地下取水系统在海水淡化工程中的应用

Application of Subsurface Water Intake System in Seawater Desalination Projects

海水淡化已经成为解决世界滨海地区城市和生活用水短缺的重要手段,地下取水系统是海水淡化工程的重要组成部分,在提供充足和稳定的水源方面发挥了非常重要的作用。为了提升中国海水淡化工程地下取水技术水平,在参阅大量文献基础上,首先对地下取水系统的类型进行了介绍;然后,以反渗透海水淡化工艺为例,采取个例分析、数据挖掘再加工、环境影响分析和归纳总结等方法,对地下取水系统的优劣势进行了分析;最后,就地下取水系统对不同海岸地貌的适应性以及地下取水设施的投资和运行成本进行了分析。结果表明:①地下取水系统相比开敞式地表海水取水系统,具有消除海洋生物撞击和夹带、去除藻类和一些有机物、净化改善水质、替代或部分替代海水淡化预处理等优势;②地下取水设施因选址、建设和地下水开采运行等因素,也可能存在破坏海滩地貌形态,导致近岸海洋栖息地环境变化,引起滨海敏感地区海水入侵和地下取水水质污染等问题;③地下取水系统对不同海岸环境的适应性,不仅取决于海岸地貌类型,还取决于海洋水文及海岸带水文地质条件;④地下取水系统相比地表海水取水系统具有较强的优势,不同类型地下取水系统的投资费用取决于取水工程的建设规模、取水量以及取水构筑物和管材等多种因素。目前,海水淡化地下取水系统研究尚不充分,未来一方面要加强组合式地下取水设施及取水口设计的创新性研究,另一方面要注重海水淡化地下取水的海岸海洋环境效应尤其是生态环境效应的研究。

Seawater desalination has being become a reliable solution to the shortage of urban and domestic water in the coastal areas around the world.As an integral part of the desalination process,subsurface water intake system is different from the direct seawater intake system,which refers to the water facilities that taking salty water from beaches,coastal aquifers or submarine mediums,playing an important role for providing adequate and consistent flow of feed water.Unfortunately,there is little research and application on subsurface water intake system of seawater desalination in China.In order to fill the knowledge gap and promote the related subsurface water intaking technologies in China,the types of the subsurface water intake systems was firstly introduced based on the review of many literatures.Secondly,taking the reverse osmosis process as an example,the advantages and disadvantages of the subsurface water intake system were discussed by some cases,data mining and reprocessing,environmental impact and systematic summaries.Finally,adaptive assessment of subsurface water intake system for different coastal geomorphology was analyzed,as well as the investment cost of subsurface water intake system.The results show the following understandings:①comparing with the open-ocean intakes for seawater reverse osmosis desalination,the alternative subsurface water intake system can offer the advantages for eliminating the impingement and entrainment,removing algae and some organic matters,purifying and improving raw water quality,completely or partly replacing seawater desalination pretreatment;②due to inappropriate site selection,irregular construction and groundwater exploitation operations,the subsurface water intake system may also cause some issues such as changes in the original beach morphology,threats to coastal marine habitats and induction of saltwater intrusion and intake water pollution in sensitive coastal areas;③subsurface water intake system is adaptive to coastal environment,which depends not only on coastal geomorphology,but even more on the nearshore hydrologic and hydrogeological conditions,especially the hydraulic properties of coastal aquifers;④the investment and operation costs for the subsurface water intake system have strong advantages over the surface water intake systems,of which the investment cost depends on the factors such as water intake capacity,building scales,infrastructure structures and construction materials.Due to the limitations in research at present,it is necessary to strengthen the joint water intake facilities and the innovative intake design,and in the meantime,it should be more focused on coastal and marine environmental effects,especially the ecological environmental effects on the subsurface water intakes of desalination in the future.