Case Study

Grundfos Dosing Pumps contributes to desalination plants


Over 100 million litres of drinking water a day will soon be flowing to the residents of Minjur; the credit goes to Grundfos dosing pumps.

In Minjur, a town in Thiruvallur district of Chennai in India, will soon be able to overcome the problem of inadequate supply of water; an issue faced by many growing urban areas. Grundfos dosing pumps has come up with a solution to help solve this problem by contributing to one of the world’s largest seawater desalination plants. This 100-million litres per day (MLD) desalination plant is being built by Chennai Metrowater and Technology partners with Befesa Construcciion y Tecnologia Ambiental of Spain. It treats seawater through reverse osmosis (RO) to make it potable.

Spread out across a 60-acre site, the plant contains five modules of 20 MLD each. Among impressive details are the intake tower that draws seawater from 10 metres below sea level, and separate pipelines to draw raw water and discharge wastewater. An important part of the entire process is the chemical adjustment both before and after the removal of salts. Befesa turned to Grundfos for custom-made dosing solutions to fit the bill.

The seawater desalination plant in Minjur will draw over 230 million litres of seawater every day in order to produce 100 million litres of potable water each day. This is equal to 1,00,000 cu.m per day. The RO process can be divided in three main processes:
• Pre-treatment: Seawater is filtered and chemically adjusted before proceeding
• Reverse osmosis: Seawater is passed across the membranes for salt removal
• Post-treatment: The treated water is chemically adjusted in order to make it drinkable

For the pre and post-treatment steps, several chemicals need to be dosed. Flow rates can vary from very low to very high, depending on the number of RO trains that are running at a time. Chennai Municipality also wished for a turnkey solution that would fit perfectly into the rest of the plant.

Grundfos DME dosing pumps
Grundfos DME dosing pumps, with its unique digital dosing system, were selected as the absolute solution to satisfy the needs. A complete dosing skid, equipped with three or four dosing pumps (depending upon needs) was therefore designed by Grundfos. The dosing team at Bombas Grundfos España S.A. included the pumps, a pulsation dampener, a flow meter and a counter pressure valve. A total of 28 Grundfos DME dosing pumps went into the total package including the customised skids. All design, construction, and delivery work was done by Bombas Grundfos España S.A.

Jose María Centeno, International Operations Manager, Befesa Construcciion y Tecnologia Ambiental of Spain states, “The technical characteristics and capabilities of the Grundfos DME dosing pumps have proven to be excellent. We are also very pleased that the design of the skids was made suitable for requirements of the project. We worked well with Grundfos, who asked very important questions when creating dosing skids. Furthermore, we feel very confident in installing these pumps, thanks to the qualified staff from Grundfos India, who can provide local service support. We will operate the plant for the next 25 years, so this is an important factor for us.”

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