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Song Q, Tong X, Dai P, Xie X, Xie R, Fan P, Ma Y, Chen H. Activation Mechanism of Fe 2+ in Pyrrhotite Flotation: Microflotation and DFT Calculations. Molecules 2024; 29:1490. [PMID: 38611768 PMCID: PMC11013166 DOI: 10.3390/molecules29071490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/22/2024] [Accepted: 03/22/2024] [Indexed: 04/14/2024] Open
Abstract
In industrial manufacturing, pyrrhotite(Fe1-xS), once depressed, is commonly activated for flotation. However, the replacement of CuSO4 is necessary due to the need for exact control over the dosage during the activation of pyrrhotite, which can pose challenges in industrial settings. This research introduces the use of FeSO4 for the first time to efficiently activate pyrrhotite. The impact of two different activators on pyrrhotite was examined through microflotation experiments and density functional theory (DFT) calculations. Microflotation experiments confirmed that as the CuSO4 dosage increased from 0 to 8 × 10-4 mol/L, the recovery of pyrrhotite initially increased slightly from 71.27% to 87.65% but then sharply decreased to 16.47%. Conversely, when the FeSO4 dosage was increased from 0 to 8 × 10-4 mol/L, pyrrhotite's recovery rose from 71.27% to 82.37%. These results indicate a higher sensitivity of CuSO4 to dosage variations, suggesting that minor alterations in dosage can significantly impact its efficacy under certain experimental conditions. In contrast, FeSO4 might demonstrate reduced sensitivity to changes in dosage, leading to more consistent performance. Fe ions can chemically adsorb onto the surface of pyrrhotite (001), creating a stable chemical bond, thereby markedly activating pyrrhotite. The addition of butyl xanthate (BX), coupled with the action of Fe2+ on activated pyrrhotite, results in the formation of four Fe-S bonds on Fe2+. The proximity of their atomic distances contributes to the development of a stable double-chelate structure. The S 3p orbital on BX hybridizes with the Fe 3d orbital on pyrrhotite, but the hybrid effect of Fe2+ activation is stronger than that of nonactivation. In addition, the Fe-S bond formed by the addition of activated Fe2+ has a higher Mulliken population, more charge overlap, and stronger covalent bonds. Therefore, Fe2+ is an excellent, efficient, and stable pyrrhotite activator.
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Affiliation(s)
| | | | | | | | | | | | | | - Hang Chen
- Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China; (Q.S.); (X.T.); (P.D.); (X.X.); (R.X.); (P.F.); (Y.M.)
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Zhang Y, Pei J, Zheng S, Li Y, Lv N, Ma L. Enhanced dewaterability of sludge by Fe(II)-sludge biochar activate persulfate. ENVIRONMENTAL TECHNOLOGY 2024; 45:854-866. [PMID: 36161866 DOI: 10.1080/09593330.2022.2129457] [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: 05/14/2022] [Accepted: 09/17/2022] [Indexed: 06/16/2023]
Abstract
Sludge biochar supported Fe(II) (Fe(II)-SBC) was successfully prepared using waste activated sludge as peroxydisulfate (PDS) activator to condition sludge for deep dewatering. The experimental results showed that Fe(II)-SBC with FeO on it could effectively active PDS to produce SO 4 - ⋅ and HO ⋅ . The radicals could destroy the structure of sludge cells and extracellular polymeric substance (EPS), transformed the hydrophilic and tightly bound EPS into soluble-EPS, degrade partial proteins and polysaccharides and released bound water. The negatively charged groups on sludge floc were dripped off by SO 4 - ⋅ /HO ⋅ or neutralized with Fe2+, Fe3+, H+, or Fe(II)-SBC, leading to an increase in zeta potential to -2.24 mV and sludge destabilization. The residual Fe(II)-SBC served as a skeleton builder that decreased the compression coefficient of the sludge cake to 0.75. Under the combined functions, the CST and SRF were reduced by 70% and 82.7%, respectively, and Wc was reduced to 72.4%. The byproducts of Fe3+ and SO42- finally remained in sludge cake in the form of NaFeSi2O6 and CaSO4.
