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Effect of hydrogen peroxide on natural phytoplankton and bacterioplankton in a drinking water reservoir: mesocosm-scale study.


Allan A. Santos

Dayvson O. Guedes


Samylla Oliveira

Ana B.F. Pacheco

Sandra M.F.O. Azevedo



Cyanobacterial blooms are increasingly reported worldwide, presenting a challenge to water treatment plants and concerning risks to human health and aquatic ecosystems. Advanced oxidative processes comprise efficient and safe methods for water treatment. Hydrogen peroxide (H2O2) has been proposed as a sustainable solution to mitigate bloom-forming cyanobacteria since this group presents a higher sensitivity compared to other phytoplankton, with no major risks to the environment at low concentrations. Here, we evaluated the effects of a single H2O2 addition (10 mg L?1) over 120 h in mesocosms introduced in a reservoir located in a semi-arid region presenting a Planktothrix-dominated cyanobacterial bloom. We followed changes in physical and chemical parameters and in the bacterioplankton composition. H2O2 efficiently suppressed cyanobacteria, green algae, and diatoms over 72 h, leading to an increase in transparency and dissolved organic carbon, and a decrease in dissolved oxygen and pH, while nutrient concentrations were not affected. After 120 h, cyanobacterial abundance remained low and green algae became dominant. 16S rRNA sequencing revealed that the original cyanobacterial bloom was composed by Planktothrix, Cyanobium and Microcystis. Only Cyanobium increased in relative abundance at 120 h, suggesting regrowth. A prominent change in the composition of heterotrophic bacteria was observed with Exiguobacterium, Paracoccus and Deinococcus becoming the most abundant genera after the H2O2 treatment. Our results indicate that this approach is efficient in suppressing cyanobacterial blooms and improving water quality in tropical environments. Monitoring changes in abiotic parameters and the relative abundance of specific bacterial taxa could be used to anticipate the regrowth of cyanobacteria after H2O2 degradation and to indicate where in the reservoir H2O2 should be applied so the effects are still felt in the water treatment plant intake.


SANTOS, A.A., GUEDES, D.O., BARROS, M.U.G., OLIVEIRA, S., PACHECO, A.B.F., AZEVEDO, S.M.F.O., MAGALHÃES, V.F., PESTANA, C.J., EDWARDS, C., LAWTON, L.A. and CAPELO-NETO, J. 2021. Effect of hydrogen peroxide on natural phytoplankton and bacterioplankton in a drinking water reservoir: mesocosm-scale study. Water research [online], 197, article 117069. Available from:

Journal Article Type Article
Acceptance Date Mar 17, 2021
Online Publication Date Mar 20, 2021
Publication Date Jun 1, 2021
Deposit Date Mar 26, 2021
Publicly Available Date Mar 26, 2021
Journal Water Research
Print ISSN 0043-1354
Electronic ISSN 1879-2448
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 197
Article Number 117069
Keywords Water quality; Cyanobacteria; Advanced oxidative process; Remediation; Metagenomics; Exiguobacterium
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