Artificial-intelligence-model to optimize biocide dosing in seawater-cooled industrial process applications considering environmental, technical, energetic, and economic aspects.

This research introduces an Artificial Intelligence (AI) based model designed to concurrently optimize energy supply management, biocide dosing, and maintenance scheduling for heat exchangers. This optimization considers energetic, technical, economic, and environmental considerations. The impact of biofilm on heat exchangers is assessed, revealing a 41% reduction in thermal efficiency and a 113% increase in flow frictional resistance of the fluid compared to the initial state. Consequently, the pump's power consumption, required to maintain hydraulic conditions, rises by 9%. The newly developed AI model detects the point at which the heat exchanger's performance begins to decline due to accumulating dirt, marking day 44 of experimentation as the threshold to commence the antifouling biocide dosing. Leveraging this AI model to monitor heat exchanger efficiency represents an innovative approach to optimizing antifouling biocide dosing and reduce the environmental impact stemming from industrial plants.

A review of experimental Assessment Processes of material resistance to marine and freshwater biofouling.

Biofouling presents hazards to a variety of freshwater and marine underwater infrastructures and is one of the direct causes of species invasion. These negative impacts provide a unified goal for both industry practitioners and researchers: the development of novel antifouling materials to prevent the adhesion of biofouling. The prohibition of tributyltin (TBT) by the International Maritime Organization (IMO) in 2001 propelled the research and development of new antifouling materials. However, the evaluation process and framework for these materials remain incomplete and unsystematic. This mini-review starts with the classification and principles of new antifouling materials, discussing and summarizing the methods for assessing their biofouling resistance. The paper also compiles the relevant regulations and environmental requirements from different countries necessary for developing new antifouling materials with commercial potential. It concludes by highlighting the current challenges in antifouling material development and future outlooks. Systematic evaluation of newly developed antifouling materials can lead to the emergence of more genuinely applicable solutions, transitioning from merely laboratory products to materials that can be effectively used in real-world applications.

Preliminary hazard assessment of a new nature-inspired antifouling (NIAF) agent.

A recently synthesized aminated 3,4-dioxygenated xanthone (Xantifoul2) was found to have promising antifouling (AF) effects against the settlement of the macrofouler Mytilus galloprovincialis larvae. Preliminary assessment indicated that Xantifoul2 has reduced ecotoxicological impacts: e.g., being non-toxic to the marine crustacea Artemia salina (<10 % mortality at 50 µM) and showing low bioconcentration factor in marine organisms. In order to meet the EU Biocidal Product Regulation, a preliminary hazard assessment of this new nature-inspired antifouling (NIAF) agent was conducted in this work. Xantifoul2 did not affect the swimming ability of the planktonic crustacean Daphnia magna, the growth of the diatom Phaeodactylum tricornutum, and the cellular respiration of luminescent Gram-negative bacteria Vibrio fischeri, supporting the low toxicity towards several non-target marine species. Regarding human cytotoxicity, Xantifoul2 did not affect the cell viability of retinal human cells (hTERT-RPE-1) and lipidomic studies revealed depletion of lipids involved in cell death, membrane modeling, lipid storage, and oxidative stress only at a high concentration (10 µM). Accelerated degradation studies in water were conducted under simulated sunlight to allow the understanding of putative transformation products (TPs) that could be generated in the aquatic ecosystems. Both Xantifoul2 and photolytic-treated Xantifoul2 in the aqueous matrix were therefore evaluated on several nuclear receptors (NRs). The results of this preliminary hazard assessment of Xantifoul2, combined with the high degradation rates in water, provide strong evidence of the safety of this AF agent under the evaluated conditions, and provide the support for future validation studies before this compound can be introduced in the market.

Assessment of the effectiveness of antifouling solutions for recreational boats in the context of marine bioinvasions.

The recreational boating sector is a major vector for the introduction of non-indigenous species (NIS) via biofouling. Despite applying control measures to prevent the growth of fouling communities, most vessels are NIS carriers. This study assessed the effectiveness of different antifouling strategies in a manipulative experiment by testing two common coating typologies (biocide-based and foul-release coatings), accompanied with simulated maintenance practices. The experiment was carried out in the Gulf of La Spezia (Italy) and samples were collected at two different periods. Results showed significant differences among antifouling treatments regarding community structure, diversity, coverage and biovolume of the sessile component, alongside a significant decrease in the performance of biocide-based coating with time. Interestingly, peracarid NIS/native species ratio was higher for biocide-based treatments, suggesting potential biocide resistance. This study highlights the urgent need to develop common and feasible biofouling management plans and provides insights towards identification of best practices for recreational vessels.

