1
|
Dubey P, Farooqui A, Patel A, Srivastava PK. Microbial innovations in chromium remediation: mechanistic insights and diverse applications. World J Microbiol Biotechnol 2024; 40:151. [PMID: 38553582 DOI: 10.1007/s11274-024-03936-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 02/21/2024] [Indexed: 04/02/2024]
Abstract
The ubiquity of hexavalent chromium (Cr(VI)) from industrial activities poses a critical environmental threat due to its persistence, toxicity and mutagenic potential. Traditional physico-chemical methods for its removal often entail significant environmental drawbacks. Recent advancements in remediation strategies have emphasized nano and bioremediation techniques as promising avenues for cost-effective and efficient Cr(VI) mitigation. Bioremediation harnesses the capabilities of biological agents like microorganisms, and algae to mitigate heavy metal contamination, while nano-remediation employs nanoparticles for adsorption purposes. Various microorganisms, including E. coli, Byssochlamys sp., Pannonibacter phragmitetus, Bacillus, Aspergillus, Trichoderma, Fusarium, and Chlorella utilize bioreduction, biotransformation, biosorption and bioaccumulation mechanisms to convert Cr(VI) to Cr(III). Their adaptability to different environments and integration with nanomaterials enhance microbial activity, offering eco-friendly solutions. The study provides a brief overview of metabolic pathways involved in Cr(VI) bioreduction facilitated by diverse microbial species. Nitroreductase and chromate reductase enzymes play key roles in nitrogen and chromium removal, with nitroreductase requiring nitrate and NADPH/NADH, while the chromium reductase pathway relies solely on NADPH/NADH. This review investigates the various anthropogenic activities contributing to Cr(VI) emissions and evaluates the efficacy of conventional, nano-remediation, and bioremediation approaches in curbing Cr(VI) concentrations. Additionally, it scrutinizes the mechanisms underlying nano-remediation techniques for a deeper understanding of the remediation process. It identifies research gaps and offers insights into future directions aimed at enhancing the real-time applicability of bioremediation methods for mitigating with Cr(VI) pollution and pave the way for sustainable remediation solutions.
Collapse
Affiliation(s)
- Priya Dubey
- Department of Biosciences, Integral University, Lucknow, India
- Environmental Technologies, CSIR-National Botanical Research Institute, Lucknow, India
| | - Alvina Farooqui
- Department of Biosciences, Integral University, Lucknow, India.
| | - Anju Patel
- Environmental Technologies, CSIR-National Botanical Research Institute, Lucknow, India.
| | | |
Collapse
|
2
|
Gu T, Niu W, Huo L, Zhou L, Jia Y, Li R, Wu Y, Zhong H. Molasses-based in situ bio-sequestration of Cr(VI) in groundwater under flow condition. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 344:123337. [PMID: 38266698 DOI: 10.1016/j.envpol.2024.123337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/08/2024] [Accepted: 01/08/2024] [Indexed: 01/26/2024]
Abstract
The in situ biosequestration of Cr(VI) in groundwater with molasses as the carbon source was studied based on column experiments and model simulation in this study. Compared with biological reduction, molasses-based chemical reduction did not cause significant Cr(VI) removal at molasses concentration as high as 1.14 g L-1. The molasses at a concentration as low as 0.57 g L-1 could support biofilm-based Cr(VI) sequestration under flow conditions and showed better sequestration performances than D-glucose and emulsified vegetable oil (8 g L-1). The existence of molasses (1.14 g L-1) decreased the pH of the effluent from 7.5 to 6.3 and the oxidation-reduction potential from 275 mV to 220 mV in the groundwater, which was responsible for reduction and thus the sequestration of Cr(VI). Advection-dispersion-reaction model well described the process of the Cr(VI) transport with biosequestration in the column (R2 ≥ 0.96). Owing to the Cr(VI) toxicity to the biofilms, the removal ratio decreased by 24% with a rise of Cr(VI) concentration from 8.6 to 43 mg L-1. The prolongation of hydraulic retention time could promote the performance of Cr(VI) biosequestration. The chemical form of Cr deposited as the product of bio-reduction was confirmed as Cr(OH)3·H2O and other complexes of Cr(III). Our work demonstrated the efficacy of molasses for in situ sequestration of Cr(VI) under the dynamic flow condition and provide some useful information for Cr-contaminated groundwater remediation.
