Research Progress of Brackish Water Desalination by Reverse Osmosis

Brackish water (BW) desalination is a primary path to relieve the shortage of water. As one of the BW desalination methods, reverse osmosis (RO) technology has advantage for both technology and process procedure. The expounding of this research studied or reviewed recent years, reverse osmosis membrane, energy recovery, new energy and application technology in BW desalination of RO at home and abroad. Wind power and solar energy can be combined with energy recovery device for RO. The research also explains that BW desalination by RO is practical and feasible in some areas in China.

Sustainable Application of a Novel Water Cycle Using Seawater for Toilet Flushing

Global water security is a severe issue that threatens human health and well-being. Finding sustainable alternative water resources has become a matter of great urgency. For coastal urban areas, desalinated seawater could serve as a freshwater supply. However, since 20%-30% of the water supply is used for flushing waste from the city, seawater with simple treatment could also partly replace the use of freshwater. In this work, the freshwater saving potential and environmental impacts of the urban water system （water-wastewater closed loop） adopting seawater desalination, seawater for toilet flushing （SWTF）, or reclaimed water for toilet flushing （RWTF） are compared with those of a conventional freshwater system, through a life-cycle assessment and sensitivity analysis. The potential applications of these processes are also assessed. The results support the environmental sustainability of the SWTF approach, but its potential application depends on the coastal distance and effective population density of a city. Developed coastal cities with an effective population density exceeding 3000 persons.km-2 and located less than 30 km from the seashore （for the main pipe supplying seawater to the city） would benefit from applying SWTF, regardless of other impact parameters. By further applying the sulfate reduction, autotrophic denitrification, and nitrification integrated （SANI） process for wastewater treatment, the maximum distance from the seashore can be extended to 60 km. Considering that most modern urbanized cities fulfill these criteria, the next generation of water supply systems could consist of a freshwater supply coupled with a seawater supply for sustainable urban development.

Enhancement of freshwater production of the seawater greenhouse condenser

Seawater greenhouse(SWGH)is a technology established to overcome issues related to open field cultivation in arid areas,such as the high ambient temperature and the shortage of freshwater.It adopts the humidification-dehumidification concept where evaporated moisture from a saline water source is condensed to produce freshwater within the greenhouse body.Various condenser designs are adopted to increase freshwater production in order to meet the irrigation demand.The aim of this study was to experimentally investigate the practicality of using the packed-type direct contact condenser in the SWGH to produce more freshwater at low costs,simple design and high efficiency,and to explore the impact of the manipulating six operational variables(inlet air temperature of the humidifier,air mass flowrate of the humidifier,inlet water temperature of the humidifier,water mass flowrate of the humidifier,inlet water temperature of the dehumidifier and water mass flowrate of the dehumidifier)on freshwater condensation rate.For this purpose,a direct contact condenser was designed and manufactured.Sixty-four full factorial experiments were conducted to study the effect of the six operational variables.Each variable was operated at two levels(high and low flowrate),and each experiment lasted for 10 min and followed by a 30-min waiting time.Results showed that freshwater production varied between 0.257 and 2.590 L for every 10 min.When using Minitab statistical software to investigate the significant variables that contributed to the maximum freshwater production,it was found that the inlet air temperature of the humidifier had the greatest influence,followed by the inlet water temperature of the humidifier;the former had a negative impact while the latter had a positive impact on freshwater production.The response optimizer tool revealed that the optimal combination of variables contributed to maximize freshwater production when all variables were in the high mode and the inlet air temperature of the humidifier was in the low mode.The comparison between the old plastic condenser and the new proposed direct contact condenser showed that the latter can produce 75.9 times more freshwater at the same condenser volume.

