Removal efficiency and mechanism of humic-acid-type dissolved organic nitrogen by biochar-pyrite composite bioretention facilities

JIAN Longyu; WANG Xinyue; LIU Junxi; CHEN Lei; MA Haiyuan; CHAI Hongxiang

doi:10.13205/j.hjgc.202609002

Volume 44 Issue 9

Sep. 2026

Turn off MathJax

Article Contents

Article Navigation > ENVIRONMENTAL ENGINEERING > 2026 > 44(9): 9-17

JIAN Longyu, WANG Xinyue, LIU Junxi, CHEN Lei, MA Haiyuan, CHAI Hongxiang. Removal efficiency and mechanism of humic-acid-type dissolved organic nitrogen by biochar-pyrite composite bioretention facilities[J]. ENVIRONMENTAL ENGINEERING , 2026, 44(9): 9-17. doi: 10.13205/j.hjgc.202609002

Citation:

JIAN Longyu, WANG Xinyue, LIU Junxi, CHEN Lei, MA Haiyuan, CHAI Hongxiang. Removal efficiency and mechanism of humic-acid-type dissolved organic nitrogen by biochar-pyrite composite bioretention facilities[J]. ENVIRONMENTAL ENGINEERING , 2026, 44(9): 9-17. doi: 10.13205/j.hjgc.202609002

Citation:

JIAN Longyu, WANG Xinyue, LIU Junxi, CHEN Lei, MA Haiyuan, CHAI Hongxiang. Removal efficiency and mechanism of humic-acid-type dissolved organic nitrogen by biochar-pyrite composite bioretention facilities[J]. ENVIRONMENTAL ENGINEERING , 2026, 44(9): 9-17. doi: 10.13205/j.hjgc.202609002

PDF( 1775 KB)

Removal efficiency and mechanism of humic-acid-type dissolved organic nitrogen by biochar-pyrite composite bioretention facilities

doi: 10.13205/j.hjgc.202609002

Key Laboratory of Ecology and Environment of the Three Gorges Reservoir Area, Ministry of Education, Chongqing University, Chongqing 400045, China

Received Date: 2025-10-15
Available Online: 2026-11-05

Abstract

Abstract

Conventional bioretention systems often exhibit poor removal efficiency for humic-acid-type dissolved organic nitrogen （DON）， and the underlying transformation mechanisms remain unclear. In this study， biochar-pyrite composite bioretention systems were constructed to evaluate their performance and mechanisms in removing humic-acid-type DON under alternating rainfall-dry conditions. The results showed that systems amended with pyrite and/or biochar significantly enhanced UV₂₅₄ and COD removal， achieving 55% to 66% and 32% to 50%， respectively. Total nitrogen （TN） and nitrate nitrogen （NO₃^--N） removal ranged from 43% to 57% and from 43% to 60%， respectively， with the biochar-pyrite system performing best. Dissolved oxygen （DO） and oxidation-reduction potential （ORP） in the effluent decreased markedly， indicating a shift to a reducing environment favorable for denitrification and organic nitrogen mineralization. During dry periods， pore-water UV₂₅₄ decreased and then stabilized， while COD initially declined and later rebounded， suggesting slow microbial decomposition of adsorbed humic substances into smaller bioavailable molecules. High-throughput sequencing revealed enrichment of taxa related to complex organic degradation and sulfur/iron cycling， such as Thiobacillus and Pseudomonas. Integrating physicochemical and microbial evidence， a synergistic removal pathway of biochar adsorption and slow release-microbial degradation-pyrite-driven sulfur-based autotrophic denitrification was proposed. The biochar-pyrite composite demonstrated stable and efficient removal of humic-acid-type DON under wet-dry cycles， providing guidance for optimizing stormwater bioretention systems.
- bioretention facility,
- biochar,
- pyrite,
- humic acid,
- dissolved organic nitrogen （DON）

FullText(HTML)

References(24)

