Valorisation des boues hydroxydes de potabilisation des eaux : Caractérisation et applications comme coagulant et adsorbant pour les rejets des margines [Valorization of drinking water treatment sludge (DWTS): Characterization and applications as coagulant and sorbent for Olive Mill Wastewater (OMW)]

In conventional treatment process for producing drinking water,usually coagulation flocculation is a very important step for the clarification of surface water. the coagulant and flocculant employed are often the aluminium sulfate and the polyelectrolyte. practically,total quantity of the reagents injected during the treatment is accumulated in the sludge at the end of the treatment cycle. the present work aims the valorization of hydroxide sludge through the identification of their potential of the elimination of pollution. this valuation is its re-use as coagulant and adsorbent for the treatment of olive oil mill wastewater (omw).the first part of this study is devoted to the characterization of the material to determine its chemical and mineralogical composition. the second part is oriented towards a study of the behavior of sludge as an additive to assess,first,the coagulant power through a comparative study with major conventional reagents,aluminium sulfate al2 (so4)3,18h2o and ferric chloride fecl3 and second,by studying its adsorbing performance for the removal of dissolved solids represented by the chemical oxygen demand (cod) and coloration of the omw. the design of experiment technique (doe) was used to study the effects of ph,reagent forms (aluminum sulfate,ferric chloride,fresh sludge and dry sludge),coagulant and flocculant concentrations on the removal of turbidity,organic pollutants and coloration of the waste. the main results show that the hydroxide sludge (drinking water treatment sludge -dwts) consist mainly of silica,aluminium oxide,iron oxide,magnesium,calcium and potassium with the following rate: sio2 (45.05%),al2o3 (25.93%),fe2o3 (7.84%),cao (3.79%),mgo (3.79%) and k2o (3.81%). performance monitoring of hydroxide sludge to clean up industrial waste showed that in the case of treatment of the olive oil mill wastewater (omw),the removal rate of turbidity and cod vary successively from 59 to 93.5% and from 49.4 to 68% depending on the experimental conditions. these sludge have also shown their ability to reduce or eliminate the colouring of omw which in appearance is annoying to the environment.