Study on the Exploitation of Bohai Sea Ice as Freshwater Resources

Water shortage is a major issue in northern China. With the transfer of China＇s economic center from south to north, Circum-Bohai Economic Circle has gradually formed and developed as the third pole of China＇s economy after Yangtze River Delta and Pearl River Delta, the problem of water has inevitably become more and more serious. South-to-North Water Diversion and Sea Water Desalination are helpful to solve this dilemma, but some difficulties appeared during the course of the two projects. By contrast, sea ice desalination can be considered as a third way to alleviate freshwater crisis in Bohai Rim. Firstly, the amount of sea ice in Bohai Sea is as much as 1.27 billion m3 even in normal years. Then the salinity of sea ice is only 1/4 to 1/7 as that of sea water. And furthermore, desalinized water of sea ice can meet national water quality standard for drinking. Purposely use the abundant sea ice resources as water source for industry, agriculture and living is very likely to open a new path for the solution of freshwater shortage, which can promote rapid and healthy development of Circum-Bohai Economic Circle.

An Overview of Conventional and Non-Conventional Water Resources in Arid Region: Assessment and Constrains of the United Arab Emirates (UAE)

The aridity, population growth, agriculture and industrial activities threaten the water resources in the United Arab Emirates (UAE). In UAE, groundwater quantity is reduced and its quality is also deteriorated due to the scanty of rainfall and over pumping for different uses. The deficit of groundwater is met by desalinated water and reused of treated wastewater. Agricultural activities have negative impacts on water resources and this causes reduction of groundwater quality as the agriculture the main land use in the UAE and it accounts for more than 70% of groundwater use. The treated wastewater is an alternative source for agricultural activities. To improve the current water situation, a national water resources strategy has been prepared and imple-mented to assist in achieve this target and maintain the country’s water security. This paper intends to give an overview of water resources in the UAE with emphasis on challenges facing the management of these resources.

Performance Evaluation and Design of RO Desalination Plant: Case Study

The aim of this paper is to design a water desalination plant using Reverse Osmosis membrane to treat salt water to be usable for drinkable, domestic, industrial or agricultural uses. RO unit is designed to conservative standards for versatility in the event of feed water quality variations. The design includes a feed water flush cycle to minimize membrane fouling and piping corrosion during shutdown. The system will be all appropriate controls and instrumentation for automatic operation. All system components are available and of heavy duty industrial design and fabricated with the highest quality workmanship. Quality control will be maintained throughout all manufacturing processes. The system will produce permeate water minimum of 3600 m3/day with a quality of approximately 100 ppm total dissolved solids (TDS) when operating on well feed water with a 10,000 ppm TDS and a temperature of 25 - 30 degrees C. The design permeate recovery is 50%;and energy recovery device which saves $30,556.28/year.

Performance of Nanofiltration (NF) and Low Pressure Reverse Osmosis (LPRO) Membranes in the Removal of Fluorine and Salinity from Brackish Drinking Water

Certain areas in Senegal have a serious problem of high fluoride and salinity in underground water because of soil properties. This water currently used for drink has a bad taste on consumption and caused diseases like dental fluorosis and skeletal fluorosis. A membrane filtration plant constructed by Pall Corporation was improved through nanofiltration (NF) and Low Pressure Reverse Osmosis (LPRO). Both NF and LPRO membranes were shown applicable for salinity and fluoride ions removal from brackish and high fluorinated drinking water in a remote community. The NF membrane has given a fluorine retention rate varying between 63.3% and 71% while the LPRO membrane allow to reach 97 to 98.9% for fluorine rejection. Highest salinity rejection rates expressed through conductivity measurements are around 46% and 97% for respectively NF and LPRO.

The Stady of Legislation on the Utilization of Domestic Sea Water

The contradiction between shortage of water resource and lack of legislation for using seawater as domestic water was revealed. We started our work from present situation of legislation for using seawater as domestic water. Necessity and feasibility of legislation for using seawater as domestic water were explored which contribute to the healthy development of domestic seawater industry.

