Understanding Reverse Osmosis Systems: A Guide by Daly Middle East

## What Is Reverse Osmosis Water System and How Does It Work?

An RO water system is an engineered solution designed to purify water by removing undesirable substances. At Daly Middle East, our RO systems, known as watermakers, are primarily used for desalination, transforming brackish or seawater into freshwater suitable for various uses.

## Who Benefits from an RO Watermaker?

Our clients, including offshore rigs, ships, and marine facilities, rely on RO systems to generate freshwater on-site, avoiding the high costs and logistical challenges of transporting water from land. These systems are crucial for small, self-contained communities in remote locations, providing a reliable source of freshwater.

The reverse osmosis process at Daly Middle East involves several key stages to transform seawater into high-quality freshwater suitable for various applications on offshore rigs and marine facilities. Here’s how it works:

1. Feed Water Supply

The process begins by sourcing seawater directly from the sea at the location of the rig. Typically, this is achieved via the existing seawater ring main.

2. Pre-Filtration

The seawater is first passed through a pre-filter skid designed to remove any suspended solids. This is crucial as the current can sometimes carry drill cuttings or other waste materials into the vicinity of the deep well.

3. Dechlorination

If the incoming seawater has been chlorinated, it can be directed through an optional dechlorination unit. This step ensures that the chlorine is removed before the seawater enters the reverse osmosis units.

4. Booster Pump

To maintain the necessary feed water pressure, an optional booster pump can be included if the seawater ring main pressure is insufficient.

5. High-Pressure Pumping

A high-pressure pump, operating at around 55 to 60 bar, forces the filtered seawater through a series of semipermeable membranes. These membranes allow only freshwater molecules to pass through while rejecting the concentrated salt water.

6. Brine Rejection

Approximately 40% of the feed water is recovered as freshwater (permeate), while the remaining 60% is rejected as brine. This brine is then disposed of or managed according to environmental regulations.

7. Remineralisation

The permeate water (freshwater) is then directed through a remineralisation column. This process adds essential minerals back into the permeate water to stabilize its pH, which helps protect downstream metal pipes and storage tanks from corrosion. Additionally, since RO water can taste flat and lacks sufficient minerals, remineralisation improves the taste and hardness of the water, making it more suitable for consumption.

## Custom-Built RO Systems

For clients with specific needs, Daly Middle East offers custom-engineered RO systems with higher recovery rates. These systems are tailored to the operational specifications, including salinity levels, required water volume, available feed water, and electrical supply.

### Daly RO45 and Daly RO82 Specifications

Our standard units, the Daly RO45 and Daly RO82, are designed for optimal performance in the Arabian Gulf. These units deliver between 45m³ to 82m³ of freshwater per day from seawater with salinity levels up to 42,000ppm. Key specifications include:

**Output**: 45m³ – 82m³ freshwater/day

**Dimensions**: 1350mm (width) x 2000mm (length) x 1812mm (height)

**Frame Type**: Skid Mounted, Carbon Steel Epoxy Coated

**Electrical Panel**: Schneider Type

**Piping and Fittings**: PVC for low-pressure, 316 SS for high-pressure

**Electrical Requirements**: 480VAC, 60Hz, 3 Phase

### Pre-Filter Skid Specifications

**Skid Type**: Dual Cartridge Filter Assemblies

**Frame Type**: Skid Mounted, Carbon Steel Epoxy Coated

**Optional Booster Pump**: Available based on sea water ring main pressure

**Electrical Panel**: Schneider Type with Start/Stop buttons, indicators, and main isolator

## Conclusion

Reverse osmosis is a vital water treatment process, especially for offshore and remote locations where freshwater is scarce. Daly Middle East offers both standard and custom-built RO systems to meet diverse needs, ensuring a reliable supply of high-quality freshwater.

For more information or to discuss your specific requirements, contact Daly Middle East. Our experts are ready to provide solutions tailored to your operational needs.