Papers by Keyword: Coagulation Mechanism

Abstract: Natural organic matter (NOM) is easily soluble in surface water and difficult to be removed thoroughly. In this paper, polyaluminum chloride-polyacrylamide (PAC-PAM), as a new water treatment material, was proposed to solve this problem by coagulation treatment. The performance, mechanism and kinetic process of NOM removal were investigated systematically. Results showed that the optimum dosage of PAC and PAM was 10 mg/L and 0.5 mg/L for NOM removal of Yellow River water. In this condition, NOM could be removed effectively due to positively charged PAM addition. The size, growth rate and recovery factor of flocs generated by PAC-PAM reached 419 μm, 34.9 μm/min and 0.48, respectively, while only 355 μm, 27.9 μm/min and 0.31 were obtained by PAC. Moreover, the adsorption and bridging effect of PAM assisted the formation of multi-branched flocs, which brought fast settle velocity and low turbidity of supernatant after coagulation.

Abstract: A new composite coagulant, polymeric ferric aluminum chloride-polydimethyl diallylammonium chloride (PFAC-PD), was prepared by combing Polymeric ferric aluminum chloride (PFAC) with polydimethyl diallylammonium chloride (PDMDAAC). The turbidity, ultraviolet absorbance at 254 nm (UV254) and specific ultraviolet absorbance (SUVA) removal and flocculating mechanisms of the new composite coagulant and the traditional coagulants (PFAC, adding PFAC before adding PDMDAAC and adding PFAC after adding PDMDAAC) were investigated in treating surface water. The results indicated that the new composite coagulants exhibited better flocculation efficiency than PFAC and successive addition of PFAC and PDMDAAC. The neutralization ability of the coagulants was in the following order: PFAC-PD > PD+PFAC > PFAC+PD > PFAC.

Abstract: A new polyferric silicate chloride(PFSC) was prepared by using sodium silicate, ferric chloride as raw materials, at the same time, its coagulation performance and the influencing factors were observed. The water containing algae was processed by PFSC coagulant and coagulation mechanism were discussed. The results showed that the best reaction time of PFSC preparation was 1h, temperature was 40°Cand Fe/Si mole ratio was 1. The removal efficiencies of chlorophyll a and turbidity were 82.40% and 94.97% respectively at 14mgFe•L-1 of dosage. Coagulation mechanism of PFSC is considered as the cooperation of oxidization/adsorption/charge-neutralization, adsorption-bridging and sweeping, which is the effect of silicic acid, iron and iron hydrolysate on the suspended particles in wastewater.