SummaryEvery day, more than 7,000 different marine species are transferred to different ecosystems via ballast water in ships. The introduction of invasive species can cause problems for native species. After realizing the serious potential problems associated with the transport of organisms in ballast water, national and international regulations were developed. In 2004, the International Maritime Organization introduced the International Convention for the Control and Management of Ships' Ballast Water and Sediments. With these regulations, the problems caused by ballast water have attracted attention and many companies have started to research and develop technologies for the management of ballast water. Today, there are hundreds of different systems for ballast-water treatment, and the selection of the most suitable system for a specific vessel is an increasingly important issue as the Convention nears enforcement on September 8, 2017. The goal of this study is to demonstrate that the application of key performance indicators (KPIs) to the selection of a ballast-water treatment system (BWTS) leads to a very useful tool with which shipyards can compare BWTSs. This allows them to make better choices and to designate the most suitable system for each of their ships. In this study, we examine two types of vessel from a shipyard in Istanbul, Turkey. They have different ballast-water capacities and equipment, and the most suitable system for each is selected by using the KPI method.

A B S T R A C TThe transportation of exotic species in ballast tanks is one of the most important global environmental problems facing the shipping industry. Electrochemical techniques offer one of the most viable solutions for ballast water problems. This work reports laboratory experiments conducted by Istanbul Technical University (ITU) for the best and optimal electrochemical cell design for EU Project BaWaPla (Contract 031529), in which a new hybrid ballast water treatment system has been developed. The capability of an electrochemical system to effectively eliminate these organisms depends on various internal and external parameters. Five different electrochemical cells were assessed for the BaWaPla system. The variable parameters of the cell design were the geometry and dimensions of the electrodes. In additional to cell design, the effects of Ca 2+ and Mg 2+ concentrations, along with ammonia, were also investigated as external parameters for system capability. The results show that the enlargement of electrode surfaces result in increased chlorine concentrations in the disinfectant. On the other hand, suitable electrode and coating materials are essential for "reverse polarity" operation in order to avoid scaling of Ca 2+ and Mg 2+ ions on electrodes and clogging the membrane. Ammonia, if present in ballast water, has a negative effect on disinfection quality. Experiments show that presence of 7.8 mg/L ammonia in electrolyte may cause up to 73% loss of free available chlorine and 38% loss of total available chlorine concentrations. Measures should be considered, both in the design stage and during the disinfection process, to reduce the negative effect of ammonia.

SummaryBallast tank sediments may cause several problems in a wide range changing from environmental to economical. Its contribution to biological invasion is an important concern. Thus, the sediment management is included as an integral component of the "The International Convention on the Control and Management of Ships' Ballast Water and Sediments". The reduction of the amount of the sediment to be removed is of great importance for management issues. Therefore, the convention underlines that ships should be designed and constructed with a view to minimize the uptake and undesirable entrapment of sediments and facilitate removal of sediments. Design and construction solutions can effectively be developed after determination of the problem areas. In this study, sediment accumulation pattern and problem areas in the ballast tank model of a longitudinally framed double bottom tanker is determined. The problem areas are found to be at the mid-section of the tank closer to the centre girder.

Abstract

Chlorine disinfection is one of the most common used techniques to eliminate the ballast water organisms. However safety risks during handling and onboard storage of chlorine gas or HOCl solutions are subjects of concern. Electrochemical generation of active chlorine on board would eliminate such unfavorable features of chlorine disinfection. The characteristics of seawater have a direct effect on the capability of an electrochemical system to function successfully. Seawater contains a wide range of salts at various concentrations and combinations. Additionally, coastal seawater may also contain ammonia beside domestic based organic pollutants. The aim of this study is to determine the effect of ammonia which will go under electrochemical process during disinfectant production. It is figured out that ammonia leads to less total and free available chlorine concentrations in electrochemically generated disinfectant. Consequently, the presence of ammonia increases the volume of disinfectant needed to disinfect the same amount of biomass. This work has been conducted within the project “BaWaPla — Sustainable Ballast Water Management Plant”, funded by the European Union under contract number 031529, which is started at 15/11/2006 and finalized at 15/05/2010.