Abstract
We have studied some post-electroflocculation wastewater sludge treatments using a jar-test method, by which the aluminium-containing sludge flocculates at the optimal polymer dosage under an optimized mixing condition, developing larger flocs with improved strength and then exhibiting increased settleability as well as ease of dewatering. Cationic polymer conditioner successfully decreased the final sediment volume and the capillary suction time about 70% and 50% for the conditioned sludge, respectively. The main driving force for the adsorption of cationic polymer flocculant onto the negatively charged sludge particles is the charge neutralization mechanism, as indicated by the lowering of zeta potential. The experimental results indicated that the minimum polymer dose required for the lowest capillary suction time, wherein maximum flocculation occurs under corresponding mixing conditions, gives a reasonable agreement with that at zero point of charge for optimal sludge conditioning. It was also pointed out that verification and control of mixing conditions in conditioning processes are very important for attaining an optimized sludge flocculation and subsequent maximum dewaterability enhancement.
