Degradation of sulfamethoxazole in low-C/N ratio wastewater by a novel membrane bioelectrochemical reactor

Abstract

Sulfamethoxazole (SMX) pollution in wastewater threatens public health. A novel membrane bioelectrochemical reactor (MBER) with loop operation was developed for SMX degradation in low-C/N ratio wastewater. A gas-permeable silicone membrane module was used to precisely control the dissolved oxygen in the catholyte and save energy. Compared with a traditional membrane bioreactor (i.e., open-circuit reactor), the removal of SMX was increased from 49.91% to 71.10% in the proposed MBER (i.e., closed-circuit reactor). Sequencing analyses revealed that SMX was removed via cometabolism with NH₄⁺-N and COD removal in both the anode and cathode chambers. Six intermediates were detected as degradation products in the cathodic effluent; these intermediates pose a similar potential threat to the environment as SMX. Two possible degradation pathways, deduced from the sequencing analyses and degradation products, were proposed. These results provide a new technology for improving SMX removal through the integration/coupling of bioelectrochemical technology into a membrane bioreactor.

Keywords: Bioelectrochemical technology; Current generation; Membrane bioreactor; Microbial community; Sulfamethoxazole removal.