Chronic toxicity of graphene and graphene oxide in sequencing batch bioreactors: A comparative investigation



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Journal of Hazardous Materials


The present study investigates the chronic toxicity of graphene (G) and graphene oxide (GO) in activated sludge. Sequencing batch bioreactors were fed with influents containing 0, 1 and 5 mg L?1 of GO or G (12 h cycles) for ten days. Reduction in performance of the bioreactors in relation to chemical oxygen demand, ammonia and phosphate removals was observed after three days in the bioreactors fed with 5 mg L?1 of nanomaterials. After about eight days, these reactors reached a steady state nutrient removal, which corresponded to recovery of certain groups of ammonia oxidizing bacteria and phosphate accumulating bacteria despite the increasing accumulation of nanomaterials in the sludge. These results suggested that biological treatment can be affected transiently by initial exposure to the nanomaterials, but certain groups of microorganisms, less sensitive to these nanomaterials, can potentially strive in the presence of these nanomaterials. Results of 16S rRNA gene deep sequencing showed that G and GO affected differently the microbial communities in the activated sludge. Between the two nanomaterials investigated, GO presented the highest impact in nutrient removal, gene abundance and changes in microbial population structures.



Graphene oxide, Graphene, Phosphate accumulating bacteria, Ammonia oxidizing bacteria, Community structure


Copyright 2018 Journal of Hazardous Materials. This is a pre-print of a published version of a paper that is available at: Recommended citation: Nguyen, Hang N., and Debora F. Rodrigues. "Chronic toxicity of graphene and graphene oxide in sequencing batch bioreactors: a comparative investigation." Journal of hazardous materials 343 (2018): 200-207. DOI: 10.1016/j.jhazmat.2017.09.032. This item had been deposited in accordance with publisher copyright and licensing terms and with the author's permission.