2012|13 Annual Report Fraunhofer IGB

10 8 CLEANLEACHATE – ELECTROCHEMICAL TREATMENT OF LANDFILL LEACHATE Dipl.-Ing. Christiane Chaumette Highly contaminated landﬁll leachate The most frequently employed method of waste management is disposal of waste on a landﬁll site. However, a major disad- vantage of landﬁll operations is the generation of contaminat- ed leachate caused by rainfall. Water contained in the waste and water released by biological degradation processes also adds to the landﬁll leachate. Together with the leachate, con- taminants are released which come from biological decompo- sition processes of the landﬁll material, or are simply washed out. The leachate therefore has toxic properties and contains substances that are not easily biodegradable. Treatment plants with biological processes can only treat the wastewater to a limited extent. Above all, persistent organic substances (meas- ured as chemical oxygen demand, COD), ammonium and hal- ogenated organic substances (measured as dissolved organic halogens, AOXs) are present in the landﬁll leachate in critical concentrations and have to be removed before discharge into the aquatic environment or transfer to a municipal, biological wastewater treatment plant. Processing landﬁll leachate The treatment of landﬁll leachate is a considerable cost factor for the landﬁll site operator. Contaminated leachate requir- ing treatment is generated even decades after the closure of a landﬁll site. Membrane and adsorption processes (e.g. with activated carbon) are frequently used. However, these have the disadvantage that the contaminants are not eliminated but are merely concentrated. Subsequently the concentrate has to be disposed of or further processed. On a worldwide scale the quantity of landﬁll waste is increasing, while at the same time the legislation is becoming more stringent. This results in a growing demand for cost- and energy-efﬁcient as well as reliable processes for the treatment of landﬁll leachate. Combination of electrochemical oxidation and reduction Within the EU-funded project CleanLeachate and togeth- er with European partners from industry and research, the Fraunhofer IGB has developed an electrochemical process that permits the reliable treatment of landﬁll leachate without the need to add auxiliary substances to the wastewater. Both am- monium and dissolved organic substances can be eliminated from the landﬁll leachate by means of electrochemical oxida- tion at the anode of the reactor and dissolved organic halo- gens by the subsequent reduction at the reactor cathode. In contrast to membrane ﬁltration, electrochemical treatment completely degrades the dissolved substances. There is no need for the disposal of residues. Divided electrolytic cell For oxidation and reduction reactions, the electrolytic cell is separated into two chemical reaction compartments by means of an ion exchange membrane; the water passes through them one after another, but nevertheless the two compart- ments form one electric circuit. The contaminants in the water are thus subjected to two treatment processes. The basis for developing the process was ﬁrst established in laboratory ex- periments. The divided electrolytic cell was then developed in cooperation with our project partner Eilenburger Elektrolyse- und Umwelttechnik GmbH (EUT, Electrolysis and Environmen- tal Technology). Six different anode materials provided by our project partner MAGNETO were tested in the lab with a view ENVIRONMENT 1 2

2012|13 Annual Report Fraunhofer IGB

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