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Easy Understanding Seawater Desalination Process

In this page,  you would read Seawater Desalination Process in simple way.

Many customers consulted us “ How does a desalination plant work?” “How can sea water be desalinated ?” “What the process of water desalination system?” and so on. Generally, we could not explain in just several words, and also the customer can not completely figure out. Here is a simple description of seawater desalination process. Hope everyone can work out what it is after reading it.

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Let’s Begin

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Overview

A complete seawater desalination system is composed by 7 parts, intake system, pre-treatment system, reverse osmosis system, energy recovery system, chemical cleaning system, chemical dosing system, power providing and automatic controlling system. All these for a large tons desalination plant, not the same complicate as desalination plants which lower 100 tons per day. To let customer easy to understand, this page will introduce process for desalination plant lower than 100 tons per day.

Like the process picture shows, seawater desalination process need to go through at least 3 basic steps, pre-treatment, pressurization and reverse osmosis(RO) system. In each step, including several parts. more details about 3 basic steps would be read here.

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Pre-treatment System

Pre-treatment system is to protect the reverse osmosis membranes from becoming clogged by solid particles that can be suspended in the seawater, the seawater should be filtered before passing through the membranes,

Usually, pre-treatment system would be composed by multi-media filter (sand filter), activated carbon filter, and cartridge filter.

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  • Multimedia Filter

Multimedia filter contain a series of layered granular materials, these material can be anthracite, sand, pebbles and or gravel, which assembled in layers.

The filters can remove sand, twigs, seaweed and other particles from the seawater.

In some cases, other types of membranes known as ultrafiltration and microfiltration membranes are used instead of multimedia filters to pre-treat the seawater.

multimedia filter
  • Activated Carbon Filter

Activated carbon filter can effectively reduce certain organic compounds and chlorine in drinking water, it can also reduce the quantity of lead, dissolved radon, and harmless taste- and odor-causing compounds. 

  • Cartridge Filter

Cartridge filters are much smaller than  sand filters, and is usually tall and narrow in shape, typically made from synthetic material, that is wound into cartridges. These remove even smaller solid particles from the seawater, such as fine sanding clay before the seawater proceeds to the reverse osmosis membrane.

cartridge filter
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RO System

How reverse osmosis work ?

Reverse osmosis system is the core system for seawater desalination process. It would be composed by high pressure pump and RO membranes. and the RO membranes need be packed in pressure vessels.

The water flow out from pre-treatment system, high pressure pump increase the pressure of the water up to 1000 PSI. the pressure needs to be sufficiently high to overcome the naturally occurring pressure. and force water from the salt water side through the reverse osmosis membranes to the fresh water side.

The salt particles in the seawater are rejected from passing through the membrane to the fresh water side, and remain behind on the concentrated salt water side.

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Cleaning System

 Fresh water cleaning

[vc_feature_boxes columns=”1″ style=”style2″ padding=”medium” vpadding=”medium” bg_color=”#ffffff” bg_opacity=”1″ inner_hpadding=”medium” inner_vpadding=”medium” bg_shadow=”” bg_radius=”yes” box_style=”style2″ icon_side=”left” fc_align=”” fi_align=”” divider=”yes” di_color=”light” di_style=”normal” di_type=”tiny” icon_style=”style2″ icon_size=”normal” icon_bw=”1″ icon_br=”50%” icon_c_opc=”1″ icon_c_hover_opc=”1″ icon_bc_opacity=”1″ icon_bgc_opacity=”1″ icon_bgc_opacity_hover=”2″ icon_c=”#1e73be” icon_c_hover=”#4f7f2f” icon_bc=”#1e73be” icon_bgc_hover=”#ffffff”][vc_feature_box ftarget=”_self” title=”Why seawater desalination plants need cleaning system?” ttarget=”_self” title_heading=”h4″ css_animation_delay=”100″ css_animation_type=”box” icon=”256|fontawesome” css_animation=”fadeInTop”]To protect RO membranes from being clogged and keep them long-term working life. The water flow into RO system after pre treatment system. almost solid particles have been removed that can be suspended in the seawater through cartridge filters. But all salt need to be removed by reverse osmosis membranes, so, we design the fresh water cleaning process additional.[/vc_feature_box][vc_feature_box ftarget=”_self” title=”How often it need to be cleaned by fresh water?” ttarget=”_self” title_heading=”h4″ css_animation=”fadeInTop” css_animation_delay=”100″ css_animation_type=”box” icon=”256|fontawesome”]Every time after running, reverse osmosis system should be cleaned by fresh water.[/vc_feature_box][/vc_feature_boxes]

Chemical cleaning

[vc_feature_boxes columns=”1″ style=”style2″ padding=”medium” vpadding=”medium” bg_color=”#ffffff” bg_opacity=”1″ inner_hpadding=”medium” inner_vpadding=”medium” bg_shadow=”” bg_radius=”yes” box_style=”style2″ icon_side=”left” fc_align=”” fi_align=”” divider=”yes” di_color=”light” di_style=”normal” di_type=”tiny” icon_style=”style2″ icon_size=”normal” icon_bw=”1″ icon_br=”50%” icon_c=”#1e73be” icon_c_opc=”1″ icon_c_hover=”#35933d” icon_c_hover_opc=”1″ icon_bc=”#1e73be” icon_bc_opacity=”1″ icon_bgc_opacity=”1″ icon_bgc_hover=”#ffffff” icon_bgc_opacity_hover=”2″][vc_feature_box ftarget=”_self” title=”Why chemical cleaning ?” ttarget=”_self” title_heading=”h4″ css_animation=”fadeInTop” css_animation_delay=”100″ css_animation_type=”box” icon=”256|fontawesome”]After a long term working, RO system would be contaminated by chemical and physical pollution, such as bacterial and salt. therefore, RO system should be washed through chemicals because these pollutants can not be removed by only fresh water cleaning.[/vc_feature_box][vc_feature_box ftarget=”_self” title=”When will the system should be chemical cleaning?” ttarget=”_self” title_heading=”h4″ css_animation_delay=”100″ css_animation_type=”box” icon=”102|fontawesome” css_animation=”fadeInTop”]

  • Production water capacity decrease by 10%~15%.
  • Pressure increases by 15%.
  • Water flow decrease by 15%.

[/vc_feature_box][vc_feature_box ftarget=”_self” title=”How often chemical cleaning ?” ttarget=”_self” title_heading=”h4″ css_animation=”fadeInTop” css_animation_delay=”100″ css_animation_type=”box” icon=”256|fontawesome”]Every six months to one year. it depend on the raw water quality, means the higher TDS, the more times chemical cleaning.[/vc_feature_box][/vc_feature_boxes]

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Control System

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PLC control

Liquid level control