Ballast Water Treatment Research Articles

Ballast water treatment by ozone nanobubbles

AbstractBACKGROUNDThe uncontrolled discharge of untreated ballast water, which is essential for a ship's optimal operation, is one of the major causes of sea environmental pollution by shipping. Among the disinfection methods available for ballast water treatment, ozonation is a commonly used method, but its performance is limited by the rapid ozone auto‐decomposition rate. Nanobubbles (NBs) technology has attracted much scientific interest as it is characterized by a long residence time in the aqueous phase and a high surface area; therefore, ozone nanobubbles (OzNBs) are expected to enhance disinfection capacity and residual activity. The present study was designed to provide further insight into the inactivation of heterotrophic bacteria in saline water and to examine the use of OzNBs for disinfection of saline water.RESULTSThe survival rate of Escherichia coli (E. coli), which was used as indicator microorganism, along with the ozone consumption at different salinities (1.5, 4, 8 and 15 PSU) and bacterial concentrations (107, 106, and 105 CFU mL−1) with and without supplementation of OzNBs were investigated. The results indicated a statistical difference in the residual concentration of total residual oxidants (TRO) with the presence of OzNBs at salinity level 1.5 PSU and at 4 PSU only at the lowest bacterial content. At a low salinity and high bacterial concentration, the concentration of TRO was 6‐fold higher in the presence of OzNBs.CONCLUSIONThe salinity of water has a strong impact on the residual concentration of ozone. When salinity is increased, ozone reacts more rapidly with the bromide and chloride ions. The use of OzNBs exhibited a greater disinfection performance and higher residual activity. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Effects of physicochemical parameters of water on byproduct formation during electrolysis of ballast water

Introduction: Disinfection byproducts (DBPs) generated during ballast water treatment using active substances have gained increasing interest owing to their potential impact on the marine environment. This study aimed to investigate the occurrence and distribution of DBPs, which are secondary products generated during electrolysis, using land-based tests.Methods: DBP levels were compared under various water conditions, including chloride and bromide ion compositions, hold time, and organic matter-related parameters.Results: After electrolysis, trihalomethane (THM) and haloacetic acid (HAA) levels increased from day 0 to day 5 under all salinities, whereas haloacetonitrile (HAN) level decreased. THMs were found to be the most dominant DBP group, followed by HAAs and HANs. In marine water and brackish water, brominated DBPs were dominant owing to high levels of bromide ions, while chlorinated DBP concentrations were relatively high in fresh water.Discussion: After electrolysis, the specific ultraviolet absorption of the treated water was >4, indicating a high likelihood of generating carbonaceous DBPs such as THMs and HAA. These findings contribute to a better understanding of the general mechanisms through which physicochemical factors affect the formation of DBPs during electrolysis treatment of ballast water. This understanding is valuable in addressing issues related to the treatment and release of treated ballast water into the marine environment, which is an emerging environmental concern.

Analysis of the evolutionary game between maritime regulators and carriers under the discharge of ballast nuclear wastewater from ships

The Japanese government officially announced the discharge of Fukushima nuclear wastewater into the sea on April 13, 2021, which has caused concern and strong opposition from countries worldwide and international environmental organizations. Through the analysis of relevant data, it is found that the hazards of ship ballast nuclear wastewater are reflected in the following: ship ballast water flows widely, the high discharge of ship ballast water, and the high reserves of Fukushima nuclear wastewater. In this case, the evolutionary game models of the maritime regulator and the carrier, and the society, maritime regulator and the carrier were constructed, respectively. In the evolutionary game model between the maritime regulator and the carrier, the carrier is not very motivated to deal with the ship's ballast water due to the influence of several related factors, especially the exorbitant treatment cost. After introducing the social supervision and reward system, maritime regulators found that controlling their own supervision cost and giving appropriate rewards to freighters with the participation of social supervision can effectively improve the motivation of freighters to deal with the ship's ballast water. In addition, through the comparative analysis of the before-and-after game model, it is found that the high cost required by the carriers to deal with ships' ballast water will directly affect the stable state that the game model tends to be. Therefore, the sustainable growth of the port's ecological environment benefits from pursuing affordable and effective ship's ballast water treatment.

