Mitigation of N2O emissions via enhanced denitrification in a biological landfill leachate treatment using external carbon from fermented sludge

Kyeong Hwan Kang; Minseok Yang; Shahbaz Raza; Heejong Son; Young-Kwon Park; Jinhua Wang; Young Mo Kim

doi:10.1016/j.chemosphere.2023.139114

Mitigation of N₂O emissions via enhanced denitrification in a biological landfill leachate treatment using external carbon from fermented sludge

Chemosphere. 2023 Sep:335:139114. doi: 10.1016/j.chemosphere.2023.139114. Epub 2023 Jun 1.

Authors

Kyeong Hwan Kang¹, Minseok Yang², Shahbaz Raza¹, Heejong Son³, Young-Kwon Park⁴, Jinhua Wang⁵, Young Mo Kim⁶

Affiliations

¹ Department of Civil and Environmental Engineering, Hanyang University, Seongdong-gu, Seoul, 04763, Republic of Korea.
² School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea.
³ Busan Water Authority, Gimhae-si, Gyeongsangnam-do, 50804, Republic of Korea.
⁴ School of Environmental Engineering, University of Seoul, Dongdaemun-gu, Seoul, 02504, Republic of Korea.
⁵ Key Laboratory of Agricultural Environment in Universities of Shandong, College of Resources and Environment, Shandong Agricultural University, Tai'an, 271018, China. Electronic address: wjh@sdau.edu.cn.
⁶ Department of Civil and Environmental Engineering, Hanyang University, Seongdong-gu, Seoul, 04763, Republic of Korea. Electronic address: youngmo@hanyang.ac.kr.

PMID: 37270035
DOI: 10.1016/j.chemosphere.2023.139114

Abstract

The effects of an external carbon source (C-source) on the mitigation of N₂O gas (N₂O_(g)) emissions from landfill leachate were investigated via enhanced denitrification using anaerobically fermented sewage sludge. Anaerobic fermentation of sewage sludge was conducted under thermophilic conditions with progressively increasing organic loading rates (OLR). Optimal conditions for fermentation were determined based on the efficiency of hydrolysis and the concentrations of sCOD and volatile fatty acids (VFAs) as follows: at an OLR of 40.48 ± 0.77 g COD/L·d with 1.5 days of solid retention time (SRT), 14.68 ± 0.59% of efficiency of hydrolysis, 14.42 ± 0.30 g sCOD/L and 7.85 ± 0.18 g COD/L of VFAs. Analysis of the microbial community in the anaerobic fermentation reactor revealed that degradation of sewage sludge might be potentially affected by proteolytic microorganisms producing VFAs from proteinaceous materials. Sludge-fermentate (SF) retrieved from the anaerobic fermentation reactor was used as the external C-source for denitrification testing. The specific nitrate removal rate (K_NR) of the SF-added condition was 7.54 mg NO₃^-N/g VSS·hr, which was 5.42 and 2.43 times higher than that of raw landfill leachate (LL) and a methanol-added condition, respectively. In the N₂O_(g) emission test, the liquid phase N₂O (N₂O-^N_(l)) of 20.15 mg N/L was emitted as N₂O_(g) of 19.64 ppmv under only LL-added condition. On the other hand, SF led to the specific N₂O_(l) reduction rate (K_N2O) of 6.70 mg N/g VSS hr, resulting in mitigation of 1.72 times the N₂O_(g) emission compared to under the only-LL-added condition. The present study revealed that N₂O_(g) emissions from biological landfill leachate treatment plants can be attenuated by simultaneous reduction of NO₃^-N and N₂O_(l) during enhanced denitrification via a stable supply of an external C-source retrieved from anaerobically fermented organic waste.

Keywords: Anaerobic fermentation; Denitrification; External organic carbon; Landfill leachate; Nitrous oxide emission; Sewage sludge.

MeSH terms

Bioreactors
Carbon
Denitrification
Fatty Acids, Volatile
Nitrogen
Sewage*
Water Pollutants, Chemical*

Substances

Sewage
Water Pollutants, Chemical
Carbon
Fatty Acids, Volatile
Nitrogen