Automotive catalysts are the largest consumption source of platinum group metals (PGMs). When it exceeds its useful life, spent automotive catalysts (SACs) are the most important secondary PGMs resource and are classified as hazardous solid waste. Recycling SAC is a promising solution to alleviate the shortage of PGMs resources for projects and reduce environmental pollution. The technology for recovering PGMs by iron-melting collection can obtain Fe-PGMs alloy and harmless glass slag. In this paper, the spontaneous aggregation and growth behaviour of Fe and PGMs in slag at melting temperature were studied, and the settling velocity of Fe-PGMs particles in the slag was calculated to be 6.68 × 10-3 m/s. The effects of melting time, melting temperature and Fe dosage on PGMs recovery were determined, and the optimal conditions were 10 wt% Fe, 1500°C and 40 min. The toxicity test verifies that the slag obtained is a clean slag harmless to the environment. This work explains the mechanism of Fe collection of PGMs and provides a pathway for efficient and harmless recovery of PGMs from SAC.
{"title":"Iron capture mechanism for harmless recovering platinum group metals from spent automobile catalyst.","authors":"Shubo A, Shuchen Sun, Ganfeng Tu, Ronghui Liu, Faxin Xiao, Ruifeng Shi, Chengfu Sui, Kuopei Yu","doi":"10.1080/09593330.2024.2398809","DOIUrl":"https://doi.org/10.1080/09593330.2024.2398809","url":null,"abstract":"<p><p>Automotive catalysts are the largest consumption source of platinum group metals (PGMs). When it exceeds its useful life, spent automotive catalysts (SACs) are the most important secondary PGMs resource and are classified as hazardous solid waste. Recycling SAC is a promising solution to alleviate the shortage of PGMs resources for projects and reduce environmental pollution. The technology for recovering PGMs by iron-melting collection can obtain Fe-PGMs alloy and harmless glass slag. In this paper, the spontaneous aggregation and growth behaviour of Fe and PGMs in slag at melting temperature were studied, and the settling velocity of Fe-PGMs particles in the slag was calculated to be 6.68 × 10<sup>-3</sup> m/s. The effects of melting time, melting temperature and Fe dosage on PGMs recovery were determined, and the optimal conditions were 10 wt% Fe, 1500°C and 40 min. The toxicity test verifies that the slag obtained is a clean slag harmless to the environment. This work explains the mechanism of Fe collection of PGMs and provides a pathway for efficient and harmless recovery of PGMs from SAC.</p>","PeriodicalId":12009,"journal":{"name":"Environmental Technology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142344173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-26DOI: 10.1080/09593330.2024.2402098
Emma van Dommelen, Lillian Des Rosiers, Elizabeth Crafton, Natalie M Hull
Microcystins (MCs), a toxin produced by some species of the photosynthetic autotrophic cyanobacteria, are the most studied and monitored cyanotoxin in water. Water treatment plant (WTP) residuals are the byproduct of water treatment consisting of solids removed from WTP processes and have been shown to contain cyanobacterial cells. However, the presence of MCs in WTP residuals has not been systematically demonstrated. Samples from four different WTPs across the United States were used to quantify MCs in residuals while assessing extraction and quantification methods adapted from water samples for solid matrices. MCs were present in 100% of samples. MC-LA was the most prevalent variant in these samples (70.05% of MCs quantified by UPLC-PDA). Natural degradation observed in a WTP storage lagoon was also investigated to determine the impact of physical, chemical, and biological processes on MC concentrations in high-biomass residuals. This study demonstrates that residuals of various characteristics across the United States contain MCs, and no one method was found to maximize results consistently across all samples. Cyanotoxins accumulating in WTP residuals are a growing concern. Implications of this work can help regulations and future studies of potential reuse applications and understanding of potential ecological significance of MCs accumulating in WTP residuals.
