Review on the state of science on membrane bioreactors for municipal wastewater treatment.

Over the past two decades the field of application for membrane bioreactors has broadened towards the municipal wastewater treatment sector. The Global Water Research Coalition (GWRC) determined MBR technology to be of priority for collaborative research and decided to conduct a project with the aim to determine the current state of the science in the field of MBR for municipal wastewater treatment and to develop a phased research strategy represented by priority research projects, like a State of the Science report with regard to MBR technology. This paper describes the state of the science with regard to MBR technology for municipal wastewater treatment by 2007, derived by literature review on recent publications, database analysis and international questionnaires.The research efforts from the past seven years can be characterised by the following prioritised list: (1) membrane fouling, (2) effluent quality, (3) energy consumption (aeration) and (4) cost considerations. The research needs for the near future as identified with the questionnaire are comparable to the main topics of research as identified in the literature review: membrane fouling is still the main problem requiring thorough attention from scientists; effluent quality is a main driver for the application of the technology. There remain some important questions however, with regard to the removal of EDC and micro pollutants. Much of the research activities on MBR are repeated more than once by research groups world-wide. This is only partially caused by a lack of knowledge exchange between researchers. However, lacking information exchange between Europe and the USA on MBR research is identified as a potential bottleneck. Another point of attention is the fast that research results can not easily be translated to other (more practical) situations, since much of the research is carried out at pilot scale.     

化学除磷在城市污水处理中的应用

阐述了城市污水处理中除磷的重要性和迫切性,而在普遍采用的生物除磷技术不能满足出水磷的排放标准时可考虑采用化学除磷技术.系统分析了化学除磷的原理、方法、工艺、研究进展及应用前景,并指出了现阶段化学除磷技术研究与发展的目标.     

Production integrated treatment of textile wastewater by closing raw material cycles.

A method for the in-house treatment of partial wastewater flows and the recycling of treated process water into the textile finishing process was developed in order to recycle effluents from textile finishing industry and feed them back into the production process. The method is based on a two-stage biological anaerobic-aerobic process to split colouring wastewater agents and to degrade organic substances contained in the water as well as a chemical stage to remove the remaining color of the water with the help of ozone. In the framework of a research and development project a demonstration plant for a treatment capacity of 1440 m3 per working day was installed and started in a textile finishing company. At the plant, a wastewater flow and a recycling flow are treated separately in two different treatment lanes. Approximately 40% of the total wastewater flows, i.e. 576 m3/d are treated in the wastewater lane, and a maximum of 60% of total wastewater, i.e. 864 m3/d are treated in the recycling lane. Thanks to the preliminary treatment of wastewater flows, which are discharged into the municipal sewage works, a reduction of average COD levels in the sewage works effluents could be achieved.     

Computational intelligence-based optimisation of wastewater treatment plants.

Methods of computational intelligence (CI), especially fuzzy control and neuronal networks, are used for controlling and optimising of wastewater treatment plants. Areas of application are the control of sludge water dosage, of phosphate elimination by optimal precipitant dosage as well as an optimal aeration in the nitrification zone. In two municipal wastewater treatment plants with 60,000 and 12,600 person equivalents the controllers have been installed and optimised and they have been in operation for several years. Results of operation of the plants are presented in comparison to previously used classical control. Performance increased significantly and the outflow values could be kept securely below the government requirements without increase of the energy consumption. Peak loads in the inflow were eliminated in the plant and did not increase outflow concentrations. Results of operation for more than three years clearly show that the CI controller is a cost-efficient method for a sustainable rise of performance in municipal wastewater treatment plants.     

A pilot study on a step-feeding anoxic/oxic activated sludge system.

A four stage pilot plant of step-feed biological nutrient removal (BNR) was employed to investigate reactor performance and process stability. The results obtained showed that step-feed BNR is efficient and cost-effective for nitrogen and carbonaceous removal from municipal wastewater. The total average removal efficiencies of COD, NH3-N, TN and TP could reach as high as 89.5, 97.8, 73 and 75%, respectively, with 50% of return activated sludge (RAS), 9 h of hydraulic retention time (HRT) and 20 d of sludge retention time (SRT). Step-feed BNR is an alternative and effective technology of nutrient removal for municipal wastewater treatment.     