Toxicity evaluation of chlorinated natural water using Photobacterium phosphoreum: Implications for ballast water management

Chlorination of ballast water could produce harmful disinfection by-products (DBPs) and total residual oxidants. The International Maritime Organization calls for toxicity testing of discharged ballast water with fish, crustacea and algae to reduce the risk, but it is difficult to evaluate the toxicity of treated ballast water in a short time. Therefore, the purpose of this study was to analyze the applicability of luminescent bacteria to the assessment of residual toxicity of chlorinated ballast water. The toxicity unit for all treated samples were higher for Photobacterium phosphoreum than for microalgae (Selenastrum capricornutum and Chlorella pyrenoidosa), after adding neutralizer, all samples showed little effect on the luminescent bacteria and microalgae. For the DBPs, except for 2,4,6-Tribromophenol, Photobacterium phosphoreum could produce more sensitive and rapid test results than other species, the results in Photobacterium phosphoreum showed that the toxicity of DBPs in order of: 2,4-Dibromophenol > 2,6-Dibromophenol > 2,4,6-Tribromophenol > Monobromoacetic acid > Dibromoacetic acid > Tribromoacetic acid, and most binary mixtures (aromatic DBPs and aliphatic DBPs) presented synergistic effects based on the CA model. The aromatic DBPs in ballast water deserve more attention. In general, for ballast water management, the use of luminescent bacteria to evaluate the toxicity of treated ballast water and DBPs is desirable, this study could provide beneficial information for enhancing ballast water management.

A study on treatment efficacy of ballast water treatment system applying filtration + membrane separation + deoxygenation technology during shipboard testing

The efficacy of a BWMS with filtration + membrane separation + deoxygenation technology in treating ballast water was investigated under marine operational circumstances in five shipboard tests. The shipboard tests were carried out between August 2020 and March 2021 onboard a bulk carrier JIN HAI HUA, which sailed between Mawei, Qinhuangdao and Caofeidian in China throughout spring, summer, and fall season. The discharge results in all five tests met the D-2 standard in IMO BWMS Code, with the shortest holding time of less than three days. The BWMS does not involve application of chemicals or generation of by-products, and is considered to be an appropriate choice for certain types of ships.

Experimental Inactivation of Microalgae in Marine Ballast Water by Microbubbles Generated through Hydrodynamic Cavitation

This paper presents a novel approach to microbubble technology for the treatment of aquatic invasive organisms in ship ballast water. The microbubbles are produced by hydrodynamic cavitation with a sudden and dramatic water pressure drop. The air and ozone microbubbles, respectively, verified the bioavailability of ship ballast water treatment using marine microalgae as an indicator. Besides the effects of an ozone injection dose, the morphological changes of cells and the effluent toxicity were investigated. Compared with the ozone microbubble treatment, the inactivation of marine microalgae by air microbubbles required a long treatment time. In the storage experiment, it was found that air microbubbles did not inhibit the growth of microalgae cells, and that the injection of active matter such as ozone was still necessary to ensure the validity of biological invasion. However, even with very low doses of ozone, the inactivation effect of ozone microbubbles was still very evident. Overall, it helps to minimize the use of active matter to reduce the toxicity of treated water, and this has the capability to develop into an environmentally acceptable and practical ballast water treatment technology.

The critical adenosine triphosphate (ATP) concentration in treated ballast water

Measuring Adenosine triphosphate (ATP) provides a proxy to check compliance with IMO's ballast water D-2 standard: <10 cells mL−1 in the 10–50 μm size class. Measured with standard boiling techniques the ATP concentration in aquatic eukaryotic microorganisms is 0.6 mol m−3. Model calculations with 10–50 μm spherical organisms show their ATP content is 0.2 to 20 pg cell−1, in line with several cell lysis data. However, at 10 cells mL−1, these ATP contents lead to a maximum of only 2 to 200 pg ATP mL−1, at least 7.5× below a D-2 test kit 1500 pg ATP mL−1 upper limit. Different cell shape and ATP extraction scenarios to reach 1500 pg ATP mL−1 are discussed but remain improbable. Because cell lysis data are inconclusive, and a novel phosphoric acid-benzalkonium chloride method indicates up to 3× higher ATP concentrations, an independent test kit validation and a comparison of all three techniques are recommended.

