Optimization of operational factors of a membrane bioreactor with gravity drain.

A new membrane bioreactor with gravity drain for municipal wastewater treatment was tested and its operational factors were investigated in this study. These factors include pressure head, MLSS, aeration intensity (an air flow rate per unit floor area) and temperature. Results of batch experiments showed that a critical pressure head of the MBR was 0.85-1.5 m-H2O. At a pressure head of 0.85 m-H2O, statistical analysis of batch experiments showed that aeration intensity significantly affected membrane flux, and the MLSS had no impact on membrane flux under a temperature of 22.0 +/- 1.0 degrees C. Results of the long-term continuous experiment showed that temperature significantly affected membrane flux. The impact of temperature on membrane flux in this case was about 4-10 times of that analyzed by using a classical cake layer model. During this experiment, the average removal efficiencies of COD, BOD5 and NH4+-N were over 85%, 97% and 94%, respectively.     

NF/RO膜去除饮用水中药品的影响因素研究进展

药品是近几年在水体中普遍发现的痕量有机污染物,它对环境和人体健康带来的威胁受到了人们极大的关注.高压膜技术如纳滤和反渗透被认为是理想的药品去除方法.结合国内外的研究进展,重点阐述了纳滤和反渗透膜对药品去除效果的各种影响因素.     

PIV measurements in environmental flows: Recent experiences at the Institute for Hydromechanics in Karlsruhe

Particle-Image-Velocimetry (PIV) has been applied to many different environmental flows in the last twelve years at the Institute for Hydromechanics, Karlsruhe Institute of Technology. The present paper gives an overview about the most important results gained with PIV during this period and summarizes the advantages and disadvantages of this measurement technique. PIV applications to determine velocities at the water surface as well as internal flows characteristics are discussed with respect to physical and technical aspects. It can be concluded that PIV is still not a standard tool, every application needs adaptation and comprises certain limitations. Every element of the measurement system (window size, camera, spatial and temporal resolution, etc.) has to fit exactly the physical problem to be examined.     

川渝边界水域经营管理权争议调处的成功实践与思考

四川省、重庆市边界大洪湖地区因水域经营管理权争执,给两地带来了不稳定隐患,成为两地党委、政府十分重视的问题。2008年10月,四川省、重庆市水利部门和地方党委、政府．本着互谅互让、共筑和谐的精神,联合调处矛盾,妥善化解争议。维护边际稳定,使大洪湖重新成为连接两地友谊的纽带,受到两地群众的好评。     

Evaluation of a long-term operation of a submerged nanofiltration membrane bioreactor (NF MBR) for advanced wastewater treatment.

Nanofiltration (NF) is considered as one of the most promising separation technologies to obtain a very good-quality permeate in water and wastewater treatment. A submerged NF membrane bioreactor (NF MBR) using polyamide membranes was tested for a long-term operation and the performance of the NF MBR was compared with that of a microfiltration MBR (MF MBR). Total organic carbon (TOC) concentration in the permeate of the NF MBR ranged from 0.5 to 2.0 mg/L, whereas that of the MF MBR showed an average of 5 mg/L. This could be explained by the tightness of the NF membrane. Although the concentration of organic matter in the supernatant of the NF MBR was higher than that in the permeate due to high rejection by the NF membrane, the NF MBR showed excellent treatment efficiency and satisfactory operational stability for a long-term operation.     

Commissioning and operational experiences for the 160ML/d Woodman Point Sequencing Batch Reactor--control of settleability and denitrification using bioselectors.

Achieving and maintaining good biomass settling characteristics is a critical process design objective for any activated sludge wastewater treatment plant (WWTP), whether intermittent or continuous technology. One way of ensuring good sludge settleability in intermittent WWTPs is the incorporation of bioselectors in the process. A bioselector is essentially a small discrete reactor volume designed primarily for carbon absorption, in which activated sludge organisms are exposed to a high substrate concentration for a relatively short time. It is normally very much smaller than an anoxic zone and the activated sludge recycle is only a fraction of that typically adopted in continuous plants. With proper conditioning, recycled biomass rapidly absorbs and stores soluble organic wastewater components before transfer to the main treatment basin. This absorption and storage mechanism, and careful management of aeration throughout the intermittent treatment cycle, plays a crucial role in many subsequent growth and treatment processes, including sludge floc formation, denitrification and biological phosphorus removal. This paper examines some design considerations, and reviews the benefits of bioselectors by reference to the commissioning and initial operation of the new 160ML/d Woodman Point Sequencing Batch Reactor in Perth, Western Australia. The applicability of bioselectors in continuous plants is discussed.     

