Control of microbial activity by engineered barriers in subterranean waste disposal

Tutkimustuotos: VäitöskirjaCollection of Articles


The activity of microorganisms in subterranean waste disposal systems can be for good and bad in terms of environmental impacts of the waste disposal. The main objective of this thesis was to assess how the activities of methanotrophs (MOB) and sulfate reducers (SRM) can be affected by the characteristics of different soil and bentonite materials used in the engineered release barriers of municipal solid waste landfills and spent nuclear fuel (SNF) repositories. The other objective was to identify factors by which these microbial processes could be managed.

The MOB activity in landfill cover soils contribute to mitigation of CH4 emissions. In the screened soils, the MOB activities were 10x higher in compost- based intermediate biocover soils than in mineral final cover soils. The activities correlated with the nitrate content and activity of heterotrophs in the soils, the latter of which was connected to soil organic matter (OM) content. The effect of different methods on increasing MOB activity in selected cover soils was assessed. An addition of compost to the soil (22 w-%) resulted in the greatest MOB activity increase due to facilitated diffusion of gases and increased nutrient content.

In SNF repositories, SRM produce sulfide that can corrode copper canisters sealing the SNF. The water-soluble OM released by the studied bentonites sustained the growth of SRM and other microorganisms at the simulated interface of compacted bentonite and bedrock, and the highest activities were associated with the use of Bulgarian bentonite in the experimental setup. The water-soluble OM quantity of all the bentonites was shown to be low relative to the total organic carbon content, even after being slightly increased by the simulated repository conditions (e.g., <20 w-%). The mineralogy of the bentonites (gypsum content and iron mineral composition) were also found to control the SRM activity.

To conclude, both MOB and SRM activities were shown to be dependent on the different physicochemical properties of the soils and bentonites, most of which could be managed by material selection. The findings of this work increased the understanding of controls of the specific microbial activities in the studied waste disposal barriers and, thus, can provide valuable information for planning and maintaining the barriers in practice.
KustantajaTampere University
ISBN (elektroninen)978-952-03-2048-5
ISBN (painettu)978-952-03-2047-8
TilaJulkaistu - 2021
OKM-julkaisutyyppiG5 Artikkeliväitöskirja


NimiTampere University Dissertations - Tampereen yliopiston väitöskirjat
ISSN (painettu)2489-9860
ISSN (elektroninen)2490-0028


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