Résumé : |
The biological treatment of effluent is normally employed as the secondary stage in the processing of tannery waste waters. This stage normally follows full physical/chemical treatment, and is usually in the form of the activated sludge treatment process. The cost of plant and equipment is high, and the operation requires close attention. Moreover, the process consumes a considerable amount of energy, and forms large volumes of biological sludge that is difficult to dewater. An alternative method has been developed to suit tannery effluents by the author, Richard Daniels. Known technically as "engineered reedbeds", the method is a simple, effective and low-cost alternative to the activated sludge treatment process: the energy use is negligible, and no biological sludge remains for treatment and disposal. In addition, the process has been found effective for polishing or tertiary treatment of effluents when conventional plant and equipment has failed to meet target requirements. The evolution, application and performance of this technology - specifically developed for the leather manufacturer - are set down in the following paper. |