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.

The rise and fall of photosynthesis: hormetic dose response in plants

“…An inverted U-shaped dose-response relationship of chlorophylls and photosynthesis response to stresses was found to be consistent with biomass response pattern of higher terrestrial plants (Tang et al 2009;Jia et al 2015;Nascentes et al 2018;Li et al 2019;Lassalle et al 2019;Gohari et al 2020b;Khan et al 2020;Lian et al 2020) and aquatic duckweed (Zaltauskaite and Kaciene 2020) microalgae (Zhou et al 2016). However, it should be highlighted that increased photosynthetic rate may not necessarily translate to increased photosynthetic efficiency or growth; e.g.…”

“…Therefore, the analysis was repeated after excluding these two values to test how they might have affected the results (this figure does not include the two extreme values for presentation purposes). The result (H = 13.68, P < 0.01) was similar with the first analysis (and multiple comparisons same), suggesting that the two extreme values did not affect the analysis Li et al 2020b), micro/nano-plastics (Tang et al 2018;Chae et al 2019;Zhao et al 2019;Su et al 2020;Song et al 2020;Zhang et al 2020), and other types of stresses (Zhou et al 2016;Deng et al 2017;Zhang et al 2018Zhang et al , 2020Cai et al 2020;Liu et al 2020b;Xue et al 2020). These dose responses come from 16 species (one non-identified), and 31% were statistically significant compared with the control group, according to the original analysis (some papers did not report statistics).…”

Benefits from hazards, benefits from nothing, and benefits from benefits: the combined effects of five quaternary ammonium compounds to Vibrio qinghaiensis Q67

“…Currently, S-shaped CRCs are commonly used in the toxicity evaluation for mixtures [17][18][19] and the hormetic effect of mixture has been ignored. This effect of QACs mixtures was observed at cellular levels [20,21], so the hormetic effect of QACs should be considered for environmental protection.…”