Discharge compliance at Shanghai port – A case study on discharged ballast water from vessels with Ballast Water Treatment System

Discharge compliance at Shanghai port – A case study on discharged ballast water from vessels with Ballast Water Treatment System

Development dynamic compliance cost model for implementation of ballast water management convention: shipowner perspective

The Ballast Water Management Convention (BWMC) regulates ship ballast water management to avoid the spread of aquatic invasive species. The convention requires all ships, including existing ones, to have a Ballast Water Treatment System (BWTS) onboard before September 8, 2024. There are some concerns about the compliance costs of BWMC, especially the additional cost of retrofitting cases. The ship retrofitting cost will depend on various factors, and it can be difficult for a shipowner to determine accurately. The procedure is intricate, and there are many factors to consider, such as the ship's size, BWTS system complexity, and the price of materials and modification level. In this paper, A proposed approach involves expert judgment to capture the effect of multi-stakeholder and estimate the compliance cost. As an essential part of the research methodology, the system dynamics method and life cycle cost are combined to develop a compliance cost model during the ship's lifetime. The simulation model shows that the confidence level of retrofitting costs for each BWTS is more than 94%. Therefore, the model can be used to estimate additional costs. As a result, BWTS type A is the most economical system for small tankers, with an estimated cost of USD 802,860 for the remaining 12 years of the ship's lifetime. Shipowners can use this model as a supporting decision tool to determine which BWTS would be suitable and assist in determining the budget necessary to comply with the BWMC.

Ballast Water Problem: Current Status and Expected Challenges

Transporting non-native species in ballast tanks has been a major challenge over the years. The number of surviving species in the host environment is quite small compared to those of all introduced. However, even a single species can cause great harm to the environment, economy, and public health. Ballast water treatment issues are difficult and complex as the performance of the treatment is highly affected by the variable characteristics of the seawater. In addition, targeted organisms are in a wide spectrum. The International Convention on the Control and Management of Ship Ballast Water and Sediments requires ships to manage ballast water with a Type Approved System in compliance with the Ballast water discharge standard defined in the Convention. The Ballast Water Management Systems Approval (G8) Guide was revised in 2016 and accepted as the BWMS Code (Ballast Water Management Systems Approval Code) as the mandatory regime in 2018. According to the implementation schedule of this mandatory approval regime, the ballast water management system installed on or after 28 October 2020 must be type-approved according to the IMO’s revised G8 requirements. Several systems use different methods with their limitations. However, the ballast water problem does not seem to end only with the installation of the systems on ships. Although substantial international progress has been made in ballast water management (both technically and regulatory), there are still several issues regarding effectiveness, compliance monitoring, and the environment.

Operation cost analysis of UV-based ballast water treatment system used on a bulk carrier ship

According to IMO rules, when a new machine system needs to be integrated into the ship, it is required to have low fuel consumption in terms of energy efficiency and emissions. The same is true for ballast treatment. Many different types of ballast water treatment systems (BWTS) are available on the marine market. Ship operators want to choose BWTS that will consume minimum fuel and operate at maximum efficiency. Therefore, in this study, fuel consumption under both IMO and USCG conditions, and hence the operational cost, is calculated if the UV-based BWTS system is integrated into a bulk carrier ship. As a result, the highest cost is $9773 when the most expensive fuel, MGO, is used and operation is performed with a single ballast pump. In USCG mode, the minimum cost is $6382 and the maximum cost is $18929 under the same conditions. It is seen that if the fuel price increases to 1.4 $/kg, the cost of using BWTS in IMO mode can increase to $11392, and if it drops to 0.3 $/kg, the cost of using BWTS in IMO mode can decrease to $1826. It is seen that the highest cost can go up to $22066 and the lowest cost can go down to $3983, with the change of fuel prices in the use of BWTS in USCG mode. With the resulting formulation, with the power consumption of the BWTS and the diesel generator shop trail test fuel consumption values, researchers or shipping companies can repeat the calculations for all kinds of different fuels and different amounts of ultraviolet (UV) chambers for variable ballast operations with different ballast tank capacities. Consequently, it is thought that this study is useful in determining the additional operational cost of UV-based BWTSs.

The effect of filtration and electrolysis on ballast water treatment

Ballast water is required to be treated to reach D-2 standard according to the International Maritime Organization (IMO). Filtration and electrolysis are important technologies for ballast water management systems (BWMS). However, the clogging of filters during the operation of BWMS leads to significant system trips and downtime. In this paper, a mesoscale experiment system was set up and the effects of filtration on ballast water treatment using electrolysis were investigated. The results showed pore size of filter had significant effect on filtration efficiency, total residual oxidant (TRO) decay and inactivation efficacy. The filtration efficiency of filter with 50 μm pore size was over 80% for ≥50 μm organisms. For 200–2000 μm pore sizes (200 μm, 500 μm, 1000 μm and 2000 μm), the filtration efficiency was less than 10%. The effect of filtration on TRO depended on pore size and holding time. Our results indicated that increasing pore size of electrolysis may not a good way for new BWMS design. If electrolysis was applied alone to treat ballast water, higher initial TRO concentration was needed. In our investigation, the initial TRO was more than 12 mg/L.

