Global Energy Giant BP Confirms Severn Trent De Nora’s BALPURE Ballast Water Management Systems as its Preferred Solution with Large Contract Win Contract calls for 14 BALPURE systems to be installed aboard BP crude oil tankers being constructed by one of the world’s largest shipbuilders, STX Offshore & Shipbuilding. Severn Trent De Nora, a supplier of equipment for seawater electrochlorination, has received a big order for its BALPURE ballast water management system from STX Offshore & Shipbuilding for global energy giant British Petroleum (BP).