Ballast Tanks Of Ships Research Articles

Transoceanic ships as a source of alien dinoflagellate invasions of inland freshwater ecosystems

Ships' ballast water and sediments have long been linked to the global transport and expansion of invasive species and thus have become a hot research topic and administrative challenge in the past decades. The relevant concerns, however, have been mainly about the ocean-to-ocean invasion and sampling practices have been almost exclusively conducted onboard. We examined and compared the dinoflagellate cysts assemblages in 49 sediment samples collected from ballast tanks of international and domestic routes ships, washing basins associated with a ship-repair yard, Jiangyin Port (PS), and the nearby area of Yangtze River (YR) during 2017–2018. A total of 43 dinoflagellates were fully identified to species level by metabarcoding, single-cyst PCR-based sequencing, cyst germination and phylogenetic analyses, including 12 species never reported from waters of China, 14 HABs-causing, 9 toxic, and 10 not strictly marine species. Our metabarcoding and single-cyst sequencing also detected many OTUs and cysts of dinoflagellates that could not be fully identified, indicating ballast tank sediments being a risky repository of currently unrecognizable invasive species. Particularly important, 10 brackish and fresh water species of dinoflagellate cysts (such as Tyrannodinium edax) were detected from the transoceanic ships, indicating these species may function as alien species potentially invading the inland rivers and adjacent lakes if these ships conduct deballast and other practices in fresh waterbodies. Significantly higher numbers of reads and OTUs of dinoflagellates in the ballast tanks and washing basins than that in PS and YR indicate a risk of releasing cysts by ships and the associated ship-repair yards to the surrounding waters. Phylogenetic analyses revealed high intra-species genetic diversity for multiple cyst species from different ballast tanks. Our work provides novel insights into the risk of bio-invasion to fresh waters conveyed in ship's ballast tank sediments and washing basins of shipyards.

The prevalence of potential pathogens in ballast water and sediments of oceangoing vessels and implications for management

Ballast water and sediments can serve as prominent vectors for the widespread dispersal of pathogens between geographically distant areas. However, information regarding the diversity and distribution of the bacterial pathogens in ballast water and sediments is highly limited. In this study, using high-throughput sequencing and quantitative PCR, we investigated the composition and abundance of potential pathogens, and their associations with indicator microorganisms. We accordingly detected 48 potential bacterial pathogens in the assessed ballast water and sediments, among which there were significant differences in the compositions and abundances of pathogenic bacterial communities characterizing ballast water and sediments. Rhodococcus erythropolis, Bacteroides vulgatus, and Vibrio campbellii were identified as predominant pathogens in ballast water, whereas Pseudomonas stutzeri, Mycobacterium paragordonae, and Bacillus anthracis predominated in ballast sediments. Bacteroidetes, Vibrio alginolyticus, Vibrio parahaemolyticus, and Escherichia coli were generally detected with median values of 8.54 × 103−1.22 × 107 gene copies (GC)/100 mL and 1.16 × 107−3.97 × 109 GC/100 g in ballast water and sediments, respectively. Notably, the concentrations of Shigella sp., Staphylococcus aureus, and V. alginolyticus were significantly higher in ballast sediments than in the water. In addition, our findings tend to confirm that the indicator species specified by the International Maritime Organization (IMO) might underestimate the pathogen risk in the ballast water and sediments, as these bacteria were unable to predict some potential pathogens assessed in this study. In summary, this study provides a comprehensive insight into the spectrum of the potential pathogens that transferred by ship ballast tanks and emphasizes the need for the implementation of IMO convention on ballast sediment management.

DEVELOPMENT OF BALLAST WATER PURIFICATION AND DISINFECTION TECHNOLOGY

The technology of purification and disinfection of ballast water developed by the authors is presented in the paper. Based on the results of a systematic analysis of the problem and on research experience in this field, it has been shown that the quality of ballast water discharged overboard after its use as ballast is determined by such basic factors as purification technology and design features of treatment devices, as well as conditions for operations with ballast water. The technology of ballast water purification as a complex of operations for purification, treatment and disinfection is determined by environmental requirements for the quality of purified and discharged overboard water, as well as the properties of the initial ballast water. The analysis of modern environmental requirements for the discharge of ballast water is given. It is shown that these requirements establish the level of permissible bacteriological danger of the discharged ballast water, taking into account the dispersed characteristics of the bacteriologically dangerous substance. These requirements determine the composition of operations that should be included in the technology of purification and disinfection of ballast water. Based on the results of the analysis of environmental requirements for the quality of purified ballast water, which determine the required water quality, a number of technological solutions collectively representing the technology of water purification and disinfection are proposed and justified. As disinfection, the use of ozone as an effective oxidizer is proposed. The use of sedimentation is proposed to regulate the content of dispersed particles of pollutants. Technological solutions also take into account the need for operations with a large amount of ballast water, as well as high reception and discharge capacity. It is proposed to carry out the disinfection process in small volumes of sediment, which is a concentrated mass of bacteriological substance obtained during preliminary coagulation and sedimentation, for which ship ballast tanks can be used. The proposed technology can be applied both in ship installations and in offshore environmental protection equipment - floating or coastal, for example, port facilities.

