Depuration

Depuration is the process of making shellfish free from impurities using controlled purification systems with sterilized water. Live oysters, mussels and clams are held in tanks of clean, disinfected seawater so they pump out sand, mud and microbes. Systems may be flow-through or recirculating, and sterilization uses chlorine, UV light, ozone, membrane filters or iodophors. Depuration reliably cuts bacterial loads but works less well against viruses and cannot remove biotoxins or heavy metals, so heavily polluted shellfish cannot be made safe this way. Regulated plants operate under strict controls on water quality, temperature and holding time.