In vitro and in vivo assessment of antimicrobial, enzymatic, and antifouling properties of self-potent lichen symbiotic bacteria.

This study aimed to comprehensively assess the antimicrobial, antifouling, and antibiofilm-forming potential of lichen symbiotic bacteria against marine fouling bacterial strains. A total of 50 lichen-associated bacteria (LAB) isolates were successfully characterized and evaluated for their effectiveness in mitigating biofouling caused by various marine biofoulers. Through a battery of biological assays encompassing enzymatic, antagonistic, antimicrobial, and antifouling assays, 15 LAB isolates were identified based on their antagonist activities. Notably, the strain LAB4 exhibited remarkable performance across all bioassays, demonstrating its proficiency as an antifouling agent. The production of crude LAB extracts was successfully scaled up using a large-scale fermentor and further optimized. Additionally, a phylogenetic analysis of the isolated strain Bacillus proteolyticus D65's 16S ribosomal RNA gene revealed a high query coverage and percentage identity of 92.62% (accession no. MK883171.1). In conclusion, the lichen bacterial symbiotic isolate B. proteolyticus exhibited significant in vitro and in vivo inhibition of foulants. This study highlights the potential of lichens as a valuable source of yet unexplored bacteria. The bacterial consortium associated with Parmotrema sp. holds promise in combatting biofouling, which poses a substantial threat to the maritime industries and their economic stability.

Contaminant occurrence, water quality criteria and tiered ecological risk assessment in water: A case study of antifouling biocides in the Qiantang River and its estuary, Eastern China.

Antifouling biocides may cause adverse effects on non-target species. This study aims to determine the distribution, sources, and ecological risks of antifouling biocides in the surface waters of the Qiantang River and its estuary in eastern China. The concentrations of total antifouling biocides were ranged from 12.9 to 215 ng/L for all water samples. Atrazine, diuron and tributyltin were the major compounds in the water bodies of the study area. The acute and chronic toxicity criteria for tributyltin, diuron and atrazine were derived for freshwater and saltwater, respectively, based on the species sensitivity distribution approach. The freshwater and saltwater criteria were slightly different, and the toxicity to aquatic organisms could be summarized as tributyltin > diuron > atrazine. The graded ecological risk rating showed that the long-term risk of TBT was significant in coastal waters. The pollution of TBT in the Qiantang River deserves further attention.

Biofouling occlusion of ships' internal seawater systems: operational, economic, and biosecurity consequences.

Biofouling of ships' internal seawater systems (ISS) can cause significant operational issues and is a potential transfer mechanism for marine nonindigenous species. This study used an engine room simulator and economic evaluation to quantify impacts on commercial ship performance of biofouling occlusion within various ISS nodes (sea chest, strainer, and heat exchangers). A characteristic hockey-stick relationship between occlusion and impact emerged, whereby engine room systems could tolerate up to 55% occlusion of a single node without operational impact, followed by rapid performance deterioration. The relative magnitude of impacts varied by ISS node and in response to changes in ambient seawater temperatures. System tolerance was much lower when simultaneous occlusion of multiple nodes was assessed. In economic terms, consequences included required freight rate increases of 1-26% prior to forced (automatic) slowdown of the ship and up to 82% increases if slowdown conditions were required.

Design and In Situ Validation of Low-Cost and Easy to Apply Anti-Biofouling Techniques for Oceanographic Continuous Monitoring with Optical Instruments.

