The goal of this study is to assess the technical feasibility of remediating siloxane contaminants in biogas via a photochemical process. Specifically, we studied in the laboratory a process that involves the use of an ultraviolet (UV) photodecomposition reactor (PhoR) to convert siloxane trace impurities, commonly found in biogas produced in water treatment plants and landfills, into silica particulates. These can then be effectively removed from the reactor effluent with the use of a downstream filter. High siloxane conversions were obtained, which demonstrates the effectiveness of the technique. The proposed technology is presently being field-tested in a California landfill.

We present in this paper the results of the field testing at a California Landfill of a UV photodecomposition reactor (PhoR) used for the removal of siloxane impurities from landfill gas (LFG). Prior to its field testing, the PhoR technology was tested in the laboratory with simulated LFG and was shown to be capable of completely removing the trace siloxane compounds and to convert them into silica particulates. The key objective of the field test was to validate the ability of the PhoR system to treat real LFG in a practical setting. The field-scale PhoR again proved quite efficient in attaining complete siloxane removal at different concentrations in the real landfill environment. These promising findings have led us to propose a scaled-up, commercial size PhoR system, competitive to conventional adsorption systems that can be practically applied in existing landfill plants to obtain 99+% siloxanes removal rates without associated secondary emissions.