Survival and recovery of planktonic organisms in prolonged darkness and their implications on ballast water management

Understanding the population dynamics of transported organisms in the ship's ballast tanks during shipping operations and their ability to survive and colonize in the receiving environment (destination) can aid in developing effective ballast water treatment and management strategies. In the present study a natural plankton pool harvested from a tropical coast was used to study their survival in prolonged darkness and their regrowth potential upon re-illumination in laboratory conditions. In darkness, phytoplankton density and chlorophyll-a biomass decreased with increase in nutrient levels attributing to cell lysis. However, when subjected to vital staining using SYTOX® green, about 60% of phytoplankton survived in the dark tanks. Upon re-illumination after 36 days of incubation in darkness, >80% of recovered phytoplankton were pennate diatoms. On the other hand, zooplankton failed to survive/recover during the experiments when incubated in the dark. Less than 30% of the live zooplankton stained using Neutral Red in the dark tanks failed to recover during experiments. The data obtained clearly shows that prolonged dark incubation may promote the growth of opportunistic organisms and may alter their invasive potential through time and cause serious negative impacts to the receiving environment when transported by ballast water.

Deciphering the characterization, ecological function and assembly processes of bacterial communities in ship ballast water and sediments

Various microorganisms are transported worldwide via the water and sediments inside ship ballast tanks. Nevertheless, the ecological functions and assembly processes of bacterial communities in ballast water and sediments remain poorly understood. Here, we investigated the bacterial composition, community assembly processes, and putative functions through analyses of 70 ballast water and sediment samples obtained from various ships. The results showed that the ballast sediments contained a higher diversity of bacterial communities, whereas the ballast water was characterized by the dominance of Proteobacteria. Both the composition and potential function structures of bacterial communities were clearly different between the ballast water and sediment samples. The ballast water exhibited an abundance of microorganisms that involved in sulfur oxidation, whereas the bacterial species associated with nitrogen metabolism were abundant in the sediments. Co-occurrence network analysis revealed that the communities in ballast sediment samples possessed more complex network structures with higher modularity and positive associations among bacterial populations. Stochastic processes, especially the dispersal limitation process played the most important influence in the assembly of the communities in ballast water. Meanwhile, the bacterial communities in the ballast sediments were primarily governed by the homogeneous selection of determinacy. The results from this study will help us understand the ecological processes related to the bacterial communities in the ballast tanks and provide a foundation for the management of ballast water and sediments.

Pseudocochlodinium profundisulcus Resting Cysts Detected in the Ballast Tank Sediment of Ships Arriving in the Ports of China and North America and the Implications in the Species' Geographic Distribution and Possible Invasion.

Over the past several decades, much attention has been focused on the dispersal of aquatic nonindigenous species via ballast tanks of shipping vessels worldwide. The recently reclassified dinoflagellate Pseudocochlodinium profundisulcus (previously identified as Cochlodinium sp., Cochlodinium geminatum, or Polykrikos geminatus) was not reported in China until 2006. However, algal blooming events caused by this organism have been reported almost every year since then in the Pearl River Estuary and its adjacent areas in China. Whether P. profundisulcus is an indigenous or an invasive species has thus become an ecological question of great scientific and practical significance. In this study, we collected the sediments from ballast tanks of ships arriving in the ports of China and North America and characterized dinoflagellate resting cysts via a combined approach. We germinated two dark brownish cysts from the tank of an international ship (Vessel A) arriving at the Jiangyin Port (China) into vegetative cells and identified them as P. profundisulcus by light and scanning electron microscopy and phylogenetic analyses for partial LSU rDNA sequences. We also identified P. profundisulcus cyst from the ballast tank sediment of a ship (Vessel B) arriving in the port of North America via single-cyst PCR and cloning sequencing, which indicated that this species could be transported as resting cyst via ship. Since phylogenetic analyses based on partial LSU rDNA sequences could not differentiate all sequences among our cysts from those deposited in the NCBI database into sub-groups, all populations from China, Australia, Japan, and the original sources from which the cysts in the two vessels arrived in China and North America were carried over appeared to share a very recent common ancestor, and the species may have experienced a worldwide expansion recently. These results indicate that P. profundisulcus cysts may have been extensively transferred to many regions of the world via ships’ ballast tank sediments. While our work provides an exemplary case for both the feasibility and complexity (in tracking the source) of the bio-invasion risk via the transport of live resting cysts by ship’s ballast tanks, it also points out an orientation for future investigation.