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Affiliation(s)
- Yanping Zhang
- School of Civil Engineering and Transportation, Hebei University of Technology, Tianjin, People's Republic of China
| | - Jiahua Pei
- School of Civil Engineering and Transportation, Hebei University of Technology, Tianjin, People's Republic of China
| | - Songchao Zheng
- School of Civil Engineering and Transportation, Hebei University of Technology, Tianjin, People's Republic of China
| | - Yibing Li
- School of Civil Engineering and Transportation, Hebei University of Technology, Tianjin, People's Republic of China
| | - Ning Lv
- School of Civil Engineering and Transportation, Hebei University of Technology, Tianjin, People's Republic of China
| | - Liran Ma
- School of Civil Engineering and Transportation, Hebei University of Technology, Tianjin, People's Republic of China
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Zhu Y, Xiao K, Ou B, Liu Y, Yu W, Jian S, Hu X, Liu H, Lei P, Yang J. Behavior of organic components and the migration of heavy metals during sludge dewatering by different advanced oxidation processes via optical spectroscopy and molecular fingerprint analysis. WATER RESEARCH 2023; 243:120336. [PMID: 37454458 DOI: 10.1016/j.watres.2023.120336] [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: 01/19/2023] [Revised: 07/04/2023] [Accepted: 07/08/2023] [Indexed: 07/18/2023]
Abstract
A comparative study of the different advanced oxidation processes (Fe(II)-Oxone, Fe(II)-H2O2, and Fe(II)-NaClO) was carried out herein to analyze the characteristics of organic components and the migration of heavy metals in waste activated sludge. With the Fe(II)-Oxone and Fe(II)-H2O2 treatments, sludge dewaterability was significantly improved, however, sludge dewaterability was deteriorated by the Fe(II)-NaClO treatment. The enhanced sludge dewaterability by the Fe(II)-Oxone and Fe(II)-H2O2 treatments was strongly correlated with the shifted organic components, particularly proteins, in soluble extracellular polymeric substances (S-EPS), while the deteriorated sludge dewaterability by the Fe(II)-NaClO treatment was strongly correlated with the over release of organic components from bound EPS (B-EPS) to S-EPS. For both the Fe(II)-Oxone and Fe(II)-H2O2 treatments, the radicals preferentially attacked humic acid-like organic components over the protein-like organic components in S-EPS, while for the Fe(II)-NaClO treatment, interestingly, the radicals preferentially attacked the protein-like organic components in both S-EPS and B-EPS. The hydrophilic functional groups like phenolic OH and CO of polysaccharides may be more preferentially migrated to S-EPS of sludge by the Fe(II)-NaClO treatment compared to the other two treatments. With the Fe(II)-Oxone and Fe(II)-H2O2 treatments, the proportion of aliphatic compounds as well as the much oxygenated organic components with a low desaturation and a low molecular weight increased. While with the Fe(II)-NaClO treatment, the proportion of low oxygenated organic components with a high desaturation and a high molecular weight increased. The concentration of total organic carbon, particularly the concentration of proteins, may be the key factor determining the shift of Zn and Cu from sludge solid to liquid phase, along with the high oxidation extent of organic components and close binding to CHOS and CHON compounds as indicated by density functional theory (DFT) calculation. This study systematically revealed the simultaneous sludge dewatering and migration of heavy metals when the role of organic components was factored into herein.
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Affiliation(s)
- Yuwei Zhu
- School of Environmental Science & Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei 430074, China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Luoyu Road 1037, Wuhan, Hubei 430074, China
| | - Keke Xiao
- School of Environmental Science & Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei 430074, China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Luoyu Road 1037, Wuhan, Hubei 430074, China.
| | - Bei Ou
- School of Environmental Science & Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei 430074, China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Luoyu Road 1037, Wuhan, Hubei 430074, China
| | - Yuan Liu
- School of Environmental Science & Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei 430074, China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Luoyu Road 1037, Wuhan, Hubei 430074, China
| | - Wenbo Yu
- School of Environmental Science & Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei 430074, China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Luoyu Road 1037, Wuhan, Hubei 430074, China
| | - Sifeng Jian
- Central & Southern China Municipal Engineering Design and Research Institute Co., Ltd., Wuhan, Hubei 430010, China
| | - Xinli Hu
- Central & Southern China Municipal Engineering Design and Research Institute Co., Ltd., Wuhan, Hubei 430010, China
| | - Haiyan Liu
- Central & Southern China Municipal Engineering Design and Research Institute Co., Ltd., Wuhan, Hubei 430010, China
| | - Peishu Lei
- Central & Southern China Municipal Engineering Design and Research Institute Co., Ltd., Wuhan, Hubei 430010, China
| | - Jiakuan Yang
