The growth suppression effects of UV-C irradiation on Microcystis aeruginosa and Chlorella vulgaris under solo-culture and co-culture conditions in reclaimed water

• Published in: The Science of the total environment 2020-04, Vol.713, p.136374-136374, Article 136374
• Main Authors: Li, Shang, Dao, Guo-Hua, Tao, Yi, Zhou, Ji, Jiang, Hai-Sha, Xue, Yuan-Mei, Yu, Wen-Wen, Yong, Xiao-Lei, Hu, Hong-Ying
• Format: Article
• Language: English
• Subjects: Chlorella vulgaris; Coculture Techniques; Growth suppression of microalgae; Harmful Algal Bloom; Microcystis; Microcystis aeruginosa; Reclaimed water; Ultraviolet Rays; UV-C irradiation
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.136374

Harmful algal blooms (HABs) are serious problems in landscape waters sourced from reclaimed water. In this study, the suppression effects of UV-C irradiation on microalgal growth were researched to find a possible preventive approach. Microcystis aeruginosa and Chlorella vulgaris were exposed to UV-C irradiation and then cultured in real reclaimed water for 7–18 d. UV-C irradiation at 50–200 mJ cm−2 could inhibit the growth of M. aeruginosa, C. vulgaris, and both microalgae in co-culture for 3–14, 1–3, and 1–5 d respectively. In addition, UV-C irradiation could cause damage to the cell integrity. At 100–200 mJ cm−2 UV-C, the proportion of microalgal membrane damage (Pmd) in M. aeruginosa cells increased rapidly to 56%–76% from day 3, whereas that in C. vulgaris cells increased to 23%–62% within 3 d. The photochemical efficiency (represented by Y value) of the irradiated groups was negatively affected immediately after UV-C irradiation and recovered gradually during the incubation. The Y value of M. aeruginosa cells began to recover from days 3 to 14, whereas that of C. vulgaris recovered much more quickly, from days 0.1 to 1. Overall, the irradiation-induced suppressive effects on algal growth correlated positively with the UV-C doses. Because M. aeruginosa was more sensitive to UV-C irradiation, UV-C irradiation not only controlled the total biomass of the mixed algae but also selectively reestablished the dominance of the nontoxic C. vulgaris. [Display omitted] •The growth suppression effects of UV-C irradiation on microalgae in reclaimed water were investigated.•The damage and recovery processes of microalgae were detected after UV-C irradiation.•The sensitivities of Microcystis aeruginosa and Chlorella vulgaris to UV-C irradiation were compared.•Apart from solo-culture conditions, the growth suppression effects of co-culture conditions were also investigated.•UV-C irradiation selectively reestablished the dominance of nontoxic C. vulgaris.