Presentation Information
[P04-596]Removal of fluoride ions from simulated industrial wastewater using Chlorella sp. cultivation
○Chiu-Mei Kuo1, Li-Chen Chen1, Jia-Jhih Shen2, Chih-Hung Liu2 (1. Department of Chemical Engineering, Chung Yuan Christian University (Taiwan), 2. Department of Semiconductor Process Equipment Technology, Industrial Technology Research Institute (Taiwan))
Keywords:
Chlorella,wastewater treatment,fluoride ions,removal efficiency
[Purpose]
This study aimed to utilize Chlorella sp. cultured in simulated industrial wastewater at different sodium fluoride (NaF) concentrations, and then further investigate the effects of different pH, light intensities, and photoperiods on microalgal growth and removal efficiency of fluoride ion (F−). Furthermore, waste gas generated after atmospheric plasma (AP) treatment of fluoride-containing monomers was collected for microalgae cultivation to evaluate the F− removal efficiency.
[Method]
Chlorella sp. was cultured in a modified BG-11 medium at 25°C and 150 rpm to investigate the effects of NaF additions of 0 (control group), 210, 420, 630, and 840 ppm on microalgal growth. Subsequently, Chlorella sp. was cultured in BG-11 medium containing 210 mg/L NaF for 8 days, and the effects of different pH (4, 6, 8, 10), light conditions (30, 45, 60 µmol/m²/s), and light (L) and dark (D) photoperiods (24L/24D/12L:12D/6L:18D/18L:6D) on microalgal growth and F− removal efficiency were investigated. Furthermore, the waste gas generated after the fluorine-containing monomers were treated by AP was collected and then aerated into BG-11 medium to investigate the efficiency of sterilized and non-sterilized fluorine-containing culture media for the growth and the F− removal efficiency.
[Results]
As the NaF concentration increased, the biomass concentration of Chlorella sp. generally decreased, indicating that high concentrations of fluoride inhibited microalgal growth. However, at a lower NaF concentration of 210 mg/L, microalgal growth remained stable, a characteristic that facilitates F− removal by microalgae. When 210 mg/L NaF was added to BG-11 medium, the microalgae maintained good growth within an initial pH range of 6–10. At pH 10, the biomass concentration and biomass productivity were 163.2 mg/L and 15.3 mg/g, respectively. At a lower light intensity of 30 µmol/m²/s, the biomass concentration reached 200.7 mg/L, and the maximum biomass productivity was 26.6 mg/g. Under a 6D:18L condition, although the biomass concentration and maximum biomass productivity were lower than those under continuous light, the F− removal efficiency and F− removal capacity reached 28.8% and 57.5 mg/g, respectively, representing 1.4- and nearly 1.7-fold increases compared to continuous light. Furthermore, the waste gas generated after the fluorine-containing monomers were collected and treated by atmospheric plasma was then introduced into the BG-11 culture medium. The results showed that the Chlorella sp. growth was not affected by whether the culture medium was sterilized or not. Among them, the microalgae growth performance was the best in the unsterilized fluorine-containing culture medium, with 500.5 mg/L biomass concentration, 8.1% F− removal efficiency, and 3.9 mg/g removal capacity, showing that Chlorella sp. has the potential to treat fluoride-containing wastewater.
[Consideration]
Chlorella sp. has the ability to remove F−, but future research should explore how to increase the daily fluoride-containing wastewater treatment capacity of microalgae and establish a stable F− removal process.
[Conclusion]
Chlorella sp. can grow well in a wide pH range of 6-10 in an environment containing 210 mg/L NaF. This characteristic is beneficial for the application of microalgae in alkaline wastewater treatment, while also achieving the benefit of removing F−.
This study aimed to utilize Chlorella sp. cultured in simulated industrial wastewater at different sodium fluoride (NaF) concentrations, and then further investigate the effects of different pH, light intensities, and photoperiods on microalgal growth and removal efficiency of fluoride ion (F−). Furthermore, waste gas generated after atmospheric plasma (AP) treatment of fluoride-containing monomers was collected for microalgae cultivation to evaluate the F− removal efficiency.
[Method]
Chlorella sp. was cultured in a modified BG-11 medium at 25°C and 150 rpm to investigate the effects of NaF additions of 0 (control group), 210, 420, 630, and 840 ppm on microalgal growth. Subsequently, Chlorella sp. was cultured in BG-11 medium containing 210 mg/L NaF for 8 days, and the effects of different pH (4, 6, 8, 10), light conditions (30, 45, 60 µmol/m²/s), and light (L) and dark (D) photoperiods (24L/24D/12L:12D/6L:18D/18L:6D) on microalgal growth and F− removal efficiency were investigated. Furthermore, the waste gas generated after the fluorine-containing monomers were treated by AP was collected and then aerated into BG-11 medium to investigate the efficiency of sterilized and non-sterilized fluorine-containing culture media for the growth and the F− removal efficiency.
[Results]
As the NaF concentration increased, the biomass concentration of Chlorella sp. generally decreased, indicating that high concentrations of fluoride inhibited microalgal growth. However, at a lower NaF concentration of 210 mg/L, microalgal growth remained stable, a characteristic that facilitates F− removal by microalgae. When 210 mg/L NaF was added to BG-11 medium, the microalgae maintained good growth within an initial pH range of 6–10. At pH 10, the biomass concentration and biomass productivity were 163.2 mg/L and 15.3 mg/g, respectively. At a lower light intensity of 30 µmol/m²/s, the biomass concentration reached 200.7 mg/L, and the maximum biomass productivity was 26.6 mg/g. Under a 6D:18L condition, although the biomass concentration and maximum biomass productivity were lower than those under continuous light, the F− removal efficiency and F− removal capacity reached 28.8% and 57.5 mg/g, respectively, representing 1.4- and nearly 1.7-fold increases compared to continuous light. Furthermore, the waste gas generated after the fluorine-containing monomers were collected and treated by atmospheric plasma was then introduced into the BG-11 culture medium. The results showed that the Chlorella sp. growth was not affected by whether the culture medium was sterilized or not. Among them, the microalgae growth performance was the best in the unsterilized fluorine-containing culture medium, with 500.5 mg/L biomass concentration, 8.1% F− removal efficiency, and 3.9 mg/g removal capacity, showing that Chlorella sp. has the potential to treat fluoride-containing wastewater.
[Consideration]
Chlorella sp. has the ability to remove F−, but future research should explore how to increase the daily fluoride-containing wastewater treatment capacity of microalgae and establish a stable F− removal process.
[Conclusion]
Chlorella sp. can grow well in a wide pH range of 6-10 in an environment containing 210 mg/L NaF. This characteristic is beneficial for the application of microalgae in alkaline wastewater treatment, while also achieving the benefit of removing F−.
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