- School of Environmental Science & Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei 430074, China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Luoyu Road 1037, Wuhan, Hubei 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei 430074, China
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Zhang X, Zhang H, Wang Z, Liu T, Guo D, Hu Z. Enhanced paper sludge dewatering and in-depth mechanism by oxalic acid/Fe 2+/persulfate process. CHEMOSPHERE 2023; 311:136966. [PMID: 36280120 DOI: 10.1016/j.chemosphere.2022.136966] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 10/17/2022] [Accepted: 10/18/2022] [Indexed: 06/16/2023]
Abstract
As a typical advanced oxidation process, Fe2+-persulfate (PDS) oxidation technology has been widely and efficiently reported for enhancing sludge dewaterability. However, higher dosage of Fe2+ must be added, which will restrain the oxidation efficiency of Fe2+-PDS process. In this work, the oxalic acid (OA)/Fe2+-PDS process was studied to improve paper sludge dewatering. With the OA dosage of 6 μmol (g total solid (TS))-1, Fe2+ dosage of 0.3 mmol (g TS)-1, and PDS dosage of 0.6 mmol (g TS)-1, sludge dewaterability was improved more efficiently. The specific resistance to filtration and water content of sludge cake were decreased by 70.7% and 8.0%, respectively. In comparison with Fe2+-PDS process, the viscosities of sludge suspension and supernatant were further reduced by 3.73% and 51.77%, respectively, and the contents of extracellular polymeric substances fractions were increased. The improved sludge dewaterability in OA/Fe2+-PDS process was mainly contributed by the synergistic effect of oxidative disintegration by free radicals and flocs re-flocculation, the contributions of which were the orders: metal cations > sulfate radical > hydroxyl radical. OA enhanced the efficient disintegration of sludge flocs, released more bound water, generated more Fe3+-oxalate complexes, and finally increased the sludge particle size significantly, forming a larger aggregation and obvious cracks. Additionally, the stabilization of several heavy metals was improved due to the chelating capacity of OA. These works will provide a novel approach for sludge dewatering in the PDS oxidation process.
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Affiliation(s)
- Xin Zhang
- School of Environmental and Natural Resources, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, 310023, China; State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510000, China; Zhejiang Shanying Paper CO., LTD, Jiaxing, Zhejiang, 314000, China; Northeast Petroleum University, Daqing, Heilongjiang, 163318, China.
| | - Hongtao Zhang
- School of Environmental and Natural Resources, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, 310023, China
| | - Zhenchang Wang
- School of Environmental and Natural Resources, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, 310023, China
| | - Tao Liu
- Zhejiang Shanying Paper CO., LTD, Jiaxing, Zhejiang, 314000, China
| | - Daliang Guo
- School of Environmental and Natural Resources, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, 310023, China
| | - Zhijun Hu
- School of Environmental and Natural Resources, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, 310023, China
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Chen K, Sun Y, Fan J, Gu Y. The dewatering performance and cracking-flocculation-skeleton mechanism of bioleaching-coal fly ash combined process for sewage sludge. CHEMOSPHERE 2022; 307:135994. [PMID: 35973485 DOI: 10.1016/j.chemosphere.2022.135994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 07/27/2022] [Accepted: 08/07/2022] [Indexed: 06/15/2023]
Abstract
High water content in sludge will affect the transportation and subsequent disposal of sludge. Bioleaching is a biological sludge conditioning technology, which can effectively improve the dewatering performance of sludge and reduce the content of heavy metals in sludge. Coal fly ash, as a skeleton builder, can also improve the dewatering performance of sludge. In this study, bioleaching combined with coal fly ash (BL-CFA) process was employed to improve sludge dewatering performance. Based on the results of response surface methodology (RSM), the capillary suction time (CST) and water content (WC) of sludge decreased by 52.27% and 38.92%, respectively. The dewatering effect of BL-CFA is superior compared with single process. For extracellular polymeric substances (EPS), the content of protein and polysaccharide in tightly and loosely EPS (TB-EPS and LB-EPS) of sludge decreased after BL-CFA process, while that in soluble EPS (S-EPS) increased. Three-dimensional fluorescence indicated that the weakened fluorescent areas of proteinoid and soluble microbial by-product-like (SMP) organic in LB-EPS and TB-EPS, which is beneficial to the improvement of sludge dewatering performance. Fourier transform infrared (FTIR) spectroscopy showed that the polysaccharides and proteins in the sludge were cleaved and released into the supernatant after BL-CFA process. The variation of particle size revealed that flocculation occurred after adding CFA into acidified sludge, and a supporting structure was formed in the sludge with the assist of CFA through the analysis of the scanning electron microscopy (SEM). Based on the above results, a triple dehydration mechanism was proposed for BL-CFA process, namely, cracking-flocculation-skeleton construction, which endows the combined process with superior sludge dewatering effect and application potential.
