Towards practical integration of MBR with electrochemical AOP: Improved biodegradability of real pharmaceutical wastewater and fouling mitigation

Soorena Gharibian; Hossein Hazrati

doi:10.1016/j.watres.2022.118478

Towards practical integration of MBR with electrochemical AOP: Improved biodegradability of real pharmaceutical wastewater and fouling mitigation

Water Res. 2022 Jun 30:218:118478. doi: 10.1016/j.watres.2022.118478. Epub 2022 Apr 19.

Authors

Soorena Gharibian¹, Hossein Hazrati²

Affiliations

¹ Faculty of Chemical Engineering, Sahand University of Technology, Sahand New Town, East Azerbaijan, P.O. Box: 51335-1996, Iran; Environmental Engineering Research Center, Sahand University of Technology, Sahand New Town, Iran; Biotechnology Research Center, Sahand University of Technology, Sahand New Town, Iran.
² Faculty of Chemical Engineering, Sahand University of Technology, Sahand New Town, East Azerbaijan, P.O. Box: 51335-1996, Iran; Environmental Engineering Research Center, Sahand University of Technology, Sahand New Town, Iran; Biotechnology Research Center, Sahand University of Technology, Sahand New Town, Iran. Electronic address: h.hazrati@sut.ac.ir.

PMID: 35472746
DOI: 10.1016/j.watres.2022.118478

Abstract

In the current study, we report enhanced treatment of real pharmaceutical wastewater by integration of Electrooxidation (EO) with Membrane Bio-Reactor (MBR) for the first time. Integrated pre-pilot EO-MBR plant consisted of a 3D printed electrochemical flowcell equipped with graphite electrodes installed in the effluent recirculation line of an MBR equipped with a hollow fiber membrane module. Results demonstrated that 5 V was the optimum voltage level for an isolated EO system. Isolated EO system led to 40% COD removal and 2.5 fold biodegradability index (BOD₅/COD) improvement after 24 hr treatment at the optimum voltage of 5 V and 160 mL.min^-1 flowrate. Almost complete removal of COD and BOD₅ was observed for the EO-MBR system with 160 mL.min^-1 recirculation rate and 24 hr HRT, while respective values were 60 and 87% for the MBR system at same operational conditions. Oxidation of pharmaceutical compounds identified in real wastewater and the fate of main oxidation-recalcitrant by-products were confirmed using liquid chromatography techniques. In addition, the integrated EO-MBR system led to significant membrane fouling mitigation with a 28 day extended operational time before reaching the Trans Membrane Pressure (TMP) limit value of 30 kPa. Measurements revealed reduced Extracellular Polymeric Substances (EPS) Concentration of membrane sludge cake layer of EO-MBR along with significant reduction of proteinaceous compounds in the LB-EPS fraction of cake layer in comparison with isolated MBR system. Fouling behavior improvement of the EO-MBR system was attributed to the electrophilic attack of electrochemically generated hydroxyl radicals to the electron-rich moieties of EPS organic foulants. Reduced proteinaceous/humic-like substances of LB-EPS from the cake layer were further confirmed by Emission Excitation matrix (EEM) and Fourier Transform InfraRed (FTIR) spectroscopic methods. The results of current research provide a helpful basis for future studies by elucidating the complex operating/fouling mechanism of integrated Advanced Oxidation Processes (AOPs) with MBR systems for enhanced treatment of organics polluted wastewaters with low biodegradability.

Keywords: AOP; Biodegradability; Electrooxidation; Flowcell; Fouling; MBR; Pharmaceutical wastewater.

MeSH terms

Bioreactors*
Drug Industry*
Humic Substances
Industrial Waste*
Membranes, Artificial
Sewage
Wastewater* / chemistry
Water Purification* / methods

Substances

Humic Substances
Industrial Waste
Membranes, Artificial
Sewage
Waste Water