References

[1]	LI L，DAVIS A P. Urban stormwater runoff nitrogen composition and fate in bioretention systems［J］. Environmental Science& Technology，2014，48（6）:3403-3410.
[2]	LUSK M G，TOOR G S，INGLETT P W. Organic nitrogen in residential stormwater runoff:implications for stormwater management in urban watersheds［J］. Science of the Total Environment，2020，707:135962.
[3]	DAVIS A P，HUNT W F，TRAVER R G，et al. Bioretention technology:overview of current practice and future needs［J］. Journal of Environmental Engineering，2009，135（3）:109-117.
[4]	MORSE N，PAYNE E，HENRY R，et al. Plant-microbe interactions drive denitrification rates，dissolved nitrogen removal，and the abundance of denitrification genes in stormwater control measures［J］. Environmental Science& Technology，2018，52（16）:9320-9329.
[5]	MORSE N R，MCPHILLIPS L E，SHAPLEIGH J P，et al. The role of denitrification in stormwater detention basin treatment of nitrogen［J］. Environmental Science& Technology，2017，51（14）:7928-7935.
[6]	YOU Z，ZHANG L，PAN S Y，et al. Performance evaluation of modified bioretention systems with alkaline solid wastes for enhanced nutrient removal from stormwater runoff［J］. Water Research，2019，161:61-73.
[7]	LI R，WEI D，WANG W，et al. Pyrrhotite-sulfur autotrophic denitrification for deep and efficient nitrate and phosphate removal:synergistic effects，secondary minerals and microbial community shifts［J］. Bioresource Technology，2020，308:123302.
[8]	ZHANG Y，WEI D，MORRISON L，et al. Nutrient removal through pyrrhotite autotrophic denitrification:implications for eutrophication control［J］. Science of the Total Environment，2019，662:287-296.
[9]	CHEN Y，SHAO Z，KONG Z，et al. Study of pyrite based autotrophic denitrification system for low-carbon source stormwater treatment［J］. Journal of Water Process Engineering，2020，37:101414.
[10]	KLÜPFEL L，KEILUWEIT M，KLEBER M，et al. Redox properties of plant biomass-derived black carbon（biochar）［J］. Environmental Science& Technology，2014，48（10）:5601-5611.
[11]	SAQUING J M，YU Y H，CHIU P C. Wood-derived black carbon（biochar）as a microbial electron donor and acceptor［J］. Environmental Science& Technology Letters，2016，3（2）:62-66.
[12]	BISWAL B K，VIJAYARAGHAVAN K，TSEN-TIENG D L，et al. Biochar-based bioretention systems for removal of chemical and microbial pollutants from stormwater:a critical review［J］. Journal of Hazardous Materials，2022，422:126886.
[13]	TIAN J，JIN J，CHIU P C，et al. A pilot-scale，bi-layer bioretention system with biochar and zero-valent iron for enhanced nitrate removal from stormwater［J］. Water Research，2019，148:378-387.
[14]	JIA Y，ZHANG H，GU T，et al. Denitrification in bioretention systems based on corncob biochar produced at low pyrolysis temperature:the efficacy and the mechanisms［J］. Chemical Engineering Journal，2023，460:141829.
[15]	TAYLOR G D，FLETCHER T D，WONG T H F，et al. Nitrogen composition in urban runoff—implications for stormwater management［J］. Water Research，2005，39（10）:1982-1989.
[16]	MOHTADI M，JAMES B R，DAVIS A P. Adsorption of compounds that mimic urban stormwater dissolved organic nitrogen［J］. Water Environment Research，2017，89（2）:105-116.
[17]	INSELSBACHER E，OYEWOLE O A，NÄSHOLM T. Early season dynamics of soil nitrogen fluxes in fertilized and unfertilized boreal forests［J］. Soil Biology and Biochemistry，2014，74:167-176.
[18]	KONG Z，MA H，SONG Y，et al. A long term study elucidates the relationship between media amendment and pollutant treatment in the stormwater bioretention system:stability or efficiency?［J］. Water Research，2022，225:119124.
[19]	KONG Z，SHAO Z，SHEN Y，et al. Comprehensive evaluation of stormwater pollutants characteristics，purification process and environmental impact after low impact development practices［J］. Journal of Cleaner Production，2021，278:123509.
[20]	State Environmental Protection Administration of China. Monitoring and analysis methods for water and wastewater［M］. 4th ed.（supplemented edition）. Beijing:China Environment Press，2002. 国家环境保护总局. 水和废水监测分析方法［M］. 4版增补版. 北京:中国环境出版社，2002
[21]	DAI T，WEN D，BATES C T，et al. Nutrient supply controls the linkage between species abundance and ecological interactions in marine bacterial communities［J］. Nature Communications，2022，13（1）:175.
[22]	KONG Z，SHAO Z，CHEN Y，et al. Biochar-pyrite bi-layer bioretention system for dissolved nutrient treatment and by-product generation control under various stormwater conditions［J］. Water Research，2021，206:117737.
[23]	ZHOU X，WANG M，LIU J，et al. Simultaneous enhancement of nitrogen removal and nitrous oxide reduction by a saturated biochar-based intermittent aeration vertical flow constructed wetland:effects of influent strength［J］. Chemical Engineering Journal，2018，334:1842-1850.
[24]	RYU J，LEE S，PARK J，et al. Humic acid removal and microbial community function in membrane bioreactor［J］. Journal of Hazardous Materials，2021，417:126088.