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1.
《分离科学与技术》2012,47(15):3571-3596
Abstract

Membrane bioreactor (MBR) has been deemed to be a promising technology for wastewater treatment and reclamation; however, the MBR filtration performance inevitably decreases with filtration time attributed to the deposition of soluble and particulate materials onto and into the membrane under the interactions between activated sludge components and the membrane. Cake layer formation on membrane surfaces has been a major challenge in the operation of MBRs under supra-critical flux operation, and/or caused by uneven distribution of aeration intensities, etc.; however, it was argued that a thin cake layer might improve filtration operation by some researchers. This paper provides a critical review on the formation mechanisms, properties, the role of sludge cake in membrane filtration, and the corresponding strategies of controlling cake fouling in MBRs. Drawbacks and benefits of the formation of sludge cake were also discussed in order to better understand the characteristics and role of sludge cake formation in MBRs.  相似文献   

2.
《分离科学与技术》2012,47(12):2595-2614
Abstract

The models of particle fouling and membrane blocking in a submerged membrane filtration are developed in this study. The effects of operating conditions, such as aeration intensity (air flow rate) and filtration pressure, on the filtration flux, membrane blocking, and cake formation are discussed thoroughly. The experimental results show that the filtration resistances due to cake formation and membrane blocking play significant roles in determining the overall filtration resistance, but the latter one is more dominant. An increase in aeration intensity leads the filtration flux to increase due to the reduction of cake formation on the membrane surface. However, a higher filtration pressure causes more severe membrane internal blocking and then to lower filtration flux. The cake properties and the filtration resistance due to membrane blocking are analyzed and can be regressed to empirical functions of filtration pressure. A force balance model for particle deposition on the membrane surface is also derived. In order to estimate the shear stress acting on the membrane surface, the diameter, shape, and rising velocity of air bubbles are analyzed based on hydrodynamics. Once the model coefficients are obtained, the pseudo‐steady filtration flux under various conditions can be estimated by the proposed model and the basic filtration equation. The calculated results agree fairly well with the available experimental data.  相似文献   

3.
《分离科学与技术》2012,47(6):840-848
This paper investigated the effect of food to microorganisms (F/M) ratios in the MBRs on membrane fouling propensities at fluxes of 10, 20, and 30 L/m2 hr (LMH). The high F/M-MBR had different biomass properties, more soluble extracellular polymeric substances (EPS), and faster fouling rate compared to the low F/M-MBR. However, the fouling mechanisms at the three fluxes were dissimilar. At a low flux, the microbial flocs dominant cake layers facilitated catching the soluble EPS to increase resistance. At a high flux, the great accumulation of soluble EPS (especially soluble polysaccharides) to form gel-like cake layers predominantly induced membrane fouling. Supplemental materials are available for this article. Go to the publisher's online edition of Separation Science and Technology to view the free supplemental file.  相似文献   

4.
不同污泥对印染废水中残余染料的吸附特性   总被引:1,自引:0,他引:1  
马捷汀  代瑞华 《净水技术》2011,30(5):160-165
研究了四种不同污泥(活性污泥、厌氧污泥、干活性污泥、干厌氧污泥)对染料阳离子嫩黄X-4GL的吸附,并考察了胞外聚合物(EPS)在此过程中所起的作用.结果表明四种污泥对阳离子嫩黄的吸附在90min内基本达到平衡,干活性污泥的吸附性能最好,干厌氧污泥的吸附性能最差,污泥浓度为250 mg/L时,其吸附量分别为133和50 ...  相似文献   

5.
《分离科学与技术》2012,47(3):440-445
In this study, biomass characteristics including bacterial community, extracellular polymeric substances (EPS) production, and membrane fouling propensity were examined when the membrane bioreactors (MBRs) were fed with different substrates (i.e., different C/N/P ratios). Denaturing gradient gel electrophoresis (DGGE) analysis revealed that significant shifts of bacterial communities happened when increasing nitrogen or phosphorus loading in the MBRs, which followed in an almost similar way. At steady state, the biomass from the low C/N- and C/P-MBRs had comparable concentrations and produced similar EPS levels as those in the control MBR. However, the median particle size increased when the MBRs fed with low C/N- or C/P- substrate, possibly associated with the filamentous bacteria propagating in the MBRs. Increasing nitrogen or phosphorus loading 1-fold could not induce more serious membrane fouling compared to the control MBR.  相似文献   

