Compact Marine Seawater RO System for Commercial Fishing Vessels & Cargo Ships

What is a Marine Seawater RO Desalination System?

A typical skid-mounted compact seawater RO system for large cargo ships, with a desalination capacity of 50 ton/day. Components: Siemens control cabinet, pumps, dosing tanks, filters, reverse osmosis membranes, UV sterilizer, middle tank, piping components, etc.

A marine seawater reverse-osmosis (SWRO) desalination system is a critical shipboard technology that utilizes advanced membrane separation to transform high-salinity seawater into fresh water that meets international health standards. Recognizing the challenges of cramped engine rooms and highly corrosive environments on deep-sea fishing vessels and large cargo ships, Metalsin has developed a specialized compact architecture. This skid-mounted design integrates high-pressure pumps, membrane modules, pre-treatment filtration, and control systems into a single, robust steel frame. This configuration significantly reduces the equipment footprint and enables “plug-and-play” installation—providing a vital guarantee for crew potable water and operational safety during long-haul voyages.

Technical Specifications & Performance Features

A compact seawater RO desalination skid for fishing ships, with the capacity of 10 t/d.

Metalsin‘s compact marine SWRO systems are engineered to withstand extreme offshore conditions, with daily desalination capacities ranging from 10 to 50 tons per day, perfectly suited for various commercial vessel sizes. Built with industrial-grade SS316L stainless steel or high-strength FRP, these systems offer exceptional resistance to salt spray and maritime corrosion. Core components feature world-renowned brands, such as DOW Filmtec low-energy membranes and Danfoss axial piston pumps, ensuring salt rejection rates exceeding 99%. This efficiency minimizes the load on shipboard generators and reduces energy consumption, successfully extending maintenance cycles during extended periods at sea.

The marine seawater RO desalination system, supplied in skid-mounted pattern: Reliable, space-saving freshwater solutions for demanding maritime environments.

Operationally, the series integrates fully automated control logic (Siemens PLC), featuring comprehensive high/low-pressure protection, automatic flushing, and real-time water quality monitoring. This allows crew members to operate the system via an intuitive HMI touchscreen with a “one-key” start, requiring no specialized chemical expertise. The modular design facilitates easy transport through narrow ship corridors and ensures operational stability even in rough seas, providing a continuous water supply for fish preservation, crew amenities, and boiler makeup water.

System Process Workflow

Based on the technical flow diagram, the system demonstrates a rigorous multi-stage treatment sequence. Raw seawater is initially drawn by a feed pump into a pre-treatment phase consisting of flocculant dosing, a multi-media filter, and an activated carbon filter to eliminate suspended solids, organics, and odors. Subsequently, the water passes through precision filters for ultra-fine cleaning. Before entering the core desalination stage, the water chemistry is optimized via pH adjustment and scale inhibitor dosing systems to protect the longevity of the RO membranes.

The standard desalination process flow chart of a seawater RO system for the fishing or cargo vessels.

The core purification phase utilizes a high-efficiency double-pass reverse osmosis (RO) process. Driven by a high-pressure pump, the water cycles through 1st and 2nd stage RO systems for deep desalination. The treated fresh water then passes through a UV sterilizer for physical disinfection and undergoes final refinement through terminal activated carbon and precision filters. This sophisticated logic ensures that the product water is not only crystal clear but fully compliant with both maritime regulations and WHO drinking water standards.