CHARACTERIZATION OF SLUDGE FROM THE TREATMENT OF DRINKING WATER AND THEIR VALUATION IN THE TREATMENT OF LEACHATE

The water purification plants generate hydroxide sludge. Most of this sludge is either dried or stored onsite, disposed of in landfill or discharged to various receiving environments without any prior treatment. The present work consists in the characterization of the sludge resulting from the treatment of water purification in the perspective of their environmental valorization especially in the field of decontamination of the leachates of the public dumps. The physico-chemical, mineralogical and microscopic analyzes carried out on sludge from water purification plants revealed that these sludges are silico-aluminous clays, consisting of a heterogeneous mixture of particles of irregular shapes in sheet and granular compound minerals of rounded forms, and very rich in silica, aluminum and iron. This sludge was used for the organic depollution of young and mature leachates from solid waste collection trucks and dump storage ponds, respectively. On the basis of the results of the tests carried out, it turns out that the characteristics of the sludges in question give them the properties of a good adsorbent for the organic matter with a yield of 58 % reduction for the young leachate under the conditions of pH = 6, a contact time of 40 min and a sludge mass of 4 g.L-1. An 86.25 % reduction yield for mature leachates under pH = 6 conditions, a contact time of 30 min and a sludge mass of 2 g.L-1.