Municipal wastewater treatment in Poland - efficiency, costs and returns to scale

This paper reports the costs of municipal wastewater collection and treatment in Poland. Our study provides detailed cost estimates for the collection and treatment of municipal wastewater, based on an empirical sample of 1,400 operators, who jointly collect and treat over 80% of wastewater in Poland. The unit costs of collection and treatment, and the nitrogen and phosphorus treatment efficiency were investigated, and the effects of plant capacity on unit costs (scale effects) were explored. Primary, secondary and tertiary treatment cost functions were analysed econometrically using the Box-Cox regression model, indicating high non-linearity and significant scale effects. We found that wastewater treatment costs were increasing with technology efficiency (moving from the primary, through the secondary, to the tertiary treatment), and decreasing with higher wastewater treatment plant capacity. Our results provide a comprehensive picture of municipal wastewater treatment in Poland but potentially, as the technology is fairly generic, they can also be used for applications in other countries, after accounting for capital and labour cost differences. The paper thus provides a valuable input into cost-benefit analyses of nutrient loading reduction achieved by extending or intensifying municipal wastewater treatment.     

Potentials and limits of anaerobic digestion of sewage sludge: energy self-sufficient municipal wastewater treatment plant?

Anaerobic digestion is the only energy-positive technology widely used in wastewater treatment. Full-scale data prove that the anaerobic digestion of sewage sludge can produce biogas that covers a substantial amount of the energy consumption of a wastewater treatment plant (WWTP). In this paper, we discuss possibilities for improving the digestion efficiency and biogas production from sewage sludge. Typical specific energy consumptions of municipal WWTPs per population equivalent are compared with the potential specific production of biogas to find the required/optimal digestion efficiency. Examples of technological measures to achieve such efficiency are presented. Our findings show that even a municipal WWTP with secondary biological treatment located in a moderate climate can come close to energy self-sufficiency. However, they also show that such self-sufficiency is dependent on: (i) the strict optimization of the total energy consumption of the plant, and (ii) an increase in the specific biogas production from sewage sludge to values around 600 L per kg of supplied volatile solids.     

养殖业粪污治理与资源化利用模式探讨

通州区养殖业粪污治理与资源化利用工程是中英合作"华北乡村水环境项目"的延续.该项目利用厌氧-好氧生物处理技术对猪场排放污水进行处理,产生沼气用于村民生活燃料,同时采用有机肥制作,灌溉果园等措施实现污染物的"零"排放,在治理污染的同时,较好地实现了粪污的资源化利用,在养殖业污水治理模式的探索方面作了有益的尝试.     

Electron beam treatment of textile dyeing wastewater: operation of pilot plant and industrial plant construction.

A pilot plant for treating 1000 m3/day of dyeing wastewater with e-beam has been constructed and operated since 1998 in Daegu, Korea together with the biological treatment facility. The wastewater from various stages of the existing purification process has been treated with an electron beam in this plant, and it gave rise to elaborating the optimal technology of the electron beam treatment of wastewater with increased reliability for instant changes in the composition of wastewater. Installation of the e-beam pilot plant resulted in decolorizing and destructive oxidation of organic impurities in wastewater, appreciable reduction of chemical reagent consumption, in reduction of the treatment time, and in increase in the flow rate limit of existing facilities by 30-40%. Industrial plant for treating 10,000 m3/day each, based upon the pilot experimental result, is under construction and will be finished by 2005. This project is supported by the International Atomic Energy Agency (IAEA) and Korean Government.     

垂直流人工湿地系统保护饮用水源的实例

简述了复合垂直流人工湿地污水处理系统专有技术的由来,并结合石岩人工湿地一期工程叙述了垂直流人工湿地的工艺原理、技术特点、植物特点、处理效果等,结果表明采用垂直流人工湿地生态污水处理系统保护饮用水源,能达到污水净化和美化环境的“双赢”目标。     

我国城市污水处理厂污泥产沼气的前景分析

污泥厌氧消化具有稳定污泥和回收能量以及处理后污泥可作农肥的突出优点.我国城市污水处理厂污泥多,污泥厌氧消化的推广空间巨大.污泥厌氧消化推广的主要问题是规模较小、投资高、技术复杂、维修量大等,而沼气利用不理想大大削弱了该工艺的优势.必须降低投资、简化运行和提高沼气利用的效益,加速研究配套政策,才能改变投入高、产出低的现状,才能使污泥厌氧消化成为污泥处理的首选工艺.     

