Applying organic polymer flocculants in conditioning and advanced dewatering of landfill sludge as a substitution of ferric trichloride and lime: Mechanism, optimization and pilot-scale study. (December 2020)

• Record Type: Journal Article
• Authors: Zhao, Xiaodan; Jiang, Jie; Zhou, Zhen; Yang, Jiazhe; Chen, Guang; Wu, Wei; Sun, Dongqi; Yao, Jie; Qiu, Zhan; He, Kankan; Wu, Zhichao; Lou, Ziyang
• Is Part Of: Chemosphere. Volume 260(2020)
• Publication Date: 2020-12
• Subjects: Conditioning -- Sludge dewatering -- Landfill -- Polyacrylamide -- Poly dimethyl diallyl ammonium chloride -- Response surface methodology; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.127617
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: In this study, poly dimethyl diallyl ammonium chloride (PDADMAC) and polyacrylamide (PAM) were applied to substitute ferric trichloride (FeCl3 ) and lime conditioning for advanced dewatering of landfill sludge (LS). Four response surface methodology (RSM) models were constructed for FeCl3 -lime, FeCl3 -PAM, PDADMAC-lime and PDADMAC-PAM, and identical dosages, namely 29.86, 57.91, 5.73 and 2.99 mg/g dry solids (DS) for FeCl3, lime, PDADMAC and PAM, were obtained by solving the system of four RSM equations at water content of 60% to investigate conditioning mechanisms. Compared to FeCl3 -lime, PDADMAC-PAM conditioning had strong charge neutralization and bridging performance, and obtained conditioned LS with large flocs size, strong network structure and rapid dewatering rate. By integrating RSM with nonlinear programming for optimization, the total cost of PDADMAC-PAM route was saved by 7.9% and close to FeCl3 -lime, and the optimized condition with dosages of 1.93 and 3.47 kg/t DS was further confirmed by pilot-scale experiments. The results indicated that PDADMAC-PAM was a feasible substitute for FeCl3 -lime in sludge conditioning, and showed more advantage if dewatered sludge was further treated by incineration. Graphical abstract: Image 1 Highlights: FeCl3 – lime conditioning was substituted by PDADMAC – PAM for landfill sludge (LS). Four response surface (RSM) models were constructed to study conditioning mechanism. PDADMAC – PAM dosages were 10% of FeCl3 – lime to dewater LS to water content <60%. PDADMAC – PAM conditioning had strong charge neutralization and bridging performance. Response surface coupled nonlinear programming saved cost of PDADMAC – PAM by 7.9%.