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Evaluation of different binder combinations of cement, slag and ckd for s/s treatment of tbt contaminated sediments

Lindh Per, Lemenkova Polina

Acta Mechanica et Automatica

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2021

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Vol. 15, no. 4

236--248

EN

The seabed in the ports needs to be regularly cleaned from the marine sediments for safe navigation. Sediments contaminated by tributyltin (TBT) are environmentally harmful and require treatment before recycling. Treatment methods include leaching, stabilisation and solidification to remove toxic chemicals from the sediments and improve their strength for reuse in the construction works. This study evaluated the effects of adding three different binder components (cement, cement kiln dust (CKD) and slag) to treat sediment samples collected in the port of Gothenburg. The goal of this study is to assess the leaching of TBT from the dredged marine sediments contaminated by TBT. The various methods employed for the treatment of sediments include the application of varied ratios of binders. The project has been performed by the Swedish Geotechnical Institute (SGI) on behalf of the Cementa (HeidelbergCement Group) and Cowi Consulting Group, within the framework of the Arendal project. An experiment has been designed to evaluate the effects of adding CKD while reducing cement and slag for sediment treatment. Methods that have been adopted include laboratory processing of samples for leaching using different binder combinations, followed by statistical data processing and graphical plotting. The results of the experiment on leaching of TBT for all samples are tested with a varied ratio of cement, slag, CKD and water. Specimens with added binders 'cement/CKD' have demonstrated higher leaching compared to the ratio 'cement/slag/CKD' and 'cement/slag'. The 'CKD/slag' ratio has presented the best results followed by the ‘cement/slag/CKD’, and can be used as an effective method of s/s treatment of the sediments. The results have shown that the replacement of cement and slag by CKD is effective at TBT leaching for the treatment of toxic marine sediments contaminated by TBT.

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Biofouling statków i sposoby jego zwalczania

Domański J., Cieślak J., Borowski S.

Ochrona przed Korozją

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2011

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nr 11

622-626

PL

Zjawisko biofoulingu polega na tworzeniu się biofilmu przy udziale mikroorganizmów wydzielających EPS (extracellular polymeric substances) oraz jego późniejszą kolonizacje przez florę i faunę wodną. Gatunki te powodują problemy natury technicznej, ekonomicznej i ekologicznej. W przypadku statków obrastanie powierzchni powoduje wzrost zużycia paliwa, wiąże się to m.in. ze wzrostem chropowatości powierzchni, co powoduje zwiększenie oporu środowiska i spadek mocy silnika. Dodatkowym niebezpieczeństwem jest fakt przenoszenia organizmów żywych do nowych ekosystemów. Inwazyjne gatunki są zagrożeniem dla globalnej różnorodności biologicznej oraz dla lokalnych ekosystemów, gdyż konkurują z miejscowymi gatunkami, m.in. zajmując ich nisze pokarmowe i ekologiczne, nierzadko doprowadzając do ich wyginięcia. Biofouling podobnie jak środowisko wodne prowadzi do korozji materiałów technicznych. Do budowy konstrukcji używanych w środowisku wodnym używa się drewna, betonu, laminatu oraz stopów metalu. Każdy z tych materiałów ma inną podatność na korozję oraz biofouling. Występowanie tego zjawiska jest uzależnione m.in. od rodzaju środowiska wodnego, szybkości poruszania się statku lub rodzaju stosowanych zabezpieczeń. W celu zapobiegania porastaniu stosuje się głównie farby przeciwporostowe, których składnikiem są biocydy zapobiegające rozwojowi organizmów żywych. Początkowo używano tlenków miedzi, niezbyt dawno związków cyny, np. TBT (tributylocyna), jednakże z powodu wysokiej toksyczności zastępowane są one preparatami nowych generacji opartymi na polimerach czy silikonie.

EN

The phenomenon of biofouling is based on the formation of biofilm through the action of microorganisms producing extracellular polymeric substances, and further colonization of the film by aquatic flora and faunaleading to various technical, economical, and ecological problems. The fouling layer which has accumulated on a ship is responsible for higher fuel consumption due to an increase in surface roughness , which results in higher flow resistance and a drop in engine power. The transmission of living organisms to new ecosystems is an additional danger. Invasive species are harmful for global biodiversity as well as for local ecosystems since they compete with autochthonous species, i.e. they occupy their ecological and food niches. Biofouling, like the water environment itself, also leads to biodeterioration of the technical materials used by people. Constructions used in water environments are made of wood, concrete, laminate or metal alloys. Each material mentioned above has different susceptibility to deterioration and biofouling. The intensity of this phenomenon is affected by the kind of aqueous environment, moving speed or the type of chemicals used as preservatives, etc. To avoid fouling by organisms, antifouling coating paints are usually used. They contain biocides that prevent the growth of living organisms. Once copper oxides were used, nowadays TBT (tributyltin) is frequently applied, however due to its high toxicity, new compounds based on polymers or silicone are being introduced.

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Organotins used in antifouling paints: environmental impact and contamination in a case study (Southern Venice Lagoon)

Berto D., Boscolo R., Cacciatore F., Giani M.

Oceanological and Hydrobiological Studies

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2006

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Vol. 35, No.3

269-283

EN

Butyltins, including tributyltin (TBT), are widely used as biocides in antifouling paints. Evidence of the damaging effect of organotin (OTs) compounds on the reproduction and growth of various marine organisms has prompted action by many countries to regulate or ban their use in antifouling products. Organotin chemical and physical characteristics, toxicity and their use in antifouling paints are described in this article. TBT concentrations in seawater were investigated in the Southern Venice Lagoon as a case study, and results indicated the continuous use of TBT-based antifouling paints.