Collapse
Affiliation(s)
- Tianyuan Gu
- State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
| | - Wenjing Niu
- Environmental Science and Technology Information Service Center, Zhoukou 466000, China
| | - Lili Huo
- State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
| | - Lian Zhou
- Ningbo Institute of Digital Twin, Eastern Institute of Technology, Ningbo 315200, China
| | - Yufei Jia
- State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
| | - Rongfu Li
- Institute of Microbiology, Jiangxi Academy of Sciences, Nanchang 330012, China
| | - Yongming Wu
- Institute of Microbiology, Jiangxi Academy of Sciences, Nanchang 330012, China
| | - Hua Zhong
- State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China; Ningbo Institute of Digital Twin, Eastern Institute of Technology, Ningbo 315200, China.
| |
Collapse
|
3
|
Akhzari F, Naseri T, Mousavi SM, Khosravi-Darani K. A sustainable solution for alleviating hexavalent chromium from water streams using Lactococcus lactis AM99 as a novel Cr(VI)-reducing bacterium. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 353:120190. [PMID: 38306859 DOI: 10.1016/j.jenvman.2024.120190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 01/03/2024] [Accepted: 01/20/2024] [Indexed: 02/04/2024]
Abstract
Chromium, extensively used in various industries, poses significant challenges due to its environmental impact. The threat of Cr(VI) causes critical concerns in aquatic ecosystems as a consequence of the fluidity of water. The conventional approach for the treatment of effluents containing Cr(VI) is reducing Cr(VI) to low-noxious Cr(III). This research is related to a Gram positive bacterium newly isolated from tannery effluent under aerobic conditions. To characterize functional groups on the isolate, Fourier transform infrared spectroscopy was utilized. The effect of different factors on Cr(VI) bioreduction was investigated, including temperature, initial Cr(VI) concentration, acetate concentration, and Tween 80 surfactant. Under optimal conditions (37 °C and 0.90 g/L sodium acetate), the bioreduction rate of the isolate, identified as Lactococcus lactis AM99, achieved 88.0 % at 300 mg/L Cr(VI) during 72 h (p < 0.05). It was observed that Cr(VI) bioreduction was enhanced by the acetate in both the quantity and intensity, while Tween 80 had no impact on the reaction. The strain AM99 exhibited remarkable characteristics, notably a marginal decrease in growth at elevated concentrations of hexavalent chromium and an exceptional potential to reduce Cr(VI) even at very low biomass levels, surpassing any prior findings in the associated research. Furthermore, The isolate could tolerate 1400 mg/L Cr(VI) in a solid medium. These distinctive features make the isolate a promising and well-suited candidate for remediating Cr(VI)-polluted environments. Additionally, the impact of biogenic extracellular polymer produced by the strain AM99 on reduction was examined at different temperatures.
Collapse
Affiliation(s)
- Farid Akhzari
- Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran
| | - Tannaz Naseri
- Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran
| | - Seyyed Mohammad Mousavi
- Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran; Modares Environmental Research Institute, Tarbiat Modares University, Tehran, Iran.
| | - Kianoush Khosravi-Darani
- Department of Food Technology Research, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| |
Collapse
|
4
|
Tumolo M, De Paola D, Uricchio VF, Ancona V. Biostimulation effect of different amendments on Cr(VI) recovering microbial community. N Biotechnol 2023; 78:29-41. [PMID: 37793602 DOI: 10.1016/j.nbt.2023.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 09/15/2023] [Accepted: 09/30/2023] [Indexed: 10/06/2023]
Abstract
The present study used Cr(VI)-polluted microcosms amended with lactate or yeast extract, and nonamended microcosms as control, to investigate how a native bacterial community varied in response to the treatment and during the pollutant removal. Results suggested that providing electron donors resulted in a proliferation of a few bacterial species, with the consequent decrease in observed species richness and evenness, and was a driving force for the bacterial compositional shift. Lactate promoted, in the first instance, the enrichment of fermentative bacteria belonging to Chromobacteriaceae, including Paludibacterium, and Micrococcaceae as observed after 4 days. When the rate of Cr(VI) removal was maximum in microcosms amended with lactate, the most represented taxa were Pseudarcicella and Azospirillum. Using yeast extract as a carbon source and electron donor led instead to the significant enrichment of Shewanella, followed by Vogesella and Acinetobacter on the 4th day, corresponding to 90% of Cr(VI) removed from the system. After the complete Cr(VI) removal, achieved in 7 days in the presence of yeast extract, α-diversity was notably increased. The amendment-specific turnover of the enriched bacterial taxa resulted in a different kinetic of pollutant removal. In particular, yeast extract promoted the quickest Cr(VI) reduction, while lactate supported a slower, but also considerable, pollutant removal from water. Since it is reasonable to assume that a macroscopic effect, such as the observed Cr(VI) removal, involved the overrepresented taxa, deepening the knowledge of the native bacterial community and its changes were used to hypothesize the possible microbial pathways involved.
Collapse
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
| | - Domenico De Paola
- Institute of Biosciences and Bioresources, Italian National Research Council (IBBR-CNR), 70126 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.