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Affiliation(s)
- Kai Chen
- School of Civil Engineering, Southeast University, Nanjing, 210096, China
| | - Yue Sun
- School of Civil Engineering, Southeast University, Nanjing, 210096, China.
| | - Jun Fan
- Nanjing Huachuang Environmental Technology Research Institute Co., Ltd, Nanjing, 210096, China
| | - YingPeng Gu
- School of Civil Engineering, Southeast University, Nanjing, 210096, China
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6
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Lv H, Liu Y, Wu X, Lv R, Zhou X, Ma X, Xiong Q. A closed-loop electrokinetic system for recovery of PbO 2@Fe composite derived from lead-containing sludge. CHEMOSPHERE 2022; 304:135338. [PMID: 35709836 DOI: 10.1016/j.chemosphere.2022.135338] [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: 05/17/2022] [Revised: 06/10/2022] [Accepted: 06/11/2022] [Indexed: 06/15/2023]
Abstract
Lead-containing sludge produced from lead-acid battery factory will cause environmental hazards if they are not treated properly. A novel process was developed to recycle lead from sludge back into Fe-doped PbO2 electrodes and realize sludge reduction in this study. The effects of Fenton conditioning on Pb removal efficiency in electro-kinetic (EK) treatment process and its mechanism as well as electro-dewatering (ED) performance were investigated. It was found that the oxidation of Fenton can promote desorption and release of Pb from the organic binding state, and improve the removal efficiency of Pb during EK process, as well as enhance sludge ED performance. About 63.8 wt% Pb can be removed from sludge during EK process, achieving sludge reduction of 63.5 wt% by ED treatment. The composite PbO2@Fe electrode recovered from lead-containing sludge showed a high electrocatalytic activity for acid red G (ARG) degradation. The electrode obtained by electrodeposition at 20 mA cm-2 had the largest exchange current density (3.26 × 10-5 A cm-2). In the experiment of dye wastewater electrocatalytic degradation, over 99.5% organic matter was degraded within 80 min.
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Affiliation(s)
- Hang Lv
- Hubei Engineering University, Wuhan, Hubei, 432000, China; School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Yao Liu
- College of Environmental and Biological Engineering, Wuhan Technology and Business University, Wuhan, Hubei, 430065, China
| | - Xu Wu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Ruibing Lv
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Xiangjun Zhou
- College of Urban and Environmental Sciences, Hubei Normal University, Huangshi, Hubei, 435002, China
| | - Xiao Ma
- College of Urban and Environmental Sciences, Hubei Normal University, Huangshi, Hubei, 435002, China
| | - Qiao Xiong
- College of Urban and Environmental Sciences, Hubei Normal University, Huangshi, Hubei, 435002, China.
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7
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Hung CM, Chen CW, Huang CP, Dong CD. Removal of 4-nonylphenol in activated sludge by peroxymonosulfate activated with sorghum distillery residue-derived biochar. BIORESOURCE TECHNOLOGY 2022; 360:127564. [PMID: 35788388 DOI: 10.1016/j.biortech.2022.127564] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 06/15/2023]
Abstract
The presence of 4-nonylphenol (4-NP), an endocrine disrupting chemical, waste activated sludge (WAS) or biosolids at elevated content requires effective method for 4-NP reduction in total sludge management. Herein, sorghum distillery residue-based biochar-activated peroxymonosulfate (SDRBC/PMS) system was studied as pretreatment of WAS. Results indicated 91% of 4-NP removal at pH 6.0 in the presence of 3.1 × 10-6 M and 0.8 g L-1 PMS and SDRBC500, individually. The synergetic effects of singlet oxygen (1O2) and the abundant functional sites (C = O/C-O content) of SDRBC significantly improved 4-NP degradation. The decreased fluorescent dissolved organic matter (DOM) in the sludge also enhanced the pretreatment efficiency. Moreover, the enrichment of the Nitrospira functional bacteria in the microbial community yielded the highest 4-NP degradation in the SDRBC/PMS-pretreated sludge. The SDRBC/PMS system functions mainly via nonradical-mediated oxidation pathway in pretreating WAS in particular and potentially by combined advanced oxidation and biodegradation processes for wastewater treatment in general.
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Affiliation(s)
- Chang-Mao Hung
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
| | - Chiu-Wen Chen
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
| | - Chin-Pao Huang
- Department of Civil and Environmental Engineering, University of Delaware, Newark, USA
| | - Cheng-Di Dong
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan.