Biofouling is the major factor that limits long-term monitoring studies with automated optical instruments. Protection of the sensing areas, surfaces, and structural housing of the sensors must be considered to deliver reliable data without the need for cleaning or maintenance. In this work, we present the design and field validation of different techniques for biofouling protection based on different housing materials, biocides, and transparent coatings. Six optical turbidity probes were built using polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), PLA with copper filament, ABS coated with PDMS, ABS coated with epoxy and ABS assembled with a system for in situ chlorine production. The probes were deployed in the sea for 48 days and their anti-biofouling efficiency was evaluated using the results of the field experiment, visual inspections, and calibration signal loss after the tests. The PLA and ABS were used as samplers without fouling protection. The probe with chlorine production outperformed the other techniques, providing reliable data during the in situ experiment. The copper probe had lower performance but still retarded the biological growth. The techniques based on transparent coatings, epoxy, and PDMS did not prevent biofilm formation and suffered mostly from micro-biofouling.

Assessment of the Antibiofilm Performance of Chitosan-Based Surfaces in Marine Environments.

Marine biofouling is a natural process often associated with biofilm formation on submerged surfaces, creating a massive economic and ecological burden. Although several antifouling paints have been used to prevent biofouling, growing ecological concerns emphasize the need to develop new and environmentally friendly antifouling approaches such as bio-based coatings. Chitosan (CS) is a natural polymer that has been widely used due to its outstanding biological properties, including non-toxicity and antimicrobial activity. This work aims to produce and characterize poly (lactic acid) (PLA)-CS surfaces with CS of different molecular weight (Mw) at different concentrations for application in marine paints. Loligo opalescens pens, a waste from the fishery industry, were used as a CS source. The antimicrobial activity of the CS and CS-functionalized surfaces was assessed against Cobetia marina, a model proteobacterium for marine biofouling. Results demonstrate that CS targets the bacterial cell membrane, and PLA-CS surfaces were able to reduce the number of culturable cells up to 68% compared to control, with this activity dependent on CS Mw. The antifouling performance was corroborated by Optical Coherence Tomography since PLA-CS surfaces reduced the biofilm thickness by up to 36%, as well as the percentage and size of biofilm empty spaces. Overall, CS coatings showed to be a promising approach to reducing biofouling in marine environments mimicked in this work, contributing to the valorization of fishing waste and encouraging further research on this topic.

A multi-criteria decision analysis model for ship biofouling management in the Baltic Sea.

Biofouling of ship hulls form a vector for the introduction of non-indigenous organisms worldwide. Through increasing friction, the organisms attached to ships' hulls increase the fuel consumption, leading to both higher fuel costs and air emissions. At the same time, ship biofouling management causes both ecological risks and monetary costs. All these aspects should be considered case-specifically in the search of sustainable management strategies. Applying Bayesian networks, we developed a multi-criteria decision analysis model to compare biofouling management strategies in the Baltic Sea, given the characteristics of a ship, its operating profile and operational environment, considering the comprehensive environmental impact and the monetary costs. The model is demonstrated for three scenarios (SC1-3) and sub-scenarios (A-C), comparing the alternative biofouling management strategies in relation to NIS (non-indigenous species) introduction risk, eco-toxicological risk due to biocidal coating, carbon dioxide emissions and costs related to fuel consumption, in-water cleaning and hull coating. The scenarios demonstrate that by the careful consideration of the hull fouling management strategy, both money and environment can be saved. We suggest biocidal-free coating with a regular in-water cleaning using a capture system is generally the lowest-risk option. The best biocidal-free coating type and the optimal in-water cleaning interval should be evaluated case-specifically, though. In some cases, however, biocidal coating remains a justifiable option.

Concentrations and risk assessment of metals and microplastics from antifouling paint particles in the coastal sediment of a marina in Simon's Town, South Africa.

Maintenance of maritime vessels includes the removal of paint from hulls that are sources of metals, antifouling paint particles (APPs) and microplastics (MPs) that end up in the coastal environment. Simon's Town is a small urban town in False Bay, Cape Town, South Africa, where maritime activities take place (there is a naval harbour, marina and shipyard). The aim of this study was to measure metals, APPs and MPs in Simon's Town, to assess the impact of maritime activities and a storm water pipe in a sheltered marina. Sediment samples were collected from six sites during winter 2018. Sediment and extracted APPs were analysed for metal concentrations (Al, As, B, Ba, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sb, Sn, Sr, V and Zn) and MPs characterised based on type (shape and polymer), colour and size. Highest average metal concentrations in sediment for all sites were Fe (32228 ± SEM 4024), Al (12271 ± 1062) and Cu (1129 ± 407). Metals in paint particles were highest for Fe (80873 ± 19341), Cu (66762 ± 13082) and Zn (44910 ± 1400 µg/g). Metal and MP fragment concentrations were highest at the slipway of the shipyard, decreasing with increased distance from the slipway. MP filaments were highest close to the storm water outfall pipe. Our results suggest that shipyards are potential sources of metals and MP fragments (mainly APPs), with storm water pipes potential sources of MP filaments. Various indices applied to assess the potential impacts of metals and MPs suggest that these contaminants have the potential to adversely impact the intertidal ecosystem investigated.