| |
Collapse
|
5
|
Padma S, Srinivas B, Ghanta KC, Dutta S. Bioremediation of Cr(VI) using indigenous bacterial strains isolated from a common industrial effluent treatment plant in Vishakhapatnam. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2023; 88:2889-2904. [PMID: 38096076 PMCID: wst_2023_358 DOI: 10.2166/wst.2023.358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
The present study focuses on removing hexavalent chromium (Cr(VI)) using indigenous metal-resistant bacterial strains isolated from a common industrial effluent treatment plant, a contaminated site in Vishakhapatnam. Three high metal-resistant isolates were screened by growing them in nutrient agar media containing different Cr(VI) concentrations for 24 h at 35 ± 2 °C. The three strains' minimum inhibitory concentrations of Cr(VI) were examined at neutral pH and 35 ± 2 °C temperature. Morphological, biochemical, and molecular characterizations were carried out, and the strains were identified as Bacillus subtilis NITSP1, Rhizobium pusense NITSP2, and Pseudomonas aeruginosa NITSP3. Elemental composition and functional group analysis of the native and metal-loaded cells were done using energy-dispersive spectroscopy and Fourier-transform infrared spectroscopy, respectively. The operating conditions were optimized using a one-factor-at-a-time analysis. When compared with three bacterial isolates, maximum Cr(VI) removal (80.194 ± 4.0%) was observed with Bacillus subtilis NITSP1 with an initial Cr(VI) concentration of 60 mg/L, pH 7.0, an inoculum size of 2% (v/v), and an incubation period of 24 h. The logistic model was used to predict the variation of biomass growth with time. The present study can be extended to remove heavy metals from industrial wastewater in an environmental-friendly manner.
Collapse
Affiliation(s)
- Seragadam Padma
- Department of Chemical Engineering, Gayatri Vidya Parishad College of Engineering (A), Vishakhapatnam 530048, India; Department of Chemical Engineering, National Institute of Technology Durgapur, Durgapur 713 209, India E-mail:
| | - Badri Srinivas
- Department of Chemical Engineering, Gayatri Vidya Parishad College of Engineering (A), Vishakhapatnam 530048, India
| | - Kartik Chandra Ghanta
- Department of Chemical Engineering, National Institute of Technology Durgapur, Durgapur 713 209, India
| | - Susmita Dutta
- Department of Chemical Engineering, National Institute of Technology Durgapur, Durgapur 713 209, India
| |
Collapse
|
6
|
Wu Q, Li Q, Zhang Y, Wan R, Peng S. Cr(VI) reduction by Agrobacterium sp. Cr-1 and Lysinibacillus sp. Cr-2, novel Cr(VI)-reducing strains isolated from chromium plant soil. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:109724-109737. [PMID: 37776430 DOI: 10.1007/s11356-023-30181-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 09/26/2023] [Indexed: 10/02/2023]
Abstract
The bioremediation of Cr(VI)-contaminated soil is a promising strategy; however, the performance of Cr(VI)-reducing bacteria is limited by the toxicity of Cr(VI). In this study, two novel Cr(VI)-reducing bacteria were isolated from a Cr salt plant and identified as Agrobacterium sp. and Lysinibacillus sp. The Cr(VI) reduction conditions of the two strains were optimized. At a Cr(VI) concentration of 500 mg/L, Agrobacterium sp. Cr-1 reduced Cr(VI) with a removal rate of 96.91%, while that for Lysinibacillus sp. Cr-2 was 92.82%. First-order reaction kinetic equations simulated the positive relationship between time and Cr(VI) concentration during Cr(VI) reduction in these two strains. Agrobacterium sp. Cr-1 was further studied, and the effects of different cell components on Cr(VI) reduction were detected. The extracellular extracts of Agrobacterium sp. Cr-1 played a major role in Cr(VI) reduction, followed by intracellular extracts and cell membranes. The scanning electron microscope-energy dispersive spectrometer (SEM-EDS) images show that the precipitation was Cr. The high Cr(VI) reducing ability of Agrobacterium sp. Cr-1 suggests that this strain is promising for the remediation of Cr(VI)-contaminated sites.
Collapse
Affiliation(s)
- Qing Wu
- School of Environmental Science and Engineering, Tianjin University, NO. 135 Yaguan Road, Tianjin, 300350, Jinnan District, China.
| | - Qiannan Li
- School of Environmental Science and Engineering, Tianjin University, NO. 135 Yaguan Road, Tianjin, 300350, Jinnan District, China
| | - Ying Zhang
- School of Environmental Science and Engineering, Tianjin University, NO. 135 Yaguan Road, Tianjin, 300350, Jinnan District, China
| | - Ruihan Wan
- School of Environmental Science and Engineering, Tianjin University, NO. 135 Yaguan Road, Tianjin, 300350, Jinnan District, China
| | - Sen Peng
- School of Environmental Science and Engineering, Tianjin University, NO. 135 Yaguan Road, Tianjin, 300350, Jinnan District, China
| |
Collapse
|
7
|
Li Y, Huang Y, Li Z, Tang X, Liu X, Hughes SS. Mechanisms of chromium isotope fractionation and the applications in the environment. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 242:113948. [PMID: 35999763 DOI: 10.1016/j.ecoenv.2022.113948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 07/31/2022] [Accepted: 08/01/2022] [Indexed: 06/15/2023]
Abstract
Chromium (Cr) is a toxic heavy metal that gives rise to environmental pollution and human risk. Chromium stable isotopes have a wide range of applications in both environmental field and earth science field. In this contribution, we focus on the application of the Cr isotope in both tracing pollution sources and monitoring Cr(Ⅵ) pollution. Meanwhile, we also provide a description of the main influencing factors controlling Cr isotope fractionation, chromium isotope analytical methods, and terrestrial Cr release. Chromium isotope tracing of contaminant sources is a new application method, it has a tremendous advantage in searching for the source of Cr pollution, which has not been covered in previous reviews. At the end of the article, the current status of Cr isotope applications in the paleo-environment is explained. Although there are still some uncertainties in practical applications, chromium isotope system shows great promise in the environmental aspects.
