Trials to Assess the Effectiveness of Ionization, Chlorination and UV Irradiation for the Disinfection of Seawater

Summary

Clean supplies of water are essential for the industry to maintain high standards of hygiene and quality. Where seawater is used, regulations demand that the water is free from microbiological contamination and that disinfection is carried out where required. In an operation such as shrimp processing where the product is cooled in seawater, cross contamination as a result of using contaminated seawater may result in food poisoning. It is thought that seawater containing a disinfectant residual may also be used to slow the microbiological spoilage of the product itself. For example using treated water in an RSW system may improve fish quality and extend shelf life. A series of practical trials were carried out to determine the effectiveness of electrolytic ionization, UV irradiation and chlorination for killing bacteria in seawater, with a view to the development of a commercial system for use on shrimp boats. A trial was also carried out to determine the effect on white fish quality of using ionized water in an RSW system. All treatments except chlorination using sodium hypochlorite proved to be unsuitable due to poor bacteriocidal performance and/or prohibitive costs. Sodium hypochlorite gave effective coliform bacterial kills at dose levels as low as 5 mg/1 of chlorine. A marginal improvement in quality was determined over a 7 day period with treated RSW versus untreated RSW.

Publication Reference No.

SR473

Publication date

01 May 1996