What Is Sea Water Reverse Osmosis? Understand How It Works!

As water demand rises and freshwater sources become scarce in some regions, many companies are adopting technologies that provide independent, sustainable water supplies.

In response to this need, the Sea Water Reverse Osmosis (SWRO) system has become a widely adopted solution for treating seawater into high-quality, clean water for industrial use to support business operations.

To better understand how the SWRO system works, its benefits, and its applications across various industrial sectors, read the full discussion in this article.

What Is Sea Water Reverse Osmosis (SWRO)?

Sea Water Reverse Osmosis (SWRO) is a desalination technology that converts seawater into freshwater using reverse osmosis (RO).

This technology works by applying high pressure to seawater, allowing water molecules to pass through a semipermeable membrane or filter layer that only allows water molecules to pass through, thereby removing ions, molecules, and larger particles from the seawater.

SWRO is specifically designed to treat seawater with a salinity level (salt content) of approximately 35,000 ppm (parts per million), or about 35 grams of salt per liter of water. This figure is significantly higher than that of brackish or freshwater.

As a result, SWRO systems are designed to use high-pressure pumps, specialized membranes, and pretreatment processes to ensure optimal filtration.

A major difference between SWRO (Sea Water Reverse Osmosis) and BWRO (Brackish Water Reverse Osmosis) lies in the type of raw water and the operating pressure used.

SWRO is designed to treat high-salinity seawater, requiring approximately 600–900 psi, while BWRO is used to treat brackish water with lower salt content and generally requires only 300–500 psi.

With its consistent ability to produce high-quality water, SWRO is widely adopted across sectors requiring large, sustainable water supplies.

This technology is commonly used in manufacturing, power generation, industrial parks, oil and gas, mining, and commercial facilities in coastal areas with limited freshwater resources.

The adoption of SWRO continues to rise with the growing demand for clean water across various sectors. According to a report by the EU Blue Economy Observatory (2024), there are more than 22,000 desalination plants in operation worldwide, with a total production capacity of approximately 135 million cubic meters of water per day.

These figures demonstrate that desalination, including SWRO, has become a key technology for supporting water supply resilience in various countries, particularly in coastal areas and regions with limited freshwater resources.

How Sea Water Reverse Osmosis (SWRO) Works

In general, the SWRO process consists of the following stages:

Pretreatment: In the initial stage, seawater is filtered to remove sand, silt, algae, organic matter, microorganisms, and other suspended particles.
Pressurization: After passing through the initial filtration stage, the seawater is pumped using a high-pressure pump. This pressure must exceed the natural osmotic pressure of seawater to allow the water to pass through the reverse osmosis membrane.
Reverse osmosis process: In this stage, seawater is passed through a semipermeable membrane. Salts, minerals, heavy metals, bacteria, viruses, and other contaminants are retained on the membrane surface, while clean water or permeate passes through.
Post-treatment: In this process, water quality is adjusted to meet specific usage requirements, such as pH adjustment, the addition of specific minerals, or disinfection, to comply with applicable operational standards and regulations.
Brine Disposal: In industrial facilities, brine is generally disposed of in accordance with environmental regulations or through additional treatment processes to minimize its impact on aquatic ecosystems.

Advantages of Sea Water Reverse Osmosis (SWRO)

The implementation of SWRO offers various advantages for the industrial sector, particularly in ensuring clean water availability to support operations. Here are some of the key benefits from using SWRO technology:

1. Energy Efficiency

Modern SWRO technology is equipped with an Energy Recovery Device (ERD), which recovers energy from the brine stream (high-salinity wastewater).

This technology can significantly reduce the energy consumption of high-pressure pumps compared to conventional desalination systems, thereby reducing operational costs.

2. Optimal Water Quality

SWRO can remove more than 99% of dissolved salts as well as various contaminants such as bacteria, viruses, heavy metals, and other particles.

The result is high-quality water that can be used as process water, boiler feedwater, or for other operational needs after undergoing quality adjustments in accordance with industry standards.

3. Abundant Water Source

SWRO utilizes abundant seawater as its raw water source. Consequently, companies can reduce their reliance on freshwater sources while ensuring water availability to support sustainable operations.

Factors Affecting Sea Water Reverse Osmosis (SWRO)

Various parameters influence the performance of Sea Water Reverse Osmosis (SWRO). Among these factors, operational pressure and recovery rate are two key aspects that must be considered to ensure the system operates optimally. Here is an explanation:

1. Operational Pressure

Operational pressure is the pressure generated by a high-pressure pump to force seawater through the reverse osmosis membrane.

Given that seawater has a higher salt content, the required pressure is also greater than for RO systems for freshwater or brackish water.

Pressure must be regulated precisely. Pressure that is too low can reduce the amount of purified water produced, resulting in underperformance relative to production capacity.

Conversely, excessively high pressure will increase energy consumption, accelerate membrane wear, and raise operational costs. Therefore, operational pressure is generally adjusted based on the characteristics of the feedwater, the type of membrane, and the target water production.

2. Recovery Percentage

The recovery percentage is the ratio of the volume of clean water (permeate) produced to the total volume of seawater entering the system.

For example, if a system has a recovery rate of 45%, this means that for every 100 liters of seawater treated, approximately 45 liters become treated water, while the remaining 55 liters are discharged as brine (wastewater with a higher salt concentration).

The higher the recovery rate, the more fresh water can be produced from the same volume of raw water. However, an excessively high recovery rate can increase the risk of scaling (the formation of mineral deposits on the membranes) and fouling (the buildup of particles, organic matter, or microorganisms on the membranes).

Conversely, a recovery rate that is too low is safer for the membranes but results in less efficient use of raw water.

Optimize Industrial Water Treatment with CDI

Proper water treatment can be a strategic step to ensure the availability of clean water while maintaining industrial operational efficiency.

For the system to function optimally, you need a partner that not only provides water treatment technology but also has experience in managing water infrastructure for various industrial needs.

PT Krakatau Tirta Industri (KTI), an affiliate of PT Chandra Daya Investasi Tbk (CDI), offers reliable, sustainable industrial water and demineralized water solutions.

The core business of KTI is supplying clean water to various industrial sectors, including the Chandra Asri Group. KTI utilizes raw water sources from the Cidanau River, the Cipasauran River, and the Nadra Krenceng Reservoir to ensure a reliable and sustainable water supply.

To support these services, KTI operates several water treatment facilities, such as the Krenceng Water Treatment Plant (WTP) and the Cidanau WTP.

KTI also provides deionized water services designed to meet industrial needs and higher water-quality specifications. These services are supported by a Water Treatment Plant (WTP) that treats water to meet the standards required for various industrial processes.

If you need integrated industrial water and demineralized water solutions to support the continuity of your business operations, CDI and KTI are ready to be your trusted partners.

Entrust your company’s industrial water management needs to CDI and KTI as #YourGrowthPartner.