Study on the dinoflagellate cysts in ballast tank sediments of international vessels in Chinese shipyards

The problem of aquatic invasive species caused by discharge of ballast water and sediments from ships’ ballast tanks has become extremely prominent. Seventeen sediment samples taken from ballast tanks of different ships docked in two Chinese shipyards were examined to identify the variety of resting dinoflagellate cysts. Twenty-two dinoflagellate cyst taxa were identified in these samples, including 11 photosynthetic and eleven heterotrophic species. These species represent 10 genera with the dominating assemblages of Alexandrium minutum, Scrippsiella acuminata, Lingulodinium polyedra, Protoperidinium sp. and Protoperidinium conicum. The total abundance of the dinoflagellate cysts ranged from 36 to 448 cysts g−1 dry weight, which demonstrated a wide range of diversity for different ships. It was observed that the number of taxa and concentrations of cysts in ballast tank sediments were slightly greater for ships performing short voyage than ships performing longer voyage. The compositions of dinoflagellate cysts in sediments from ships sailing diverse routes were more variable than those sailing same routes. Sediment moisture content proved to be well correlated to the total cyst abundance (r = 0.7422, P < 0.01). Furthermore, nine toxic and harmful species were observed from all sediment samples, which indicated a wide range of distribution and potential risk of harmful algal blooms if being discharged to Chinese waters. As a result, full attention should be drawn to the studies on dinoflagellate cysts in the ballast tank sediments from ships arriving at China, this is of great significance for preventing introduction of toxic and harmful dinoflagellate cysts and protecting native marine biodiversity.

Технология очистки и обеззараживания балластной воды

The paper considers the problem of transferring microorganisms with ballast water used in the ship operation. It is noted that the search for a solution to the above problem takes a significant amount of time and requires developing special purifying equipment for disinfecting ballast water. Currently, there are various plants ensuring the decreased number of microorganisms in the process of disinfection. There has been proposed a new technology for ballast water treatment and decontamination that involves depositing microorganisms, removing them from the total volume of ballast water followed by ozone treatment. Actually, the volume of water containing sediment and decontaminated with ozone is significantly less than the total volume of ballast water and makes up about 3-5% of it. Microorganisms depositing takes place due to coagulation and sedimentation. The diagram of the ballast water purification and disinfection technology has been presented. The basic circuit of the ballast water disinfection plant includes a ship's ballast tank, receiving pipeline, reagent tank, metering pump, coagulant, collector, bulkhead, contact column, ozone generator, dehydration device and ultraviolet lamps. The operating conditions of the ship plants have space and time limits. The above technological solutions infer carrying out some operations (coagulation, sedimentation) and disinfection by using the ultraviolet lamps inside the ballast tanks for saving space. The proposed technology can be applied both on board a ship and in the floating or onshore environmental protection equipment, for example, in the port facilities.

