Immobilisering av metaller i grundvatten: En utvärdering av befintliga metoder
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Groundwater is one of the world’s most important and fragile sources of drinking water. Groundwater is opposite to surface water well protected from contaminants and external influences. A bigger challenge is how to remove a contaminant, if it spreads to the groundwater aquifer. Contaminated groundwater is a worldwide problem. The biggest source to groundwater contaminants is anthropogenic activities, e.g. landfills, mines and careless chemical use. The mobility of elements plays an important role in this context. Elements have different properties that make them mobile in specific environments. Plant and animal uptake of metals increases when the metals occur in mobile form. Metals are vital to most living organisms but to high doses can be direct toxic (Singh et al. 2011). This is the main reason why mobility of metals is a very important topic worldwide. 3M SlipNaxos is located in Västervik, southeastern Sweden. The company has been producing abrasives and sandpaper since 1917. Groundwater sampling shows very high levels of chlorinated hydrocarbons and metals, mainly Al, Cd, Mn, Ni and Zn. The metals most likely originates from a landfill located at the property, meanwhile the hydrocarbons originates from use of detergent and engine oils. 3M SlipNaxos consulted Golder Associates to complete a risk assessment for the property and if necessary a soil and groundwater remediation. In this report several different in situ methods have been evaluated, based on existing technical reports. Two products have been evaluated in laboratory. The two products that have been used are Bluegard63 Olivine powder and Bluegard N2 Sodium Silicate. Laboratory tests including nano scaled zero valent iron (nZVI) were supposed to be carried out, but had to be excluded because of the need to use soil rather than groundwater to achieve an accurate result. The tests including Bluegard 63 were performed according to the one-step batch leaching test (SS-EN 1245-2) with five different liquid-to-solid (LS)-ratios. The concentrations of Al, Cd, Mn, Ni and Zn was in average reduced by 99.7%, 69.8%, 96.2%, 92.9% and 99.9% respectively. A smaller LS-ratio resulted in a more efficient adsorption. The average pH-value increased with three units during the batch leaching test, it is therefore hard to tell how high percentage that was adsorbed by the olivine powder and how high percentage that was immobilized by the increased pH. A desorption test was performed according to the standard mentioned above. The results shoved a desorption at pH 5 of 0.20%, 41.84%, 0.07%, 0.45% and 0.01% of the adsorbed contaminants. The test with sodium silicate was performed by titration to four predetermined pH values. The result showed reduction in Al, Cd, Mn, Ni and Zn concentrations by -1.0%, -6.54%, 0.75%, 3.04% and 0.25%, meaning that the concentration of Al and Cd increased compared to the values of the reference tests.
Place, publisher, year, edition, pages
2014. , 42 p.
Teknik, Immobilisering, in situ, metaller, grundvatten
IdentifiersURN: urn:nbn:se:ltu:diva-46653Local ID: 445fa22f-8a06-4c74-ba23-79b44104a52cOAI: oai:DiVA.org:ltu-46653DiVA: diva2:1019968
Subject / course
Student thesis, at least 30 credits
Natural Resources Engineering, master's
Validerat; 20140603 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved