Key Lab of Environmental Engineering (Shaanxi Province), School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No.13 Yanta Road, Xi'an, 710055, PR China; International S&T Cooperation Center for Urban Alternative Water Resources Development, Key Laboratory of Northwest Water Resource, Environment and Ecology (Ministry of Education), Xi'an University of Architecture and Technology, No.13 Yanta Road, Xi'an, 710055, PR China.
Key Lab of Environmental Engineering (Shaanxi Province), School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No.13 Yanta Road, Xi'an, 710055, PR China.
Environ Res. 2024 Jan 1;240(Pt 2):117429. doi: 10.1016/j.envres.2023.117429. Epub 2023 Oct 20.
Biochar-assisted anaerobic digestion (AD) has been proposed an advanced system for swine wastewater (SW) management. However, the effects of metallic nutrients in SW, such as copper/zinc ions (Cu/Zn), on the biochar-assisted AD of SW are not well understood. This study investigated the influences of individual Cu/Zn or dewatered swine manure-derived biochar, as well as their combined additions, on the AD of SW. The results showed that exposure to 50 mg/L Cu/Zn temporary inhibited methane production, but the addition of 20 g/L biochar alleviated this inhibition by shortening the methanogenic lag time and increasing methane yield. Following a period of acclimation, both Cu/Zn and biochar promoted methane production, although metagenomic analysis revealed distinct mechanisms underlying their promotion. Cu/Zn enhanced ATP processing, including electron exchange between NADH/NAD and succinate/fumarate transformation, by 26.0-35.8%. Additionally, the gene encoding Coenzyme M methylation was upregulated by 36.2% along with enrichments of Methanocullus and Methanosarcina, contributing to accelerated hydrolysis and methanogenesis rates by 54.7% and 44.8%, respectively. On the other hand, biochar mainly stimulated bacterial F-type ATPase activities by 28.4%, likely facilitating direct interspecies electron transfer between Geobacter and Methanosarcina for syntrophic methanogenesis. The combined addition of Cu/Zn and biochar resulted in "win-win" benefits, significantly increasing the maximum methane production rate from 40.3 mL CH/d to 53.7 mL CH/d. Moreover, the introduction of biochar into AD of SW facilitated the transformation of more Cu/Zn from a reducible Fe-Mn oxides form to a residual form, which potentially reduced the metallic toxicity of the digestate for soil amendment. The findings of this study provide novel insights into understanding the synergistic impacts of heavy metals and biochar in regulating SW during AD, as well as the management of associated digestate.
生物炭辅助厌氧消化（AD）已被提议作为一种先进的猪废水（SW）管理系统。然而，SW 中金属营养物（如铜/锌离子（Cu/Zn））对生物炭辅助 SW 的 AD 的影响尚不清楚。本研究调查了单独的 Cu/Zn 或脱水猪粪衍生生物炭，以及它们的组合添加对 SW 的 AD 的影响。结果表明，暴露于 50mg/L Cu/Zn 会暂时抑制甲烷生成，但添加 20g/L 生物炭通过缩短产甲烷滞后时间和增加甲烷产量来缓解这种抑制。经过一段时间的驯化，Cu/Zn 和生物炭都促进了甲烷生成，尽管宏基因组分析揭示了它们促进作用的不同机制。Cu/Zn 通过 26.0-35.8%增强了 ATP 处理，包括 NADH/NAD 之间的电子交换和琥珀酸/富马酸的转化。此外，编码辅酶 M 甲基化的基因上调了 36.2%，同时富集了 Methanocullus 和 Methanosarcina，分别将水解和产甲烷速率提高了 54.7%和 44.8%。另一方面，生物炭主要通过 28.4%刺激细菌 F 型 ATP 酶活性，可能促进 Geobacter 和 Methanosarcina 之间的直接种间电子转移，从而促进共营养产甲烷。Cu/Zn 和生物炭的联合添加产生了“双赢”的效果，从 40.3mLCH/d 显著提高了最大甲烷生成速率至 53.7mLCH/d。此外，在 AD 中引入生物炭促进了更多的 Cu/Zn 从可还原的 Fe-Mn 氧化物形式转化为残留形式，这可能降低了消化液用于土壤改良的金属毒性。本研究的结果为理解重金属和生物炭在 AD 过程中调节 SW 以及相关消化液的管理方面的协同影响提供了新的见解。