Exploring the potential of membrane bioreactors to enhance metals removal from wastewater: pilot experiences.

The potential of membrane bioreactors to enhance the removal of selected metals from low loaded sewages has been explored. A 1400 litre pilot plant, equipped with an industrial submerged module of hollow fibre membranes, has been used in three different configurations: membrane bioreactor, operating in sequencing batch modality, for the treatment of real mixed municipal/industrial wastewater; membrane-assisted biosorption reactor, for the treatment of real leachate from municipal landfills; continuously fed membrane bioreactor, for the treatment of water charged with cadmium and nickel ions. The results show that: (a) in treating wastewaters with low levels of heavy metals (< one milligram per litre concentration), operating high sludge ages is not an effective strategy to significantly enhance the metals removal; (b) Hg and Cd are effectively removed already in conventional systems with gravitational final clarifiers, while Cu, Cr, Ni can rely on a additional performance in membrane bioreactors; (c) the further membrane effect is remarkable for Cu and Cr, while it is less significant for Ni. Basically, similar membrane effects recur in three different experimental applications that let us estimate the potential of membrane system to retain selected metal complexes. The future development of the research will investigate the relations between the membrane effect and the manipulable filtration parameters (i.e., permeate flux, solids content, filtration cycle).     

Scale formation in NF/RO: mechanism and control.

Scale formation of soluble salts is one of the major factors limiting the application of nanofiltration (NF) and reverse osmosis (RO) membranes. This article reviews the scale formation mechanisms in membrane systems, methods to retard scale formation, and a new hybrid system consisting of MF-NF/RO. Two distinct mechanisms in NF/RO fouling by scale formation including surface and bulk crystallization have been identified and investigated. The hydrodynamic operating conditions as well as module geometry determines which fouling mechanism is dominant. An increase in solute concentration at the membrane surface by concentration polarization is responsible for surface crystallization. Conventional methods for scale control only retard the rate of scale formation and their performances are unpredictable. On the other hand, using a MF-NF/RO hybrid system for continuous removal of crystal particles from the retentate stream appears to be effective at high recovery of permeate. When applying the MF-NF/RO hybrid system, substantial improvement in flux is observed in spiral wound module, whereas it is negligible in case of the tubular module. This is because the microfilter could only removes crystals formed in the retentate through the bulk crystallization that is the dominant fouling mechanism in the spiral wound module.     

三峡水库2007年运行调度分析

2007年是三峡工程初期运行期的第一年,也是工程综合效益全面发挥的第一年。枯水期,三峡水库实施流量补偿调节,满足了通航要求;汛期,根据防总防洪调度指令实施调节,保护长江中下游的安全。     

Comparing the effluent organic matter removal of direct NF and powdered activated carbon/NF as high quality pretreatment options for artificial groundwater recharge.

Direct nanofiltration and nanofiltration combined with powdered activated carbon known as the PAC/NF process were tested regarding the removal of effluent organic matter for reclamation of tertiary effluent from a municipal wastewater treatment plant. They can be regarded as a promising treatment alternative for high quality water reuse applications, especially for direct injection. The total removal for DOC was above 90% with permeate concentrations below 0.5 mg/l. Size exclusion chromatography and fluorescence EEM proved to trace origin of the organic matter even in low concentration ranges. The type and dosage of adsorbent influences the process performance significantly and allows process optimization.     

Recent Introductions of the Ruffe (Gymnocephalus cernuus) to Coregonus and Perca Lakes in Europe and an Analysis of Their Natural Distributions in Sweden and Finland

Although the ruffe (Gymnocephalus cernuus) is native to many parts of Europe, its distribution has recently increased through accidental introductions. This synthesis reviews this situation and perceived possible consequences for Coregonus spp. and Eurasian perch (Perca fluviatilis), presents case histories from Lake Constance and Bassenthwaite Lake, and examines natural distributions of ruffe, Coregonus spp., and perch in northern Europe. In Lake Constance, a large mesotrophic lake in central Europe supporting whitefish (Coregonus lavaretus) and perch fisheries, the ruffe was first recorded in 1987 and now occupies many areas, feeding extensively on the eggs of inshore-spawning whitefish. In contrast, Bassenthwaite Lake is a small eutrophic U.K. lake without commercial fisheries, but containing perch and vendace (Coregonus albula), where the ruffe was first recorded in 1991 and is now widespread. Although predation by ruffe on vendace eggs was not recorded during spawning in late 1995, it was in late 1996. Vendace and perch populations have shown no marked changes between 1991 and 1996, but the cyprinid roach (Rutilus rutilus) has declined. Among 705 lakes in Sweden, differences were found in the features of lakes in which ruffe occur allopatrically and sympatrically with vendace, white-fish, and perch, but nevertheless such coexistence was found in 59, 37, and 210 lakes, respectively. In Finland, ruffe were found to inhabit 427 of 710 lakes, including many in which they coexisted with vendace, whitefish, and perch. Factors influencing the distribution of ruffe in Finland included lake size, acidity, trophic status, hypolimnetic anoxia, and availability of spawning substratum.     

