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Some naval vessels add seawater to carbon steel fuel ballast tanks to maintain stability during fuel consumption. Marine sediments often contaminate ballast tank fluids and have been implicated in stimulating fuel biodegradation and enhancing biocorrosion. The impact of the marine sediment was evaluated in model ballast tank reactors containing seawater, fuel (petroleum-F76, Fischer–Tropsch F76, or a 1:1 mixture), and carbon steel coupons. Control reactors did not receive fuel. The marine sediment was added to the reactors after 400 days and incubated for another year. Sediment addition produced higher estimated bacterial numbers and enhanced sulfate reduction. Ferrous sulfides were detected on all coupons, but pitting corrosion was only identified on coupons exposed to FT-F76. Aerobic hydrocarbon-degrading bacteria increased, and the level of dissolved iron decreased, consistent with the stimulation of aerobic hydrocarbon degradation by iron. We propose that sediments provide an inoculum of hydrocarbon-degrading microbes that are stimulated by dissolved iron released during steel corrosion. Hydrocarbon degradation provides intermediates for use by sulfate-reducing bacteria and reduces the level of fuel components inhibitory to anaerobic bacteria. The synergistic effect of dissolved iron produced by corrosion, biodegradable fuels, and iron-stimulated hydrocarbon-degrading microbes is a poorly recognized but potentially significant biocorrosion mechanism. [ABSTRACT FROM AUTHOR]

This paper analyzes the failure of anticorrosive coating failure and zinc alloy sacrificial anode used in seawater ballast tank of offshore oil engineering FPSO at temperatures more than 50 °C. Based on the measurement of anode contact resistance, analysis of the chemical composition of anode materials and the corrosion products (passivation layer), and the simulation of the actual working environment, the main reasons leading to the failure of the anticorrosive coating in this environment and the failure of the zinc anode cathodic protection system are confirmed. The risk analysis is provided for the corrosion control design and anode material selection in this environment to avoid similar failure risks. It can avoid shutdown and major safety accidents caused by this problem. [ABSTRACT FROM AUTHOR]

Some naval vessels add seawater to carbon steel fuel ballast tanks to maintain stability during fuel consumption. Marine sediments often contaminate ballast tank fluids and have been implicated in stimulating fuel biodegradation and enhancing biocorrosion. The impact of the marine sediment was evaluated in model ballast tank reactors containing seawater, fuel (petroleum-F76, Fischer–Tropsch F76, or a 1:1 mixture), and carbon steel coupons. Control reactors did not receive fuel. The marine sediment was added to the reactors after 400 days and incubated for another year. Sediment addition produced higher estimated bacterial numbers and enhanced sulfate reduction. Ferrous sulfides were detected on all coupons, but pitting corrosion was only identified on coupons exposed to FT-F76. Aerobic hydrocarbon-degrading bacteria increased, and the level of dissolved iron decreased, consistent with the stimulation of aerobic hydrocarbon degradation by iron. We propose that sediments provide an inoculum of hydrocarbon-degrading microbes that are stimulated by dissolved iron released during steel corrosion. Hydrocarbon degradation provides intermediates for use by sulfate-reducing bacteria and reduces the level of fuel components inhibitory to anaerobic bacteria. The synergistic effect of dissolved iron produced by corrosion, biodegradable fuels, and iron-stimulated hydrocarbon-degrading microbes is a poorly recognized but potentially significant biocorrosion mechanism.

The biocorrosion of carbon steel poses a risk for ships combining seawater and fuel in metal ballast tanks. Ballast tanks were simulated by duplicate reactors containing carbon steel coupons and either petroleum F76 (petro-F76), Fischer–Tropsch F76 (FT-F76), or a 1:1 mix of both fuels, to investigate whether the alternative fuel FT-F76 influenced this risk. The polycarbonate reactors were inoculated with seawater, and the control reactors did not receive fuel. The reactors were monitored for 400 days, and they all reached a pH and open circuit potential where elemental iron was oxidized, indicating corrosion. The reactors containing petro-76 or fuel mix had higher levels of dissolved iron; one of each replicate had lower concentrations of sulfate than the original seawater, while the sulfate concentration did not decrease in the other incubations. The high sulfate reactors, but not the low sulfate reactors, had a high relative abundance of microaerophilic sulfide-oxidizing bacteria. The FT-F76 and the no-fuel reactors had a high relative abundance of iron-sequestering Magnetovibrio. Although dissolved iron and loss of sulfate under anoxic conditions are associated with biocorrosion, our results suggest that in our reactors these indicators were altered by iron-sequestering and sulfide-oxidizing microbes, which is consistent with the slow diffusion of oxygen across the polycarbonate reactors.

