Seawater intake facilities are basically classified into three types, including beach well intake, subsurface water intake and open sea water intake. This paper will consider the seawater intake technology options available for desalination plants, and will review the technologies employed to provide a reliable quantity of seawater at the best quality available.
1. Beach Well Intake
Beach well intake means that seawater out from intake well constructed as close to the coastline as possible is filtered by seabed as the water source of desalination plant. This kind of seawater is especially attracted by seawater desalination reverse osmosis plant with the advantages of low turbidity and good quality due to particles in sea water are trapped from natural filtration. Seawater desalination intake project is the vital part of desalination plant, which is to ensure that sufficient, consistent and reliable feed water can be delivered for seawater desalination plant within the entire lifetime. The intake facilities and construction of intake structure both have important impact on seawater desalination plant investment, production cost, system operation stably and ecological environment. Investment of seawater desalination, scale of construction, and process for water quality requirements should be taken into consideration while developing intake projects. At the same time, water intake and its facilities are selected based on hydrology water quality in intake area, geology conditions, meteorological data and natural disaster.
2. Subsurface Water Intake
The deep seawater of open ocean is delivered to the shore-side through building intake pipes and then supplied to desalination project by pump plant constructed in the coastline, this is called” subsurface water intake”. Generally speaking, when sea level below 1~6m, intake water contains small fish, water grass, seaweed and other microorganism, thus water quality is not good. The content of these materials is 20 times reduction when intake level is above beneath sea level 35m, and water quality is good, which can greatly reduce the operating cost of the pre-treatment equipment. Meanwhile, water temperature in subsurface is lower, benefit to thermal seawater desalination process. This kind of intake is usually adopted on areas where seabed is quite precipitous, which is within 50 m from the coast and water depth up to 35 m.
3. Open Sea Water Intake
Open sea water intake is the most common intake project. Although its water quality not good, it is still widely adopted due to advantages of small investment, wide application range and full application experience.
Intake facilities for seawater desalination project are basically classified into the above three types, including beach well intake, subsurface water intake and open sea water intake. Good-quality raw water can be delivered by beach well intake, thereby it reduces investment and the operating cost of the pre-treatment equipment, nevertheless it should be taken marine geological structure, hydrology water quality and water quality unstable factors when operating into consideration, and confirmed after looking into in-depth investigation. Subsurface water intake is capable of delivering quite good water, but this kind of intake is probably less adopted because of its large investment and complicated construction. Open sea water intake-a kind of more popular intake method, can be used for different seawater desalination projects.
While designing seawater intake project, We should comprehensively take corrosion of metallic materials in seawater, sea creatures and the influence of tides into consideration.