PTA废水生物处理工艺综述

PTA废水是由对二甲苯(PX)生产PTA过程中产生的排水。废水成分复杂,含大量芳香烃有机物,包括难降解有机物TA和甲基苯甲酸。分析了PTA废水中的芳香烃有机物好氧降解、厌氧降解机理以及TA降解机理。分析结果表明:芳香烃有机物好氧降解速率明显高于厌氧降解速。目前,对于PTA废水处理研究集中在好氧处理和厌氧处理工艺上,重点介绍了PTA废水厌氧、好氧及厌氧-好氧处理的几种工艺及其处理效果。综合投资、能耗、污泥量、操作、处理效率等多种因素,总结出PTA废水处理的最优工艺为厌氧-好氧处理工艺,常用工艺组合包括上旋流厌氧反应器+两级好氧、水解+A/O、两级A/O等。并讨论分析了重金属钴、锰,营养物质N,P,Mg,Fe等以及温度、pH对PTA废水处理效率的影响。同时,展望了PTA废水的研究发展趋势。     

城市污水处理厂节能水平评估标准探讨

以我国现行典型城市污水处理厂实际运行情况为依托,结合国内外经验成果,在筛选影响城市污水处理厂节能水平重要因子的前提下,初步提出采用打分形式对城市污水处理厂节能水平进行评估的设想,从而建立城市污水处理厂节能水平等级划分标准。     

Evaluation of rapid methods for in-situ characterization of organic contaminant load and biodegradation rates in winery wastewater.

Rapid methods for the in-situ evaluation of the organic load have recently been developed and successfully implemented in municipal wastewater treatment systems. Their direct application to winery wastewater treatment is questionable due to substantial differences between municipal and winery wastewater. We critically evaluate the use of UV-VIS spectrometry, buffer capacity testing (BCT), and respirometry as rapid methods to determine organic load and biodegradation rates of winery wastewater. We tested three types of samples: actual and treated winery wastewater, synthetic winery wastewater, and samples from a biological batch reactor. Not surprisingly, respirometry gave a good estimation of biodegradation rates for substrate of different complexities, whereas UV-VIS and BCT did not provide a quantitative measure of the easily degradable sugars and ethanol, typically the main components of the COD in the influent. However, our results strongly suggest that UV-VIS and BCT can be used to identify and estimate the concentration of complex substrates in the influent and soluble microbial products (SMP) in biological reactors and their effluent. Furthermore, the integration of UV-VIS spectrometry, BCT, and mathematical modeling was able to differentiate between the two components of SMPs: substrate utilization associated products (UAP) and biomass associated products (BAP). Since the effluent COD in biologically treated wastewaters is composed primarily by SMPs, the quantitative information given by these techniques may be used for plant control and optimization.     

Innovations in wastewater treatment: the moving bed biofilm process.

This paper describes the moving bed biofilm reactor (MBBR) and presents applications of wastewater treatment processes in which this reactor is used. The MBBR processes have been extensively used for BOD/COD-removal, as well as for nitrification and denitrification in municipal and industrial wastewater treatment. This paper focuses on the municipal applications. The most frequent process combinations are presented and discussed. Basic design data obtained through research, as well as data from practical operation of various plants, are presented. It is demonstrated that the MBBR may be used in an extremely compact high-rate process (<1 h total HRT) for secondary treatment. Most European plants require P-removal and performance data from plants combining MBBR and chemical precipitation is presented. Likewise, data from plants in Italy and Switzerland that are implementing nitrification in addition to secondary treatment are presented. The results from three Norwegian plants that are using the so-called combined denitrification MBBR process are discussed. Nitrification rates as high as 1.2 g NH4-N/m2 d at complete nitrification were demonstrated in practical operation at low temperatures (11 degrees C), while denitrification rates were as high as 3.5g NO3-Nequiv./m2.d. Depending on the extent of pretreatment, the total HRT of the MBBR for N-removal will be in the range of 3 to 5 h.     

