Insight into efficient phosphorus removal/recovery from enhanced methane production of waste activated sludge with chitosan-Fe supplementation. (15th December 2020)

• Record Type: Journal Article
• Authors: Zhang, Boaiqi; Zhao, Ziwen; Chen, Nan; Feng, Chuanping; Lei, Zhongfang; Zhang, Zhenya
• Is Part Of: Water research. Volume 187(2020)
• Publication Date: 2020-12-15
• Subjects: Chitosan-Fe(III) complex -- Waste activated sludge -- Methane production -- Phosphorus recovery -- Anaerobic digestion; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2020.116427
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: P can be successfully recovered as vivianite from WAS with CTS-Fe addition. 95% of P was removed/recovered from liquid digestate in CTS-Fe added AD reactor. CTS-Fe addition enhanced cumulative methane yield by 32.2% during AD of WAS. P transformation and its pathways during AD were systematically investigated. Abstract: Fe(III)-loaded chitosan (CTS-Fe) composite was used for the first time to remove and recover phosphorus (P) from waste activated sludge (WAS) via anaerobic digestion (AD). The P transformation pathway and the effect of CTS-Fe addition on the AD process were investigated using batch experiments. The P fractionation results indicate that non-apatite inorganic phosphorus (NAIP) reduction in the solid phase of sludge at 20 g/L of CTS-Fe addition (6.72 mg/g-SS) was 2.4 times higher than that in the control (2.77 mg/g-SS, no CTS-Fe addition). This is probably brought about by the added CTS-Fe enhanced the reduction of Fe(III)-P compounds in the sludge with phosphate released into the liquid phase. CTS-Fe can efficiently recover 95% of P from the liquid digestate of WAS. Notably, partial Fe(III) on the CTS-Fe was reduced and effectively combined with P to form vivianite crystals on the CTS-Fe surface during the AD process. Characterization analysis demonstrated that ligand exchange and chemical precipitation were the dominant mechanisms for P removal/recovery. Furthermore, the addition of CTS-Fe increased methane production by 11.9 - 32.2% under the tested conditions, likely attributable to the enhanced hydrolysis of WAS under CTS-Fe supplementation. As the P-loaded CTS-Fe particles can be easily separated and recovered from the AD system and further reutilized in agriculture, this study could provide a new approach for simultaneous P removal/recovery and enhanced methane production from AD of WAS. Graphical Abstract: Image, graphical abstract