title: Combination of photoreactor and packed bed bioreactor for the removal of ethyl violet from wastewater.
abstract: An efficient treatment system that combines a photoreactor and packed bed bioreactor (PBR) was developed and evaluated for treating ethyl violet (EV)-containing wastewater. Initial experiments demonstrated that the optimal operating parameters for the photoreactor in treating EV-containing wastewater were 2h reaction time, pH of 7, and 2 min liquid retention time. Under these conditions, the photocatalytic reaction achieved a 61% EV removal efficiency and resulted in a significant BOD/COD increase in the solution. The results displayed by the coupled photobiological system achieved a removal efficiency of 85% and EC50 of the solution increased by 19 times in a semi-continuous mode when the EV concentration was <150 mg +L(-)(1). The effect of shock loading on the EV removal was temporary but coexisting substrate (glucose and crystal violet) at specific levels would affect the EV removal efficiency of the PBR. Phylogenetic analysis in the PBR indicated that the major bacteria species were Bdellovibrio bacteriovorus, Ralstonia pickettii, Stenotrophomonas maltophilia, and Comamonas sp. Furthermore, the possible degrading mechanisms of this coupled system were demethylation, deethylation, aromatic ring opening, nitrification, and carbon oxidation. The intermediates were characterized using gas chromatography-mass spectrometry analysis. These results indicated that the coupled photobiological system provides an effective method of EV removal.
authors.affiliation: Department of Tourism and Leisure, Hsing Wu University, Taipei 244, Taiwan.
authors.forename: Chih-Yu
authors.initials: CY
authors.lastname: Chen
authors.affiliation: Department of Biological Science and Technology, China University of Science and Technology, Taipei 115, Taiwan.
authors.forename: Shao-Hsiung
authors.initials: SH
authors.lastname: Yen
authors.affiliation: Department of Biological Science and Technology, China University of Science and Technology, Taipei 115, Taiwan. Electronic address: ycchung@cc.cust.edu.tw.
authors.forename: Ying-Chien
authors.initials: YC
authors.lastname: Chung
mesh_terms: D001419:Bacteria / Q000145:classification / Q000378:metabolism*; D001426:Bacterial Proteins; D019149:Bioreactors; D004396:Coloring Agents / Q000378:metabolism / Q000528:radiation effects; D058645:Denaturing Gradient Gel Electrophoresis; D008969:Molecular Sequence Data; D010782:Photolysis; D016133:Polymerase Chain Reaction; D012394:Rosaniline Dyes / Q000378:metabolism* / Q000528:radiation effects*; D017422:Sequence Analysis, DNA; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000378:metabolism* / Q000528:radiation effects*
chemical_list: D001426:Bacterial Proteins; D004396:Coloring Agents; D012394:Rosaniline Dyes; D014874:Water Pollutants, Chemical; C034887:ethyl violet
keywords: Ethyl violet; Photo-biological system; Photocatalysis; Wastewater