Deep sea mining of methane hydrates

Simon Bergue, Théo Herry, Pierre Landoeuer, Lucas Magnan, Paul Venturino

Maritime English and communication studies

Christophe Collard, Pieter Decancq, Alison Noble, Ludwina Van Son

Communication and seafaring are inextricably linked. The International Convention on Standards of Training, Certification and Watchkeeping (STCW) for Seafarers 1978, as amended clearly states that Administrations shall require every [shipping] company to ensure "effective oral communication" onboard. In 1973 English was approved as the lingua franca at sea. Over the last 50 years the IMO has taken steps to enhance safety by facilitating and improving communication at sea. The Standard Marine Navigational Vocabulary was adopted in 1977 followed by the current Standard Marine Communication Phrases in 2002. By the same token it is known that communication amongst the multinational crew relies not only on (Maritime) English skills, but on other aspects such as (inter)cultural awareness, leadership qualities and group dynamics.

Should we protect shipwrecks?

Ben De Meyer, Sandra Knoop, Sofie Gysbrechts and Bart De Vos

Chitosan and chitosan-nanocomposite coatings for the prevention of biofouling

Sergey Dobretsov and Laila Al-Naamani

Marine biofouling is a worldwide problem affecting maritime industries. Global concerns about the high toxicity of antifouling paints have highlighted the need to develop less toxic antifouling coatings. Chitosan is a natural polymer with antimicrobial, antifungal and antialgal properties that is obtained from partial de-acetylation of crustacean waste. In the current study, chitosan and chitosan-ZnO nanocomposite coatings were fabricated and their antifouling activities were investigated using the diatom Navicula sp., the marine bacterium Pseudoalteromonas nigrifaciens and the bryozoan Bugula neritina. In the first experiment, chitosan coating on plastic substrate showed 88% reduction in settlement of bryozoan larvae compared to the control after 3 hours incubation at dark conditions with no larval mortality. In the second experiment, the biofilms scraped from immersed chitosan coated panels showed no bacteria after 1 week of immersion. After the second week of immersion, less than 1500 bacteria/mm2 were observed on the chitosan-coated panels, while 1000-fold higher number of bacteria on uncoated ones. Chitosan-ZnO nanocomposite coatings led to better inhibition of bacterial growth in comparison to chitosan coatings alone, as determined by flow cytometry. This study demonstrates the antifouling potential of chitosan and chitosan-ZnO nanocomposite coatings, which can be used for the prevention of biofouling.

Analysis of corrosion rates on wreckage steel: a model exercise in the North Sea

Kris De Baere, Sven Van Haelst, Raf Meskens, Remke Willemen, Deirdre Luyckx, Geert Potters

The Belgian North Sea is harboring around three hundred shipwrecks, steel ship wrecks. The major part dates from the First and Second World War. Several of these wrecks are a memorial and resting place for the many crews and soldiers who died while defending their country.

At present eleven wrecks are protected in Belgian waters. These wrecks tell a dark story of our European history, but one that determined our society today. It is important to cherish and protect these memories.

However, such recognition will not be enough to protect these ships from ongoing corrosion and their final demise. Corrosion is a "call of nature" and doing nothing will put the preservation at risk. Preservation entails conservation as we do not have the ability to maintain the condition of the wrecks without human involvement. We need to analyze and explore the different conservation possibilities.

The first step is to determine the rate of corrosion. Many corrosion models do exist but very few are applicable for long immersion periods in sea water. Research shows the four-phase model of Rob Melchers to be most convenient.

Melchers subdivides the corrosion process of immersed steel in an aerobic and an anaerobic part. The aerobic part is complex and in function of a lot of parameters such as dissolved oxygen, temperature, salinity, pH, water velocity and much more. However, after a few years, the corrosion layer passivates and gradually inhibits the rate of oxygen diffusion, stopping the corrosion redox reaction and allowing for microbial induced corrosion (MIC) to take over. Finally, the corrosion process becomes linear and almost completely anaerobic, governed mostly by nutrient concentration, erosion damage and temperature.

Taken into account that some of the wrecks under study have been submersed for over 100 years, only phase 4 of the model, starting after 12.5 years, is of interest. Using the Melchers calibrated model parameters for general corrosion under immersed condition in function of an average seawater temperature of 12.5°C, an average anaerobic corrosion rate (rs) of 0,0403mm/y in North Sea seawater could be calculated.

The increase of the corrosion rate as a consequence of the presence of corrosion enhancing microbes is not at hand. DNA & XRD analysis of wreckage concretion did not show any prove of their presence on open sea conditions.

So far, in situ plate thickness measurements were performed on 6 ships of which the original building parameters could be recovered as well. These measurements have been used to validate the model.

All in all, these preliminary estimates demonstrate that the model of Melchers et al. (2014) possibly overrates the corrosion rate. Possible explanation is that the North sea water contains a lot of carbonates enhancing the formation of CaCO3 increasing the pH and inhibiting corrosion

Corrosion behavior of Lean Duplex Stainless Steel for AOP applications in wastewater treatment plants

Maarten Nagels, Barbara Rossi, Raf Dewil

Advanced Oxidation Processes (AOP) have been shown to be highly effective for the removal of various classes of recalcitrant pollutants from (waste)water. AOPs make use of highly oxidative radicals, mostly *OH, that are in situ produced and oxidize organic pollutants in a rather non-selective way. Various types of AOPs have been developed, including ozone and hydrogen peroxide based, which all differ in the production pathway of the OH*.

Because of the corrosive nature of the strong oxidizing agent OH*, reactor engineering is a non-trivial activity. Austenitic stainless steels (e.g., 304L and 316L) are the standard material that is used in water treatment plants, but do not yield sufficient corrosion resistance for application in AOP units. Hence these reactors are generally built in high corrosion resistive, but costly, Nickel alloys such as Hastelloy.

Only few literature sources exist on stainless steels' corrosion behavior in AOP applications. The aim of the research is to evaluate less expensive lean duplex steel types (2304, 2101) for their applicability as valid alternative construction materials. The corrosion behavior of various austenitic and duplex stainless steel types in ozone and Fenton units will be studied via immersion tests and cyclic potentiodynamic polarization measurements. Further, a Life Cycle Analysis (LCA), including a Life Cycle Cost assessment (LCC), will be performed. If the maintenance and repair costs are included throughout the system lifetime, lean duplex stainless steel may become a more cost effective choice. The most important factor is the corrosion resistance of stainless steel which results in long service life. The ultimate goal of the research is to provide knowledge to improve the sustainable use of AOP in wastewater purification, which will lead to a further market penetration of this technology.