The flocculating properties of chitosan‐graft‐polyacrylamide flocculants (II)—Test in pilot scale

Abstract

In this study, the flocculating properties of chitosan-graft-polyacrylamide (PAM) copolymer flocculants have been investigated in pilot scale, and the raw water from Zhenjiang part of Yangtse river in China was used as simulated waste water. The influences of dose, mechanical mixing rate, and sedimentation time to the flocculating effects have been investigated in different seasons: summer and winter, respectively. The optimal experimental conditions have been studied by orthogonal test. In addition, the structure effects of the flocculants: the grafting ratio, on the flocculating properties have been also investigated in pilot scale, which results were fully consistent to those from the beaker experiment in laboratory scale using kaolin suspension as simulated waste water. Compared to poly ferric sulfate, current used flocculants in Jinxi Water Factory, chitosan-g-PAM copolymer flocculants showed better flocculating properties, which was ascribed to the cooperative effects of the charge neutralization and bridging flocculating mechanisms of polymer flocculants. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci

Flocculation properties of biodegradable amphoteric chitosan-based flocculants

“…7, raw water at a higher temperature requires less flocculants, which can be attributed to two effects: On the one hand, the viscosity of carrier liquid decreases with temperature increase, which may result in the increase of molecular movements, and collision to form larger particles thus becomes easier; On the other hand, the more extended conformation of polymeric flocculants due to the improved solubility for the increase of temperature is also beneficial for flocculation. Therefore, a higher dosage of flocculants in winter is required, whereas a lower dosage in summer is required in water treatment [20,37].…”

“…Raw water from the Zhenjiang part of the Yangtze River in China was used at the pilot scale and its characteristics were shown in Table 3. The detailed experimental process at the pilot scale has been described in the experimental part and our previous work [20,33]. Fig.…”

“…kept constant at 100 and 50 rpm, respectively, and that in the No.1 tank varied from 100 to 200 rpm. Details of the flocculation experiment at the pilot scale have been described in our previous work [20,33]: Firstly, the raw water and the stock flocculants solution were mixed in the raw-water tank; Then the mixtures was extruded into the triple coagulative precipitation tanks by water pump for sufficient mixing, followed by flowing into the inclined-tube setting tank for separation of sedimentation primarily; at last the treated water was filtrated by sand-filtrating column for further purification. Turbidity of water before and after filtration was measured by the Turbidity Indicator model of ATZ-A22 (Wuxi Guangming Instrument Factory).…”

“…To improve its performances, modified chitosan materials have been manufactured [8,[18][19][20][21][22]. Thus, extensive attention has been given to research and application of amphoteric chitosan-based flocculants [21,22].…”

Modeling and optimization of the flocculation processes for removal of cationic and anionic dyes from water by an amphoteric grafting chitosan-based flocculant using response surface methodology

“…The optimal dosage would decrease with the increase of temperature. As temperature rises, on the one hand, the movement of colloids in water increases resulting in collision to form larger particles easier; on the other hand, the more extended conformation of polymeric flocculants due to the improved solubility for the increase of temperature is also beneficial for flocculation (Renault et al 2009b;Zhang et al 2010). Both aforementioned facts result in smaller amount of flocculants required at higher temperature.…”