Collapse
Affiliation(s)
- Ying Li
- State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, College of Geosciences, Chengdu University of Technology, Chengdu 610059, Sichuan, China
| | - Yi Huang
- State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, College of Geosciences, Chengdu University of Technology, Chengdu 610059, Sichuan, China; State Key Laboratory of Collaborative Control and Joint Remediation of Soil and Water Pollution, College of Ecology and Environment, Chengdu University of Technology, Chengdu 610059, Sichuan, China.
| | - Zijing Li
- State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, College of Geosciences, Chengdu University of Technology, Chengdu 610059, Sichuan, China
| | - Xue Tang
- State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, College of Geosciences, Chengdu University of Technology, Chengdu 610059, Sichuan, China
| | - Xiaowen Liu
- State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, College of Geosciences, Chengdu University of Technology, Chengdu 610059, Sichuan, China
| | - Scott S Hughes
- Department of Geosciences, Idaho State University, Pocatello, ID 83209, USA
| |
Collapse
|
8
|
Reductive Cr(VI) Removal under Different Reducing and Electron Donor Conditions—A Soil Microcosm Study. WATER 2022. [DOI: 10.3390/w14142179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Increased groundwater and soil contamination by hexavalent chromium have led to the employment of a variety of detoxification methods. Biological remediation of Cr(VI) polluted aquifers is an eco-friendly method that can be performed in situ by stimulating the indigenous microbial population with organic and inorganic electron donors. In order to study the effect of different redox conditions on microbial remediated Cr(VI) reduction to Cr(III), microcosm experiments were conducted under anaerobic, anoxic, and sulfate-reducing conditions and at hexavalent chromium groundwater concentrations in the 0–3000 μg/L range, with groundwater and soil collected from an industrial area (Inofyta region). As electron donors, molasses, emulsified vegetable oil (EVO), and FeSO4 were employed. To quantitatively describe the degradation kinetics of Cr(VI), pseudo-first-order kinetics were adopted. The results indicate that an anaerobic system dosed with simple or complex external organic carbon sources can lead to practically complete Cr(VI) reduction to Cr(III), while the addition of Fe2+ can further increase Cr(VI) removal rate significantly. Furthermore, Cr(VI) microbial reduction is possible in the presence of NO3− at rates comparable to anaerobic Cr(VI) microbial reduction, while high sulfate concentrations have a negative effect on Cr(VI) bioreduction rates in comparison to lower sulfate concentrations.
Collapse
|
9
|
Microbial fuel cell-based sensor for Enterobacter sp. KBH6958 activity monitoring during hydrogen production: the effects of pH and glucose concentration. J APPL ELECTROCHEM 2022. [DOI: 10.1007/s10800-022-01719-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
10
|
Lin WH, Chen CC, Ou JH, Sheu YT, Hou D, Kao CM. Bioremediation of hexavalent-chromium contaminated groundwater: Microcosm, column, and microbial diversity studies. CHEMOSPHERE 2022; 295:133877. [PMID: 35131270 DOI: 10.1016/j.chemosphere.2022.133877] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 12/11/2021] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
Sulfate reducing bacteria (SRB) have the capability of bioreducing hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] under sulfate-reducing conditions for toxicity reduction. However, a high amount of sulfate addition would cause elevated sulfide production, which could inhibit the growth of SRB and result in reduced Cr(VI) bioreduction efficiency. A slow release reagent, viscous carbon and sulfate-releasing colloidal substrates (VCSRCS), was prepared for a long-lasting carbon and sulfate supplement. In the column study, VCSRCS was injected into the column system to form a VCSRCS biobarrier for Cr(VI) containment and bioreduction. A complete Cr(VI) removal was observed via the adsorption and bioreduction mechanisms in the column with VCSRCS addition. Results from X-ray diffractometer analyses indicate that Cr(OH)3(s) and Cr2O3(s) were detected in precipitates, indicating the occurrence of Cr(VI) reduction followed by Cr(III) precipitation. Results from the Fourier-transform infrared spectroscopy analyses show that cell deposits carried functional groups, which could adsorb Cr. Addition of VCSRCS caused increased populations of total bacteria and dsrA, which also enhanced Cr(VI) reduction. Microbial diversity results indicate that VCSRCS addition resulted in the growth of Cr(VI)-reducing bacteria including Exiguobacterium, Citrobacter, Aerococcus, and SRB. Results of this study will be helpful in developing an effective and green VCSRCS biobarrier for the bioremediation of Cr(VI)-polluted groundwater.
