Landfill leachates treatment with vacuum evaporators

Business case: Condorchem Spain has been awarded the tender to carry out the second phase of capacity expansion of the municipal solid waste (MSW) treatment plant in SegriĂ , the province of Lleida (Catalonia) in Spain.

A common problem facing MSW landfills is the highly polluting and environmentally hazardous liquid effluents they generate: the leachates. These effluents originate as a result of waste organic matter degradation and decomposition as well as from rain percolating through such waste.

Consequently, MSW landfills generate dark and odorous liquid effluents characterized by a very high organic load, high conductivity and a large presence of metal ions as well as  by  high concentrations of ammoniacal nitrogen, which cannot be discharged without prior treatment.

The capacity expansion will serve two purposes: it will allow the  plant to treat a larger amount of wastes from several towns in the immediate vicinity of the landfill; and  on the other hand, it will improve the efficiency of the municipal waste treatment systems employed so that the results  comply with National and European regulations.

In this regard, it is noteworthy that the current leachate treatment system used at the MSW landfill can reduce liquid waste from 100 liters down to 50. With the new plant to be annexed to the existing one, the resulting fraction will be 25, which represents an important advance. In addition, these wastes will be sent to another plant outside the facility to complete the treatment, so as to reduce them to an inert paste-like consistency to make them appropriate for storage.

Although the initial choice was to use physicochemical and/or biological waste water purification treatments for this type of effluents, it will be necessary to develop and implement physical processes of concentration instead, which, in this case, will provide better efficiency and performance, so as to obtain the desired results.

The systems of vacuum evaporation, combined with or without pre- or post- reverse osmosis are specially indicated, since they produce high leachate reduction rates as well as purified water suitable for discharge, even under the most stringent limits by means of a simple and cost-effective method.

Additionally, the biogas generated at landfills may be reused as a source of energy supply to the vacuum evaporation system, by means of either a boiler with a biogas burner or cogeneration systems.

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