6.
Fenton试剂对剩余污泥脱水性能的改善   总被引:6,自引:0,他引:6  
潘胜  黄光团  谭学军  孙晓 《净水技术》2012,31(3):26-31,35
研究了利用Fenton试剂调理城市污水处理厂剩余污泥,通过测定污泥毛细吸水时间(CST)、污泥比阻(SRF)和泥饼含水率来表征污泥脱水性能的变化,分别考察了污泥初始pH、H2O2投加量、H2O2/Fe2+、反应温度和反应时间对污泥调理效果的影响。综合考虑,确定Fenton调理污泥的最佳条件为:pH=3、抽滤脱水和离心脱水H2O2最佳投加量分别为3 g/L和9 g/L、H2O2/Fe2(+质量比)最佳范围为8~12、反应温度50℃、反应时间60 min。对污泥离心上清液中胞外聚合物(EPS)含量的研究表明,Fenton调理后污泥上清液中蛋白质和多糖含量有大幅升高,说明Fenton试剂能有效氧化破解EPS,从而提高污泥的絮凝性,改善污泥的脱水性能。Fenton氧化后污泥颗粒粒径变小,比表面积增大。  相似文献   

7.
《分离科学与技术》2012,47(7):1371-1382
Abstract

This paper deals with the membrane fouling in membrane bioreactor (MBR). Based on the experimental data obtained in the MBR pilot plant study, the influence of F/M ratio on the irreversible and reversible fouling was discussed in the wide range of MLSS concentration. In the case of lower MLSS concentration (2,000–3,000 mg/L), irreversible fouling rate of membrane increased with increasing F/M ratio because of the accumulation of DOC in the mixed liquor. It seems that soluble microbial products with the similar size of the membrane pore will be most responsible for the irreversible fouling. In the case of higher MLSS concentration (8,000–12,000 mg/L), reversible fouling rate of membrane increased with increasing F/M ratio because of the increased suspension viscosity caused by the increased activated sludge size or volume even in the same MLSS concentration.  相似文献   

8.
《分离科学与技术》2012,47(10):1529-1536
Sludge properties, cake layer structure, and membrane fouling in a membrane bioreactor were studied under various hydraulic retention times (HRT). A decrease in HRT resulted in an increase in extracellular polymeric substance production in bulk sludge and changes in cake layer structure from gel layer to one or two cake layers. Particle size distribution in cake sludge changed with respect to HRT. An evolution in cake layer thickness and porosity was observed with trans-membrane pressure (TMP) jump. The change in cake layer structure might bear more responsibility for the TMP jump than the quantity of cake layer.  相似文献   

9.
胞外聚合物对膜污染的影响及对策   总被引:3,自引:1,他引:3  
膜生物反应器(MBR)中膜污染问题直接影响了工艺的稳定性和经济性。通过分析膜污染机理发现,胞外聚合物(EPS)在膜污染中起重要作用。从EPS的性质、组成及影响因素等方面进行了归纳总结,并对膜污染控制提出了相应的对策。  相似文献   

10.
《分离科学与技术》2012,47(7):1583-1594
Abstract

To investigate the dependence of filter ripening on particle size and surface charge, multiple experiments were conducted under different particle destabilization conditions including pH control, alum, and polymer destabilization. Laboratory‐scale filtration experiments were performed at a filtration velocity of 5 m/h using spherical glass beads with mean diameter of 0.55 mm as collectors. Particle suspensions with a broad size distribution and a 1.7 µm mean particle size were filtered through a 10 cm depth filter column. Better initial solids removal was confirmed under favorable particle and collector conditions (i.e., under smaller surface charge), but better initial particle removal does not necessarily mean better overall particle removal efficiency. It was shown that changes of the particle size distribution (PSD) in the effluent can significantly influence overall particle removal efficiency. Chemical parameters such as zeta potential can be important during the initial stage of filtration, but their importance can decrease over time depending on the specific chemical conditions. The influent PSD and the removal of certain size particles during the initial stage of filtration can significantly influence ripening, which in turn, can influence the overall particle removal efficiency.  相似文献   