寿光市城北污水处理厂改良型A~2/O反应池的启动与调试

寿光市城北污水处理厂一期工程处理能力为5万m3/d,以改良型A2/O反应池为核心处理单元,进水中约有60%为工业废水。改良型A2/O反应池的启动调试历时33d,调试结束时,活性污泥性状良好,CODCr、NH3—N、TP完全达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级B标准,反硝化作用明显。结果表明,在调试期间,污泥培养方式、内回流比、好氧池DO等对该污水处理厂改良型A2/O反应池处理能力影响比较明显。     

城市污水中污染物监测与分布规律探讨

为了明确城市污水中各种污染物质的分布规律,对典型城市二级处理出水中有机污染物、大肠杆菌、金属离子、浊度、色度等污染物进行了检测分析,在大量检测数据的基础上,通过概率纸检验和非参数假设检验等方法对污染物的分布规律进行了统计分析,发现二级处理污水中污染物在显著性水平α=0.10的条件下都服从或近似服从对数正态分布,从而可用对数正态分布函数对城市污水中污染物的出现频率进行量化描述,为水质模型的建立和运行提供基础资料.     

Technological transfer to demonstrative scale of sequencing batch biofilter granular reactor (SBBGR) technology for municipal and industrial wastewater treatment

The paper reports the results of an experimental investigation aimed at transferring to demonstrative scale an innovative technology (SBBGR-Sequencing Batch Biofilter Granular Reactor) for the treatment of municipal and industrial wastewater by financial support of the EU Life programme. When this technology was applied for treating municipal wastewater, the results showed that the system was able to remove 80-90% of COD, total suspended solids and ammonia independently of the hydraulic residence time investigated (i.e., from 12 to 4 h). In the case of tannery wastewater, chosen as representative of concentrated industrial wastewater, SBBGR technology was suitable for removing 80-90% of the COD, suspended solids and ammonia content up to organic loading values of 3.5 kg COD/m3.d. During both periods, the process was characterised by a very high sludge age value (theta(c) approximately 150 d) that led to a biomass concentration as high as 35 gTSS/L(bed) and a sludge production much lower (5-6 times lower) that than commonly reported for conventional treatment plants.     

济南市分散式污水处理站典型工艺及运行管理分析

以济南市政府投资建设的8座分散式污水处理站为例,介绍了两级生物滤池、ETS生态处理、KIC生物接触氧化3种典型工艺,分析了污水处理站的运行成本,提出了运行管理中的问题和建议。     

Occurrence of benzothiazoles in municipal wastewater and their fate in biological treatment.

A number of 2-substituted benzothiazoles that are known to be used as fungicides, corrosion inhibitors and vulcanization accelerators in industry have been analyzed in municipal wastewater and the effluents of activated sludge and membrane bioreactor (MBR) treatment over a three month period. All six analytes were regularly detected in the municipal wastewater by liquid chromatography-mass spectrometry and amount to a total concentration of 3.4 microg/L. Of these compounds benzothiazole-2-sulfonic acid (1,700 ng/L), benzothiazole (850 ng/L) and 2-hydroxybenzothiazole (500 ng/L) were most prominent. The source of the benzothiazole emission is yet unknown. Activated sludge treatment did not reduce total benzothiazole concentration significantly. Removals of the individual compounds ranged from 90% for 2-mercaptobenzothiazole and 70% for hydroxybenzothiazole to 40% for benzothiazole. The concentration of benzothiazole-2-sulfonic acid increased by 20%, whereas 2-methylthiobenzothiazole increased by 160% during activated sludge treatment, likely due to the methylation of mercaptobenzothiazole. Total benzothiazole removal in two parallely operated MBRs was significantly better (43%) than in the conventional activated sludge treatment. Namely benzothiazole and benzothiazole-2-sulfonic acid were more effectively removed. This first systematic study on the occurrence of benzothiazoles in municipal wastewater has shown that this is a relevant class of trace contaminants in municipal wastewater which is only incompletely removed in biological wastewater treatment. Emission from sewage treatment is dominated by the most polar benzothiazole-2-sulfonic acid. MBR treatment may reduce but cannot avoid this emission.