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Liang J, Zhou Y. Iron-based advanced oxidation processes for enhancing sludge dewaterability: State of the art, challenges, and sludge reuse. WATER RESEARCH 2022; 218:118499. [PMID: 35537253 DOI: 10.1016/j.watres.2022.118499] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/12/2022] [Accepted: 04/21/2022] [Indexed: 06/14/2023]
Abstract
The increasing amount of sewage sludge produced in wastewater treatment plants (WWTPs) poses a great challenge to both environment and economy globally. As a requisite process during sludge treatment, sludge dewatering can significantly minimize the sludge volume and lower the operational cost for downstream transportation and disposal. Iron-based advanced oxidation process (AOP), a robust and cost-effective technique with relatively low technical barriers for high-level sludge dewatering, has been widely explored in the past 20 years. The development was mainly driven by the demands of efficient and sustainable sludge conditioning technology and the flexible sludge management approaches. The application of iron-based AOPs in sludge dewatering process attracts more and more attention. In this work, we discussed the current application of iron-based AOPs technology in the sludge dewatering processes in a holistic manner, summarized the factors affecting the sludge dewaterability in the treatment processes, and analyzed the mechanisms of iron-based AOPs to improve dewatering processes. Furthermore, we elaborated potential advantages, limitations, and challenges associated with implementing iron-based AOPs in the full-scale plants and shared the opportunities for sludge reutilization. This review aims to contribute to the development of highly efficient iron-based AOPs for sludge dewatering and offer perspectives and directions towards the new-generation of WWTPs with the sustainable and eco-friendly benefits.
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Affiliation(s)
- Jialin Liang
- Engineering and Technology Research Center for Agricultural Land Pollution Integrated Prevention and Control of Guangdong Higher Education Institute, College of Resources and Environment, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Yan Zhou
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore.
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Li X, Shi Y, Zhou X, Wang L, Zhang H, Pi K, Gerson AR, Liu D. Adaptability of organic matter and solid content to Fe 2+/persulfate and skeleton builder conditioner for waste activated sludge dewatering. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:14819-14829. [PMID: 34617233 DOI: 10.1007/s11356-021-16404-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 09/03/2021] [Indexed: 06/13/2023]
Abstract
Sludge conditioning is important for improved dewatering, with the sludge characteristics impacting the effect of conditioning. A composite conditioner, Fe2+-activated sodium persulfate (Fe2+/SPS) combined with phosphogypsum (PG), was used to examine its impact on sludges with different organic contents (34.6-43.8%) or different solid contents (2.8-5.9%). Response surface optimization analysis shows that when the best conditioning is achieved, the reduction of the specific resistance to filtration (SRF) is not sensitive to organic matter content, but the dewatering performance of the sludge is greatly affected by the solid content. The oxidation role of Fe2+/SPS and the skeleton builder role of PG together affect the conditioning, oxidation playing a major role in conditioning, especially for greater organic matter content. The organic content (maximum ηSOL value was 0.32) also affects the effectiveness of the skeleton builder more than the solid content (Maximum ηSOL value was 0.25). Changes in PG significantly impacts the optimal molar ratio and dosage of Fe2+/SPS. Sludge with greater solid content requires greater Fe2+/SPS dosage to provide stronger oxidation to destroy flocs, and the maximum Fe2+:SPS molar ratio was 1.14 with solid content of 5.9 wt%. The composite conditioning decreases the content of extracellular polymeric substances and proteins/polysaccharides. This study provides new insight into the relationship between the oxidation role of Fe2+/SPS and the skeleton builder role of PG for sludge conditioning strategies according to the optimal conditions.
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Affiliation(s)
- Xiaoran Li
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, Hubei, China
| | - Yafei Shi
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, Hubei, China.
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Wuhan, 430068, Hubei, China.
| | - Xi Zhou
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, Hubei, China
| | - Lu Wang
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, Hubei, China
| | - Huiqin Zhang
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, Hubei, China
| | - Kewu Pi
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, Hubei, China
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Wuhan, 430068, Hubei, China
| | - Andrea R Gerson
- Blue Minerals Consultancy, Wattle Grove, Tasmania, 7109, Australia
| | - Defu Liu
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, Hubei, China
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, Wuhan, 430068, Hubei, China
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Wang Z, Wang H, Wang Z, Huang D, Qin H, He Y, Chen M, Zeng G, Xu P. Ferrocene modified g-C3N4 as a heterogeneous catalyst for photo-assisted activation of persulfate for the degradation of tetracycline. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127024] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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11
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Coupling electro-dewatering and low-temperature air-drying for efficient dewatering of sludge. Sci Rep 2021; 11:19167. [PMID: 34580359 PMCID: PMC8476545 DOI: 10.1038/s41598-021-98477-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 09/08/2021] [Indexed: 12/05/2022] Open
Abstract
This study investigated the effects of electro-dewatering on subsequent low-temperature drying at various potentials and the characteristics of low-temperature air-drying sludge were explored through experiments and multi-physical modeling. Experimental results showed that the extracellular polymeric substance (EPS) content in the sludge was reduced during electro-dewatering process, even the species of organic matter was changed, as well as the dewatered cake tend to form many seepage channels, crack and a certain number of holes. These changes in the properties and structure were conducive to the subsequent low-temperature drying process. For air-drying process, the mass of the sludge cake variation was simulated and results were consistent with the experimental phenomenon. Firstly, the weight of the sludge cake was decreased approximately linearly with time, then tended to stable and reached the dewatering limitation finally. The applied higher electric field intensity (25 V cm−1) in the front-end electro-dewatering were conducive to promote water vapor diffusion activity in air-drying stage. Energy consumption and yield analysis results indicated that the combined technology has lower energy consumption and higher yield than that of directly low-temperature drying.
