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Du X, Hong M, Yang Y, Li J, Su Y, Liu N. Removal mechanisms of aqueous Cr(VI) by anaerobic fermentation sludge. ENVIRONMENTAL TECHNOLOGY 2023; 44:3975-3987. [PMID: 35549986 DOI: 10.1080/09593330.2022.2077136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
After fermentation, activated sludge contains many acid-producing bacteria and their metabolites, which have a good reducing effect. Various active groups (e.g., hydroxyl, amino, carboxyl, and phosphate) on microbial cell surfaces can adsorb heavy metals through complexation or chelation, forming heavy metal precipitates and thereby reducing the toxicity of heavy metals. However, the effects and mechanisms of using sludge after anaerobic fermentation to remove Cr(VI) are unclear, such as the dominance of direct versus indirect biological reduction, the contribution of abiotic effects, and the influence of fermentation conditions. This paper compares Cr(VI) removal in fermented and unfermented sludges. After fermentation for 24 h, 99.9% of the Cr(VI) (50 mg/L) in anaerobic sludge was removed within 7 h, which was twice the rate in unfermented activated sludge. A series of comparative experiments demonstrated that Cr(VI) removal primarily occurred through biological effects (about 92%), which included biological reduction and biosorption. 16SrRNA gene sequencing revealed that Cr(VI) transformation primarily occurred through direct biological reduction, with the related genera being Trichococcus, Acetobacter, Aeromonas, and Tolumonas. Fourier-transform infrared (FTIR) spectroscopy results showed that the C = O and C-O functionalities on sludge were likely involved in the Cr(VI) conversion. Majority of the Cr(VI) in the system was reduced to Cr(III) and existed in the suspension, with a small amount deposited on the sludge surface. The X-ray photoelectron spectroscopy (XPS) results indicated that the majority of Cr was present as reduced Cr(III) on the sludge. These results demonstrate that after fermentation in an aqueous environment, activated sludge is an effective medium for the remediation of Cr(VI). These results are useful for designing a green and sustainable bioreduction system for the remediation of Cr(VI)-polluted water.
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Affiliation(s)
- Xiaoyan Du
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, College of Environment and Resources, Jilin University, Changchun, People's Republic of China
| | - Mei Hong
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, College of Environment and Resources, Jilin University, Changchun, People's Republic of China
| | - Yadong Yang
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, College of Environment and Resources, Jilin University, Changchun, People's Republic of China
| | - Jing Li
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, College of Environment and Resources, Jilin University, Changchun, People's Republic of China
| | - Yaoming Su
- South China Institute of Environmental Sciences, MEP, People's Republic of China
| | - Na Liu
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, College of Environment and Resources, Jilin University, Changchun, People's Republic of China
- Institute of Groundwater and Earth Science, Jinan University, Guangzhou City, People's Republic of China
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Xu R, Wang YN, Sun Y, Wang H, Gao Y, Li S, Guo L, Gao L. External sodium acetate improved Cr(VI) stabilization in a Cr-spiked soil during chemical-microbial reduction processes: Insights into Cr(VI) reduction performance, microbial community and metabolic functions. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 251:114566. [PMID: 36680991 DOI: 10.1016/j.ecoenv.2023.114566] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 01/11/2023] [Accepted: 01/18/2023] [Indexed: 06/17/2023]
Abstract
Interest combined chemical and microbial reduction for Cr(VI) remediation in contaminated sites has greatly increased. However, the effect of external carbon sources on Cr(VI) reduction during chemical-microbial reduction processes has not been studied. Therefore, in this study, the role of external sodium acetate (SA) in improving Cr(VI) reduction and stabilization in a representative Cr(VI)-spiked soils was systemically investigated. The results of batch experiments suggested that the soil Cr(VI) content declined from 1000 mg/kg to 2.6-5.1 mg/kg at 1-5 g C/kg SA supplemented within 15 days of reaction. The external addition of SA resulted in a significant increase in the relative abundances of Cr(VI)-reducing microorganisms, such as Tissierella, Proteiniclasticum and Proteiniclasticum. The relative abundance of Tissierella increased from 9.1% to 29.8% with the SA treatment at 5 g C/kg soil, which was the main contributors to microbial Cr(VI) reduction. Redundancy analysis indicated that pH and SA were the predominant factors affecting the microbial community in the SA treatments at 2 g C/kg soil and 5 g C/kg soil. Functional prediction suggested that the addition of SA had a positive effect on the metabolism of key substances involved in Cr(VI) microbial reduction. This work provides new insightful guidance on Cr(VI) remediation in contaminated soils.