一体式膜生物反应器膜污染防治理论研究

从理论上分析了一体式膜生物反应器内曝气量与污水流量、反应器设计高度、主副腔过流面积的关系,膜外污染错流临界流速与抽吸压力及主腔宽度的关系,膜管内污染的临界速度与膜管径、膜壁吸力的关系,并得出采用化学方法消除膜污染的原理。     

Efficiency of RO/NF membranes at the removal of veterinary antibiotics

The production of pharmaceuticals has increased rapidly during the last several decades as they have been used for the health of both humans and animals. Routes of environmental exposure include the release of treated wastewater, the land disposal of livestock manures and municipal biosolids (i.e. sewage sludge), as well as the use of medicated aquaculture feed. This study deals with application of reverse osmosis (RO) and nanofiltration (NF) membranes for removing of antibiotic residues (sulfamethoxazole, trimethoprim, ciprofloxacin, dexamethasone and febantel) and their mixture. According to the results obtained in this work the use of RO (LFC-1 and XLE) and the tight NF (NF90) membranes are recommended to achieve a high level of retention (>95%) of all selected veterinary antibiotics (VAs). Nanofiltration NF270, NF and HL membranes showed a lower rejection of individual components, but much higher in a mixture solution, due to the synergistic effect.     

欧洲洪水风险图编制经验的启迪

从洪水风险图发展历程看,欧洲与我国比较相似,洪水风险图的起步时间比较接近,目前也都处在一个大的发展阶段.本文从洪水风险图的发展背景、洪水风险图的种类、洪水分析计算方法、洪水风险图的制作单位和运用方式等多个方面阐述了欧洲的主要做法,对比了与我国洪水风险图编制工作的异同.为进一步适应我国洪水风险管理工作的需要,建议我国尽早开展洪水危险等级划分标准的研究以及包含风险信息的洪水风险图绘制工作,规范参与洪水风险图绘制的洪水分析计算工具,进一步明确洪水风险图的角色和使用方法等问题.     

水文学研究与进展

水文学是水利水电工程建设与管理的一门基础学科．主要研究自然界水的运动变化，包含涉及地球水圈～生物圈～大气圈各种尺度的水文循环过程及其对自然环境和人类社会影响的相互作用关系．自然界中发生的洪水与干旱灾害及全球变化影响、与人类生存社会经济可持续发展有密切联系的水资源水环境等“水”的问题，是水文学研究与应用的主要对象．对近年来国际水文科学的研究与进展进行了概述，其中包括有关全球变化研究、流域水文模拟和洪水预报预警系统、水的问题和社会可持续发展等专题，并提出了几点认识和体会．     

山口水利枢纽工程施工的几点经验

山口水利枢纽土建工程,实施了以设计为主体的总承包制,施工中积累了一定的勘测、设计、采购、施工等全过程总承包管理经验,取得了较大的经济效益及社会效益,实现了建设工程“三大控制“的最优预期效果.     

Selection of operational strategies in activated sludge processes based on optimization algorithms

This paper presents a new optimization algorithm for the selection of design and operation parameters in complex Activated Sludge (AS) processes. The algorithm estimates automatically the dimensions and operating point of the plant that minimize a global penalty function combining effluent requirements and costs. The mathematical optimization is based on a direct search algorithm integrated in a previously developed simulation package.Some illustrative examples concerning the design and operation of the Alpha process have been included to show the potential of this kind of mathematical tool when the complexity of plant configuration increases. The results obtained by the optimization procedure generate useful guidelines for the design and operation and suggest a great potential in the application for solving more complex problems when additional objectives and costs are included.     

宝鸡峡水库运行方式研究

分析了渭河的水沙持性 ,宝鸡峡枢纽的工程概况 ,通过对宝鸡峡水库运行方式的试验研究和计算分析研究 ,推荐了优化的运行方案     

中央水利经营性资产效绩评价工作探讨

开展中央水利企业经营性资产效绩评价是评价水利部部属事业单位所属企业业绩和效率的一项新制度.这项制度的建立,对于科学评价水利国有企业的经营效绩、完善水利企业经营性资产的监管和促进国有企业的改革具有十分重要的意义.针对此项工作在开展中存在的问题,提出了建议.