Management and Treatment of Organotin and Metal Contaminated Dredged Sediment
Doktorsavhandling, 2021

Modern society is dependent on international trade and most traded goods are transported by sea. To enable this, regular dredging must be done to maintain water depth in ports and waterways, resulting in large quantities of often contaminated sediment that must be handled. Management options are limited due to regulations and depend on the content of contaminants such as tributyltin (TBT) and metals (e.g., zinc and copper) in the sediment. Consequently, there is a need to investigate new treatment techniques and evaluate the sustainability of management alternatives.

In this thesis, several techniques to remove TBT and metal from sediment were developed and tested in laboratory studies, including chemical oxidation by electrolysis and Fenton’s reagent (Fenton) (Paper III), leaching with ultra-pure water, EDDS, saponified tall oil, iron colloids, humic acid, hydroxypropyl cellulose, and acid and alkaline solutions (Paper II). The highest TBT removal from natural sediment was reached using Fenton (64%) followed by electrolysis (58%). On TBT spiked sediment, Fenton and electrolysis reduced the TBT content by 98% by 100% respectively. In spiked water, TBT was degraded 100% by electrolysis. The most effective method for simultaneous TBT and metal removal was Fenton. However, due to the low pH of Fenton residue, electrolyzed sediment was instead chosen for stabilization and solidification, a method that forms a concrete-like product that could be used in construction (Paper IV). The impacts of electrolysis pre-treatment on compression strength and leaching patterns were investigated. The results show that stabilized pre-treated sediment leached less but had lower compression strength than stabilized untreated samples. The surrounding environment during curing was important, as a saline solution increased the compression strength and decreased TBT leaching, but increased metal leaching compared to a less saline solution.

Environmental impacts and costs associated with different sediment management strategies were studied using life cycle assessment (Paper V) and integrated monetary and environmental multicriteria analysis (Paper I). Metal recovery from sediment was identified as a potential future alternative, with increasing metal prices and economic incentives as highly contaminated sediments cost more to handle. However, effective and sustainable metal recovery techniques need to be further developed. The results highlight the importance of individually assessing each site when evaluating risk, determining management strategies, and assessing short- and long-term environmental impacts. The developed methods are useful for identifying economic and environmental conflicts and synergetic effects and could be useful tools in decision-making processes. The results of this thesis could contribute further to the development of full-scale treatment methods to remediate and enable the use of contaminated dredged sediment.

metals

tributyltin (TBT)

life cycle assessment (LCA)

multicriteria analysis (MCA)

stabilization and solidification (S/S)

copper (Cu)

electrolysis

dredged sediment

Fenton’s reagent

zinc (Zn)

Online on Zoom. Password 220177. Click on the link below.
Opponent: Prof. Lisbeth M. Ottosen, Technical University of Denmark, Denmark.

Författare

Anna Norén

Chalmers, Arkitektur och samhällsbyggnadsteknik, Vatten Miljö Teknik

Low impact leaching agents as remediation media for organotin and metal contaminated sediments

Journal of Environmental Management,; Vol. 282(2021)

Artikel i vetenskaplig tidskrift

Norén, A., Lointier, C., Modin, O., Strömvall, A.-M., Rauch, S., Andersson-Sköld, Y., Karlfeldt Fedje, K. Removal of organotin compounds and metals from Swedish marine sediment using Fenton’s reagent and electrochemical treatment

Norén, A., Strömvall, A.-M., Rauch, S., Andersson-Sköld, Y., Modin, O., Karlfeldt Fedje, K. Stabilization and solidification of organotin contaminated sediment: Electrolysis pretreatment, leaching, and compression strength

Svensson, L., Norén, A., Modin, O., Karlfeldt Fedje, K., Rauch, S., Strömvall, A.-M., Andersson-Sköld, Y. Environmental assessment of management options for dredged sediment – a combined LCA and MCA approach

Vad ska vi göra med det förorenade sedimentet?

Idag transporteras över 80% av världshandeln till sjöss. För att möjliggöra transporten krävs det att hamnar regelbundet avlägsnar stora mängder sediment. Sedimentet är dessvärre ofta förorenat av metaller och tennorganiska föreningar, t.ex. giftigt tributyltenn (TBT). Förorenat sediment har oftast få och dyra hanteringsalternativ. I den här avhandlingen har metoder för att rena TBT- och metallförorenat sediment utvecklats. Möjligheten att använda det renade sedimentet för konstruktionsändåmål har också undersökts med goda resultat. Dessutom har metoder utvecklats för att kunna identifiera och jämföra olika sätt att hantera sediment ur ekonomisk och miljömässig synvinkel, men även genom att kombinera livscykelanalys (LCA) med multikriterieanalys (MCA). Resultaten visar att oxidation är ett effektivt sätt för att få bort TBT från sediment och det renade sedimentet kan användas i konstruktioner. De utvecklade metoderna kan vara användbara för beslutsfattare för att kunna identifiera det mest hållbara sättet att hantera sediment på.

What should we do with the contaminated sediment?

Currently, over 80% of globally traded goods are transported by sea. To enable this, ports worldwide need to regularly remove large quantities of sediment to enable ship traffic. However, the sediment is often contaminated with metals and organotin compounds, e.g., hazardous tributyltin (TBT). For contaminated sediment, the management options are often limited and expensive. In this thesis, different TBT and metal removal techniques were developed and tested, and the possibility of using the cleaned sediment in construction was investigated. Additionally, a method was developed to investigate economic and environmental impacts related to different sediment management alternatives, as well as a combined lifecycle assessment (LCA) and multicriteria analysis (MCA) method. The results show that sediment oxidation was the most effective method for TBT removal and that the cleaned sediment could be used in construction. Both of the developed methods could be useful tools in decision-making to identify the most sustainable sediment management approach.

Behandling av tennorganiskt förorenade sediment: återvinning och stabilisering

Renova, 2018-06-28 -- 2020-06-30.

Energimyndigheten (46125-1), 2018-06-28 -- 2020-06-30.

Chalmers, 2018-06-28 -- 2020-06-30.

Behandling av marina sediment förorenade med tenn: nedbrytning, återvinning och stabilisering

Formas (942-2015-188), 2016-01-01 -- 2019-12-31.

Renova, 2016-01-01 -- 2020-12-31.

IMplementing MEasuRes for Sustainable Estuaries (IMMERSE)

Europeiska kommissionen (EU) (J-No:38-2-9-17), 2018-07-01 -- 2021-12-31.

Ämneskategorier

Samhällsbyggnadsteknik

Geovetenskap och miljövetenskap

ISBN

978-91-7905-537-0

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5004

Utgivare

Chalmers tekniska högskola

Online on Zoom. Password 220177. Click on the link below.

Online

Opponent: Prof. Lisbeth M. Ottosen, Technical University of Denmark, Denmark.

Mer information

Senast uppdaterat

2021-08-16