The biocorrosion of carbon steel poses a risk for ships combining seawater and fuel in metal ballast tanks. Ballast tanks were simulated by duplicate reactors containing carbon steel coupons and either petroleum F76 (petro-F76), Fischer–Tropsch F76 (FT-F76), or a 1:1 mix of both fuels, to investigate whether the alternative fuel FT-F76 influenced this risk. The polycarbonate reactors were inoculated with seawater, and the control reactors did not receive fuel. The reactors were monitored for 400 days, and they all reached a pH and open circuit potential where elemental iron was oxidized, indicating corrosion. The reactors containing petro-76 or fuel mix had higher levels of dissolved iron; one of each replicate had lower concentrations of sulfate than the original seawater, while the sulfate concentration did not decrease in the other incubations. The high sulfate reactors, but not the low sulfate reactors, had a high relative abundance of microaerophilic sulfide-oxidizing bacteria. The FT-F76 and the no-fuel reactors had a high relative abundance of iron-sequestering Magnetovibrio. Although dissolved iron and loss of sulfate under anoxic conditions are associated with biocorrosion, our results suggest that in our reactors these indicators were altered by iron-sequestering and sulfide-oxidizing microbes, which is consistent with the slow diffusion of oxygen across the polycarbonate reactors. [ABSTRACT FROM AUTHOR]

The development of the shipping industry has led to a large volume of ballast water discharge annually. This accelerates pollutants' transfer and dispersion, such as microplastics. Currently, empirical data on microplastics in ballast water are rarely available. This study innovatively investigated the abundance, morphological characteristics (particle size, shape, and color), and polymer composition of microplastics in ballast water from ports surrounding the Liaodong Peninsula. The results revealed that the average abundance of microplastics in 13 ships' ballast water was 6071.30 ± 1313.85 items/m3. Notably, the small microplastics (0.06–2.50 mm) were most abundant, accounting for 94.52 % of the total microplastics. Transparent, fiber, and polyethylene glycol terephthalate were the most prevalent color, shape, and polymer composition of microplastics detected in the ballast water. The risk assessment indicated that these microplastics present ecological risks to organisms. These findings suggest that ship ballast water is the potential "hotspot" for marine microplastics transport. [Display omitted] • Investigated the distribution characteristics of MPs in ballast water • The primary size of MPs in ballast water was found within the range of 0.01–2.50 mm. • Transparent and fiber were the most prevalent color and shape in ballast water. • High abundances of MPs were detected in ballast water. • Ballast water could be a potential source of MPs in marine, posing ecological risks. [ABSTRACT FROM AUTHOR]

In this study (Part II), the empirical formulation of corrosion model of a ship’s ballast tank was developed to predict nonlinear time-dependent corrosion wastage based on the advanced data processing technique proposed by Part I. The detail on how to propose generalised mathematical formulation of corrosion model was precisely documented in the previous paper (Part I). The statistical scatter of corrosion data at any exposure time was investigated by the refined method and formulated based on a 2-parameter Weibull distribution which selected the best fit PDF. Throughout the nine (9) steps, empirical formulation of the ship’s seawater ballast tank was successfully proposed and four (4) key step results were also obtained. The proposed method in Part I was verified and confirmed by this application of seawater ballast tank, thus making it possible to predict accurate behaviours of nonlinear time-dependent corrosion. Developed procedures and obtained corrosion damage model for ship’s seawater ballast tank can be used for development of engineering software.

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Invasive alien species, on successful establishment, can displace native species. The threat of invasive species arises in view of their ability to outcompete and destabilize native biodiversity. Invasive species are found across all taxonomic groups of plants, animals and microorganisms. The green macroalga Ulva flexuosa has a potential to become invasive and this species was investigated for its hitchhiking potential under laboratory conditions. Zoospores of U. flexuosa were maintained at 4°C for nearly 10 months in the dark. Recruitment potential of zoospores after dark stress was tested in a modified Provasoli medium under optimal laboratory conditions. The success rate of zoospore recruitment was 61%. The paper describes the transfer potential through shipping activities by correlating the Ulva zoospores recruitment potential and survivability.