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Affiliation(s)
- Rong Xu
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, China
| | - Ya-Nan Wang
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, China
| | - Yingjie Sun
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, China
| | - Huawei Wang
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, China.
| | - Ying Gao
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, China
| | - Shupeng Li
- Beijing Construction Engineering Environmental Remediation Co., Ltd., National Engineering Laboratory for Safety Remediation of Contaminated Sites, Beijing 100015, China
| | - Lili Guo
- Beijing Construction Engineering Environmental Remediation Co., Ltd., National Engineering Laboratory for Safety Remediation of Contaminated Sites, Beijing 100015, China
| | - Lei Gao
- School of Marine Sciences and Engineering, Nanjing Normal University, Nanjing, China.
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Tumolo M, Volpe A, Leone N, Cotugno P, De Paola D, Losacco D, Locaputo V, de Pinto MC, Uricchio VF, Ancona V. Enhanced Natural Attenuation of Groundwater Cr(VI) Pollution Using Electron Donors: Yeast Extract vs. Polyhydroxybutyrate. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19159622. [PMID: 35954976 PMCID: PMC9367865 DOI: 10.3390/ijerph19159622] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 02/08/2023]
Abstract
Remediation interventions based on the native bacteria’s capability to reduce Cr(VI) represent a valid strategy in terms of economic and environmental sustainability. In this study, a bioremediation test was carried out using viable microcosms set with groundwater and deep soil (4:1), collected from the saturated zone of an industrial site in Southern Italy that was polluted by ~130 µg L−1 of Cr(VI). Conditions simulating the potential natural attenuation were compared to the enhanced natural attenuation induced by supplying yeast extract or polyhydroxybutyrate. Sterile controls were set up to study the possible Cr(VI) abiotic reduction. No pollution attenuation was detected in the unamended viable reactors, whereas yeast extract provided the complete Cr(VI) removal in 7 days, and polyhydroxybutyrate allowed ~70% pollutant removal after 21 days. The incomplete abiotic removal of Cr(VI) was observed in sterile reactors amended with yeast extract, thus suggesting the essential role of native bacteria in Cr(VI) remediation. This was in accordance with the results of Pearson’s coefficient test, which revealed that Cr(VI) removal was positively correlated with microbial proliferation (n = 0.724), and also negatively correlated with pH (n = −0.646), dissolved oxygen (n = −0.828) and nitrate (n = −0.940). The relationships between the Cr(VI) removal and other monitored parameters were investigated by principal component analysis, which explained 76.71% of the total variance.
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Affiliation(s)
- Marina Tumolo
- Water Research Institute, Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy
- Department of Biology, University of Bari, 70126 Bari, BA, Italy
- Correspondence: (M.T.); (V.A.)
| | - Angela Volpe
- Water Research Institute, Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy
| | - Natalia Leone
- Water Research Institute, Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy
| | - Pietro Cotugno
- Department of Chemistry, University of Bari, 70126 Bari, BA, Italy
| | - Domenico De Paola
- Institute of Biosciences and Bioresources, Italian National Research Council (IBBR-CNR), 70126 Bari, BA, Italy
| | - Daniela Losacco
- Water Research Institute, Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy
- Department of Biology, University of Bari, 70126 Bari, BA, Italy
| | - Vito Locaputo
- Water Research Institute, Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy
| | | | - Vito Felice Uricchio
- Water Research Institute, Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy
| | - Valeria Ancona
- Water Research Institute, Italian National Research Council (IRSA-CNR), 70132 Bari, BA, Italy
- Correspondence: (M.T.); (V.A.)
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