AQUAPONICS AND FOOD SAFETY: EFFECTS OF UV STERILIZATION ON TOTAL COLIFORMS AND LETTUCE PRODUCTION

Aquaponics is an integrated production system where plants grow in a soil-less medium of aquaculture waste. This kind of production is seen as favourable nowadays since waste utilization could increase farm productivity and reduce environmental impacts. This research compared the microbiological quality of aquaponic water under ultraviolet (UV) sterilization and its compliance to international directives on irrigation water uses. An assessment of crop productivity was also carried out to outline differences in productive traits of lettuce (Lactuca sativa L. ‘Verde degli Ortolani’) grown in sterilized and non-sterilized aquaponic systems against a hydroponics floating system supplied with a nutrient solution of 1.6 dS cm-1. Total coliforms under UV disinfection showed counts well below 1 CFU ml-1 and a reduction in microbial loads higher than 99%. Furthermore no Escherichia coli were found in both sterilized and non-sterilized aquaponic systems. No significant differences were recorded for productive traits of lettuce (yield, mean shoot weight, shoot and root dry biomass, leaf area, specific leaf dry weight), suggesting that aquaponics is a valid method to produce vegetables with high hygienic standards.