Marble stone powder (calcite tailing) is a residual material resulting from the cutting and polishing of marble stone. Its use as adjuvant for the biologic treatment of acid mine drainage is studied. The performance of a combined chemical/biologic packed bed reactor containing a sulphate-reducing bacteria inoculum and calcite tailing as neutralising agent was compared with the individual neutralisation and biologic steps. Unlike the individual steps, the combined column is efficient in terms of metals and sulphate removal and acidity neutralisation, producing treated water suitable for irrigation. This work emphasizes on the key role played by waste calcite tailing in the inlet of the reactor. By thus adjusting pH to Values adequate for sulphate-reducing bacteria water suitable for irrigation can be obtained in a single equipment with low energy demand. This goal would be impossible without the neutralisation action. (C) 2008 Elsevier Ltd. All rights reserved.