微囊藻毒素(MCs)是由某些种类的光合自养蓝藻产生的毒素,是研究和监测最多的水中蓝藻毒素。水处理厂残留物是水处理过程中的副产品,由水处理厂处理过程中去除的固体组成,已被证明含有蓝藻细胞。然而,水处理厂残留物中 MCs 的存在尚未得到系统的证实。研究人员利用来自美国四个不同水处理厂的样本对残留物中的 MCs 进行了定量,同时评估了针对固体基质的水样提取和定量方法。100%的样品中都含有 MCs。MC-LA 是这些样品中最常见的变体(UPLC-PDA 定量的 MC 占 70.05%)。此外,还对水处理厂储存池中观察到的自然降解过程进行了调查,以确定物理、化学和生物过程对高生物量残留物中 MC 浓度的影响。这项研究表明,美国各地不同特性的残留物中都含有 MCs,而且没有发现任何一种方法能够在所有样本中始终如一地获得最佳结果。水处理厂残留物中积累的氰毒素日益受到关注。这项工作所产生的影响有助于对潜在的再利用应用进行监管和未来研究,并有助于了解水处理厂残留物中积累的 MCs 的潜在生态意义。
{"title":"Microcystins are present in water treatment plant residuals and are impacted by extraction and quantification methodology.","authors":"Emma van Dommelen, Lillian Des Rosiers, Elizabeth Crafton, Natalie M Hull","doi":"10.1080/09593330.2024.2402098","DOIUrl":"https://doi.org/10.1080/09593330.2024.2402098","url":null,"abstract":"<p><p>Microcystins (MCs), a toxin produced by some species of the photosynthetic autotrophic cyanobacteria, are the most studied and monitored cyanotoxin in water. Water treatment plant (WTP) residuals are the byproduct of water treatment consisting of solids removed from WTP processes and have been shown to contain cyanobacterial cells. However, the presence of MCs in WTP residuals has not been systematically demonstrated. Samples from four different WTPs across the United States were used to quantify MCs in residuals while assessing extraction and quantification methods adapted from water samples for solid matrices. MCs were present in 100% of samples. MC-LA was the most prevalent variant in these samples (70.05% of MCs quantified by UPLC-PDA). Natural degradation observed in a WTP storage lagoon was also investigated to determine the impact of physical, chemical, and biological processes on MC concentrations in high-biomass residuals. This study demonstrates that residuals of various characteristics across the United States contain MCs, and no one method was found to maximize results consistently across all samples. Cyanotoxins accumulating in WTP residuals are a growing concern. Implications of this work can help regulations and future studies of potential reuse applications and understanding of potential ecological significance of MCs accumulating in WTP residuals.</p>","PeriodicalId":12009,"journal":{"name":"Environmental Technology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142344174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polyhydroxyalkanoates (PHAs) are important and completely biodegradable alternatives to regular plastics, and they can be produced by activated sludge systems during wastewater treatment. Wastewaters with high organic content are being used for PHA production, which is an important resource recovery option. In this context, the effect of sludge retention time and different carbon sources, such as acetate, peptone-mixture and industrial wastewater (containing acetic acid (AA), lactic acid (LA) and propionic acid (PA)), on PHA storage was investigated. Oxygen utilisation rate (OUR) profiles were generated in respirometric tests and were evaluated by activated sludge modelling. Results showed that high storage (AA: 70%; LA: 49%; PA: 60% and industrial wastewater: 52%) was achievable in the feast phase even when the biomass was fed with a high organic acid content substrate to which it is not acclimated.
{"title":"Effect of culture history and carbon sources on polyhydroxyalkanoates production in activated sludge systems.","authors":"Bengisu Ciftcioglu-Gozuacik, Ilke Pala-Ozkok, Emine Ubay-Cokgor","doi":"10.1080/09593330.2024.2406987","DOIUrl":"https://doi.org/10.1080/09593330.2024.2406987","url":null,"abstract":"<p><p>Polyhydroxyalkanoates (PHAs) are important and completely biodegradable alternatives to regular plastics, and they can be produced by activated sludge systems during wastewater treatment. Wastewaters with high organic content are being used for PHA production, which is an important resource recovery option. In this context, the effect of sludge retention time and different carbon sources, such as acetate, peptone-mixture and industrial wastewater (containing acetic acid (AA), lactic acid (LA) and propionic acid (PA)), on PHA storage was investigated. Oxygen utilisation rate (OUR) profiles were generated in respirometric tests and were evaluated by activated sludge modelling. Results showed that high storage (AA: 70%; LA: 49%; PA: 60% and industrial wastewater: 52%) was achievable in the feast phase even when the biomass was fed with a high organic acid content substrate to which it is not acclimated.</p>","PeriodicalId":12009,"journal":{"name":"Environmental Technology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142344073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rice cultivation under flooded conditions usually leads to a high accumulation of arsenic (As) in grains. Sulphur and iron played vital roles in affecting the bioavailability of As in the soil-rice system. Herein, using pot experiments, we investigated the effects of persulphate (PS) and ferrous (Fe2+) on the transfer and accumulation of As in the soil-rice system under flooded conditions. The concentration of As and Fe in soil porewater declined with continuous flooding. Persulphate/ferrous addition significantly inhibited the formation of iron plaque and the transfer of As to the aboveground tissues of rice. The total As, dimethylarsinicacid (DMA), As (III), and As (V) in grains significantly decreased by 49∼75%, 60∼89%, 20∼24%, and 35∼36%, respectively, by persulphate/ferrous application. Furthermore, a decrease of As in husk, leaf, and, stem was also found in persulphate and ferrous treatment. To some degree, the Fe2+ can facilitate the decreased efficiency of As accumulation and translocation in rice tissue. The present study's results demonstrated that applying persulphate/Fe2+ could effectively alleviate the excessive accumulation of As in rice grains in the soil-rice system under flooding conditions.