Operating principle and flow field characteristics of a diving ballast tank for application in submerged vehicles were investigated in the present study. As understanding the complex changes in the interior air-water two-phase flow field of the ballast tank during the diving process is difficult, this study specifically performed a ballast tank diving experiment. Experimental and numerical simulations to analyse the diving motions of the ballast tank were conducted. Authors comprehensively evaluated the flow field changes in the ballast tank and its surroundings. The experimental and numerical results were compared in terms of the observed displacements and velocities during diving. Both the results indicated similar motion trajectories and velocities. Authors effectively observed the airwater two-phase flow field change inside the ballast tank using this numerical method. Therefore, the numerical model constructed in this study can be useful for analysing the diving motions of ballast tanks and can effectively predict the interior flow field characteristics of a ballast tank. [ABSTRACT FROM AUTHOR]

Purpose: The International Maritime Organization's (IMO) International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM Convention) was entered into force in September 2017. It deals with one of the greatest threats to coastal and marine environments around the world: aquatic invasive alien species (IAS) and harmful aquatic organisms and pathogens (HAOP). Although the control of IAS and HAOP through treatment of ballast water (BW) is appropriately dealt with in the Convention and its implementation, the problems generated by sediments are not treated in such a manner. Materials and methods: There are many published technical and scientific papers, discussions and commentaries proposing the remediation of the present situation. They are discussed, and recommendations are summarized. Besides, several systems for the treatment of BW use a combination of two or three techniques, with filtration usually being the first and/or the last step. Presence of sediments in BW results in the reduced applicability of such an approach. Results and discussion: The requirements for sediment management procedures are discussed along with a proposal for their implementation. In the first step, the ballast tank sediments should be freed of active biological agents for the elimination of IAS and HAOP. Instead of biological agents, we advocate the use of radiation treatment by using an electron accelerator, preferably in an on-shore installation or as a mobile, additive, sea container size units with integral power, separated for water and sediment treatment. In the second step, the concentrations of heavy metals should be determined. We recommend the use of EDXRF as an analytical method. After the determination of sediment class, the recommended disposal procedures should be followed. Conclusions: Sediment management procedures should specify the disposal requirements: (i) free of active biological agents, IAS and HAOP; (ii) chemical composition, no chemical elements in a toxic range (≤ Class 3); and (iii) displacement/storage requirements, displacing sediments characterized as harmful in appropriate sediment reception facilities/landfills. [ABSTRACT FROM AUTHOR]

Transport of ballast water is considered a significant vector for dispersion of different pollutants, including microplastics (MPs), throughout the world's oceans. However, there is limited information on MPs in ballast water. Size distribution, polymer type, and ecological risks of MPs in ballast water were investigated for the first time in this study. The mean levels of MPs in ballast water and seawater samples were 12.53 and 11.80 items/L, respectively. MPs with a size category of 50–300 μm was the most abundant. Fiber, black, and polycarbonate (PC) were the predominant shape, color, and polymer type of identified MPs in ballast water and seawater, respectively. The pollution load index (PLI), hazard index (HI), and risk quotient (RQ) indicated high levels of MP pollution, potentially indicating an ecological risk. These findings increase our understanding of the major sources (such as ballast water), transportation routes, and related ecological risks of MPs to marine ecosystems. [Display omitted] • Occurrence of microplastics nMPs) was investigated in ballast water and seawater. • MPs with size of 50–300 μm was the dominant size in ballast water and seawater. • Polycarbonate and fiber were dominant polymer and shape in ballast water and seawater. • Analysis revealed high ecological risks of MPs in ballast water and seawater. [ABSTRACT FROM AUTHOR]