Assessment of the risk posed by three antifouling biocides to Pacific oyster embryos and larvae in Hiroshima Bay, Japan.

The Pacific oyster (Crassostrea gigas) is an important species in oyster farming worldwide, including in Japan. Hiroshima Bay is one of the most important oyster farming areas in Japan. We investigated the occurrence of antifouling biocides used worldwide including diuron, Irgarol 1051 (Irgarol), and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), which have been detected at sub-ppb levels in seawater in Japan, and estimated their no observed effect concentrations (NOECs). In recent years, the spat settlement of Pacific oysters has become poor, which presents a challenge for oyster aquaculture in Hiroshima Bay; hence, we conducted embryotoxicity and larva settlement tests using Pacific oysters. Compared to diuron and Irgarol, DCOIT exhibited a higher toxicity toward oyster embryos, and the minimum 24-h NOEC toxicity value for the oyster embryos was <3 ng/L. The highest concentrations of diuron, Irgarol, and DCOIT in the environmental seawater in the Seto Inland Sea were 27.6, 3.2, and 24 ng/L, respectively. Considering the NOECs, the environmental concentrations of these biocides suggest that the ecological risks posed by diuron and Irgarol are low, whereas those posed by DCOIT are high. However, the rate of detection of DCOIT was low because it degraded rapidly in the seawater before treatment for chemical analysis, except in the case of the treatment on the research vessel.

Coupled Monte Carlo and Molecular Dynamics Simulations on Interfacial Properties of Antifouling Polymer Membranes.

We use molecular simulation to study the wetting behavior of antifouling polymer-tethered membranes. We obtain the interfacial properties (e.g., contact angle) of water at various temperatures for five polymer membranes, including a base polysulfone (PSF) membrane and four other PSF membranes grafted with antifouling polymers (two poly(ethylene glycol) (PEG) tethers and two zwitterionic tethers). We implement a coupled Monte Carlo (MC)/molecular dynamics (MD) approach to determine the interface potentials of water on the membrane surfaces in an efficient manner. Within this method, short MC and MD simulations are performed in cycles to collect the surface excess free energy of a thin water film on polymer membrane surfaces. Simulation results show that the grafting of zwitterionic tethers provides a more significant enhancement in the hydrophilicity of the PSF membrane than that of the PEG tethers. Water completely wets the surface of zwitterionic polymer membranes.

Antifouling paint biocides (Irgarol 1051 and diuron) in the selected ports of Peninsular Malaysia: occurrence, seasonal variation, and ecological risk assessment.

Irgarol 1051 and diuron are photosystem II inhibitors in agricultural activities and antifouling paints in the shipping sector. This study focused on three major ports (western, southern, and eastern) surrounding Peninsular Malaysia to construct the distribution of both biocides on the basis of the seasonal and geographical changes. Surface seawater samples were collected from November 2011 to April 2012 and pretreated using the solid-phase extraction technique followed by quantification with GC-MS and LC-MS-MS for Irgarol 1051 and diuron, respectively. Generally, the distribution of Irgarol 1051 was lowest during November 2011 and highest during April 2012, and similar patterns were observed at all ports, whereas the distribution of diuron was rather vague. The increasing pattern of Irgarol 1051 from time to time is probably related to its accumulation in the seawater as a result of its half-life and consistent utilization. On the basis of the discriminant analysis, the temporal distribution of Irgarol 1051 varied at Klang North Port, Klang South Port, and Pasir Gudang Port, whereas diuron was temporally varied only at Kemaman Port. Furthermore, Irgarol 1051 was spatially varied during November 2011, whereas diuron did not show any significant changes throughout all sampling periods. Ecological risk assessment exhibited a high risk for diuron and Irgarol 1051, but Irgarol 1051 should be of greater concern because of its higher risk compared to that of diuron. Thus, it is recommended that the current Malaysian guidelines and regulations of biocide application should be reevaluated and improved to protect the ecosystem, as well as to prevent ecological risks to the aquatic environment.