{"title":"Mitigating arsenic accumulation in rice plant in paddy soil: influence of persulphate and ferrous application.","authors":"Jianqiang Zhang, Zhiliang Chen, Qi Zou, Zihan Zeng, Menqiang Sun, Hang Wei","doi":"10.1080/09593330.2024.2405661","DOIUrl":"https://doi.org/10.1080/09593330.2024.2405661","url":null,"abstract":"<p><p>Rice cultivation under flooded conditions usually leads to a high accumulation of arsenic (As) in grains. Sulphur and iron played vital roles in affecting the bioavailability of As in the soil-rice system. Herein, using pot experiments, we investigated the effects of persulphate (PS) and ferrous (Fe<sup>2+</sup>) on the transfer and accumulation of As in the soil-rice system under flooded conditions. The concentration of As and Fe in soil porewater declined with continuous flooding. Persulphate/ferrous addition significantly inhibited the formation of iron plaque and the transfer of As to the aboveground tissues of rice. The total As, dimethylarsinicacid (DMA), As (III), and As (V) in grains significantly decreased by 49∼75%, 60∼89%, 20∼24%, and 35∼36%, respectively, by persulphate/ferrous application. Furthermore, a decrease of As in husk, leaf, and, stem was also found in persulphate and ferrous treatment. To some degree, the Fe<sup>2+</sup> can facilitate the decreased efficiency of As accumulation and translocation in rice tissue. The present study's results demonstrated that applying persulphate/Fe<sup>2+</sup> could effectively alleviate the excessive accumulation of As in rice grains in the soil-rice system under flooding conditions.</p>","PeriodicalId":12009,"journal":{"name":"Environmental Technology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142344175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-26DOI: 10.1080/09593330.2024.2406989
Jucélia T Ferreira, Fernanda M Amaral, Ana Christina Brasileiro-Vidal, Raquel P Bezerra, Albean S C Bezerra, Fabricio Motteran, Mário T Kato, Lourdinha Florencio, Osmar Menezes, Sávia Gavazza
The removal of the tetra-azo dye Direct Black 22 (DB22) using the microalga Chlorella vulgaris was evaluated in the present study, aiming to understand the contribution of different processes (biodegradation, photodegradation, and adsorption) in the removal of this contaminant. The growth and morphological characteristics of C. vulgaris were not affected by the presence of the dye in the reaction medium. The efficiency of dye removal was 62.6 ± 1.46%, 47.7 ± 7.2% of which was attributed to photodegradation, while 13.2 ± 6.5% were associated with the contribution of the microalga by an enzymatic route and 1.7 ± 9.6% with an adsorption process. Additionally, tests with the organism Allium cepa as a bioindicator revealed that DB22 and its byproducts did not induce toxicity, but cytotoxicity and genotoxicity were induced. We observed that genotoxicity was reduced after the remediation process. Our results establish photodegradation as the primary mechanism and biodegradation as the secondary mechanism driving the removal of DB22 within a Chlorella culture. Researchers must carefully consider all aspects involved in the removal process, including photodegradation, biodegradation, and adsorption processes.