11.
该文以处理超市废水实际MBR工程为基础,通过对污泥膨胀过程中进出水、溶解性微生物产物(SMP)和胞外聚合物(EPS)中的溶解性有机物(DOM)特性的研究,发现SMP和进出水的DOM主要以蛋白质为主,且SMP较EPS含有更多大分子物质;同时发现SMP比EPS和进出水中含有更多50~100 kDa、100~500 kDa和...  相似文献   

12.
在设定的膜内压力下(2 k Pa)启动并运行膜曝气生物膜反应器(MABR),对生物膜生长过程中的硝化性能及生物膜组成变化进行了分析。实验结果表明,在生物膜厚度增长到(293.3±5.8)μm的过程中,生物膜内的总氧通量先增加后减少,最高可达21.3 g O2?m?2?d?1,证实了生物膜的存在可增强MABR的氧传质能力。在生物膜厚度增长的过程中,氨氮表面去除负荷也是先增加后减少,最高可达4.91 g N?m?2?d?1,表明在MABR硝化过程中存在最佳的生物膜厚度,根据所研究最佳生物膜厚度为(119.0±3.0)μm,此时MABR具有最高的氧通量和氨氮表面去除负荷,硝化性能最好。生物膜内胞外聚合物(EPS)成分分析结果表明,随着生物膜厚度的增加,生物膜内层紧密型EPS的含量增加,导致氧传质阻力增加,这是生物膜内氧通量及氨氮去除负荷随生物膜厚度先增加后下降的内在原因。  相似文献   

13.
张健  殷祺  陈艳  徐鹏成  李惠平 《净水技术》2022,(1):51-57,102
以太湖水为研究对象,采用超滤工艺,通过分别投加混凝剂Al2(SO4)3和聚合氯化铝(PAC),分析混凝过程对超滤膜运行效果及压力的影响.结果表明:混凝可以有效提高超滤对有机物的去除效果,Al2(SO4)3和PAC投加量大于6 mg/L和3 mg/L(以Al3+计)时,混凝剂对超滤去除有机物的提升效果趋于稳定;混凝可以有...  相似文献   

14.
采用生物粉末活性炭-超滤(BPAC-UF)分体式工艺的中试装置,探究该工艺对西氿微污染原水的处理效果,在此基础上对比研究聚偏氟乙烯(PVDF)和聚氯乙烯(PVC)两种材质超滤膜的膜污染情况。PVDF膜和PVC膜两种不同材质的膜组合工艺对浊度去除率均超过95%,超滤膜可保证出水浊度要求。PVDF膜对尺寸不超过2μm的颗粒物去除效果要略优于PVC膜。初期PAC未转化为BPAC时,工艺对氨氮和CODMn的去除主要靠活性炭吸附。当PAC转化为BPAC,BPAC-UF对氨氮的去除主要是通过生物作用,后期去除率稳定在80%以上,BPAC-UF对CODMn去除率不高,稳定在25%左右。在膜污染控制方面,PVDF膜和PVC膜的跨膜压差增长趋势相似,但PVC膜的跨膜压差增速要略高于PVDF膜。经过强化物理反冲洗和化学反冲洗后,PVDF膜和PVC膜的产水性能均能恢复至较优状态,且PVDF膜恢复程度略优于PVC膜。  相似文献   

