Wang Yanqiong, Wang Hongwu, Jin Hui, Chen Hongbin
State Key Laboratory of Pollution Control and Resource Reuse, National Engineering Research Center for Urban Pollution Control, College of Environmental Science and Engineering, Tongji University, Shanghai, China.
Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China.
Front Microbiol. 2022 Aug 24;13:980396. doi: 10.3389/fmicb.2022.980396. eCollection 2022.
HA, as one of low-carbon pre-treatment technology could be enhanced by packing of iron or iron oxide powder for enhancing the transformation of large molecular weight to generate volatile fatty acids (VFAs) for fuel production. However, the controversy of iron strengthening the HA and inherent drawbacks of iron oxide, such as poor mass transfer, and difficult recovery, limit this pretreatment technology. Clean and rusty iron scraps were packed into an HA system to address these issues while focusing on the system performance and the response of core bacterial and fungal microbiomes to iron scrap exposure. Results showed that clean and rusty iron scraps can significantly improve the HA performance while considering hydrolysis efficiency (HE), acidification efficiency (AE) and VFAs production, given that VFAs ratios (C: C: C) were changed from the 14:5:1 to 14:2:1 and 29:4:1, respectively, and the obtained VFAs ratios in iron scraps addition systems were more closely to the optimal VFAs ratio for lipids production. Redundant and molecular ecological network analyses indicated that iron scraps promote the system stability and acidogenesis capacity by boosting the complexity of microbes' networks and enriching core functional microbes that show a positive response to HA performance, among which the relative abundance of related bacterial genera was promoted by 19.71 and 17.25% for R and R systems. Moreover, except for the differences between the control and iron scraps addition systems, the findings confirmed that the R system is slightly different from the R one, which was perhaps driven by the behavior of 6.20% of DIRB in R system and only 1.16% of homoacetogens in R system when considering the microbial community and fate of iron scraps. Totally, the observed results highlight the application potential of the iron scrap-coupled HA process for the generation of VFAs and provide new insights into the response of different iron scraps in microbes communities.
作为一种低碳预处理技术，水解酸化（HA）可通过填充铁或氧化铁粉末来增强，以促进大分子量物质的转化，从而生成挥发性脂肪酸（VFAs）用于燃料生产。然而，铁强化HA存在争议，且氧化铁存在诸如传质差和回收困难等固有缺点，限制了这种预处理技术的应用。将干净的和生锈的铁屑填充到HA系统中，以解决这些问题，同时关注系统性能以及核心细菌和真菌微生物群落对铁屑暴露的反应。结果表明，考虑到水解效率（HE）、酸化效率（AE）和VFAs产量，干净的和生锈的铁屑均可显著提高HA性能，因为VFAs比例（C₂:C₃:C₄）分别从14:5:1变为14:2:1和29:4:1，并且在添加铁屑的系统中获得的VFAs比例更接近脂质生产的最佳VFAs比例。冗余分析和分子生态网络分析表明，铁屑通过提高微生物网络的复杂性和富集对HA性能有积极反应的核心功能微生物，促进了系统稳定性和产酸能力，其中相关细菌属的相对丰度在R和R'系统中分别提高了19.71%和17.25%。此外，除了对照系统和添加铁屑系统之间的差异外，研究结果证实R系统与R'系统略有不同，考虑到微生物群落和铁屑的归宿，这可能是由R系统中6.20%的异化铁还原菌（DIRB）和R'系统中仅1.16%的同型产乙酸菌的行为所驱动。总的来说，观察结果突出了铁屑耦合HA工艺在生成VFAs方面的应用潜力，并为不同铁屑在微生物群落中的反应提供了新的见解。
