Ballast water management: technology choice comparing TODIM and THOR 2

This paper approaches the problem of ballast water treatment in ships. This has been identified as one of the four greatest threats to the world’s oceans. Solutions that have been considered for solving the problem are alternative water treatment technologies. In the case study reported in this paper three major water treatment technologies have been evaluated with the help of twenty-six criteria, quantitative as well as qualitative by using two discrete multicriteria methods, TODIM and THOR 2. The THOR 2 consists of the axiomatic evolution of the THOR method and both THOR 2 and THOR are made available through the THOR Web platform. Five groups of evaluation criteria are then considered: practicality; biological effectiveness; cost/benefit ratio; time frame for the implementation of standards; and environmental impact of the process' sub-products. In this paper a case study on choosing a ballast water treatment technology is presented. Three alternative ballast water management technologies are proposed by experts in the field and are evaluated with the help of twenty-six criteria, quantitative as well as qualitative. Each ballast water management method is described by a list of twenty-six attributes or criteria. After setting the problem in a clear way and consulting different experts, the two separate applications of both TODIM and THOR 2 are performed. What is denoted as Management Method #1 is indeed chosen as the best alternative according to both methods. The conclusion is that those two methods, although conceptually and analytically quite different, lead essentially to the same main results. Two other applications of both TODIM and THOR have indeed confirmed the convergence of results in spite of the conceptual and technical differences between the two methods. This suggests that formulating a decision problem in a correct, clear-cut way can be at least as important as the technical characteristics of the method per se.

Potential Applications of a Novel Ballast Water Pretreatment Device: Grinding Device

To investigate the removal efficiency of the grinding device (GD) as a potential replacement for the pretreatment filtration device of ballast water, solid grinding and viability experiment were conducted according to a treatment flow rate of 5 tons (Pilot test, PT), and 200 tons (Full-scale test, FST) per h. The solid grinding effect was observed in the particle size of ≥25 μm. Under the high-turbidity conditions (>300 mg L−1), no change in pressure (0.98 kgf/cm2) or stoppage in the GD were observed. The removal efficiency of the GD for >100 μm organism was determined to be 100% in both PT and FST, whereas the removal efficiency was determined to be 93% and 87% in the PT and FST, respectively, for the <100 μm organism. There was no statistically significant change in the removal efficiency stored within 2 h after passing through the GD, while the removal efficiency was determined to be ≥99% in the sample stored for 120 h. Future study is necessary to determine the additional removal efficiency according to the storage period after passing through the GD, but the GD might be utilized as the pretreatment device for the ballast water management system.

Evaluating the biological efficacy of a ballast water management system using filtration and electro-catalysis with an accurate definition of holding time

We employed a mesoscale experimental system and enriched natural plankton communities to investigate the efficacy of a type of ballast-water management system (BWMS) that uses a combination of filtration and electro-catalysis as the treatment technology. The water samples were collected immediately after treatment and at discharge to measure the biological efficiency of this BWMS. The main hydro chemical parameters, the TRO concentration and the plankton species composition before and after the ballast treatment process, were measured. After treatment, the concentration of TRO remained at a high level of 1.690 ± 0.573 (SD) mg/L. The biological efficacy of ballast water after treatment at holding times of 10 min, 20 min, 30 min, 40 min, and 50 min were measured. Holding time significantly impacted the biological efficacy. The discharged, treated water satisfied the D-2 standard of the International Maritime Organization (IMO) after 50 minutes of holding time.

Systems and Operation of Ballast Water in Ships with the Changing Ballast Water Management Policy

Bio-invasion caused due to ballast water discharge is one of many problems in marine pollution. Countries such as Canada, Brazil, USA and Australia recognized the problems associated with ballasting and deballasting. Countries affected with invasive species formulated specific laws for discharging ballast water in their respective ports. Under the coordination of IMO, countries came together and stressed for globally accepted guidelines that each and every ship has to comply with, while entering any port. In the wake of this, IMO in a convention (2004) on ballast water, proposed guidelines for performing proper ballast water management. This includes ballast water exchange, ballast water treatment, port reception facility, technology approval process, sampling ballast water, analysis methods of ballast water and risk assessment in the convention. Eventually the 2004 convention was found to be inadequate in providing complete elimination of bio invasion. Amendments are made to the 2004 convention over the years for ballast water management. It is found that the member states should share technology among developing countries in establishing sampling and testing laboratories. Region specific sampling analysis and research has to be formulated to understand the bio-invasion based on region and characteristics of different target species in evaluating risk assessment. The D2 standard mentioned in the 2004 convention should be changed from size specific to ‘no organism’ standard in ballast water for discharge. New combination of BWT systems and ‘no ballast’ system with modification to the ship design should be tested, developed and implemented to bring in ecological balance and sustenance in the marine ecosystems.