Bacterial communities in a bioelectrochemical denitrification system: The effects of supplemental electron acceptors

Abstract

Electrochemical treatment of nitrate (NO₃⁻), nitrite (NO₂⁻) and mixtures of nitrate and nitrite was evaluated with microbial catalysts on a cathode in three different bioelectrochemical denitrification systems (BEDS). The removal rates and removal percentage of nitrogen (N) compounds varied during biotic and abiotic operations. The biotic cathode using NO₃⁻-N as an electron acceptor showed enhanced removal percentages (88%) compared to the operation with NO₂⁻-N (85%). The simultaneous reduction of NO₃⁻-N and NO₂⁻-N occurred in the operation with a mixture of N compounds. The bacterial diversity from the initial inoculum (return sludge) changed at the end of bioelectrochemical denitrification operation after 55 days. The microbial community composition was different depending on the type of electron acceptor. BEDS operation with NO₃⁻-N and NO₂⁻-N was enriched with Proteobacteria and Firmicutes respectively. BEDS with a mixture of N electron acceptors showed enrichment with Proteobacteria. There was no clear, distinct microbial community between the cathode biofilm and suspended biomass.

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Identifiers

DOI

10.1016/j.watres.2013.12.023

PubMed

24388828

Journal

Water Research

Year

2014