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12
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Guo J, Gao Q, Chen Y, He Q, Zhou H, Liu J, Zou C, Chen W. Insight into sludge dewatering by advanced oxidation using persulfate as oxidant and Fe 2+ as activator: Performance, mechanism and extracellular polymers and heavy metals behaviors. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 288:112476. [PMID: 33827020 DOI: 10.1016/j.jenvman.2021.112476] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 03/14/2021] [Accepted: 03/23/2021] [Indexed: 06/12/2023]
Abstract
This study established a Fe2+/persulfate oxidation system to dewater sludge in WWTPs. Dewatering performance, persulfate consumption and the variations of sludge pH, TN and TP during dewatering process were monitored. EPS and ζ-potential behaviors for ameliorating sludge dewatering was investigated. Transformation, leaching toxicity and environmental risk of heavy metals in sludge during dewatering were determined. Results demonstrated that after treated by Fe2+/persulfate oxidation system with 0.6 mmol/g-VS of persulfate at Fe2+/persulfate molar ratio 0.6, WC decreased to 53.5% and SCST increased to 4.15, which implied an excellent improvement of sludge dewatering. The fast persulfate consumption, the decrease of sludge pH and the increase of TN illustrated the positive effects of Fe2+ in activating persulfate and the decomposition of EPS by the activation products, SO4•- and •OH. Another product (Fe3+) generated during persulfate activation could decrease the content of phosphorus-containing matter (released from EPS decomposition) through the precipitation reaction with PO43-. The decrease of TOC and UV-254 happened in HPO-A, HPO-N and TPI-A organic substance of EPS (mainly contained in TB-EPS fraction) indicated that the destruction of hydrophobic organic matter of EPS would stimulate the release of bound water, which was beneficial to dewater sludge. The largest protein loss in TB-EPS (from 24.5 to 10.7 mg/L) indicated that the effective decomposition of TB-EPS could significantly ameliorate sludge dewatering. The increase of ζ-potential indicated the degradation of organic matter in EPS with negative charge. To sum up, the destruction of protein-like substances in hydrophobic organic matter of TB-EPS was the main mechanism for improving sludge dewatering by Fe2+/persulfate oxidation system. 3D-EEM fluorescence spectroscopy analysis proved that these protein-like substances were mainly tryptophan protein and humic acid. Moreover, due to the disruption of EPS, the contents of heavy metals in sludge, and their leaching toxicity and environmental risk were reduced. Therefore, Fe2+/persulfate oxidation system has potential and application prospects to improve sludge dewatering and optimize sludge management in WWTPs.
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Affiliation(s)
- Junyuan Guo
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China.
| | - Qifan Gao
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China
| | - Yihua Chen
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China
| | - Qianlan He
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China
| | - Hengbing Zhou
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China
| | - Jinbao Liu
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China
| | - Changwu Zou
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China
| | - Wenjing Chen
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China
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Zhao Y, Yuan X, Li X, Jiang L, Wang H. Burgeoning prospects of biochar and its composite in persulfate-advanced oxidation process. JOURNAL OF HAZARDOUS MATERIALS 2021; 409:124893. [PMID: 33418291 DOI: 10.1016/j.jhazmat.2020.124893] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 06/12/2023]
Abstract
In the last decade, more and more refractory organic contaminants with severe health risks have been detected in the aquatic ecosystem. Sulfate radical (SO4·-)-based advanced oxidation process (SR-AOP) is recognized as an efficient approach for the removal of organic contaminants. Biochar (BC) and its composites (BCs) have been applied into SR-AOP for the double advantages of adsorption and catalytic ability. This paper gives systematic emphasis to the development and progress of biochar and its composites as catalyst in persulfate-advanced oxidation process. Synthetic techniques including the directed pyrolysis of mixed materials and post-immersed method are discussed. The physicochemical properties of biochar (such as surface area, surface functional groups, defect structure and persistent free radicals, etc.) that affect persulfate activation are provided. Then, emphasis is placed on the crucial role of biochar in affecting the catalytic property of BCs including stabilizing nanoparticles, expanding the surface area, increasing active sites and regulating electron transfer reactions. Integrating mechanistic insights and different biochar-based catalysts highlight the understanding of persulfate activation and catalytic degradation. Possible challenges are finally proposed in the fundamental research and practically scaled-up application.
