Deployment of a submarine reverse osmosis desalination prototype plant (RODSS): field tests and preliminary technical evaluations

Abstract The innovative RODSS approach (Reverse Osmosis Deep Sea System — EU-DG XIII innovation project 1998–2001) exploits seawater hydrostatic pressure at a depth of about 450m below sea level. This presentation concerns the deployment and field tests of a small-production-capacity (10m 3 /d) prototype desalination unit immersed 1 mile offshore the southwest coast of Pantelleria Island, Sicily. The desalinated water produced in the sea depth at about atmospheric pressure is continuously pumped up through a buoyancy controlled reinforced conduit to a storage tank ashore via a high-pressure pump sited in the sea depth. The RODSS prototype has required a dedicated design work for all its components: it consists of a 5m long fiber glass pressure vessel, which contains all working apparatuses (osmotic modules, desalinated water storage tank, sea water circulation pump, desalinated water delivery pump, flow meters, temperature and pressure transducers, etc.) and a sea-line (desalinated water delivery conduit and electric power cable joined together) connecting it to the plant site ashore. The deployment of the RODSS prototype is described with the help of short texts and field pictures. The field tests of the RODSS prototype concern its working characteristics and are presented with the help of dedicated tables which detail the numerical values of basic parameters such as: working pressure, water salinity and temperature, and conversion coefficient. The presentation ends with preliminary conclusions on the RODSS technology potential for seawater desalination vis-a-vis conventional RO technology.