Assessment of the environmental compatibility and antifouling performance of an innovative biocidal and foul-release multifunctional marine coating.

The control of marine biofouling has raised serious environmental concerns, thus the continuous release of toxic and persistent biocidal agents applied as anti-biofouling coatings have triggered the search for non-toxic strategies. However, most of them still lack rigorous evaluation of their ecotoxicity and antifouling effects under real scenarios and their correlation with simulated assays. In this work, the biocide releasing risk and ecotoxicity of a biocidal and foul-release polydimethylsiloxane (PDMS)-based marine coating containing grafted Econea biocide (<0.6 wt.%) were evaluated under simulated real mechanical wear conditions at a pilot-scale system, and under extreme wear scenarios (washability settings). The coating system demonstrated low environmental impact against the model Vibrio fischeri bacterium and marine algae, associated with the effective biocide grafting in the coating matrix and subsequent biocide release minimization. This multifunctional coating system also showed auspicious antifouling (AF) effects, with an AF performance index significantly higher (API > 89) than a single foul-release system (AF < 40) after two and half years at a real immersion scenario in the Portuguese shore of the Atlantic Ocean. These field results corroborated the antibiofilm performance evaluated with Pseudoalteromonas tunicata at simulated dynamic marine conditions after seven-week assays. This eco-friendly multifunctional strategy, validated by both simulated testing conditions and real field tests, is believed to be a powerful tool for the development of AF technologies and a potential contribution to the quest for new environmentally friendly antifouling solutions.

One-Step and Low-Cost Designing of Two-Layered Active-Layer Superhydrophobic Silicalite-1/PDMS Membrane for Simultaneously Achieving Superior Bioethanol Pervaporation and Fouling/Biofouling Resistance.

Recently, the coupling of biofuel fermentation broths and pervaporation has been receiving increasing attention. Some challenges, such as the destructive effects of constituents of the real fermentation broth on the membrane performances, the lethal effects of the membrane surface chemical modifiers on the microorganisms, and being expensive, are against this concept. For the first time, a continuous study on the one-step and low-cost preparation of superhydrophobic membranes for bioethanol separation is made to address these challenges. In our previous work, spraying as a fast, scalable, and low-cost procedure was applied to fabricate the one-layered active-layer hydrophobic (OALH) silicalite-1/polydimethylsiloxane (PDMS) membrane on the low-cost mullite support. In this work, the spraying method was adopted to fabricate a two-layered active-layer superhydrophobic (TALS) silicalite-1/PDMS membrane, where the novel active layer consisted of two layers with different hydrophobicities and densities. Contact-angle measurements, surface charge determination, scanning electron microscopy, atomic force microscopy, and pervaporation separation using a 5 wt % ethanol solution were used to statically evaluate the fouling/biofouling resistance and pervaporation performances of OALH and TALS membranes in this study. The TALS membrane presented a better resistance and performance. For dynamic experiments, the Box-Behnken design was used to identify the effects of substrates, microorganisms, and nutrient contents as the leading indicators of fermentation broth on the TALS membrane performances for the long-term utilization. The maximum performances of 1.88 kg/m2·h, 32.34, and 59.04 kg/m2·h concerning the permeation flux, separation factor, and pervaporation separation index were obtained, respectively. The dynamic fouling/biofouling resistance of the TALS membrane was also characterized using energy-dispersive X-ray spectroscopy of all the tested membranes. The TALS membrane demonstrated the synergistic resistance of membrane fouling and biofouling. Eventually, the novel TALS membrane was found to have potential for biofuel recovery, especially bioethanol.

Random array of inorganic nanoparticles on polymer surface for anti-biofouling property through cost-effective and high-performance dip-coating.