{"title":"Evaluating the removal of the tetra-azo dye direct black-22 in <i>Chlorella vulgaris</i> closed-cultivation systems.","authors":"Jucélia T Ferreira, Fernanda M Amaral, Ana Christina Brasileiro-Vidal, Raquel P Bezerra, Albean S C Bezerra, Fabricio Motteran, Mário T Kato, Lourdinha Florencio, Osmar Menezes, Sávia Gavazza","doi":"10.1080/09593330.2024.2406989","DOIUrl":"https://doi.org/10.1080/09593330.2024.2406989","url":null,"abstract":"<p><p>The removal of the tetra-azo dye Direct Black 22 (DB22) using the microalga <i>Chlorella vulgaris</i> was evaluated in the present study, aiming to understand the contribution of different processes (biodegradation, photodegradation, and adsorption) in the removal of this contaminant. The growth and morphological characteristics of <i>C. vulgaris</i> were not affected by the presence of the dye in the reaction medium. The efficiency of dye removal was 62.6 ± 1.46%, 47.7 ± 7.2% of which was attributed to photodegradation, while 13.2 ± 6.5% were associated with the contribution of the microalga by an enzymatic route and 1.7 ± 9.6% with an adsorption process. Additionally, tests with the organism <i>Allium cepa</i> as a bioindicator revealed that DB22 and its byproducts did not induce toxicity, but cytotoxicity and genotoxicity were induced. We observed that genotoxicity was reduced after the remediation process. Our results establish photodegradation as the primary mechanism and biodegradation as the secondary mechanism driving the removal of DB22 within a <i>Chlorella</i> culture. Researchers must carefully consider all aspects involved in the removal process, including photodegradation, biodegradation, and adsorption processes.</p>","PeriodicalId":12009,"journal":{"name":"Environmental Technology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142344074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-25DOI: 10.1080/09593330.2024.2405664
Qiumei He, Minquan Feng, Jiakang Wang
Iron is gradually being introduced into constructed wetlands (CWs) to enhance the removal of pollutants due to its active chemical properties and ability to participate in various reactions, but its effectiveness in greenhouse effect control needs to be studied. In this study, three CWs were established to evaluate the effect of iron scraps and iron-carbon as substrates on pollutants removal and greenhouse gas (GHG) emissions, and the corresponding mechanisms were explored through analysis of microbial characteristics. The results showed that iron scraps and iron - carbon are effective in enhancing the effluent quality of CWs. Iron-carbon exhibited notable efficacy in removing nitrate nitrogen (NO3--N) and chemical oxygen demand (COD), achieving stable removal rates of 98.46% and 84.89%, respectively. Iron scraps had advantages in promoting the removal of ammonia nitrogen (NH4+-N) and total nitrogen (TN), with removal rates of 43.73% and 71.56%, respectively. The emission fluxes of nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2) had temporal variability, always peaking in the early phases of operation. While iron scraps and iron-carbon effectively reduced the average emission flux of N2O and CO2, they simultaneously increased the average emission flux of CH4 (from 0.2349-2.2698 and 1.1956mg/m2/h, respectively). From the perspective of reducing global warming potential (GWP), iron - carbon had superior performance (from 146.2548-86.7447 mg/m2/h). In addition, the greenhouse gas emission flux was closely related to the microbial community structure in CWs, particularly with a more pronounced response observed in N2O emissions.
{"title":"Impact of iron-modified fillers on enhancing water purification performance and mitigating greenhouse effect in constructed wetlands.","authors":"Qiumei He, Minquan Feng, Jiakang Wang","doi":"10.1080/09593330.2024.2405664","DOIUrl":"https://doi.org/10.1080/09593330.2024.2405664","url":null,"abstract":"<p><p>Iron is gradually being introduced into constructed wetlands (CWs) to enhance the removal of pollutants due to its active chemical properties and ability to participate in various reactions, but its effectiveness in greenhouse effect control needs to be studied. In this study, three CWs were established to evaluate the effect of iron scraps and iron-carbon as substrates on pollutants removal and greenhouse gas (GHG) emissions, and the corresponding mechanisms were explored through analysis of microbial characteristics. The results showed that iron scraps and iron - carbon are effective in enhancing the effluent quality of CWs. Iron-carbon exhibited notable efficacy in removing nitrate nitrogen (NO<sub>3</sub><sup>-</sup>-N) and chemical oxygen demand (COD), achieving stable removal rates of 98.46% and 84.89%, respectively. Iron scraps had advantages in promoting the removal of ammonia nitrogen (NH<sub>4</sub><sup>+</sup>-N) and total nitrogen (TN), with removal rates of 43.73% and 71.56%, respectively. The emission fluxes of nitrous oxide (N<sub>2</sub>O), methane (CH<sub>4</sub>), and carbon dioxide (CO<sub>2</sub>) had temporal variability, always peaking in the early phases of operation. While iron scraps and iron-carbon effectively reduced the average emission flux of N<sub>2</sub>O and CO<sub>2</sub>, they simultaneously increased the average emission flux of CH<sub>4</sub> (from 0.2349-2.2698 and 1.1956mg/m<sup>2</sup>/h, respectively). From the perspective of reducing global warming potential (GWP), iron - carbon had superior performance (from 146.2548-86.7447 mg/m<sup>2</sup>/h). In addition, the greenhouse gas emission flux was closely related to the microbial community structure in CWs, particularly with a more pronounced response observed in N<sub>2</sub>O emissions.