title: Removal of FePO4 and Fe3(PO4)2 crystals on the surface of passive fillers in Fe0/GAC reactor using the acclimated bacteria.
abstract: As past studies presented, there is obvious defect that the fillers in the Fe(0)/GAC reactor begin to be passive after about 60 d continuous running, although the complicated, toxic and refractory ABS resin wastewater can be pretreated efficiently by the Fe(0)/GAC reactor. During the process, the Fe(3)(PO(4))(2) and FePO(4) crystals with high density in the passive film are formed by the reaction between PO(4)(3-) and Fe(2+)/Fe(3+). Meanwhile, they obstruct the formation of macroscopic galvanic cells between Fe(0) and GAC, which will lower the wastewater treatment efficiency of Fe(0)/GAC reactor. In this study, in order to remove the Fe(3)(PO(4))(2) and FePO(4) crystals on the surface of the passive fillers, the bacteria were acclimated in the passive Fe(0)/GAC reactor. According to the results, it can be concluded that the Fe(3)(PO(4))(2) and FePO(4) crystals with high density in the passive film could be decomposed or removed by the joint action between the typical propionic acid type fermentation bacteria and sulfate reducing bacteria (SRB), whereas the PO(4)(3-) ions from the decomposition of the Fe(3)(PO(4))(2) and FePO(4) crystals were released into aqueous solution which would be discharged from the passive Fe(0)/GAC reactor. Furthermore, the remained FeS and sulfur (S) in the passive film also can be decomposed or removed easily by the oxidation of the sulfur-oxidizing bacteria. This study provides some theoretical references for the further study of a cost-effective bio-regeneration technology to solve the passive problems of the fillers in the zero-valent iron (ZVI) or Fe(0)/GAC reactor.
authors.affiliation: Department of Environmental Science and Engineering, School of Architecture and Environment, Sichuan University, Chengdu 610065, China. laibo1981@163.com
authors.forename: Bo
authors.initials: B
authors.lastname: Lai
authors.forename: Yuexi
authors.initials: Y
authors.lastname: Zhou
authors.forename: Ping
authors.initials: P
authors.lastname: Yang
authors.forename: Juling
authors.initials: J
authors.lastname: Wang
authors.forename: Jinghui
authors.initials: J
authors.lastname: Yang
authors.forename: Huiqiang
authors.initials: H
authors.lastname: Li
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000222:Adaptation, Physiological; D001420:Bacteria, Aerobic / Q000254:growth & development / Q000502:physiology; D018441:Biofilms / Q000254:growth & development*; D002070:Butadienes / Q000737:chemistry; D002606:Charcoal / Q000737:chemistry*; D003460:Crystallization; D005160:Facility Design and Construction; D005290:Ferric Compounds / Q000302:isolation & purification*; D005296:Ferrous Compounds / Q000302:isolation & purification*; D007501:Iron / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000302:isolation & purification*; D011137:Polystyrenes / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D062065:Wastewater / Q000737:chemistry; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D000180:Acrylic Resins; D002070:Butadienes; D002606:Charcoal; D005290:Ferric Compounds; D005296:Ferrous Compounds; D007501:Iron; D010710:Phosphates; D011137:Polystyrenes; D062065:Wastewater; C024636:ABS resin; C518753:ferrous phosphate; C035885:ferric phosphate