A Study into the Coating Thickness of Ship Ballast Tanks

Ballast tanks are expected to be coated according to the IMO Performance Standard for Protective Coating regulations (PSPC15), in addition to the paint application requirements of the paint producer. In general, a coating system should consist of minimum two spray coats of light-colored epoxy coating on flat surfaces with a Nominal total Dry Film Thickness (NDFT) of 320 μm and 90% of all thickness measurements greater than, or equal to the NDFT and none of the remaining measurements below 0.9 x NDFT (the “90/10 rule”). Allegedly, the value of 320 μm in this PSPC15 rule may be misconstrued as a benchmark for coating application on flat surfaces, eventually leading to a non-PSPC15 compliance due to the resulting variation in coating thickness violating this 90/10 rule. This study indicates that over the years, the arithmetic mean in-situ DFT appears to be 498±18 μm and that too high and low thicknesses, below 288 μm and above 800 μm, were noted in the field. Analysis of a survey of ballast tank coating performance of ships indicates that too low thicknesses appear to be negatively impacting the average theoretical ballast tank performance. However, when an application mean DFT benchmark of 525 μm is used, the coating will almost surely comply to the 90/10 rule and the risk of falling below the 288 μm threshold is small, less than 2% in most cases. Consequently, using 320 μm as a mean DFT benchmark could result in a non-PSPC15 compliance with the in-situ ascertained coating thickness variation as this does not exclude coating thicknesses below 288 μm, which may then result in a significantly less than average theoretical coating performance. If the coating application is performed very evenly, the benchmark may be reduced to 429 μm with a probability of falling below 288 μm reduced to 0.1%. It should therefore be emphasized that the PSPC15 requirement is a coating system framework description, and that the requirement should be broadened to include a mean DFT as a coating applicator benchmark together with a clearly specified minimum and maximum DFT, in order to avoid any misinterpretations.

Alien Invasive Species Impacts on Large Lake Ecosystems and Their Economic Value

Globalization of trade and travel has made possible the spread of alien species across the planet. Invasive species are presently considered as one of the major threats to biodiversity in many locations throughout the world. Thousands of AIS have been transported globally by a number of anthropogenically-mediated vectors, including ship-mediated vectors (e.g., ballast water, hull-fouling), recreational boating, live bait, aquarium trade, live food fish, and unauthorized introductions. Ballast water is one of the leading vectors for transporting and introducing species, both in Canada and around the world, and is responsible for the transport of at least one third of all documented marine invasions. Since invasive species have no regard for political boundaries, efforts to prevent invasions need to be interjurisdictional. Given, also that invasive species often travel as contaminants of trade transfers, for example, in the ballast tanks of ships, reducing the spread of invasive species via this pathway would either require constraints on where ships travel, or the installation onto all ships of expensive ballast treatment technology, thereby increasing the cost of shipped goods. As such cost benefit analysis involves trade-offs with other activities, complicating decisions about how impacts can best be managed.

Retrospective eDNA assessment of potentially harmful algae in historical ship ballast tank and marine port sediments.

Microalgal bloom events can cause major ecosystem disturbances, devastate local marine economies, and endanger public health. Therefore, detecting and monitoring harmful microalgal taxa is essential to ensure effective risk management in waterways used for fisheries, aquaculture, recreational activity, and shipping. To fully understand the current status and future direction of algal bloom distributions, we need to know how populations and ecosystems have changed over time. This baseline knowledge is critical for predicting ecosystem responses to future anthropogenic change and will assist in the future management of coastal ecosystems. We explore a NGS metabarcoding approach to rapidly identify potentially harmful microalgal taxa in 63 historic and modern Australian marine port and ballast tank sediment samples. The results provide a record of past microalgal distribution and important baseline data that can be used to assess the efficacy of shipping guidelines, nutrient pollution mitigation, and predict the impact of climate change. Critically, eDNA surveys of archived sediments were able to detect harmful algal taxa that do not produce microscopic fossils, such as Chattonella, Heterosigma, Karlodinium, and Noctiluca. Our data suggest a potential increase in Australian harmful microalgal taxa over the past 30years, and confirm ship ballast tanks as key dispersal vectors. These molecular mapping tools will assist in the creation of policies aimed at reducing the global increase and spread of harmful algal taxa and help prevent economic and public-health problems caused by harmful algal blooms.

A global perspective for biodiversity history with ancient environmental DNA.

The past centuries have seen tremendous turnovers in species distributions and biodiversity due to anthropogenic impacts on a global scale. The processes are ongoing and mostly not well documented. Long-term records of biotic change can be recovered from sedimentary deposits, but traditional analyses were restricted to organisms that leave behind visible traces and molecular genetic tools were mostly employed on samples that promised good DNA preservation. In this issue of Molecular Ecology, Shaw, Weyrich, Hallegraeff and Cooper (2019) and Gomez Cabrera et al. (2019) present two studies on marine sedimentary records from warm environments, in which they successfully analyze ancient environmental DNA (aeDNA) on a decadal and centennial scale. Notably, the studies were conducted on novel samples with nonoptimal preservation conditions for ancient DNA - historical collections of ship ballast tank sediments from Australia and two coral reef cores spanning up to 750years (Figure 1) - but yielded a high diversity of taxa. This highlights that aeDNA is a promising tool to globally study biodiversity history on scales of decades to centuries - the timeframe most relevant to human society in the context of both current climate change and direct anthropogenic modifications of the environment.