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Affiliation(s)
- Yanlan Zhao
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Xingzhong Yuan
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China.
| | - Xiaodong Li
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Longbo Jiang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Hou Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China; Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
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Guo J, Jia X, Gao Q. Insight into the improvement of dewatering performance of waste activated sludge and the corresponding mechanism by biochar-activated persulfate oxidation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 744:140912. [PMID: 32683170 DOI: 10.1016/j.scitotenv.2020.140912] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 06/22/2020] [Accepted: 07/10/2020] [Indexed: 06/11/2023]
Abstract
A novel activator, corn biochar, was produced to activate persulfate to dewater waste activated sludge (WAS). Results demonstrated that the biochar-activated persulfate oxidation can effectively improve the dewatering performance of WAS. After treating WAS by biochar-activated persulfate oxidation (biochar dosage: 2.1 g/L, persulfate concentration: 7.5 mM) at the original WAS pH, standardized-capillary suction time (SCST) increased to 4.21 times and moisture content (MC) decreased to 43.4%, indicating an excellent performance of WAS dewatering. The decrease of residual persulfate with the increasing biochar dosage during WAS dewatering process illustrated that the role of persulfate in improving WAS dewatering was because of the biochar activation. The behaviors of extracellular polymers (EPS) proved that the protein in tightly bound EPS (TB-EPS) linked to WAS dewatering, and its content significantly reduced to 10.5 mg/g-volatile solids (VS) after WAS treatment. Three-dimensional fluorescence spectroscopy for EPS once again proved that the disintegration of tryptophan protein and humic acid (hydrophobic organic substances in EPS) was responsible for the improvement of WAS dewatering. To sum up, the biochar-activated persulfate oxidation was a feasible application in improving WAS dewatering.
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Affiliation(s)
- Junyuan Guo
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan 610225, China.
| | - Xiaojuan Jia
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan 610225, China
| | - Qifan Gao
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan 610225, China
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15
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Guo J, Wen X, Yang J, Fan T. Removal of benzo(a)pyrene in polluted aqueous solution and soil using persulfate activated by corn straw biochar. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2020; 272:111058. [PMID: 32669257 DOI: 10.1016/j.jenvman.2020.111058] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 07/02/2020] [Accepted: 07/04/2020] [Indexed: 06/11/2023]
Abstract
An activator, corn straw biochar, was produced and applied in persulfate-based oxidation to remove benzo(a)pyrene (BaP) in polluted aqueous solution and soil. Polluted aqueous solution remediation results showed that at pH 7, approximately 88.4% of BaP was removed by 10 mM of persulfate activated by 1.6 g/L of biochar, and degradation played a dominant role. Polluted soil remediation results demonstrated that the activated persulfate solution (at 9 g/L) by biochar (at 3 wt% of soil) can remove 93.2% of BaP. In remediation of BaP-polluted soil, increasing biochar dosage and persulfate concentration accelerated BaP degradation to some extent, while excessive biochar or persulfate inhibited the degradation of BaP probably due to the unnecessary SO4- consumption. The biochar-activated persulfate oxidation reflected a good performance in tolerating the influences of background electrolytes (such as HCO3-, Cl-, and humic acid (HA)) in soil on BaP remediation. In addition, in the removal of BaP by the oxidation systems activated by biochar, persulfate was proved as a superior oxidant compared to peroxymonosulfate and H2O2, and the removal efficiencies of BaP were 93.2%, 86.5%, and 84.4% under the same treatment condition. To sum up, the biochar-activated persulfate oxidation would be a potential application in remediation of BaP-polluted aqueous solution and soil.
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Affiliation(s)
- Junyuan Guo
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China.
