A study on posidonia residue in seawater intakes

The reliability of a sea-water desalination plant relies largely on an efficient intake system. This is not easily ensured in large areas of the Mediterranean, where the residue of a particular seagrass, Posidonia 0ceanica, is often found in large quantities. To separate or avoid this residue, which can cause operational problems, considerable technical and economical efforts are required.

This paper presents the results of a design and operation-oriented experimental study on Posidonia. This study deals with aspects such as concentration in sea-water, distribution of sizes in residue samples, sedimentation properties, bulk densities and resistance of sea-grass cakes to sea-water flow, and is supported by direct practice in desalination in Libya. Experience confirms that the analysis of the behaviour and physical properties of Posidonia residue, together with accurate site survey, enable one to design a tailored solution, thus avoiding an unreliable standardized system or an uneconomical sophisticated or over-dimensioned solution, not necessarily reliable when unassisted by field data.