In this thesis, a pilot plant to treat landfill leachate from contamination at Brudaremossen is designed, constructed and evaluated as preceding step before constructing a full scale plant on-site. Brudaremossen is a landfill site located near Lake Delsjon and leachates produced in this landfill are transferred to Goteborg’s wastewater treatment plant. Since leachate contains large quantities of harmful pollutants, it may affect the performance of the wastewater treatment process and quality of the sludge, and thus the leachates could preferable be treated locally. The organic pollutants of priority in the Brudaremossen landfill leachates are polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (oxy-PAHs), phthalates, alkylphenols (APs) and alkylphenolethoxylates (APEOs), and various petroleum hydrocarbon (PHC) fractions. The treatment technique chosen to study is sorption filtration, and the filter materials selected were activated carbon and Sphagnum peat moss. Two combinations of filter materials were examined: a column packed with granulated activated carbon (GAC) in series with another GAC column, and a column packed with peat moss followed by a column with GAC. Equal flow rates of the leachate were running through both combinations and the best alternative were identified based on the adsorbent performance. The plant was running for 120 days and influent and effluent concentrations to all the four filters were sampled weekly and selected samples analyzed for organic contaminants concentration. The result showed convincing performance in the adsorption of all the above mentioned organic pollutants. The GAC removed PHC fractions more efficiently (84-100%) than peat (31-52%), while peat was more efficiently adsorbing PAHs (14-61%). After two months of operation in-field, both of the filters indicate that PAHs, alkylphenols as well as phthalates were adsorbed effectively. Oxy-PAHs were removed efficiently by both filters. The GAC filter removed dissolved organic carbon (DOC) (85-100%) more effectively than the peat filter (2-28%), and total organic carbon (TOC) was removed well (5-100%) by both filter materials. The peat alternative overall reduced metals with better efficiency. The only complication during the operational period of the plant was the technical difficulties related to clogging of the filters due to too high concentration of iron and suspended particles. Therefore a sand filter was constructed before the filters, and influent and effluent samples from this filter were also analyzed for contaminants concentration. The need for a further pre-treatment is desirable because the sand filter was getting clogged too often and needed to be backwashed. Suggestions were made based on a laboratory test to aerate the leachates with the addition of CaCO3 as a suitable pre-treatment for the construction of the final treatment plant.