Crude Oil Washing - Seawater Washing

Seawater Washing

Originally oil tankers used one set of tanks for cargo and about one third of the same tanks were for water ballast on their empty trips. High pressure, hot, seawater jets were used to clean the tanks and the mixture of seawater and residue called slops discharged into the sea, as was the oil-contaminated ballast water. The 1954 OILPOL Convention attempted to reduce the harm by prohibiting such discharges within 50 miles (80 km) of most land and 100 miles (160 km) of certain particularly sensitive areas.