| | - Xiaoying Wen
- College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China
| | - Jiawei Yang
- National Institute of Measurement and Testing Technology, Chengdu, Sichuan, 610021, China
| | - Ting Fan
- Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, Sichuan, 610041, China
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Liang J, Zhang L, Yan W, Zhou Y. Mechanistic insights into a novel nitrilotriacetic acid-Fe 0 and CaO 2 process for efficient anaerobic digestion sludge dewatering at near-neutral pH. WATER RESEARCH 2020; 184:116149. [PMID: 32750584 DOI: 10.1016/j.watres.2020.116149] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/29/2020] [Accepted: 07/03/2020] [Indexed: 06/11/2023]
Abstract
Traditional Fenton or Fenton-like oxidation has been widely studied for waste activated sludge dewaterability. However, the narrow pH range (2.0-4.0) and the instabilities of Fe2+ and H2O2 have hindered its commercial application. Owing to the high alkalinity of anaerobic digestion (AD) sludge, traditional Fenton or Fenton-like oxidation is economically unfeasible for its dewatering. In this study, we successfully demonstrated a novel and feasible method that used nitrilotriacetic acid (NTA)-Fe0 combined with CaO2 (NTA-Fe0/CaO2) at near-neutral pH (∼6.0) (a slight pH adjustment) in which capillary suction time ratio (CST0/CST) and centrifuged weight reduction (CWR) improved by 6 folds and 42.98 ± 0.37%, respectively, under the optimal conditions. The presence of NTA accelerated the Fe0 corrosion, Fe2+ stability and turnover between Fe2+ and Fe3+. As such, Fe0 could effectively catalyze CaO2 to produce hydroxyl radicals (•OH) under near-neutral conditions. Accordingly, various molecular weight hydrophilic compounds in different extracellular polymeric substances fractions were significantly reduced after treatment. The hydrophilic functional groups especially protein molecules were largely reduced. Consequently, the viscosity of sludge and particle size effectively decreased, while the release of bound water, surface charge, flocculation, and flowability of sludge were improved. The cost-benefit analysis further demonstrated the NTA-Fe0/CaO2 treatment has high reusability and stability and is also more economical over the FeCl3/CaO and Fenton's reagent/CaO treatments. In summary, the NTA-Fe0/CaO2 process is a cost-effective and practically feasible technology for improving AD sludge dewaterability.
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Affiliation(s)
- Jialin Liang
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore; School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, China
| | - Liang Zhang
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore
| | - Wangwang Yan
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore
| | - Yan Zhou
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore.
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Phytoremediation of Cadmium: Physiological, Biochemical, and Molecular Mechanisms. BIOLOGY 2020; 9:biology9070177. [PMID: 32708065 PMCID: PMC7407403 DOI: 10.3390/biology9070177] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 12/15/2022]
Abstract
Cadmium (Cd) is one of the most toxic metals in the environment, and has noxious effects on plant growth and production. Cd-accumulating plants showed reduced growth and productivity. Therefore, remediation of this non-essential and toxic pollutant is a prerequisite. Plant-based phytoremediation methodology is considered as one a secure, environmentally friendly, and cost-effective approach for toxic metal remediation. Phytoremediating plants transport and accumulate Cd inside their roots, shoots, leaves, and vacuoles. Phytoremediation of Cd-contaminated sites through hyperaccumulator plants proves a ground-breaking and profitable choice to combat the contaminants. Moreover, the efficiency of Cd phytoremediation and Cd bioavailability can be improved by using plant growth-promoting bacteria (PGPB). Emerging modern molecular technologies have augmented our insight into the metabolic processes involved in Cd tolerance in regular cultivated crops and hyperaccumulator plants. Plants’ development via genetic engineering tools, like enhanced metal uptake, metal transport, Cd accumulation, and the overall Cd tolerance, unlocks new directions for phytoremediation. In this review, we outline the physiological, biochemical, and molecular mechanisms involved in Cd phytoremediation. Further, a focus on the potential of omics and genetic engineering strategies has been documented for the efficient remediation of a Cd-contaminated environment.
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The Effects of Energy Consumption, Economic Growth and Financial Development on CO2 Emissions in China: A VECM Approach. SUSTAINABILITY 2019. [DOI: 10.3390/su11184850] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
As one of the largest energy consumers and the greatest emitter of CO2 in the world, China now confronts the dual challenge of reducing energy use while continuing to foster economic growth. To overcome this issue, there is a need of comprehensive economic, financial, and energy policy reforms to promote sustainable development. The objective of this paper is to examine the effects of economic growth, financial development and energy consumption on carbon dioxide emission (CO2) in China from 1982 to 2017. The study applies Johansen cointegration test and vector error correction model (VECM) to investigate the long-term equilibrium and short-term causality relationship among the four variables. The causality is also checked by using the innovative accounting approach (IAA). The empirical results show the long-term cointegration relationship between them. Evidence shows that a unidirectional Granger causality running from energy consumption to financial development. Financial development and energy consumption have a statistically significant positive impact on CO2 emissions. In the long run, economic growth can curb CO2 emissions. Hence, financial innovation should be encouraged in the country to meet the demand of sustainable development. Nevertheless, optimizing energy structure and increasing the efficiency of energy utilization can never be left out from the process of development. We add light to policy makers with the construction of carbon trading to effectively address greenhouse effects in China.
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