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| Enhancing nitrogen removal in periphyton systems via enzymatic hydrolysis of agricultural waste as carbon source |
| Received:February 18, 2025 |
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| KeyWord:periphyton;agricultural waste;carbon source;denitrification;extracellular polymeric substances（EPS）;microbial community composition |
| Author Name | Affiliation | E-mail | | SUN Yuting | Zigui Ecological Station for Three Gorges Dam Project, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China
University of Chinese Academy of Sciences, Nanjing 211135, China | | | SUN Rui | Zigui Ecological Station for Three Gorges Dam Project, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China
School of Geography and Planning, Huaiyin Normal University, Huaiyin 223300, China | 8202011042@hytc.edu.cn | | WU Yonghong | Zigui Ecological Station for Three Gorges Dam Project, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China
University of Chinese Academy of Sciences, Nanjing 211135, China | |
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| Abstract: |
| In this study, hydrolysates derived from alkali- and acid-pretreated agricultural wastes were employed as alternative carbon sources, and their enhancing effects on the nitrogen removal performance of periphyton systems were systematically assessed via batch denitrification assays. Moreover, the regulatory mechanisms underlying the impacts of exogenous carbon sources on periphyton biomass accumulation and microbial community assembly were elucidated by means of biomass quantification, extracellular polymeric substances （EPS）component characterization, and high-throughput 16S rRNA gene sequencing. The results demonstrated that alkali-pretreated corn cob hydrolysate（YMX）markedly elevated the removal efficiencies of total nitrogen（TN）, ammonium nitrogen（NH+4-N）and nitrate nitrogen（NO-3-N）in the periphyton system, with the respective removal rates reaching 84.4%, 100% and 67.5%. This superior performance was attributed to its high chemical oxygen demand（COD）level [ （23.134±0.704）g·L-1] and the characteristic of sustained carbohydrate release（74% of total soluble organics）, which induced the selective enrichment of Pseudomonadota（42.1% relative abundance）, a phylum harboring complete denitrification gene clusters（nirK/nirS, norB/nosZ）. In contrast, acid-pretreated corn stover enzymatic hydrolysate（JG）exhibited a relatively low COD release capacity（ΔCOD=6.408 g·L-1）, yet it attained a NO-3-N removal rate of 70.5%, which was comparable to that of the YMX group（67.0%）. This was realized through a synergistic metabolic pathway of phototrophic carbon supply and heterotrophic denitrification, mediated by the functional microbial consortium of Cyanobacteria（55.8% relative abundance）and Lysobacter（6.4% relative abundance）. Additionally, exogenous carbon input drove microbial community reconfiguration in the periphyton system by remodeling the compositional profile of EPS. In the YMX group, the EPS polysaccharide content was increased by 16.0%, which strengthened the mechanical stability of the periphyton biofilm and thereby facilitated the metabolic activity of heterotrophic denitrifiers. In the JG group, the EPS protein content was elevated by 26.5%, which mitigated the toxic effects of phenolic inhibitors generated during acid pretreatment through specific adsorption. |
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