Abundances and profiles of antibiotic resistance genes as well as co-occurrences with human bacterial pathogens in ship ballast tank sediments from a shipyard in Jiangsu Province, China

Ship ballasting operations may transfer harmful aquatic organisms across global ocean. This study aims to reveal the occurrences and abundances of antibiotic resistance genes (ARGs) and human bacterial pathogens (HBPs) in ballast tank sediments. Nine samples were collected and respectively analyzed by real-time quantitative PCR and high-throughput sequencing technologies. Ten ARGs (aadA1, blaCTX-M, blaTEM, ermB, mefA, strB, sul1, sul2, tetM, and tetQ) and the Class-I integron gene (intI1) were highly prevalent (105–109 gene copies/g) in ballast tank sediments. The sul1 was the most abundant ARG with the concentration of 108–109 copies/g and intI1 was much more abundant than the ARGs in ballast tank sediments. The strong positive correlations between intI1 and ARGs (blaCTX-M, sul1, sul2 and tetM) indicated the potential spread of ARGs via horizontal gene transfer. In ballast tank sediments, 44 bacterial species were identified as HBPs and accounted for 0.13–21.46% of the total bacterial population although the three indicator pathogenic microbes (Vibrio cholerae, Escherichia coli, and Enterococci) proposed by the International Maritime Organization were not detected. Pseudomonas pseudoalcaligenes, Enterococcus hirae, Shigella sonnei and Bacillus anthracis were the dominant pathogens in ballast tank sediments. Zn and P in sediments had positive effects on the ARGs. Network analysis results indicated that sul1 and sul2 genes existed in several bacterial pathogens. Ballast tank sediments could be regarded as a carrier for the migration of ARGs. It is important to manage ballast tank sediments reasonably in order to prevent the dissemination of ARGs and bacterial pathogens.

Optimizing methods to estimate zooplankton concentration based on generalized patterns of patchiness inside ballast tanks and ballast water discharges.

Zooplankton populations are spatially heterogeneous in nature and inside ship ballast tanks. Sampling methods should take heterogeneity into account, particularly when estimating quantitative variables such as abundance or concentration. It is particularly important to generate unbiased estimates of zooplankton concentration in ballast water when assessing compliance with new international ballast water discharge standards. We measured spatial heterogeneity of zooplankton within ballast water using three sampling methodologies. In‐tank pump samples were collected at fixed depths within the vertical part of the ballast tank (side tank). Vertical net‐haul samples were collected from the upper portion of the tank as a depth‐integrated and historically relevant method. In‐line, time‐integrated samples were collected during ballast discharge by an isokinetic sample probe, likely representing the double bottom part of the ballast tank. The bias and precision associated with each sampling method were evaluated in reference to the estimated average abundance of the entire ballast tank, which was modeled from the data collected by all methods. In‐tank pump samples provided robust evidence for vertical stratification of zooplankton concentration in the side tank. A consistent trend was also observed for in‐line discharge samples, with zooplankton concentration decreasing through time as the ballast tank is being discharged. Sample representativeness, as compared to the tank average, varied depending on the depth or tank volume discharged. In‐line discharge samples provided the least biased and most precise estimate of average tank abundance (having lowest mean squared error) when collected during the time frame of 20%–60% of the tank volume being discharged. Results were consistent across five trips despite differences in ballast water source, season, and age.

Efficacy and residual toxicity of a sodium hydroxide based ballast water treatment system for freshwater bulk freighters

Abstract The efficacy and residual toxicity of a sodium hydroxide (NaOH) based ballast water treatment system (BWTS) were tested aboard the Great Lakes carrier M/V American Spirit in 1000 L mesocosms containing water from the ship's ballast tanks. NaOH was added to elevate the pH to 11.5 or 11.7 for 48 h, after which pH was reduced to 96% in pH 11.7 treated discharge water relative to uptake densities. Seven day whole effluent toxicity tests indicated pH 11.7 NaOH BW met the USEPA VGP daily maximum criteria for residual toxicity. Organism densities in uptake water did not meet the minimum densities for IMO G8 shipboard test validity in 2 of 4 trials for organisms ≥ 10 μm to

Recent invasion of the foraminiferNonionella stellaCushman &amp; Moyer, 1930 in northern European waters: evidence from the Skagerrak and its fjords

The eastern Pacific benthic foraminifer Nonionella stella Cushman & Moyer, 1930 was recorded for the first time in the Skagerrak (North Sea) and its fjords. In this short note we evaluate its migration, considering both dispersal by propagules and ship ballast tanks. We suggest that the predominantly southward surface currents along the western European seaboard and Morocco would impede a wide-range dispersal of N. stella propagules and hypothesize transportation by ship ballast tanks as the possible vector of N. stella immigration into northern European seas.