</p>","PeriodicalId":12009,"journal":{"name":"Environmental Technology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142344172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The formation of black odour water is primarily attributed to the elevated concentration of organic pollutants, along with an excessive amount of nitrogen and phosphorus, ultimately leading to an anoxic aquatic environment. The water temperature influence mechanism on black-odorous water restoration by microporous aeration is still lacking depth study. This paper selected (15-18) ℃ (spring and autumn), (22-25) ℃ (summer), (8-11) ℃ (winter) as temperature conditions, and investigated temperature influence on nitrogen reduction. Researches showed that: (1) The removal rates of COD, NH4+-N and TN were significantly positively correlated with temperature (r = 0.99, 0.96, 0.97), the lowest removal rates were 83.16%, 95.68%, 58.7% ((8-11) ℃), the highest values were 92.67%, 98.27%, 70.96% ((22-25) ℃), respectively. (2) At a temperature range of 22-25°C, the microbial community exhibited the highest levels of abundance, diversity, and uniformity. Notably, Proteobacteria dominated this temperature range with a relative abundance of 79.72%. Furthermore, temperature positively correlated with the majority of dominant bacterial species, suggesting that conditions at 22-25°C are highly conducive to the growth of most bacterial communities. Among these, Limnohabitans, Alsobacter, and Candidatus_Aquirestis, which possess key functions in denitrification and nitrogen removal, displayed significantly higher abundances. It explains the positive correlation between temperature and removal rates of COD, TN and NH4+-N from microbial population's perspective. Thus, the best temperature for repairing black-smelly water is (22-25) ℃. This study provides technical reference for mechanism research and practical application of microporous aeration.
{"title":"Nitrogen reducing mechanism by microporous aeration based on microbial population characteristics: water temperature factor.","authors":"Cheng Lu, Yong Wang, Shengnan Zhou, Wen Cheng, JiaXuan Wang, XinYan Zhang","doi":"10.1080/09593330.2024.2405665","DOIUrl":"https://doi.org/10.1080/09593330.2024.2405665","url":null,"abstract":"<p><p>The formation of black odour water is primarily attributed to the elevated concentration of organic pollutants, along with an excessive amount of nitrogen and phosphorus, ultimately leading to an anoxic aquatic environment. The water temperature influence mechanism on black-odorous water restoration by microporous aeration is still lacking depth study. This paper selected (15-18) ℃ (spring and autumn), (22-25) ℃ (summer), (8-11) ℃ (winter) as temperature conditions, and investigated temperature influence on nitrogen reduction. Researches showed that: (1) The removal rates of COD, NH<sub>4</sub><sup>+</sup>-N and TN were significantly positively correlated with temperature (r = 0.99, 0.96, 0.97), the lowest removal rates were 83.16%, 95.68%, 58.7% ((8-11) ℃), the highest values were 92.67%, 98.27%, 70.96% ((22-25) ℃), respectively. (2) At a temperature range of 22-25°C, the microbial community exhibited the highest levels of abundance, diversity, and uniformity. Notably, <i>Proteobacteria</i> dominated this temperature range with a relative abundance of 79.72%. Furthermore, temperature positively correlated with the majority of dominant bacterial species, suggesting that conditions at 22-25°C are highly conducive to the growth of most bacterial communities. Among these, <i>Limnohabitans</i>, <i>Alsobacter</i>, and <i>Candidatus_Aquirestis</i>, which possess key functions in denitrification and nitrogen removal, displayed significantly higher abundances. It explains the positive correlation between temperature and removal rates of COD, TN and NH<sub>4</sub><sup>+</sup>-N from microbial population's perspective. Thus, the best temperature for repairing black-smelly water is (22-25) ℃. This study provides technical reference for mechanism research and practical application of microporous aeration.</p>","PeriodicalId":12009,"journal":{"name":"Environmental Technology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142344176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Development of high-performance mixed matrix membranes (MMMs) is of great significance for CO2 separation membrane technology, in order to improve the commercial competitiveness and practical applications. Montmorillonite (MMT) was developed as a dopant to fabricate Polyether block amide (Pebax1074)-based MMMs for strengthening the CO2/N2 separation. The morphology, chemical groups, microstructure, and thermal properties of MMMs were characterised by scanning electron microscope, FTIR spectroscopy, X-ray diffraction and thermal analysis, respectively. The effects of MMT contents, permeation pressure and permeation temperature on the gas separation performance of the Pebax/MMT MMMs were investigated. The results show that the uniformly dispersed dopants MMT in the membrane matrix significantly influence the thermal stability and the structural compactness of MMMs. Moreover, the CO2 permeability monotonously increases in spite of the CO2/N2 selectivity first increasing and then decreasing with the MMT content elevating from 0% to 10% in MMMs. The highest CO2/N2 selectivity could reach to 120.3, along with the CO2 permeability of 130.6 Barrer for the MMMs made by MMT content of 6%.