京津冀平原非常规水资源利用前景分析及其生态环境效应

[研究目的]京津冀平原水资源严重短缺,供需矛盾十分突出,加大非常规水资源利用力度,形成多元供水格局,可有效缓解水资源供需矛盾,对支撑京津冀协同发展区社会经济协调发展和推动生态文明建设具有重要意义。[研究方法]文章系统开展非常规水资源供水方向、开发利用模式和供水规模分类数据统计,依据各省(直辖市)非常规水资源供水规划及配置目标,分析其开发利用前景及其生态环境效应。[研究结果]该区非常规水资源主要包括微咸水、再生水、淡化海水、雨洪水,其中微咸水主要分布于中东部平原的天津、沧州、衡水等地,供水前景为5.43×10^(8)m^(3);再生水利用以北京、天津等大中型及工业城市为主,供水前景为34.22×10^(8)m^(3);淡化海水利用以天津等滨海城市为主,供水前景为4.19×10^(8)m^(3);雨洪水利用较分散。[结论](1)微咸水用于农业灌溉存在土壤盐渍化风险,需加强水盐调控。(2)再生水用于河流生态补水,沿线地表水富营养化,地下水体未受到明显污染;地下水浅埋区开展再生水灌溉,会增加硝酸盐污染风险;建议将高风险的新兴污染物纳入再生水利用监控体系。(3)海水淡化尾液浓盐水、冷却热水可能改变天然海洋生态系统的分布、构成与多样性,应予以关注。(4)雨洪水利用可降低污水入河的水质风险,但过度利用可能影响区域生态系统的稳定性,建议城市区适度扩大利用。

基于响应面法的微咸水反渗透脱盐工艺优化

为应对淡水资源短缺,提高微咸水反渗透工艺的处理效果,设计了一种单级多通道低压反渗透(RO)中试装置,采用Box-Behnken响应面分析法(RSM)建立了微咸水RO淡化过程的模拟和优化模型.在不同的进料浓度,进水流量和浓淡水比例等工艺参数条件下,考察了系统的盐截留率和膜通量,分析和计算了系统的评价系数和单位能耗(SEC).结果表明,进料浓度和浓淡水比例是影响盐截留率的显著因素.低进料浓度、较高进水流量并不能显著提高盐截留率,反而会增加设备的单位能耗.在5000mg/L进料浓度的条件下,控制进水流量258.02L/h,浓淡水比例1.39时,脱盐效果最佳,评价系数达到10.58L/(m^(2)·h),单位能耗相对最低为5.15(kW·h)/m^(3).所建的RSM模型能够较好地模拟微咸水反渗透脱盐的过程,SEC预测精度良好,R^(2)值达到0.9925,盐截留率模型误差RMSE仅为0.36.RSM模型可以用于优化不同进料浓度下的操作条件,指导反渗透脱盐工艺的长期高效运行.

电容去离子水处理技术的研究和应用进展

随着水资源短缺、能源紧张等问题的日益加剧,高效低耗的电容去离子(CDI)脱盐技术逐渐得到广泛重视。然而,CDI技术现在仍处于研究和发展的初期阶段,并未在工业界广泛应用。本文结合CDI技术现有的应用进展,首先介绍了CDI技术的电极材料和装置构型,并指出各类电极材料和装置构型在应用中面临的挑战。然后,综述了全球现有CDI公司的发展现状及CDI技术的应用领域,对CDI技术在循环冷却水处理、市政生活废水回用等领域的应用进行了具体分析,并对应用中浓盐水排放问题进行了进一步分析讨论。最后,对CDI技术在水处理应用中的挑战进行归纳并对发展趋势进行了展望。