Characteristic and Relative Environmental Risk of Disinfection by Products Associated with Simple Glucose or Naturally Occurring Algal Organic Matter as Tested in Ballast Water Treatment System

To prevent the invasion of alien species, the International Maritime Organization and the United States Costal Guard require that a ballast water management system (BWMS) be installed on ships to treat the ballast water before discharging it. BWMS technologies use active substances, which create disinfection by-products (DBPs) during ballast water treatment. This study compared the characteristics of DBPs generated in the treatment of commercial glucose with those of algal organic matter (AOM) derived from field-collected phytoplankton using NaOCl as the active substance. During the treatment of AOM, a greater variety and higher concentrations of DBPs were generated than for glucose. For AOM in freshwater, bromoform and dibromoacetic acid were dominant because of the bromine ions present in the phytoplankton. During the treatment of glucose, the ratio of the predicted environmental concentration to the predicted no-effect concentration of dibromoacetonitrile and chloropicrin exceeded 1, indicating a potential environmental risk. Whole effluent toxicity (WET) testing showed that the chronic toxicity of phytoplankton and the total DBP concentration were highest in marine water with AOM. In addition, the results of WET testing suggested that the concentrations of haloacetic acids (HAAs) and haloacetonitriles (HANs) were important indicators for the evaluation of environmental risk. Therefore, to evaluate the risk of DBPs in international ports where phytoplankton outbreaks frequently occur, it is important to monitor not only the total DBP concentration but also the total HAA and HAN concentrations.

None detected: What “zero” indicates in direct counts of aquatic microorganisms in treated ballast water

International limits on the concentrations of living organisms in ballast water are now in force for commercial ships. Microscopy-based, “direct count” assays estimate the concentrations of organisms. These assays are used in performance tests of Ballast Water Management Systems (BWMSs), which are shipboard technologies designed to reduce living organisms in ballast water to below the discharge limits. Here, we examine the factors that affect the method detection limit (MDL) of direct count assays. The MDL depends upon the volumes sampled, concentrated (or diluted), and analyzed, so the MDL will vary as these volumes vary from analysis-to-analysis. Decreasing the MDL to detect exceedingly rare individuals (e.g., ~1 individual per m3 or fewer) is possible, but problematic, given the challenges in analyzing dynamic communities of living organisms: increasing sample and analysis volumes to lower the MDL will likely accelerate the loss of individuals, as organisms are concentrated to several orders of magnitude above in situ concentrations and held for extended times. Results of direct count assays may be widely disseminated as an indicator of the performance of BWMSs, and when no organisms are detected, concentrations may be shown as “0 organisms per m3 or mL” rather than “&amp;lt;MDL”, as appropriate. When clearly derived and reported, a numerical MDL for the direct count assay—the lowermost value distinct from “zero”—provides context to results and transparency into the sensitivity of the assay.

Transmission of stony coral tissue loss disease (SCTLD) in simulated ballast water confirms the potential for ship-born spread

Stony coral tissue loss disease (SCTLD) remains an unprecedented epizootic disease, representing a substantial threat to the persistence and health of coral reef ecosystems in the Tropical Western Atlantic since its first observation near Miami, Florida in 2014. In addition to transport between adjacent reefs indicative of waterborne pathogen(s) dispersing on ocean currents, it has spread throughout the Caribbean to geographically- and oceanographically-isolated reefs, in a manner suggestive of ship and ballast water transmission. Here we evaluate the potential for waterborne transmission of SCTLD including via simulated ballast water, and test the efficacy of commonly-used UV radiation treatment of ballast water. Two species of reef-building corals (Orbicella faveolata and Pseudodiploria strigosa) were subjected to (1) disease-exposed or UV-treated disease-exposed water, and (2) a ballast hold time series of disease-exposed water in two carefully-controlled experiments to evaluate transmission. Our experiments demonstrated transmission of SCTLD through water, rather than direct contact between diseased and healthy corals. While UV treatment of disease-exposed water led to a 50% reduction in the number of corals exhibiting disease signs in both species, the statistical risk of transmission and volume of water needed to elicit SCTLD lesions remained similar to untreated disease-exposed water. The ballast hold time (24 h vs. 120 h) did not have a significant effect on the onset of visible disease signs for either species, though there appeared to be some evidence of a concentration effect for P. strigosa as lesions were only observed after the 120 h ballast hold time. Results from both experiments suggest that the SCTLD pathogens can persist in both untreated and UV-treated ballast water and remain pathogenic. Ballast water may indeed pose a threat to the continued spread and persistence of SCTLD, warranting further investigation of additional ballast water treatments and pathogen detection methods.

