Pool water treatment is based on the continuous circulation and mechanical filtration of water using cartridge or sand filtration and the prevention of microbiological problems using chemicals and UV (when required). In addition, a heating system is usually included in the water treatment unit. The most important task of a pool water treatment system is to ensure water quality in all conditions, but aesthetics are also important in terms of keeping the water clear. Rules and regulations (e.g. USPH, Vessel Sanitation Programme) play an important role in cruise vessel pool water treatment as well as special technical requirements that are specific to onboard systems.
A pool water treatment system consists typically of circulation pumps, filters, heat-exchangers, valves and sensors as well as chemical dosing and a UV device when required (e.g. by USPH rules). In addition, there is usually a need for separate overflow tanks to compensate for the water flow from the pools to the treatment system. When designing systems for ships, where available space is always very limited resource, it is crucial to design all systems to be as compact as possible while still enabling good usability/serviceability. Use of variable frequency drives for controlling the circulation pump is crucial in order to ensure the required pool water turnover rates in all conditions and to save energy.
The pool water treatment control system should be easy to use and have intuitive and informative user interfaces (touch screens). With automatic functions (like automatic filter flushing), it is possible to ensure the correct use of equipment and efficient operation. Pool water treatment units can be integrated with the ship’s main automation system for centralised alarms and monitoring.