Effects of salinity and COD/N on denitrification and bacterial community in dicyclic-type electrode based biofilm reactor

Siyuan Zhai; Min Ji; Yingxin Zhao; Spyros G Pavlostathis; Qing Zhao

doi:10.1016/j.chemosphere.2017.10.108

Effects of salinity and COD/N on denitrification and bacterial community in dicyclic-type electrode based biofilm reactor

Chemosphere. 2018 Feb:192:328-336. doi: 10.1016/j.chemosphere.2017.10.108. Epub 2017 Oct 23.

Authors

Siyuan Zhai¹, Min Ji², Yingxin Zhao³, Spyros G Pavlostathis⁴, Qing Zhao⁵

Affiliations

¹ School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China; School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, United States.
² School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China; Tianjin Engineering Center of Urban River Eco-Purification Technology, Tianjin 300350, China.
³ School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China; Tianjin Engineering Center of Urban River Eco-Purification Technology, Tianjin 300350, China. Electronic address: yingxinzhao@tju.edu.cn.
⁴ School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, United States.
⁵ School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China.

PMID: 29117591
DOI: 10.1016/j.chemosphere.2017.10.108

Abstract

A dicyclic-type electrode based biofilm electrode reactor (BER) was developed for advanced nitrate removal from saline municipal wastewater. The denitrification efficiency was evaluated with a synthetic feed (NO₃^--N, 20 mg L^-1) under different salinity and COD to nitrogen ratios (COD/N). As the salinity increased from 0% to 1.0%, the denitrification performance of both the traditional biofilm reactor (BR) and BER was inhibited; however, the BER showed better adaptation and ability to recover. The BER achieved a high nitrate removal efficiency (≥90%) at a salinity of 1.0% and a low COD/N of 2.5 (theoretical stoichiometric 2.86 ignoring microbial growth). The abundance of Methylotenera mobilis in BR and Clostridium sticklandii in BER was higher than in the initial sludge sample used as inoculum. Likewise, the abundance of napA, nirS and nosZ genes increased as the COD/N further decreased. Under high salinity stress, the BER had a higher denitrification efficiency and the consumption of the organic carbon source (i.e., methanol) was reduced compared to BR. The cooperation between heterotrophic and autotrophic denitrifiers in the BER system provides a more efficient and feasible solution for nitrate removal from saline municipal wastewater.

Keywords: Bacterial community; Biofilm electrode reactor (BER); Denitrification; Municipal wastewater; Salinity.

MeSH terms

Autotrophic Processes
Biofilms*
Bioreactors / microbiology*
Bioreactors / standards
Denitrification*
Heterotrophic Processes
Nitrates / isolation & purification
Nitrogen / analysis
Salinity*
Sewage / microbiology
Wastewater / chemistry
Water Purification / methods

Substances

Nitrates
Sewage
Waste Water
Nitrogen