Influence of Microbial Community and Biofilm Thickness in the Removal of Organic Micro Pollutants through a Membrane Aerated Biofilm Reactor

Influence of Microbial Community and Biofilm Thickness in the Removal of Organic Micro Pollutants through a Membrane Aerated Biofilm Reactor

Sanchez-Huerta C. ^1,*, Fortunato L.¹, Leiknes T. ¹, Hong P.-Y. ¹

¹ King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Thuwal 23955-6900, Saudi Arabia

* e-mail correspondence: claudia.sanchezhuerta@kaust.edu.sa

Context. Presence of organic micropollutants (OMPs) in natural water bodies is an increasing concern due to the risk their occurrence represents for ecosystems and human health. Nitrification has been linked to biotransformation of OMPs via co-metabolism by ammonia monooxygenase enzyme. Membrane aerated biofilm reactor (MABR), which supports simultaneous nitrification-denitrification, is suggested to enhance OMPs biotransformation through their unique stratified bacterial community and substrate gradient formed within biofilm thickness.

Gap. Little is known regarding the correlation between MABR biofilm thickness, bacterial consortium development, and OMPs removal.

Aim. This study aims to find an optimal MABR biofilm thickness that allows nitrification and high biotransformation of selected OMPs while exploring functional microbial community

Methods. Lab-scale Zeelung MABR reactors are fed with municipal wastewater spiked with 13 OMPs, including pharmaceuticals and endocrinal disrupting compounds, at 50 µg L^-1. Optical coherence tomography is used to monitor biofilm thickness. OMPs quantification is performed through Gas Chromatography-Mass Spectrometry. Characterization of microbial community is investigated through 16S rRNA gene-based amplicon sequencing.

Findings. MABR is highly efficient for nitrification-denitrification process, even at biofilm thickness of 0.2±0.16 µm. An increase in biofilm thickness impacted positively the biotransformation of selected OMPs (acetaminophen, triclosan, ethinyl estradiol, estrone, bisphenol-A, ibuprofen and, naproxen). Resulting in an increase of OMP biotransformation efficiency along with nitrification-denitrification rates. 

Utilization. Results will help establish operational parameters that promote the development of microbial communities supporting OMPs biotransformation.

Fig. 1 Biofilm thickness vs COD and ammonia removal (right); and OMPs removal (left)