Minimization of dissolved methane, nitrogen and organic micropollutants emissions of effluents from a methanogenic reactor by using a preanoxic MBR post-treatment system

T Alvarino; T Allegue; N Fernandez-Gonzalez; S Suarez; J M Lema; J M Garrido; F Omil

doi:10.1016/j.scitotenv.2019.03.169

Minimization of dissolved methane, nitrogen and organic micropollutants emissions of effluents from a methanogenic reactor by using a preanoxic MBR post-treatment system

Sci Total Environ. 2019 Jun 25:671:165-174. doi: 10.1016/j.scitotenv.2019.03.169. Epub 2019 Mar 13.

Authors

T Alvarino¹, T Allegue², N Fernandez-Gonzalez¹, S Suarez¹, J M Lema¹, J M Garrido¹, F Omil¹

Affiliations

¹ Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain.
² Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain. Electronic address: tomas.allegue@usc.es.

PMID: 30928746
DOI: 10.1016/j.scitotenv.2019.03.169

Abstract

The use of a hybrid membrane bioreactor (MBR) post-treatment system is proposed as a cost-efficient technology in order to minimize the environmental impact of anaerobic effluents, treating low-strength sewage at room temperature, such as their high nitrogen content and the presence of dissolved methane. In this research, nitrite was externally added at different concentrations into the anoxic compartment, providing an extra electron acceptor besides the existing nitrate, to evaluate its effect on denitrification, methane oxidation and OMPs removal processes. The nitrite addition significantly improved the denitrification potential of the system, achieving nitrogen removals up to 35 mg TN L^-1. Moreover, higher nitrite concentrations clearly promoted an increase in the removal of some organic micropollutants (OMPs) such as diclofenac (DCF), ethinylestradiol (EE2), triclosan (TCS) and ibuprofen (IBP). Nevertheless, methane removal efficiencies or rates were not affected by this fact. Finally, COD and ammonium removals higher than 99 and 91% were observed during the entire operation, respectively. Based on the results, a future strategy in which ammonium is partially oxidized to nitrite could result in better nitrogen and OMPs removals for the proposed technology.

Keywords: Denitrification; Greenhouse gas; Hybrid bioreactor; Methane oxidation; Organic micropollutants; UASB.