Collapse
Affiliation(s)
- Wei-Han Lin
- School of Environment, Tsinghua University, Beijing, China
| | - Chien-Cheng Chen
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan
| | - Jiun-Hau Ou
- Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan
| | - Yih-Terng Sheu
- General Education Center, National University of Kaohsiung, Kaohsiung, Taiwan
| | - Deyi Hou
- School of Environment, Tsinghua University, Beijing, China.
| | - Chih-Ming Kao
- Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan.
| |
Collapse
|
11
|
Zakernezhad MJ, Seidi S, Manouchehri M. Efficient Ion Separation from Environmental and Biological Samples Using a Novel Sorbent Based on Ni-Substituted ZIF-67: Optimization, Equilibrium, Kinetic, and Thermodynamic Study. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.1c03658] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Mohammad Javad Zakernezhad
- Department of Analytical Chemistry, Faculty of Chemistry, K. N. Toosi University of Technology, P.O. Box 16315-1618, 15418-49611 Tehran, Iran
| | - Shahram Seidi
- Department of Analytical Chemistry, Faculty of Chemistry, K. N. Toosi University of Technology, P.O. Box 16315-1618, 15418-49611 Tehran, Iran
| | - Mahshid Manouchehri
- Department of Analytical Chemistry, Faculty of Chemistry, K. N. Toosi University of Technology, P.O. Box 16315-1618, 15418-49611 Tehran, Iran
| |
Collapse
|
12
|
Evaluation of Cr(VI) Reduction Using Indigenous Bacterial Consortium Isolated from a Municipal Wastewater Sludge: Batch and Kinetic Studies. Catalysts 2021. [DOI: 10.3390/catal11091100] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Hexavalent Chromium (Cr(VI)) has long been known to be highly mobile and toxic when compared with the other stable oxidation state, Cr(III). Cr(VI)-soluble environmental pollutants have been detected in soils and water bodies receiving industrial and agricultural waste. The reduction of Cr(VI) by microbial organisms is considered to be an environmentally compatible, less expensive and sustainable remediation alternative when compared to conventional treatment methods, such as chemical neutralization and chemical precipitation of Cr. This study aims to isolate and identify the composition of the microbial consortium culture isolated from waste activated sludge and digested sludge from a local wastewater treatment plant receiving high loads of Cr(VI) from an abandoned chrome foundry in Brits (North Waste Province, South Africa). Furthermore, the Cr(VI) reduction capability and efficiency by the isolated bacteria were investigated under a range of operational conditions, i.e., pH, temperature and Cr(VI) loading. The culture showed great efficiency in reduction capability, with 100% removal in less than 4 h at a nominal loading concentration of 50 mg Cr(VI)/L. The culture showed resilience by achieving total removal at concentrations as high as 400 mg Cr(VI)/L. The consortia exhibited considerable Cr(VI) removal efficiency in the pH range from 2 to 11, with 100% removal being achieved at a pH value of 7 at a 37 ± 1 °C incubation temperature. The time course reduction data fitted well on both first and second-order exponential rate equation yielding first-order rate constants in the range 0.615 to 0.011 h−1 and second order rate constants 0.0532 to 5 × 10−5 L·mg−1·h−1 for Cr(VI) concentration of 50–400 mg/L. This study demonstrated the bacterial consortium from municipal wastewater sludge has a high tolerance and reduction ability over a wide range of experimental conditions. Thus, show promise that bacteria could be used for hexavalent chromium remediate in contaminated sites.
Collapse
|
13
|
Shang W, Qiao B, Xu QM, Cheng JS. Potential biotransformation pathways and efficiencies of ciprofloxacin and norfloxacin by an activated sludge consortium. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 785:147379. [PMID: 33957591 DOI: 10.1016/j.scitotenv.2021.147379] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/19/2021] [Accepted: 04/21/2021] [Indexed: 06/12/2023]
Abstract
Fluoroquinolones (FQs), such as ciprofloxacin (CIP) and norfloxacin (NOR), are types of emerging trace pollutants that have attracted great attention. In this study, an activated sludge (AS) consortium with high bio-removal capability to CIP and NOR was obtained by acclimating with CIP and NOR for 10 d. Meanwhile, a CIP- and NOR- transforming bacterial strain (S5), which is highly homologous to the 16S rRNA gene sequence of Enterobacter sp., was isolated from the acclimated AS. The bio-removal efficiency of CIP under the acclimated AS consortium was better than that under the pure culture of Enterobacter sp. S5 (93.1% vs. 89.3%), while the bio-removal efficiency of NOR under the acclimated AS consortium was lower than that under the pure culture of Enterobacter sp. S5 (83.9% vs. 89.8%). The biotransformation and bio-adsorption were two main ways to bio-remove CIP and NOR. However, the CIP and NOR biotransformation efficiencies of the acclimated AS were higher than under the pure culture of Enterobacter sp. S5, while the CIP and NOR adsorption of acclimated AS were lower than that under the pure culture of Enterobacter sp. S5. The N-acetylciprofloxacin and N-acetylnorfloxacin were the main biotransformation products of CIP and NOR. It is possible that acetyltransferase may be involved in the biotransformation process. Whether under the pure culture or AS consortium, the cytotoxicity of CIP and NOR transformation products to gram-negative bacteria was alleviated. Therefore, the acclimated AS and Enterobacter sp. S5 might provide a new strategy for removing contaminants and alleviating of FQs resistance.
