Author(s)

JingXian Zheng¹, Dan Meng^1,2, YangWu Chen^1*

Affiliation(s)

¹CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology,Chinese Academy of Sciences, Chengdu 610041, China.

²Environmental Science and Engineering, Southwest Jiaotong University, Chengdu 611756, China.

Corresponding Author

YangWu Chen

ABSTRACT

Free Nitrous Acid (FNA) Pretreatment Enhances Organic Matter Hydrolysis in the Digestion Stage, but Its Impact on the Dynamics of Antibiotic Resistance Genes (ARGs) During Aerobic Digestion of Residual Sludge Remains Unexplored.This study employed an orthogonal experimental design to assess the dynamics of ARGs in the aerobic digestion of residual sludge under varying FNA pretreatment sludge ratios, temperatures, and pH levels. The aim was to identify the optimal conditions for ARG reduction and elucidate the underlying mechanisms. Results indicated that the optimal conditions for ARG reduction were a residual sludge to FNA-pretreated sludge ratio of 2:1, a temperature of 45°C, and pH = 10, yielding reductions of 84.13% and 76.03%, respectively. Range analysis revealed that the key environmental factors influencing ARG reduction were pH > temperature > sludge ratio. Under high-temperature and alkaline conditions, concentrations of ammonia nitrogen (NH₃), soluble extracellular polymeric substances (S-EPS), and soluble chemical oxygen demand (SCOD) increased, suggesting that these conditions facilitate cell lysis, thereby promoting ARG reduction. Microbial community analysis showed that the relative abundance of potential ARG-hosting bacteria (e.g., Saccharimonadales, Caldilineaceae, SC-I-84, Ellin6067, unclassified_Blastocatellaceae, Nitrospira, Gemmatimonadaceae, and OLB12) decreased in parallel with ARG reduction, indicating that the high-temperature, alkaline aerobic digestion environment may mitigate ARG dissemination by inhibiting the proliferation of potential host bacteria.

KEYWORDS

Free Nitrous Acid (FNA) pretreatment; Aerobic digestion; High temperature; Strong alkaline conditions; Antibiotic Resistance Genes (ARGs); Microbial community structure

CITE THIS PAPER

JingXian Zheng, Dan Meng, YangWu Chen. The effect of free nitrous acid pretreatment and aerobic digestion on the dynamics of antibiotic resistance genes in residual sludge. Eurasia Journal of Science and Technology. 2024, 6(7): 47-55. DOI: https://doi.org/10.61784/ejst3055.

REFERENCES

[1] I, Ahmed, Y, Zhang, P, Sun, et al. Co-occurrence pattern of ARGs and N-functional genes in the aerobic composting system with initial elevated temperature. J. Environ. Manage., 2023, 343, 118073. DOI: 10.1016/j.jenvman.2023.118073.

[2] H M, Jang, J W, Lee, Y B, Kim, et al. Fate of antibiotic resistance genes and metal resistance genes during thermophilic aerobic digestion of sewage sludge. Bioresour. Technol., 2018, 249, 635-643. DOI: 10.1016/j.biortech.2017.10.073.

[3] Q, Wang, Z, Yuan. Enhancing aerobic digestion of full-scale waste activated sludge using free nitrous acid pre-treatment. RSC Adv., 2015, 5(25): 19128-19134. DOI: 10.1039/C4RA17215A.

[4] S, Liu, X, Yang, X, Yao. Impacts of ammonia nitrogen on autothermal thermophilic micro-aerobic digestion for sewage sludge treatment. Chemosphere, 2018, 213, 268-275. DOI: 10.1016/j.chemosphere.2018.09.037.

[5] X S, Wu, Y Y, Hu, J H, Cheng, et al. The Efficiency of Thermal-Alkaline Hydrolysis-Conventional Aerobic Digestion Process of Excess Sludge and the Change of Antibiotic Resistance Genes. Journal of South China Normal University (Natural Science Edition). 2019, 51(3): 36-46. DOI: https://journal-n.scnu.edu.cn/article/doi/10.6054/j.jscnun.2019043.

[6] J, Hao, B Li, J, Tan, et al. Double Advantages of Nutrients and Biostimulants Derived from Sewage Sludge by Alkaline Thermal Hydrolysis Process for Agricultural Use: Quality Promotion of Soil and Crop. Adv. Sci., 2024, 11(13): 2307793. DOI: 10.1002/advs.202307793.

[7] H, Duan, L, Ye, X, Lu, et al. Self-Sustained Nitrite Accumulation at Low pH Greatly Enhances Volatile Solids Destruction and Nitrogen Removal in Aerobic Sludge Digestion. Environ. Sci. Technol., 2019, 53(3): 1225-1234. DOI: 10.1021/acs.est.8b04498.

[8] P, Zhu, Y, Wu, Y, Ru, et al. Industrial-scale aerobic composting of livestock manures with the addition of biochar: Variation of bacterial community and antibiotic resistance genes caused by various composting stages. Environ. Pollut., 2022, 314, 120270. DOI: 10.1016/j.envpol.2022.120270.

[9] G, Sheng, H, Yu, X, Li. Extracellular polymeric substances (EPS) of microbial aggregates in biological wastewater treatment systems: A review. Biotechnol. Adv., 2010, 28(6): 882-894. DOI: 10.1016/j.biotechadv.2010.08.001.

[10] S, Li, G, Duan, Y, Xi, et al. Insights into the role of extracellular polymeric substances (EPS) in the spread of antibiotic resistance genes. Environ. Pollut., 2024, 343, 123285. DOI: 10.1016/j.envpol.2023.123285.

[11] H M, Jang, J H, Ha, J M, et al. Comprehensive microbial analysis of combined mesophilic anaerobic–thermophilic aerobic process treating high-strength food wastewater. Water Res., 2015, 73, 291-303. DOI: 10.1016/j.watres.2015.01.038.

[12] E, Stegmann, H J, Frasch, R, Kilian, et al. Self-resistance mechanisms of actinomycetes producing lipid II-targeting antibiotics,” Int. J. Med. Microbiol. IJMM, 2015, 305(2): 190-195. DOI: 10.1016/j.ijmm.2014.12.015.

[13] Q, He, Q, Zhang, M, Li, et al. Harnessing diurnal dynamics: Understanding the influence of light–dark cycle on algal-bacterial symbiotic system under aniline stress. Bioresour. Technol., 2025, 416, 131796. DOI: 10.1016/j.biortech.2024.131796.

[14] J Q, Su, B, Wei, W Y, Yang, et al. Antibiotic resistome and its association with bacterial communities during sewage sludge composting. Environ. Sci. Technol., 2015, 49(12): 7356-7363. DOI: 10.1021/acs.est.5b01012.

[15] W, Sun, X, Qian, J, Gu, et al. Mechanism and Effect of Temperature on Variations in Antibiotic Resistance Genes during Anaerobic Digestion of Dairy Manure. Sci. Rep., 2016, 6, 30237. DOI: 10.1038/srep30237.

[16] M M H, Ellabaan, C, Munck, A, Porse, et al. Forecasting the dissemination of antibiotic resistance genes across bacterial genomes. Nat. Commun., 20201, 12(1): 2435. DOI: 10.1038/s41467-021-22757-1.