The potential risks of ballast tank sediments have garnered global attention. This study collected sediment samples from ballast tanks of four transoceanic ships and determined 27 metal(loid) s by GB 5085.6-2007 and 9 metal(loid)s by GB 18668-2002. The pollution characteristics and ecological risk assessment of 8 typical heavy metals measured by both standards were analyzed and compared. Concentrations of Cd, Zn, and As were found to be high in the ballast tank sediments, and attention should also be directed toward Sn and Mn, which were rarely studied in ballast tank sediments. The concentration of Ni had significant differences between the two standards (P < 0.05). The results of ecological risk methods indicate that Cd, Zn, and As pose significant ecological risks. GB 5085.6-2007 demonstrated sensitivity in reflecting the ecological risks of heavy metals. Overall, this study provides valuable insights into establishing a unified standard for heavy metals for future ballast tank sediment management. • The concentrations of Cd, Zn, and As in ballast tank sediments were high, posing a significant ecological risk. • Rarely studied heavy metals in ballast tank sediments, such as Mn and Sn, also pose serious risks and deserve attention. • There were statistically significant differences between the two standards for the detection concentration of Ni (P < 0.05). • GB 5085.6-2007 can more sensitively reflect the ecological risk of heavy metals and identify more pollution risks. [ABSTRACT FROM AUTHOR]

Ballasting with water tanks is essential for improving the efficiency, cost and safety of lifting operation with revolving floating cranes. An optimisation model of ballast water high-efficiency adjustment was presented for the tube tunnel type ballast system. The water level variation of each ballast tank during ballasting process, the ballast water filling mass from sea before lifting and discharging mass after lifting operation are taken as optimisation variables, the minimal ballasting time during lifting process as the optimisation objective, and keeping the hull balance and stability in the lifting process as the constraint conditions. The ballast water allocation optimisation can be characterised by a multi-step decision process, and a dynamic programming method is presented which divides the decision stages based on the crane revolving angles in the rotary lifting process. An example is given to illustrate and analyse the proposed model and approach. [ABSTRACT FROM AUTHOR]

Ballast 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 FROM AUTHOR]

The wave load on a navigation lock sliding gate equipped with a ballast tank is investigated assuming the linear wave theory is valid and using the eigenfunction expansion matching method to solve the governing equations. The correctness and the limits of the solution have been checked by comparing the results with those of a numerical code which solve the full non linear Navier-Stokes equations. The results relating to the effect of the geometrical parameters and wave characteristics on the load acting on the gate are presented and discussed. The ballast tank is found to increase the complexity of the phenomenon in relation to the wave interaction with the gate. The results indicate that the peak value of the vertical force occurs for wave numbers mostly dependent on the tank length and on the tank position along the depth, while the thickness has a smaller influence. The ballast tank has also a significant effect on the horizontal dynamic force acting on the gate, which vanishes when the wave number takes particular values. Finally, the moment applied to the gate shows a dependency on the geometrical and hydrodynamic parameters similar to that of the forces. [ABSTRACT FROM AUTHOR]

Ballast tanks are of great importance in the lifetime of modern merchant ships. Making a ballast tank less susceptible to corrosion can, therefore, prolong the useful life of a ship and, thereby, lower its operational cost. An option to reinforce a ballast tank is to construct it out of a corrosion-resistant steel type. Such steel was recently produced by POSCO Ltd., South Korea. After 6 months of permanent immersion, the average corrosion rate of A and AH steel (31 samples) was 535 g m year, while the Korean CRS was corroding with 378 g m year. This entails a gain of 29 %. Follow-up measurements after 10, 20, and 24 months confirmed this. The results after 6 months exposure to alternating wet/dry conditions are even more explicit. Furthermore, the physical and metallurgical properties of this steel show a density of 7.646 t/m, the elasticity modulus 209.3 GPa, the tensile strength 572 MPa, and the hardness 169HV10. Microscopically, the metal consists of equiaxed and recrystallized grains (ferrite and pearlite), with an average size of between 20 and 30 µm (ASTM E 112-12 grain size number between 7 and 8) with a few elongated pearlitic grains. The structure is banded ferrite/pearlite. On the basis of a series of energy dispersive X-ray spectrometer measurements the lower corrosion rate of the steel can be attributed to the interplay of Al, Cr, their oxides, and the corroding steel. In addition, the role of each element in the formation of oxide layers and the mechanisms contributing to the corrosion resistance are discussed. [ABSTRACT FROM AUTHOR]