engleski

Electrochemical treatment of landfill leachate

The aim of this research was development of appropriate procedure for the treatment of landfill leachate taken from the Piškornica, Mraclinska Dubrava and Viševac sanitary landfills. Due to the complex nature of the effluent a combined treatment approach was applied. The pretreatment step included simultaneous treatment with calcium oxide and electrocoagulation/electrooxidation by stainless steel electrode set. The main treatment included electrocoagulation/electrooxidation using the set of stainless steel, iron and aluminum electrodes. Pretreatment allows the destruction of the humic and fulvic acids and optimization of pH values for the formation of reactive oxidative species, as well as the transformation of NH4-N into volatile NH3-N. This pretreatment allows the softening of the water and 100% removal of the bacteria, between 90 and 96% removal of color, turbidity and suspended solids, approximately 65% removal of NH3-N and more than 98% removal of fluorides, phosphates and heavy metals, while the hardly biodegradable organic matter decomposes into more easily degradable carboxylic acids. In the presence of added calcium oxide and electrochemically generated coagulant the removal of the fluorides, phosphates and heavy metals occur trough the formation of poorly soluble fluorapatite, hydroxyl apatite, and various hydroxides. During the main treatment electrochemically generated reactive oxidative species carried out rapid decomposition of the organic matter and ammonia, resulting in the removal of COD up to 98%, color and turbidity up to 99% and ammonia up to 97%. Following the electrochemical treatment the suspension was passed through an electromagnet in order to speed the separation of the sludge from the treated water. Applied treatment approach resulted in clear, colorless and odorless effluent with the values of all measured parameters significantly lower compared to the upper permissible limit for discharge into the environment.

landfill leachate ; CaO ; electrocoagulation/electrooxidation/electroreduction ; stainless steel/iron/aluminum anode

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