Abstract In situ thermal remediation technologies provide efficient and reliable cleanup of contaminated soil and groundwater, but at a high cost of environmental impacts and resource depletion due to the large amounts of energy and materials consumed. This study provides a detailed investigation of four in situ thermal remediation technologies (steam enhanced extraction, thermal conduction heating, electrical resistance heating, and radio frequency heating) in order to (1) compare the life‐cycle environmental impacts and resource consumption associated with each thermal technology, and (2) identify options to reduce these adverse effects. The study identifies a number of options for environmental optimization of in situ thermal remediation. In general, environmental optimization can be achieved by increasing the percentage of heating supplied in off peak electricity demand periods as this reduces the pressure on coal‐based electricity and thereby reduces the environmental impacts due to electricity production by up to 10%. Furthermore, reducing the amount of concrete in the vapor cap by using a concrete sandwich construction can potentially reduce the environmental impacts due to the vapor cap by up to 75%. Moreover, a number of technology‐specific improvements were identified, for instance by the substitution of stainless steel types in wells, heaters, and liners used in thermal conduction heating, thus reducing the nickel consumption by 45%. The combined effect of introducing all the suggested improvements is a 10 to 21% decrease in environmental impacts and an 8 to 20% decrease in resource depletion depending on the thermal remediation technology considered. The energy consumption was found to be the main contributor to most types of environmental impacts; this will, however, depend on the electricity production mix in the studied region. The combined improvement potential is therefore to a large extent controlled by the reduction/improvement of energy consumption.
Abstract This article focuses on off‐site, on‐site, and in situ treatment methods for chlorinated solvent and petroleum hydrocarbon source and plume zones at contaminated sites. Physical remediation methods often include in situ contaminant mass transfer followed by an on‐site treatment. Chemical and biological remediation methods provide contaminant mass destruction, which is preferable. However, physical methods such as thermal remediation technologies have shown very high efficiency within short time frames. The major challenges for chemical and biological methods are contaminations in low‐permeability settings and source zones with dense nonaqueous phase liquids, which cause long remediation time frames. Finally, considerations for choice of remediation technologies and the recent development in the use of decision support tools for environmental comparison of remedial alternatives and their life cycle impacts are addressed.
Emission of methane from landfills due to anaerobic decomposition of organic material is oneof the most important environmental concerns with regards to solid waste management. Thisis due to the amount of methane released from landfills globally and the relatively high globalwarming potential of methane. An approach to reduce emissions is to improve conditions forbiological oxidation of methane in the top cover using engineered biocovers.A demonstration project was initiated at the Technical University of Denmark under the EULife Environment program, where this technology is applied in full scale at section I on Fakselandfill in Denmark. Construction of the full scale biocover at the test site was completed attime of writing.The main project objective was to document the construction and efficiency of the system.The project actions consist of a logical order of tasks performed in able to meet the objectivesof the project. At first the landfill was characterized. Expected landfill gas production wasestimated based upon the collected data using models. Then, a baseline study was performed,consisting of an evaluation of the spatial variability in methane emission at the site. The totalmethane emission from the landfill was measured by use of a tracer technique.Mixtures of locally available soils and organic waste residuals were tested by laboratory batchand column experiments. A cover improvement plan included details on material additions toselected areas of the landfill, maintenance plans of the total landfill cover. A plan formonitoring performance was setup. The emissions after the cover improvement will becompared to the emissions obtained during the baseline study. Scenarios for other landfillswill be calculated based on the experiences obtained from the studied landfill.
