Unraveling the capability of graphene nanosheets and γ-Fe2O3 nanoparticles to stimulate anammox granular sludge
Unraveling the capability of graphene nanosheets and γ-Fe2O3 nanoparticles to stimulate anammox granular sludge
复制标题
DOI：
10.1016/j.jenvman.2020.111495
复制
发表时间：
2021-01-01
影响因子：
8.7
通讯作者：
Elsamadony, Mohamed
中科院分区：
文献类型：
--
作者：
Elreedy, Ahmed;Ismail, Sherif;Elsamadony, Mohamed
在这项研究中，我们研究了纳米材料在厌氧氨氧化（anammox）过程中的潜力，包括氮的去除、微生物的富集和关键酶的活性。选择石墨烯纳米片（GNs）和γ - fe2o3纳米颗粒（NPs）分别是因为它们作为导电材料和电子穿梭体的催化功能。结果表明，在最佳投加量（10 mg/L）条件下，污泥的氮去除率比对照提高了46 +/- 3.1%，NH4+-N和NO2——N去除率分别达到86.5 +/- 2.7%和97.1 +/- 0.5%。添加10 mg/L GNs后，肼脱氢酶（HDH）活性提高1.1倍。GNs的存在通过增强细胞外聚合物质（EPS）的疏水相互作用促进厌氧氨氧化造粒。对于γ - fe2o3纳米粒子的使用，100 mg/L的剂量使NRR增加55 +/- 3.8%；然而，未观察到对HDH酶活性和EPS组成的影响。考虑到γ - fe2o3 NPs的非生物使用进一步提高了吸附效率（接近92%），我们得出结论，观察到的促进作用主要是由γ - fe2o3 NPs引起的。此外，16S rRNA分析显示，当使用10 mg/L γ - fe2o3 NPs时，C. Jettenia属（厌氧氨氧化相关细菌）的相对丰度从11.9%增加到12.3%，而当使用100 mg/L γ - fe2o3 NPs时，其相对丰度下降到8.3%。最终，纳米材料可以促进厌氧氨氧化过程的效率，这种促进和相关机制取决于它们的剂量和组成。
In this study, we investigated the potentials of nanomaterials to enhance anaerobic ammonium oxidation (anammox) process, in terms of nitrogen removal, microbial enrichment, and activity of key enzymes. Graphene nanosheets (GNs) and gamma-Fe2O3 nanoparticles (NPs) were selected due to their catalytic functions as conductive material and electron shuttles, respectively. The obtained results revealed that the optimum dosage of GNs (10 mg/L) boosted the nitrogen removal rate (NRR) by 46 +/- 3.1% compared to the control, with maximum NH4+-N and NO2--N removal of 86.5 +/- 2.7% and 97.1 +/- 0.5%, respectively. Moreover, hydrazine dehydrogenase (HDH) enzyme activity was augmented by 1.1-fold when using 10 mg/L GNs. The presence of GNs promoted the anammox granulation via enhancement of hydrophobic interaction of extracellular polymeric substances (EPS). Regarding the use of gamma-Fe2O3 NPs, 100 mg/L dose increased NRR by 55 +/- 3.8%; however, no contribution to HDH enzyme activity and a decrease in EPS compositions were observed. Given that the abiotic use of gamma-Fe2O3 NPs further resulted in high adsorption efficiency (similar to 92%), we conclude that the observed promotion due to gamma-Fe2O3 NPs was mainly abiotic. Moreover, the 16S rRNA analysis revealed that the relative abundance of genus C. Jettenia (anammox related bacteria) increased from 11.9% to 12.3% when using 10 mg/L GNs, while declined to 8.3% at 100 mg/L gamma-Fe2O3 NPs. Eventually, nanomaterials could stimulate the efficiency of anammox process, and this promotion and associated mechanism depend on their dose and composition.