海水垂向入侵问题研究进展

随着全球气候变暖,风暴潮在沿海地区的频率和强度均可能增长,由此引发的海水垂向入侵可能会造成大面积的含水层淡水咸化。同时,由人类活动引起的沿海虾塘咸水养殖规模日益增长,由此引发的咸水垂向入侵可能会导致沿海地区地下水水质及生态环境的恶化。虽然已有一部分学者在海水(咸水)垂向入侵的研究中取得了成果,但由于海水(咸水)垂向入侵过程复杂,其对地下水咸化及恢复规律依然有待深入研究。文章阐述了海水垂向入侵的危害及前人的研究办法,总结了他们的研究成果并得出了海水垂向入侵的影响因子,指出了洪水和养殖活动对沿海地区含水层的威胁。得出的结果如下:研究海水垂向入侵常用的方法包括室内试验和数值模拟;海水垂向入侵主要与地形地貌、含水层性质和水文气象条件有关;虾塘养殖等人类活动可能会成为垂向咸水入侵的潜在来源。建议未来在海水垂向入侵研究中将多种现场观测实验方法结合起来。数值模拟应注重与现场观测实验数据相互验证,模型简化的方式有必要仔细考虑。虾塘养殖等人类活动可能造成的垂向咸水入侵问题应更多地受到关注。

磁化微咸水对南疆盐渍土壤水分入渗及盐分淋出特征的影响

为探究磁化微咸水灌溉对南疆盐渍土入渗及盐分离子迁移特征的影响,采用恒定磁场强度400 mT对矿化度分别为0、2、3、5 g/L微咸水进行磁化处理,以未磁化处理为对照,对比分析各处理累积入渗量、湿润锋运移距离和淋洗后不同土壤剖面总盐、脱盐率、盐分离子和SAR的影响规律。结果表明:磁化微咸水入渗减小了相同时间内的累积入渗量和湿润锋深度,降低了Philip入渗模型吸渗率,土壤含水率比未磁化微咸水提高5.00%~6.29%;磁化处理显著降低了土壤含盐量,对0~50 cm土壤内总盐含量磁化处理较未磁化降低11.79%~41.64%,在同一磁化强度下,土壤含盐量随矿化度的增加而增加,脱盐率随矿化度的增加而降低。在同一矿化度下,磁化处理含盐量低于未磁化处理,脱盐率高于未磁化处理。磁化微咸水灌溉有利于降低土壤中盐分离子含量,0~50 cm土层K^(+)、Na^(+)、Ca^(2+)、Mg^(2+)、HCO_(3)^(-)、Cl^(-)、SO_(4)^(2-)含量磁化较未磁化处理降低16.90%~25.97%、43.62%~64.68%、11.15%~31.44%、-8.12%~49.07%、-74.14%~13.43%、21.46%~52.81%、6.66%~13.10%。磁化微咸水灌溉处理显著降低0~50 cm土层深度处土壤SAR。

苦咸水淡化处理研究进展

在我国一些干旱缺水地区,苦咸水是该地区仅有的可利用的水资源,因此苦咸水淡化成为了解决干旱地区域缺水的重要途径。为更系统的了解目前苦咸水淡化处理工艺及其流程,本文综述了近年来国内外苦咸水淡化处理技术和工艺流程,系统地总结了各处理方法的优缺点,并对未来苦咸水淡化技术的研究方向进行展望。

透平式能量回收一体机水润滑转子稳定性研究

为了保障膜法海水淡化系统中透平式能量回收一体机的稳定运行,对一体机水润滑转子的稳定性展开研究。基于流体动压滑动轴承理论,同时考虑水润滑轴承和口环间隙水膜的流体动压润滑效应,在MATLAB平台上利用有限差分法、扰动增量法求解雷诺方程,得到水润滑滑动轴承及口环的动力特性系数,并对水润滑转子系统的动力学特征方程进行求解,进而判别转子系统的稳定性,研究了临界状态下系统转速与质量的关系。结果表明:口环间隙水膜的承载力在转子稳定性分析中不可忽略,否则将产生较大误差;考虑口环产生的动压润滑效应后,滑动轴承处水膜压力约减小40%,系统动力特性系数增加,系统的临界转速相较仅考虑滑动轴承时提升了3 000 r/min,临界质量提升了8.4%;滑动轴承的主刚度系数与交叉阻尼系数受转速的影响明显高于口环处。研究结果为提高海水淡化一体机水润滑转子系统的可靠性提供了参考。