Collapse
Affiliation(s)
- Wei Shang
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Yaguan Road 135, Jinnan District, Tianjin 300350, PR China; SynBio Research Platform, Collaborative Innovation Centre of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Yaguan Road 135, Jinnan District, Tianjin 300350, PR China
| | - Bin Qiao
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Yaguan Road 135, Jinnan District, Tianjin 300350, PR China
| | - Qiu-Man Xu
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Science, Tianjin Normal University, Binshuixi Road 393, Xiqing District, Tianjin 300387, PR China.
| | - Jing-Sheng Cheng
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Yaguan Road 135, Jinnan District, Tianjin 300350, PR China; SynBio Research Platform, Collaborative Innovation Centre of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Yaguan Road 135, Jinnan District, Tianjin 300350, PR China.
| |
Collapse
|
14
|
Yang X, Liu P, Yao M, Sun H, Liu R, Xie J, Zhao Y. Mechanism and enhancement of Cr(VI) contaminated groundwater remediation by molasses. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 780:146580. [PMID: 34030333 DOI: 10.1016/j.scitotenv.2021.146580] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/15/2021] [Accepted: 03/15/2021] [Indexed: 06/12/2023]
Abstract
The remediation of Cr(VI)-contaminated groundwater with molasses has many advantages compared with traditional in-situ chemical methods, including high cost-effectiveness and negligible secondary contamination. Hence, the reaction conditions and mechanisms of molasses were investigated in this study. The results showed that Cr(VI) was chemically reduced by molasses at acidic pH (3.0), wherein the dominant active components were the hydroxyl and carbonyl groups of molasses. At neutral pH (7.0), molasses mainly acted as an electron donor for direct or indirect reduction of Cr(VI) by microorganisms. The main functional microorganisms were Bacillus and Clostridium Sensu Stricto. Compared with chemical reduction, bio-reduction could completely reduce higher concentrations of Cr(VI) when molasses was added at a concentration of 3 g/L. Ascorbic acid was added to promote the removal rate of bioremediation. Owing to the antioxidant properties of ascorbic acid, the reaction rate increased by 9.3% and 37.5% when 0.05 g/L of ascorbic acid was added to the 50 and 100 mg/L Cr(VI) bioremediation systems, respectively. Due to the decrease in pH during bioremediation, NaHCO3 was added to buffer the pH changes and promote Cr(III) precipitation. Compared with the addition of NaHCO3 and molasses simultaneously, separate additions were more effective for precipitation. Furthermore, X-ray absorption near-edge structure analysis revealed that after chemical reduction and biological reduction, Cr was attached to the solid medium in the form of Cr(III).
Collapse
Affiliation(s)
- Xinru Yang
- Key Laboratory of Groundwater Resources and Environment of Ministry of Education, College of New Energy and Environment, Jilin University, Changchun 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, College of New Energy and Environment, Jilin University, Changchun 130021, China; National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun 130021, China
| | - Peng Liu
- School of Environmental Studies, China University of Geosciences, 388 Lumo Rd., Wuhan, Hubei 430074, China
| | - Meng Yao
- Key Laboratory of Groundwater Resources and Environment of Ministry of Education, College of New Energy and Environment, Jilin University, Changchun 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, College of New Energy and Environment, Jilin University, Changchun 130021, China; National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun 130021, China
| | - He Sun
- Key Laboratory of Groundwater Resources and Environment of Ministry of Education, College of New Energy and Environment, Jilin University, Changchun 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, College of New Energy and Environment, Jilin University, Changchun 130021, China; National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun 130021, China
| | - Ruxue Liu
- Key Laboratory of Groundwater Resources and Environment of Ministry of Education, College of New Energy and Environment, Jilin University, Changchun 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, College of New Energy and Environment, Jilin University, Changchun 130021, China; National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun 130021, China
| | - Jiayin Xie
- Key Laboratory of Groundwater Resources and Environment of Ministry of Education, College of New Energy and Environment, Jilin University, Changchun 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, College of New Energy and Environment, Jilin University, Changchun 130021, China; National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun 130021, China
| | - Yongsheng Zhao
- Key Laboratory of Groundwater Resources and Environment of Ministry of Education, College of New Energy and Environment, Jilin University, Changchun 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, College of New Energy and Environment, Jilin University, Changchun 130021, China; National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun 130021, China.
