Operational problems of constructed wetland for landfill leachate treatment: case study

The present paper discusses the quality fluctuations of leachate from municipal landfill in Gdansk (Poland) over the last 5 years and the evaluation of a wetland system designed for treatment of the leachate. The research has been conducted during a 5-year period. The constructed wetland for leachate treatment was built in 2001; it consists of 2 horizontal subsurface flow reed beds, working in parallel. In the period 2005–2006 it underwent modernization due to unsatisfactory treatment results caused by bed clogging. After the modernization the treatment effectiveness is satisfactory. The effluent from bed I met Polish outflow standards, while in the effluent from bed II COD, total N and TSS exceeded the required concentrations. In spite of this, pretreatment of leachate (iron removal) should be quickly introduced to protect the system against the reoccurrence of clogging problems.