MXenes/多糖复合材料在水处理方面的研究进展

总结了近五年来MXenes/多糖复合材料在水处理方面的研究进展。简要介绍了MXene的制备方法。接着根据形态不同,对水处理中的MXenes/多糖复合材料进行了分类,介绍了其制备工艺。讨论了MXenes/多糖复合材料在水体净化、水油分离和海水淡化三方面的应用研究情况。对MXenes/多糖复合材料的发展前景和挑战进行了展望。研究对进一步设计高效水处理MXenes/多糖复合材料具有重要参考价值。

菱形流道对流动电极电容去离子脱盐性能的影响

流动电极电容去离子(FCDI)作为一种新兴的除盐技术,具有理论无限吸附和适用于高浓度盐水除盐的优势。但是,在FDCI系统运行过程中,流动电极在蛇形流道内很容易出现颗粒聚集和沉降,使脱盐率降低甚至出现堵塞流道问题。设计菱形流道并应用于FCDI系统,利用流态模拟分析菱形流道内流态,以选择适宜的流道结构来避免低速区和颗粒聚集区的形成。模拟结果表明,菱形L2流道内导流体的引入大幅度地降低了流道内的低速区并改善了颗粒沉积情况。此外,脱盐实验结果表明,在高含盐量(16 g·L^(-1))下,菱形L2流道FCDI系统依然能获得较高的脱盐性能。

水资源对我国绿氢产业的影响分析

[目的]文章旨在研究分析我国水资源对绿氢产业发展的影响,揭示水资源与绿氢产业发展之间的矛盾,分析绿氢产业未来发展趋势,为我国可再生能源制氢项目发展布局提供有益参考。[方法]为了证明水资源会在“三北”等地区限制我国绿氢产业发展,结合实地调研情况和文献材料,从水资源政策、传统化工产业用水和制氢技术等角度进行分析论证。[结果]分析结果表明,在我国水资源相关政策限制下,绿氢产业布局应考虑水资源的制约,大规模制取绿氢以及绿氢对化石能源制氢替代,并不能有效节水,反而会促进化工产业用水量增加;在水资源制约下,我国绿氢产业发展须从全局用水角度考虑布局,并要充分结合既有化工产业的发展趋势,同时应考虑海水等可利用的丰富资源。[结论]我国绿氢产业发展不应忽略了既有政策框架、技术水平、产业布局和既有资源特性的问题,布局绿氢项目时,应充分考虑现状和未来趋势,从全局谋划、产业协调发展、资源有效利用等角度考量,解决水资源对绿氢产业的限制问题。

新型热泵增湿除湿海水淡化系统性能研究

为解决增湿除湿海水淡化技术高能耗问题,提出了一种新型热泵增湿除湿海水淡化系统,将热泵蒸发器用作二级除湿器,并增设过冷器对深度除湿后的空气进行复温。选用R134a为热泵工质,通过数学模型的建立与求解,分析讨论了制冷剂充注量、进料海水温度和液气质量比对系统性能的影响,并与现有文献中的热泵增湿除湿海水淡化系统性能进行对比。结果表明,系统存在最佳的制冷剂充注量、进料海水温度和液气质量比;当进料海水流量为720 kg/h时,最佳制冷剂充注量为240 kg/h,对应的最佳淡水产量和造水比分别为28.83 kg/h和7.21,均优于文献报道值,表明新系统具备实际产品开发的价值和广阔的应用前景。

混合电容去离子技术及法拉第电极材料研究进展

介绍了混合电容去离子技术的基本原理,并简要回顾了发展历程;从混合电容去离子的原理和现状分析,认为混合电容去离子技术的研究关键在于电极材料,依次介绍了过渡金属氧化物、聚阴离子型化合物、普鲁士蓝类似物等法拉第电极材料的研究现状,提出现阶段的研究重点仍是提高电极材料的脱盐能力和循环稳定性,并对混合电容去离子技术未来的发展方向进行了展望。