| |
Collapse
|
15
|
Ifthikar J, Ibran Shahib I, Jawad A, Gendy EA, Wang S, Wu B, Chen Z, Chen Z. The excursion covered for the elimination of chromate by exploring the coordination mechanisms between chromium species and various functional groups. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.213868] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|
16
|
Pushkar B, Sevak P, Parab S, Nilkanth N. Chromium pollution and its bioremediation mechanisms in bacteria: A review. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 287:112279. [PMID: 33706095 DOI: 10.1016/j.jenvman.2021.112279] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 02/10/2021] [Accepted: 02/25/2021] [Indexed: 06/12/2023]
Abstract
Environment pollution is at its peak and is creating havoc for living beings. Industrial wastes containing toxic pollutants have contributed to a great extent in this disastrous environment pollution. Chromium (Cr3+/Cr6+) is highly toxic and one of the most common environmental pollutants because of its extensive use in industries especially tanneries. Lack of efficient treatment methods has resulted in extensive chromium pollution. Bioremediation of chromium using bacteria is very thoughtful due to its eco-friendly and cost-effective outcome. Bacteria possess numerous mechanisms such as biosorption, reduction, efflux or bioaccumulation, naturally or acquired to counter the toxicity of chromium. This review focuses on the bacterial responses against chromium toxicity and scope for their application in bioremediation. The differences and similarities between Gram negative and positive bacteria against chromium are also highlighted. Further, the knowledge gap and future prospects are also discussed in order to fill these gaps and overcome the problem associated with real-time applicability of bacterial bioremediation.
Collapse
Affiliation(s)
- Bhupendra Pushkar
- Department of Biotechnology, University of Mumbai, Kalina, Santacruz (E), Mumbai, 400098, Maharashtra, India; Global Biotech Forum, Maharashtra, India.
| | - Pooja Sevak
- Department of Biotechnology, University of Mumbai, Kalina, Santacruz (E), Mumbai, 400098, Maharashtra, India; Society for Innovations in Biosciences, Maharashtra, India
| | - Sejal Parab
- Department of Biotechnology, University of Mumbai, Kalina, Santacruz (E), Mumbai, 400098, Maharashtra, India
| | - Nikita Nilkanth
- Department of Biotechnology, University of Mumbai, Kalina, Santacruz (E), Mumbai, 400098, Maharashtra, India
| |
Collapse
|
17
|
Bioremediation of hexavalent chromium from wastewater using bacteria-a green technology. Biodegradation 2021; 32:449-466. [PMID: 34009530 DOI: 10.1007/s10532-021-09947-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 05/15/2021] [Indexed: 10/21/2022]
Abstract
Hexavalent chromium has high toxic effect on the ecological system. The aim of the present study is to isolate and characterize the bacteria that can reduce the toxicity of hexavalent chromium from liquid effluent. The bacterial isolate was identified as Bacillus sp. ltds1 after 16 S rRNA gene sequencing, and annotation has been submitted in National Center for Biotechnology Information (NCBI) GenBank. The bacterial strain was found able to grow in Luria Broth medium at 100 mg/L Cr6+ concentration. A maximum Cr6+ bioremediation (95.24 ± 2.08 %) could be achieved using the said isolate at 40 mg/L, pH 7, and inoculum concentration 4 % at 24 h. The residual chromium was found in the form of less toxic trivalent chromium (Cr3+), which confirms that the bacterial isolate can transform toxic Cr6+ to non-toxic Cr3+. Fourier Transform Infra-Red (FTIR) study was performed to analyze the functional groups and overall nature of chemical bonds involved in the remediation process, whereas, Energy-Dispersive Spectroscopy (EDS) studies of native and treated cells showed the changes in elemental composition in response to metal stress. Artificial Neural Network (ANN) based prediction model is developed based on experimental points. The developed model was found to predict the bioremediation of Cr6+ at various operating conditions. Particle Swarm Optimization (PSO) is used to optimize the variables like the initial concentration of metal, pH, temperature, and inoculum concentration for the said bacterial strain. The results showed that the isolate could be applied as a potential bioremediation agent for Cr6+ removal.
Collapse
|
18
|
Chen J, Tian Y. Hexavalent chromium reducing bacteria: mechanism of reduction and characteristics. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:20981-20997. [PMID: 33689130 DOI: 10.1007/s11356-021-13325-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 03/03/2021] [Indexed: 06/12/2023]
Abstract
As a common heavy metal, chromium and its compounds are widely used in industrial applications, e.g., leather tanning, electroplating, and in stainless steel, paints and fertilizers. Due to the strong toxicity of Cr(VI), chromium is regarded as a major source of pollution with a serious impact on the environment and biological systems. The disposal of Cr(VI) by biological treatment methods is more favorable than traditional treatment methods because the biological processes are environmentally friendly and cost-efficient. This review describes how bacteria tolerate and reduce Cr(VI) and the effects of some physical and chemical factors on the reduction of Cr(IV). The practical applications for Cr(VI) reduction of bacterial cells are also included in this review.
Collapse
Affiliation(s)
- Jia Chen
- College of Biomass Science and Engineering, Sichuan University, Chengdu, 610065, People's Republic of China
- Key Laboratory of Leather Chemistry and Engineering, (Sichuan University), Ministry of Education, Chengdu, 610065, People's Republic of China
| | - Yongqiang Tian
- College of Biomass Science and Engineering, Sichuan University, Chengdu, 610065, People's Republic of China.
