BP Refinery Rotterdam is the second largest oil refinery in Europe. It processes 19 million tons of crude oil per annum. The refinery contains a treatment plant for water released during the refining processes and used as ballast for the oil tankers. Treatment comprises oil separation, filtration through sand filters and biological filters. The effluent passes to a post-treatment lagoon before being discharged into the Beerkanaal.

BP required improvements to the treatment plant in order to secure compliance with EU legislation concerning effluent discharges. VBTM and its partner Brushmoor Ltd undertook a full-scale trial of a novel biological treatment process, which improved the quality of the effluent considerably and provided a solution to secure compliance.