title: Long-term effect of low concentration Cr(VI) on P removal in granule-based enhanced biological phosphorus removal (EBPR) system.
abstract: In light of the fact that most wastewater in China contained both industrial and domestic wastewater, a 52-d systematical investigation was conducted on the long-term effect of low concentration Cr(VI) (0.3-0.8 mg L(-1)) on P removal performance of granule-based EBPR system in this study. The mechanisms were likewise discussed. Results showed that high Cr(VI) concentration (⩾0.5 mg L(-1)) could significantly inhibit P removal, while this phenomenon was not found when Cr(VI) concentration was less than (or equal to) 0.4 mg L(-1). Most of the granules was disintegrated and filamentous bacteria overgrew inducing sludge bulking occurred at 0.7 mg L(-1) Cr(VI). During the exposure test, the abundance of poly-phosphate-accumulating organisms (PAOs) significantly decreased while the populations of glycogen accumulating organisms (GAOs) and other bacteria increased. Both production and degradation of poly-β-hydroxyakanoates (PHAs) were apparently inhibited. An improved polysaccharide/protein (PS/PN) ratio was observed with the increasing Cr(VI) concentration, implying excessive polysaccharide was secreted by microorganisms to support its resistance to the toxicity of Cr(VI). Besides, good linear regression between PS/PN ratio and the granule size (R(2)=-0.86, p<0.01) was obtained, indicating that high PS/PN was adverse to granule stability. Correlation analysis indicated that the accumulation of granules intracellular Cr was directly responsible for the observed inhibitory effect on P removal process. The long-term Cr(VI) treatment had irreversible effects on granule-based EBPR system as it could not revive after a 16-d recovery process.
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Fang
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Su
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China. Electronic address: pdsun@126.com.
authors.forename: Peide
authors.initials: P
authors.lastname: Sun
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China.
authors.forename: Juqing
authors.initials: J
authors.lastname: Lou
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China.
authors.forename: Jingyi
authors.initials: J
authors.lastname: Han
mesh_terms: D001420:Bacteria, Aerobic / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D057919:Biological Oxygen Demand Analysis; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D002681:China; D002857:Chromium / Q000494:pharmacology*; D006003:Glycogen / Q000378:metabolism; D010758:Phosphorus / Q000302:isolation & purification* / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D002857:Chromium; D006003:Glycogen; D010758:Phosphorus; D012722:Sewage; D062065:Wastewater; C074702:chromium hexavalent ion
keywords: Cr(VI); Granule-based enhanced biological phosphorus removal system; Long-term; Ratio of polysaccharide/protein; Recovery