- Key Laboratory of Leather Chemistry and Engineering, (Sichuan University), Ministry of Education, Chengdu, 610065, People's Republic of China.
| |
Collapse
|
19
|
Patel RJ, Patel UD, Nerurkar AS. Moving bed biofilm reactor developed with special microbial seed for denitrification of high nitrate containing wastewater. World J Microbiol Biotechnol 2021; 37:68. [PMID: 33748870 DOI: 10.1007/s11274-021-03035-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 03/08/2021] [Indexed: 12/07/2022]
Abstract
Biological denitrification is the most promising alternative approach for the removal of nitrate from wastewater. MBBR inoculated with activated sludge is a widely studied approach, but very few studies have focused on the bioaugmentation of biofilm forming bacteria in MBBR. Our study revealed that the use of special microbial seed of biofilm forming denitrifying bacteria Diaphorobacter sp. R4, Pannonibacter sp. V5, Thauera sp. V9, Pseudomonas sp.V11, and Thauera sp.V14 to form biofilm on carriers enhanced nitrate removal performance of developed MBBR. Various process parameters C/N ratio 0.3, HRT 3 h at Nitrate loading 2400 mg L-1, Filling ratio 20%, operated with Pall ring carrier were optimized to achieve highest nitrate removal. After 300 days of continuous operation results of whole genome metagenomic studies showed that Thauera spp. were the most dominant and key contributor to the denitrification of nitrate containing wastewater and the reactor was totally conditioned for denitrification. Overall, findings suggest that bench-scale MBBR developed with biofilm forming denitrifying microbial seed accelerated the denitrification process; therefore in conclusion it is suggested as one of the best suitable and effective approach for removal of nitrate from wastewater.
Collapse
Affiliation(s)
- Roshni J Patel
- Department of Microbiology and Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, 390002, India
| | - Upendra D Patel
- Department of Civil Engineering, Faculty of Technology and Engineering, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, 390001, India
| | - Anuradha S Nerurkar
- Department of Microbiology and Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, 390002, India.
| |
Collapse
|
20
|
Huang J, Shi B, Han W, Qiu S, Li H, Hou P, Wu W, Tang J. Effect of pH on hexavalent chromium removal driven by henna (Lawsonia inermis) fermentation. Biochem Eng J 2021. [DOI: 10.1016/j.bej.2020.107919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
21
|
Ma L, Chen N, Feng C. Practical application potential of microbial-phosphorus minerals-alginate immobilized particles on chromium(VI)-bioreduction. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 742:140685. [PMID: 32721757 DOI: 10.1016/j.scitotenv.2020.140685] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/24/2020] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
Due to the widespread use of chromium (Cr) across various industrial processes, the process of in-situ remediation of Cr-contaminated groundwater has received extensive attention. Previous studies of solid-phase phosphorus sources and microbial immobilization co-strengthening materials have demonstrated that their performance in continuous flow reactions is of great significance towards practical application of these technologies. It was suggested that Microbial-Phosphorus minerals-Alginate (MPA) immobilized particles showed superior performance (high Cr removal efficiency, low phosphorus surplus, and high environmental resistance) in comparisons of non-immobilization systems and different immobilization methods under continuous flow conditions. Microbial community analysis revealed significant differences between different systems as well as between variations in environmental factors, providing further support for the above conclusions. Synthetic wastewater (synthesized by actual groundwater) was also introduced to further verify the practical application potential of MPA immobilized particles. The results of this study provide a new insight and relevant bench scale data to support the enhancement of in-situ Cr(VI) bioremediation.
Collapse
Affiliation(s)
- Linlin Ma
- School of Water Resources and Environment, MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Nan Chen
- School of Water Resources and Environment, MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, PR China.
| | - Chuanping Feng
- School of Water Resources and Environment, MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, PR China
| |
Collapse
|
22
|
Xiang L, Lin J, Yang Q, Lin S, Chen S, Yan B. Facile preparation of hierarchical porous polydopamine microspheres for rapid removal of chromate from the wastewater. JOURNAL OF LEATHER SCIENCE AND ENGINEERING 2020. [DOI: 10.1186/s42825-020-00036-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Abstract
Cr(VI) containing industrial wastewaters are highly toxic and carcinogenic, and severely threats living creatures and the environment. Therefore, it is highly desired yet challenging to develop an available and economical adsorbent for simultaneously detoxifying Cr(VI) anions to Cr(III) ions and removing them from the wastewater. Here we propose a facile method for rapid removal of Cr(VI) ions from the wastewater by using a synthetic polydopamine microsphere (PPM) adsorbent with hierarchical porosity. The as-prepared PPM exhibits high Cr(VI) removal capacity of 307.7 mg/g and an outstanding removal efficiency. They can effectively decrease the Cr(VI) concentration to lower than 0.05 mg/L well below the limits for drinking water standard of WHO regulations in 60 s at pH 2. More importantly, PPMs can reduce the lethal Cr(VI) anions to Cr(III) ions with low toxicity, and simultaneously immobilize them on the matrices of PPMs.
Graphical abstract
Collapse
|