Ballast water treatment systems: design, regulations, and selection under the choice varying priorities.

This paper investigates the role of ballast water treatment systems (BWTSs) and proposes a selection procedure for conventional merchant ships based on the financial, legal, and operational circumstances. Through the metallurgical revolution of the nineteenth century, commercial ships are converted to steel hull from wooden structures. By this innovative shift, use of ballast water became an essential part of ships for improving propulsion and stability while reducing stress on hull (instead of rocks). However, the content of ballast water is emerged since it relocates marine species from an ecological composition (usually cargo discharging port) to another one (loading port). Uncontrolled relocation of marine species may cause severe damage to existing ecological basis on ballast discharging area. BWTSs are developed for ships to eliminate marine species (i.e., aquatic invasive species) content by using a filtering device. It ensures an eco-friendly ballasting and de-ballasting process. The selection of proper BWTS is another debate since the BWTSs are designed with cost-quality and cost (eco)-performance variations. The proposed approach denoted that both tonnage and the age of ship are indicative factors on selection. The cost of installation varies based on installation space and active vs. project vessel cases.