Nitrogen removal in improved subsurface wastewater infiltration system: Mechanism, microbial indicators and the limitation of phosphorus

Liping Jia; Xuelin Cheng; Linchuan Fang; Xuguang Huang

doi:10.1016/j.jenvman.2023.117456

Nitrogen removal in improved subsurface wastewater infiltration system: Mechanism, microbial indicators and the limitation of phosphorus

J Environ Manage. 2023 Jun 1:335:117456. doi: 10.1016/j.jenvman.2023.117456. Epub 2023 Feb 21.

Authors

Liping Jia¹, Xuelin Cheng¹, Linchuan Fang², Xuguang Huang³

Affiliations

¹ College of Chemistry and Environmental Science, Minnan Normal University, Zhangzhou, 363000, China.
² CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China.
³ College of Chemistry and Environmental Science, Minnan Normal University, Zhangzhou, 363000, China. Electronic address: huangxuguang@mnnu.edu.cn.

PMID: 36822044
DOI: 10.1016/j.jenvman.2023.117456

Abstract

To enhance the nitrogen removal capacity, scrap iron filings and Si-Al porous clay mineral material (PCMW) was used to improve a subsurface wastewater infiltration system (SWIS). The results showed TN and NH₄⁺-N removal efficiencies of improved SWIS were 20.72% and 5.49% higher than those of the control SWIS, respectively. Based on the response of the removal performance, microbial community and function analysis of 16s rRNA amplicon sequencing results, the amending soil matrix substantially enriched the nitrogen removal bacteria (Rhizobiales_Incertae_Sedis and Gemmatimonadaceae), and significantly improved the activities of key enzymes (Hao, NasAB, NarGHI, NirK, NorBC, NirA and NirBD), particularly at co-occurrence zone of nitrification and denitrification (70-130 cm depth). The amending soil matrix not only extended the growth space of microbes, but also provided additional electrons and carbon sources for denitrifying bacteria by regulating the structure and function of the microbial community. In addition, amending soil matrix could enhance phosphate metabolism genes and phosphate solubilizing microbes in the denitrification zone by increasing the phosphorus source, thus strengthening nitrogen metabolism. Nitrospiraceae, Rhizobiales_Incertae_Sedis and Gemmatimonadaceae related to nitrogen removal and Bacillaceae with phosphate-solubilizing ability could be used as microbial indicators of nitrogen removal in SWISs. The reciprocal action of environmental on microbial characteristics exhibited microbial functional were related to DO, Fe²⁺, TOC, TP, TN, NH₄⁺-N and NO₃^--N. Those could be used as physicochemical and biological indicators for application and monitoring of SWIS. In conclusion, this study provided a low-cost and efficient enhancement approach for the application of SWIS in decentralized domestic sewage treatment, and furnished theoretical support for subsequent applications.

Keywords: Microbial indicators; Nitrogen removal; Phosphorus limitation; Subsurface wastewater infiltration system.

MeSH terms

Bacteria / metabolism
Bioreactors
Denitrification*
Nitrification
Nitrogen / chemistry
Phosphates
Phosphorus
RNA, Ribosomal, 16S
Sewage
Soil
Waste Disposal, Fluid
Wastewater*

Substances

Wastewater
Phosphorus
Nitrogen
RNA, Ribosomal, 16S
Phosphates
Soil
Sewage