On the fit of experimental methodology for constructive alum sludge conditioning using waste polysaccharide into reuse dewatered sludge in contaminants’ immobilization

Globally, Alum Sludge ( Al-S) is disposed of from waterworks plants, causing massive problems since it has high water content. Consequently, Al-S conditioning to improve its dewatering performance prior to sludge disposal is essential. Polysaccharides derived from waste chitosan were applied as a polymer conditioner. According to the principle of advanced oxidation processes (AOPs), the Fenton system, in its modified form as a dual oxidation and polymer conditioning, was applied. Polycationic linear polysaccharide substance augmented with iron and H 2 O 2 were added to the Al-S and capillary suction time (CST) and specific resistance for filtration (SRF) were applied to evaluate its dewaterability. The highest CST and SRF reduction reached 70 and 62%, respectively, at the optimal operational conditions of 40 and 300 mg L -1 of catalyst and H 2 O 2 , respectively, at natural pH of the used sludge. Moreover, response surface methodology (RSM) based on Box-Behnken design was used to optimize the system performance. Furthermore, the temperature increase of the Al-S showed a negative impact on both CST and SRF and the room temperature was more favorable for conditioning. Further, for the object for sustainability, the conditioned Al-S was thereby used as a source of Fenton oxidation for Malachite Green (MG) dye oxidation that resulted in 98% removal.