Reverse Osmosis (RO) System

A reverse osmosis system is a water treatment unit that uses a semi-permeable membrane and applied hydraulic pressure to remove dissolved salts, heavy metals, bacteria and other contaminants from water. It is one of the most effective technologies for producing high-purity water from saline, brackish or contaminated feed sources, and is the foundation of most seawater desalination and industrial water purification systems. RO membranes reject 95 to 99.8 percent of total dissolved solids depending on membrane grade and operating conditions.

RO membranes reject dissolved salts including sodium, chloride and sulphates, heavy metals including lead, arsenic, chromium and mercury, nitrates, fluoride, bacteria, viruses, organic compounds and pharmaceutical residues. Salt rejection rates range from 95 to 99.8 percent depending on membrane type, feed water chemistry and operating pressure. RO does not remove dissolved gases such as carbon dioxide, which may require post-treatment pH correction.

Seawater RO (SWRO) operates at 55 to 70 bar to overcome seawater osmotic pressure, treating feed water with TDS up to 45,000 mg/L. Brackish water RO (BWRO) treats lower-salinity sources with TDS up to 10,000 mg/L at 10 to 25 bar, achieving higher recovery rates of 65 to 85 percent and lower energy consumption. Both use polyamide TFC membranes but are designed and engineered differently for their respective operating pressures and salinity conditions.

RO systems require multi-stage pre-treatment to protect the membrane array. This typically includes multimedia or ultrafiltration membrane filtration for suspended solids and SDI reduction, 5-micron cartridge filtration as the final pre-treatment barrier, antiscalant dosing to prevent mineral scaling on the membrane surface, pH adjustment to protect membrane integrity, and dechlorination where chlorinated feed water is used. Pre-treatment requirements are determined by the feed water quality analysis and are critical to achieving rated membrane performance and service life.

With correct pre-treatment and regular maintenance, RO membrane elements typically last 3 to 5 years in service. Membrane life depends on feed water quality, effectiveness of fouling and scaling control, CIP frequency and membrane grade. IWTE provides detailed operating and cleaning protocols to maximise service life, and supplies genuine replacement membrane elements and consumables through its spare parts programme.

Brackish water RO typically consumes 0.5 to 1.5 kWh per cubic metre of product water. Seawater RO consumes 3 to 5 kWh per cubic metre without energy recovery, reducing to 2 to 3 kWh per cubic metre with energy recovery devices integrated into the system. Energy consumption is a major determinant of operating cost, particularly for large-scale systems, and IWTE optimises system design to minimise specific energy use at the specified operating conditions.

Yes. RO systems, particularly brackish water units, are increasingly deployed with solar PV for remote and off-grid applications. Variable flow RO designs accommodate intermittent solar generation by adjusting operating conditions as power availability changes throughout the day. IWTE designs solar-compatible systems with battery backup or hybrid grid and solar integration, and all IWTE RO systems are supplied with solar-ready electrical design as standard.

Yes. IWTE provides a complete scope from system design and engineering through procurement and fabrication to site installation, commissioning, operator training and ongoing service support. Our team manages every stage to ensure the system performs to specification from day one. Operations and maintenance contracts, scheduled service visits and spare parts supply are available for all systems we supply.