15.
A mathematical model is established to simulate the formation of extracellular polymeric substances (EPS), soluble microbial products (SMP), and internal storage products (XSTO) in aerobic granular sludge. The sensitivity of these microbial products concentrations toward the key model parameters is analyzed. Independent experiments are conducted to find required parameter values and to test its predictive ability. The model is evaluated by using one‐cycle operating experimental results of a lab‐scale aerobic granule‐based sequencing batch reactor (SBR) and batch experimental results. Results show that the model is able to describe the microbial product dynamics in aerobic granules and provide further insights into a granule‐based SBR. The effect of the initial substrate and biomass concentrations on the formation of microbial products in aerobic granular sludge can therefore be analyzed by model simulation. A higher substrate concentration results in a greater concentration of EPS, SMP, and XSTO. An accumulation of biomass in the bioreactor leads to an increased production rate of EPS, SMP, and XSTO. © 2009 American Institute of Chemical Engineers AIChE J, 2010  相似文献   

16.
分析了高不挥发物质量分数聚合物聚醚多元醇(POP)中分散相颗粒形态及粒径分布对其黏度的影响,并讨论了分散剂用量、链转移剂用量、乙烯基单体比例对分散颗粒形态及粒径分布的影响.  相似文献   

17.
微生物以其独特的生理生化特性,在市政污水处理中承担着去除有机物和脱氮除磷的重要作用,然而纳米金属及其氧化物的广泛应用提高了纳米材料进入污水处理厂的可能性,致使污水处理中的微生物暴露在风险环境中。文中从微生物聚集体存在形式角度出发,概述了纳米材料对微生物特性的影响,揭示了微生物在不利条件下的应对机制,为从群体感应角度深入探究微生物应对纳米材料等胁迫作用提供重要理论依据,并对曾处于胁迫下的微生物功能修复的可能性提出展望。  相似文献   

18.
土体标度分布参数与其物理力学性质的关系研究   总被引:1,自引:0,他引:1  
土体标度分布参数可以客观地表达土体颗粒组成的整体特征,便于建立其与土体物理力学性质之间的定量关系,具有重要的理论意义和实际应用价值.以土体的标度分布理论为基础,结合土体渗透实验和直剪实验,研究了土体标度分布参数与其渗透系数、抗剪强度指标(黏聚力、内摩擦角)的关系,结果表明:土体渗透系数K与标度分布参数μ呈负对数关系,与...  相似文献   

19.
氯碱用全氟离子交换膜(PFIEM)污染与再生的研究   总被引:1,自引:0,他引:1  
郎万中  许振良  石卫  童蔚 《化学世界》2006,47(2):65-68,121
采用盐酸(HCl)和乙二胺四乙酸二钠(EDTA-2Na)作为再生剂,对氯碱行业污染并废弃的全氟离子交换膜(Perfluoro-ion-exchange membrane,PFIEM)F-8020与F-795进行了再生研究,考察了PFIEM再生过程中溶液温度、再生时间、盐酸浓度和超声波等条件对再生过程的影响。实验结果表明,当溶液温度60℃以上和盐酸浓度8%以上时,PFIEM的再生效果较好,能去除PFIEM阳极表面上的各种杂质元素;超声波水浴清洗能有效地脱除PFIEM阴极表面上的难溶物,而EDTA溶液能提高再生PFIEM的离子交换容量(Ion-exchange capacity,IEC)。采用多种分析方法,分析了PFIEM的表面元素I、EC值和水含量等参数。  相似文献   

20.
在铝栅化学机械平坦化(CMP)中磨料直接影响去除速率和表面粗糙度。采用不同粒径的磨料配置抛光液对铝栅进行CMP实验,对去除速率和表面形貌测试结果进行分析。结果表明,去除速率与参与抛光的磨料颗粒数目和单个颗粒去除速率有关,表面粗糙度与单个磨料颗粒机械作用和抛光后磨料颗粒表面吸附有关,并对抛光液稳定性进行了研究。最终选用粒径70 nm,质量分数为5%的磨料,去除速率可达到181 nm/min,表面粗糙度为9.1 nm,对今后铝栅CMP的研究提供了参考。  相似文献   

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