NEUTRALIZATION OF DYEING INDUSTRY WASTEWATER AND SLUDGE BY FIXATION OF POLLUTANTS IN VERY HIGH QUALITY HEU-TYPE ZEOLITIC TUFF

Treatment of dyeing industry wastewater of pH 7.5 with very high quality zeolitic tuff and coagulants, resulted in clear water of pH 7.2, free of odours and improved quality characteristics (colour, suspended particles, COD: Chemical Oxygen Demand, P2O5, NO3-, Cr) by 74 to 98%. The very high quality zeolitic tuff is 3 to 60% more effective than the coagulants, concerning COD, Cr and NO3-. The treatments produced sludge (using coagulants) and zeo-sludge (using very high quality zeolitic tuff and coagulants). The zeo-sludge is odourless and cohesive. The leaching by deionised water of sludge reached values up to 100% for the quality characteristics, while that of the zeo-sludge reached significantly lower values (only up to 18%). The chemical composition of the seepage water from the zeo-sludge proved the fixation of pollutants, such as NO3- and Cr by the very high quality zeolitic tuff.