared to the output from a multispecies model that integrates substrate removal kinetics and soluble microbial products (SMP) production/consumption. This paper presents an integrated analysis of the activated sludge process based on chemical, molecular biology, and mathematical tools. The model was able to describe the MBR system with a high degree of accuracy, in terms of COD removal and nitrification, as well as sludge production and population dynamics through the ratio of active nitrifters/bacteria. Both steady-state and transient conditions could be described accurately by the model, except for technical problems or sudden variations in the wastewater composition.     

Comparison of linear alkylbenzene sulfonates removal in conventional activated sludge systems and membrane bioreactors.

The potential of a membrane bioreactor (MBR) and a conventional activated sludge (CAS) system to remove polar micropollutants was evaluated using linear alkylbenzene sulfonates (LAS) as model components. Removal efficiencies over 97% were achieved in both reactor systems. The appearance of biological breakdown metabolites and the respirometric response of the sludges to LAS addition indicated that LAS removal was due to biodegradation, rather than sorption phenomena. The effect of operational variables, such as hydraulic retention time, LAS composition and hydrophobicity of the membrane used in the MBR, was negligible in the range tested. A stepwise increase in LAS influent concentration resulted in higher residual effluent concentrations but did not change the procentual removal efficiency. Because an increase in LAS and SPC effluent concentration occurred to a larger extent in the CAS than in the MBR under similar operating conditions, MBRs may turn out to be be more robust with respect to biological degradation of micropollutants than CAS.     

Performances of a hybrid adsorption/submerged membrane biological process for toxic waste removal.

This study focuses on a hybrid process, which combines adsorption on powdered activated carbon (PAC), membrane separation using immersed hollow fibers and biological activity. The first part shows that PAC addition in a complex system (containing dissolved molecules and biological particles) can reduce membrane fouling. In that system, DMP removal is function of the activated carbon concentration. Then, respirometric experiments allowed comparison of toxic sensitivity and biological degradation of different bioreactors (membrane bioreactor (MBR), adsorptive membrane bioreactor (PAC-MBR) and classical activated sludge bioreactor (AS)). Results point out that MBR sludge is less sensitive to the toxic than the AS. For high toxic concentration, PAC addition in the MBR decreases rapidly the toxic concentration under the EC50 in the bioreactor, which allows a better biodegradation of the toxic compound. DMP assimilation is completed more rapidly with the PAC-MBR than the MBR.