Managing Ship’s Ballast Water: A Feasibility Assessment of Mobile Port-Based Treatment

The International Maritime Organization (IMO) has adopted the Ballast Water Management Convention (BWMC), which requires vessels to manage their ballast water according to specific standards. While most vessels have to install a management system onboard, in some cases, a mobile solution, for example a system fitted in a container, might be a more viable solution. These mobile systems are an excellent solution as a contingency measure as well, that is when onboard systems malfunction. Research on the topic is rather scant. To that extent, this paper proposes a Bayesian network-based framework to model and assess the feasibility of mobile ballast water treatment solutions. The results based on input from experts indicate that mobile systems are a highly feasible solution. The operational and logistical feasibility of the system are the most important parameters and are areas where the manufacturers and service providers should pay more attention. With compliance deadlines approaching, malfunctions of installed systems increasing and the technology for port-based solutions becoming more mature, there will be increased focus on port-based systems. Our results can, therefore, provide valuable insights to regulators, ship and port operations and we hope that they can spark further academic research on this area.

Analysis of Ballast Water Discharged in Port—A Case Study of the Port of Ploče (Croatia)

Ballast water is recognized as a major vector for the transfer of Harmful Aquatic Organisms and Pathogens (HAOP) and a source of sea pollution that negatively affects the environment and human health. Therefore, the International Maritime Organization (IMO) adopted the International Convention for the Control and Management of Ship’s Ballast Water and Sediments (BWM Convention) in 2004. The BWM Convention introduced two standards, Ballast Water Exchange Standard (Regulation D-1) and Ballast Water Performance Standard (Regulation D-2). Ships are required to install Ballast Water Treatment (BWT) equipment in order to comply with Regulation D-2. However, the deadline for the installation of BWT is prolonged until September 2024, and many ships are still complying only with Regulation D-1. In addition, there are specific sea areas where Regulation D-1 cannot be complied with, and hence, HAOP could be easily transferred between ports. Consequently, it is essential to develop a system to protect the marine environment, human health and economy in coastal areas from the introduction of HAOP. This paper analyses ballast water discharged in the Port of Ploče (Croatia) according to ship type, age and flag they are flying. It was found that general cargo ships and bulk carriers discharged most of the ballast (87% of the total quantity) in the Port of Ploče. Moreover, discharged ballast water was analysed according to the origin, and it was found that 70% of discharged ballast originates from the Adriatic Sea. Based on the analysis of the research results and literature review, the ballast water risk assessment (BWRA) method was adopted, however, with certain modifications. The adopted method is modified by an additional risk factor (the deballasting ship’s age), different risk scoring of the deballasting ship type and adding Paris MoU Grey and Black lists flag ships as high-risk ships. As a result, the BWRA method presented in the paper could be used as an early warning system and to facilitate the implementation of adequate measures to prevent pollution by discharged ballast water.

Some Troubles Caused on BWTS after Installed on New Ships or Retrofitted on In-service Ships

Many ships in service have been started to be retrofitted BWTS (Ballast Water Treatment System) on board the vessel in the world and also new shipbuilding has started to be equipped BWTS with new design and construction for its installation after the regulation, the International Convention for the control and Management of ships' Ballast Water and Sediments, 2004 became effective on 8 September 2017. After then, ship owners have experienced some troubles and/or incidents on their BWTS installed or retrofitted in their vessels. This time, some troubles caused on BWTS's in some vessels will be shown in this paper.

バラスト水処理装置の試運転試験におけるサンプリングと分析 - 詳細分析とBWMS試験事例紹介

バラスト水処理装置の試運転試験におけるサンプリングと分析 - 詳細分析とBWMS試験事例紹介

「バラスト水処理装置とバラスト水管理条約の現状」特集号によせて

「バラスト水処理装置とバラスト水管理条約の現状」特集号によせて