Influence of low and high dosages of methyl and propyl parabens on membrane bioreactor (MBR) performance

ABSTRACT

This study aimed to evaluate the degradation of methylparaben (MeP) and propylparaben (PrP) in synthetic wastewater in a membrane bioreactor (MBR) whose operation involved three stages: stage 1 (stabilization period), with no addition of parabens; stage 2, in which the MBR was fed with 0.5 mg L⁻¹ of each paraben; and stage 3, in which both MeP and PrP were added, at 10 mg L⁻¹each. The system performance was assessed by monitoring pH, temperature, effluent flow rate, transmembrane pressure, BOD, COD, suspended solids, and paraben concentration. The results confirmed that the MBR showed a good organic matter removal efficiency (> 92.2% for BOD; >91.6% for COD) and was not significantly affected by the addition of parabens at either low or high dosages. The volatile to total suspended solids ratio remained nearly constant, suggesting that the addition of parabens at a high concentration did not negatively impact the control of suspended solids. It was possible to achieve 96.0% of MeP and PrP removal in stage 2 ([parabens]₀ = 0.5 mg L⁻¹), and 86.0% of PrP removal in stage 3 ([PrP]₀ = 10 mg L⁻¹). Finally, biodegradation was found to be the main removal mechanism of parabens in the investigated MBR.

KEYWORDS:

• Membrane bioreactor (MBR)
• parabens
• removal mechanisms
• low and high concentrations
• aerobic process

Acknowledgements

The authors express their gratitude to the Brazilian National Council for Scientific and Technological Development (CNPq, grant #131467/2017-4), to the São Paulo Research Foundation (FAPESP, grant #2016/03695-8) and to the Coordination for the Improvement of Higher Education Personnel – Brazil (CAPES) – Finance Code 001. The authors thank I. M. Barboza and A. J. M. dos Santos for their important collaboration with MBR operation and analyses.

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

This work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico [131467/2017-4]; Fundação de Amparo à Pesquisa do Estado de São Paulo [2016/03695-8]; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior [001].