The seawater desalination plant process is to convert sea water into fresh water. Firstly seawater(raw water) is delivered by intake pump and sent into desalination plant. Then raw water is pre-treated before entering into SWRO system for there is much impurities in sea water, meeting requirements on RO feed water.

SWRO plant is basically composed of the following systems, including intake system, pre-treatment system, seawater desalination RO system, energy recovery device, chemical dosing system, clean-in-place(CIP) system and PLC controlling system. Here we are going to review each system in details, wish you can get what you want from this paper!

1.Seawater Intake System

This seawater intake system is to deliver sea water into SWRO plant. There are different kinds of intake methods based on hydrology water quality in the intake area, geology conditions, meteorological data and natural disaster, such as Beach Well Intake, Subsurface Water Intake, and Open Sea Water Intake, etc.

2.Pre-treatment System

Inorganic suspended solids, sand, oil, clays, bacteria, and dissolved organic matters are susceptible to foul the reverse osmosis (RO) membranes. Required to conduct a good-quality pre-treatment process plays an important role in the operation of a seawater reverse osmosis (SWRO) plant, in order to prevent the fouling of RO membrane. KYsearo seawater desalination plants usually adopt these pre-filters, including multi-media filter, activated filter, 10um and 5um precision security filters. Please check How Multi Medium Filter Works in Desalination Systems.

  • The multi-media filter and activated carbon filter filled with refined quartz sand and cocoa-nut activated carbon respectively is to remove suspended solids, colloid particles, residual chlorine, microorganism, odor and other particles in raw water. The coagulant is added by dosing pump before raw water entering into the multimedia filter. Then flocculus formed by coagulant and colloids is removed through the filter, meeting the requirements on RO feed water (SDI15?5, turbidity?1NTU).
  • To prevent the particles in raw water and pipes from entering into HP pump and RO module, two security filters are selected one after another as RO pre-treatment. The precision of 2 sets of filters is 5?m and 1?m respectively. Under normal working conditions, filter elements should be changed in time when the pressure difference between inlet and outlet of the filter is above 1 bar. Filter structure can allow changing filter element rapidly.

3.Seawater Desalination RO System

RO system uses the semi-permeable membrane to remove organic material, colloidal particles, a bacterium from the feed water, producing desalinated fresh water. The semi-permeable membrane separates water and salt solution, water would permeate for the salt solution side under the osmotic pressure. If certain pressure larger than osmotic pressure is applied to the salt solution, water would permeate in the opposite direction. This phenomenon is called reverse osmosis. RO permeate is purified, removing 98% TDS from the feed water. RO brine is concentrated with TDS about two times of the feed water.

 4.Energy Recovery System

The function of Energy recovery device is to reduce energy consumption and cost by recycling and reusing the pressure energy from RO system high pressure concentrated seawater. Energy Recovery Device (ERD) is the key to energy-saving in the operation of any seawater reverse osmosis (SWRO) desalination products, in which PX Pressure Exchanger device is the most efficient solution available today and can reduce the energy consumption of seawater reverse osmosis (SWRO) systems by up to 60 percent.

Kysearo designs high-performance seawater desalination plant for 20 T/D ~320 T/D. It’s our main line of business manufacturing for end-use or foreign agents. This scale tons don’t need too much electrical power. To save cost for customers, KYsearo’s engineer designs the process chart without energy recovery devices. Taking it would be more convenient change and low cost into account, we use spiral wound RO membrane, Generally DOW Filmtec RO membrane.

5.Chemical Dosing System

The chemical dosing system is a very important part of the whole water treatment system, including the coagulant and bactericide dosing device in the pretreatment, anti-scalant and reductant dosing device before the 1st level RO, and the pH adjustment dosing before 2nd RO system. Each dosing device consists of a chemical tank, a dosing pump and dosing pipes. All dosing devices are well designed and centrally installed for reliable and easy operation, supervision, cleaning and maintenance.

6.CIP Cleaning System

With the better design for pre-treatment of RO device, it is no need to frequently clean membrane element. However, no matter how perfect the pre-treatment design is, there will be various kinds of pollutants forming at the surface of the membrane to some extent in long-term operation process, which degrade membrane performance and raise the pressure difference between inlet and outlet. Therefore, except for the low-pressure flushing, it is requested to remove the dirt at the surface of RO membrane by chemical cleaning regularly, as well as disinfection. Cleaning device consists of a cleaning tank, cleaning pump, and cleaning the filter. Here is the process How to Clean Seawater Reverse Osmosis System.

7.PLC Controlling System

Utilize integrated performance-testing software to conduct innovative industrial PLC control, which ensures to conduct online remote monitoring for process meters and system performance and enables to remote notify users of system faults and maintenance request in details. KYsearo system has one-click automatic switch machine function for easy-operating.

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