High colonization and propagule pressure by ship ballast as a vector for the diatom genus Pseudo-nitzschia

Most harmful diatoms belong to the marine, planktonic genus Pseudo-nitzschia and are responsible for amnesic shellfish poisoning through the production of domoic acid. Fifteen Pseudo-nitzschia species, nine of them toxigenic (approximately 60% of the species found in our samples) were recovered from 185 ship ballast tanks (water and sediment) destined for Canadian ports. Our results demonstrate that the three Canadian coastal regions receive considerable total propagule pressure (1.2 × 10 13

A field study of the effectiveness of sacrificial anodes in ballast tanks of merchant ships

Sacrificial anodes have become a standard practice for the protection of ballast tanks of merchant vessels against corrosive damage. A well protected tank should extend the life span of a ship and consequently enhances its economic value. An in situ survey comprising more than 100 merchant vessels provided the opportunity to measure the impact of these anodes on the life expectancy of these vessels. Contrary to the general belief of these anodes’ beneficial effect, no significant difference was found in our observations in terms of corrosion occurrence between ship populations with and without sacrificial anodes, across all ship ages. This may be explained by the highly variable conditions and the complex geometry in a ballast tank severely impede optimal and straightforward installation of these anodes in these tanks. Also, poorly placed anodes in it may harm the integrity of the coating of the tank. We therefore plead for uniform and clear rules on anode installation and inspection.

Reducing the cost of ballast tank corrosion: an economic modeling approach

One of the most relevant problems in ship construction and maintenance nowadays concerns the corrosion in the double hull space ballast tanks of modern merchant vessels. On the one hand, there is a general consensus that the economic life span of such a vessel depends primarily upon the corrosion state of its ballast tanks, while on the other hand, the position of these tanks, squeezed between the outer hull and the loading tanks, makes routine inspection and maintenance almost impossible.Today, ship's ballast tanks are usually constructed in grade A steel and protected with a standard epoxy coating, backed up with sacrificial zinc anodes. Such a construction has been applied without significant alterations for many years. However, the objective of this economic study is to compare this construction method with some feasible alternatives. The considered alternatives are: (1) an increase of the scantlings, eliminating the necessity to replace corroded steel but diminishing the cargo carrying capacity of the ship, (2) application of the novel and more durable TSCF25 coating (3), the use of corrosion resistant steel in ship construction or (4) a standard PSPC15 coating combined with lifetime lasting aluminum sacrificial anodes. After running each alternative through a cost model including an extensive sensitivity analysis, it is concluded that the durable coating and the use of lifetime lasting aluminum anodes are bound to improve the actual basic tank concept. Corrosion resistant steel becomes attractive depending upon the evolution of the international steel market.

Study on alternative approaches to corrosion protection of ballast tanks using an economic model

One of the most relevant problems in ship construction and maintenance nowadays is corrosion in ballast tanks of modern merchant vessels. On the one hand, there is a general consensus that the economic lifespan of such a vessel depends, to a large degree, upon the corrosion state of its ballast tanks, while on the other hand these ballast tanks, located between the outer hull and the cargo tanks, makes routine inspection and maintenance a difficult task.Today, ship's ballast tanks are usually constructed in steel and protected with an epoxy coating backed up by sacrificial zinc anodes. Such a construction has been applied without significant alterations for many years. The objective of this economic study is to compare this construction method with some potential alternatives. The considered alternatives are: (1) an increase in structural scantlings, eliminating the necessity to replace corroded at a cost of real cargo carrying capacity of the ship, (2) application of the novel and more durable TSCF25 coating (3), the use of corrosion resistant steel in ship construction and (4) a standard PSPC15 coating combined with lifetime lasting aluminum sacrificial anodes. A cost model was used to evaluate these alternative options together with sensitivity analysis. It is concluded that the durable coating and the use of lifetime lasting aluminum anodes are bound to improve the actual basic tank concept. Corrosion resistant steel becomes attractive when the steel price becomes competitive.