Emerging ballast water treatment technologies: a review

Abstract

Ballast water-shifts across the globe have been a major cause of ecological imbalance. The International Maritime Organisation (IMO) has actively taken regulated measures to minimise the species shift by adopting the International Convention for the Control and Management of Ships' Ballast Water and Sediments in 2004. Since then, vessels have been increasingly practising water exchanges. Exchanges are seen to be not completely effective. This regime has to give way for effective Ballast Water Treatment to keep up with IMO requirements as also the stricter requirements stipulated by some US ports. As full ratification of the Treaty is pending, many treatment technologies have been emerging. A review of some representative systems is presented in this paper. Brief analyses of the systems available on date and those awaiting approval have been carried out. Most of these systems use a pre-treatment employing physical filtration and in the later part treat the ballast water with physical and chemical disinfection methods. An effective method for species reduction has been to employ chemicals. In terms of capital cost, foot print and power requirements, chemical solutions fare better than the physical disinfection methods. However, it is feared that chemicals might cause greater harm to the environment. Physical disinfection methods have lesser issues than the usage of chemicals. Considering the long-term harm of chemicals, a filtration system in combination with heat treatment is suggested. Such an attempt might even emerge as a viable option before the IMO deadline of 2016.