title: Nutrient removal by Chlorella vulgaris F1068 under cetyltrimethyl ammonium bromide induced hormesis.
abstract: Toxicants are generally harmful to biotechnology in wastewater treatment. However, trace toxicant can induce microbial hormesis, but to date, it is still unknown how this phenomenon affects nutrient removal during municipal wastewater treatment process. Therefore, this study focused on the effects of hormesis induced by cetyltrimethyl ammonium bromide (CTAB), a representative quaternary ammonium cationic surfactant, on nutrient removal by Chlorella vulgaris F1068. Results showed that when the concentration of CTAB was less than 10 ng/L, the cellular components chlorophyll a, proteins, polysaccharides, and total lipids increased by 10.11, 58.17, 38.78, and 11.87 %, respectively, and some enzymes in nutrient metabolism of algal cells, such as glutamine synthetase (GS), acid phosphatase (ACP), H(+)-ATPase, and esterase, were also enhanced. As a result, the removal efficiencies of ammonia nitrogen (NH4 (+)) and total phosphorus (TP) increased by 14.66 and 8.51 %, respectively, compared to the control during a 7-day test period. The underlying mechanism was mainly due to an enhanced photosynthetic activity of C. vulgaris F1068 indicated by the increase in chlorophyll fluorescence parameters (the value of Fv/Fm, ΦII, Fv/Fo, and rETR increased by 12.99, 7.56, 25.59, and 8.11 %, respectively) and adenylate energy charge (AEC) (from 0.68 to 0.72). These results suggest that hormesis induced by trace toxicants could enhance the nutrient removal, which would be further considered in the design of municipal wastewater treatment processes. Graphical abstract The schematic mechanism of C. vulgaris F1068 under CTAB induced hormesis. Green arrows ( ) represent the increase and the red arrow ( ) represents the decrease.
authors.affiliation: Xiangtan University, Xiangtan, Hunan, China.
authors.forename: Qiongzhi
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Xiangtan University, Xiangtan, Hunan, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Li
authors.affiliation: Xiangtan University, Xiangtan, Hunan, China. gefeixtu@sina.com.cn.
authors.forename: Fei
authors.initials: F
authors.lastname: Ge
authors.affiliation: Xiangtan University, Xiangtan, Hunan, China.
authors.forename: Na
authors.initials: N
authors.lastname: Liu
authors.affiliation: Xiangtan University, Xiangtan, Hunan, China.
authors.forename: Yangduo
authors.initials: Y
authors.lastname: Kuang
mesh_terms: D001965:Bromides; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000378:metabolism*; D002708:Chlorella / Q000378:metabolism; D048408:Chlorella vulgaris / Q000378:metabolism*; D002734:Chlorophyll / Q000031:analogs & derivatives / Q000378:metabolism; D000077194:Chlorophyll A; D059165:Hormesis; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism*; D010788:Photosynthesis; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000379:methods; D062065:Wastewater; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D001965:Bromides; D000077286:Cetrimonium; D002593:Cetrimonium Compounds; D002734:Chlorophyll; D000077194:Chlorophyll A; D009584:Nitrogen; D010758:Phosphorus; D000644:Quaternary Ammonium Compounds; D062065:Wastewater; D014874:Water Pollutants, Chemical; C085815:chlorophyll a'; C051470:ammonium bromide
keywords: Algae; Hormesis; Nutrient removal; Photosynthetic activity; Quaternary ammonium cationic surfactants