Anti-biofouling treatment is required in various fields such as biomedical application, construction, civil engineering, and so on. Currently available techniques such as lithography and replica methods have several limitations in application and accessibility. We introduced a simple, biocompatible, and cost-effective anti-biofouling dip-coating method with polyurethane-inorganic (anisotropic montmorillonite and spherical TiO2) hybrid coating agent. Layer thickness of coating was as thin as 5 µm. It was cross-confirmed with thickness gauge and cross-section scanning electron microscopy. Through atomic force microscopy, inorganic nanoparticles were observed to be randomly arrayed with particles partially embedded in the polyurethane network. The calculated surface roughness of inorganic-polyurethane hybrid coating was five times larger than the neat substrate film and three times larger than coating without inorganic nanoparticles. Surface energy of the inorganic-polyurethane film decreased with increasing surface roughness as random pattern of inorganic particle reduced van der Waals interaction. Biofouling efficacy was evaluated by mucin adsorption and consecutive alcian blue assay. Results showed that coated film decreased biofouling 81% compared to bare film.

Impact of environmental biofilms: Industrial components and its remediation.

The growth of technology and requirements globally for various commodities has brought about new challenges. Biofilms are aggregations of microbial cells, which contaminate and spoil industrial components and environments. These microbial cells with extracellular polymeric substances colonize living and nonliving surfaces and pose a serious problem for all industries, affecting their processes, leading to a reduction of product quality and economic loss. Industries, such as medical, food, water, dairy, wine, marine, power plants are exposed to biofilm formation. Pipe blockages, waterlogging and reduction of the heat-transfer efficiency, hamper the operating system of plants. Many industries do not set up remedial measures to control biofilm formation as they are not aware of this threat. Various conventional methods to control these biofilms are adopted by industries in their regular workflow, but these are temporary solutions. This calls for further research into remediation of the biofilm and its control for industrial components. This review article addresses the problems of biofilms and proposes solutions for various industrial components. Nanotechnology promises several options, and bring about a new aspect into the industrial economy, by solving the problems of environmental biofilms.

Biotoxicity and life cycle assessment of two commercial antifouling coatings in marine systems.

Two commercial coating systems, each one consisting of both a primer and an antifouling ("System 1" based on Copper Oxide and "System 2" based on Zinc Oxide), have been analyzed in order to investigate their environmental impacts through Life Cycle Assessment (LCA) and laboratory tests. A cradle-to-grave analysis has been performed in order to quantify the environmental footprint of each coating solution and to define which element, material, or process mainly affect the environmental impact of such products. Moreover, it was performed a comparison between the different products to determine the most environmentally sustainable choice. In addition to LCA, several incubations of coated metal samples, by means of an innovative incubation system developed by the authors, have also been performed in marine water (Gulf of Naples, Mediterranean Sea, Italy), as critical environment favoring metal corrosion and biofouling generation. The life cycle analysis has showed that the production phase presents the highest environmental impact in almost all categories, mainly due to the use of chemical compounds. Moreover, after the laboratory tests, strong biotoxicity and contaminant diffusion, contributing to the marine toxicity potential, have been observed for both the commercial paints. As a final remark, there are straightforward indications of a strong need for anti-Microbial-Induced-Corrosion commercial coatings to substitute the toxic compounds with others in order to develop a greener solution.

Assessment of Antifouling Potential of Novel Transparent Sol Gel Coatings for Application in the Marine Environment.

In recent years, there has become a growing need for the development of antifouling technology for application in the marine environment. The accumulation of large quantities of biomass on these surfaces cause substantial economic burdens within the marine industry, or adversely impact the performance of sensor technologies. Here, we present a study of transparent coatings with potential for applications on sensors or devices with optical windows. The focus of the study is on the abundance and diversity of biofouling organisms that accumulate on glass panels coated with novel transparent or opaque organically modified silicate (ORMOSIL) coatings. The diatom assessment was used to determine the effectiveness of the coatings against biofouling. Test panels were deployed in a marine environment in Galway Bay for durations of nine and thirteen months to examine differences in biofilm formation in both microfouling and macrofouling conditions. The most effective coating is one which consists of precursor, tetraethyl orthosilicate (HC006) that has a water contact angle > 100, without significant roughness (43.52 nm). However, improved roughness and wettability of a second coating, diethoxydimethylsilane (DMDEOS), showed real promise in relation to macrofouling reduction.