title: A comparative study of abiological granular sludge (ABGS) formation in different processes for zinc removal from wastewater.
abstract: Abiological granular sludge (ABGS) formation is a potential and facile strategy for improving sludge settling performance during zinc removal from wastewater using chemical precipitation. In this study, the effect of pH, seed dosage, and flocculant dosage on ABGS formation and treated water quality was investigated. Results show that settling velocity of ABGS can reach up to 4.00 cm/s under optimal conditions, e.g., pH of 9.0, zinc oxide (ZnO) seeds dosage of 1.5 g/l, and polyacrylamide (PAM) dosage of 10 mg/l. More importantly, ABGS formation mechanism was investigated in NaOH precipitation process and compared with that in bio-polymer ferric sulfate (BPFS)-NaOH precipitation process regarding their sludge structure and composition. In the NaOH precipitation process, ABGS formation depends on some attractions between particles, such as van der Waals attraction and bridging attraction. However, during the BPFS-NaOH sludge formation process, steric repulsion becomes dominant due to the adsorption of BPFS on ZnO seeds. This repulsion further causes extremely loose structure and poor settling performance of BPFS-NaOH sludge.
authors.affiliation: School of Metallurgy and Environment, Central South University, Changsha, 410083, China.
authors.forename: Liyuan
authors.initials: L
authors.lastname: Chai
authors.forename: Xu
authors.initials: X
authors.lastname: Yan
authors.forename: Qingzhu
authors.initials: Q
authors.lastname: Li
authors.forename: Bentao
authors.initials: B
authors.lastname: Yang
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D011232:Chemical Precipitation; D005427:Flocculation; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D013054:Spectrophotometry, Atomic; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D060753:Water Quality; D015032:Zinc / Q000032:analysis*; D015034:Zinc Oxide / Q000032:analysis
chemical_list: D062065:Wastewater; D014874:Water Pollutants, Chemical; D015032:Zinc; D015034:Zinc Oxide