{"title":"Building high-speed facilitated transport channels in Pebax membranes with montmorillonite for efficient CO<sub>2</sub>/N<sub>2</sub> separation.","authors":"Bing Zhang, Renying Qian, Yu Jiang, Jian Wang, Yonghong Wu","doi":"10.1080/09593330.2024.2405666","DOIUrl":"https://doi.org/10.1080/09593330.2024.2405666","url":null,"abstract":"<p><p>Development of high-performance mixed matrix membranes (MMMs) is of great significance for CO<sub>2</sub> separation membrane technology, in order to improve the commercial competitiveness and practical applications. Montmorillonite (MMT) was developed as a dopant to fabricate Polyether block amide (Pebax1074)-based MMMs for strengthening the CO<sub>2</sub>/N<sub>2</sub> separation. The morphology, chemical groups, microstructure, and thermal properties of MMMs were characterised by scanning electron microscope, FTIR spectroscopy, X-ray diffraction and thermal analysis, respectively. The effects of MMT contents, permeation pressure and permeation temperature on the gas separation performance of the Pebax/MMT MMMs were investigated. The results show that the uniformly dispersed dopants MMT in the membrane matrix significantly influence the thermal stability and the structural compactness of MMMs. Moreover, the CO<sub>2</sub> permeability monotonously increases in spite of the CO<sub>2</sub>/N<sub>2</sub> selectivity first increasing and then decreasing with the MMT content elevating from 0% to 10% in MMMs. The highest CO<sub>2</sub>/N<sub>2</sub> selectivity could reach to 120.3, along with the CO<sub>2</sub> permeability of 130.6 Barrer for the MMMs made by MMT content of 6%.</p>","PeriodicalId":12009,"journal":{"name":"Environmental Technology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142282399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fire smoke, consisting of solid particles and liquid droplets, poses risks of asphyxiation, poisoning, making it a significant contributor to fire-related fatalities and environmental pollution. The exploration of effective smoke control methods represents a vital approach to reducing the threat of fire smoke to public health and safety. This study aims to determine the characteristics of elimination for the fire smoke generated from burning four typical materials, thereby validating the universality of electric agglomeration smoke elimination technology. The results indicate that the elimination efficiency of electric agglomeration varies with the material type of the smoke. The rate of change in smoke transmittance from fast to slow is: polyvinyl chloride (PVC), polystyrene (PS), wood, and styrene butadiene rubber (SBR), respectively. With an external potential of 4 kV, PVC smoke reaches the safe threshold after 12.1 s, while SBR smoke achieves it in just 4.9 s. Analysis of the microscopic morphology of agglomerates with scanning electron microscopy (SEM) reveals that particle size distribution is an important factor affecting electric agglomeration elimination. This is because larger initial particles carry a greater charge, enabling the formation of larger agglomerates for more efficient removal. This study provides theoretical guidance for the practical application of electric agglomeration in eliminating smoke particles.
{"title":"Study on the elimination characteristics of smoke particles with different materials using electric agglomeration technology.","authors":"Mingfeng Lu, Jie Feng, Kaige Wang, Yunchao Li, Dingkun Yuan, Guangxue Zhang, Hailin Gu","doi":"10.1080/09593330.2024.2405663","DOIUrl":"https://doi.org/10.1080/09593330.2024.2405663","url":null,"abstract":"<p><p>Fire smoke, consisting of solid particles and liquid droplets, poses risks of asphyxiation, poisoning, making it a significant contributor to fire-related fatalities and environmental pollution. The exploration of effective smoke control methods represents a vital approach to reducing the threat of fire smoke to public health and safety. This study aims to determine the characteristics of elimination for the fire smoke generated from burning four typical materials, thereby validating the universality of electric agglomeration smoke elimination technology. The results indicate that the elimination efficiency of electric agglomeration varies with the material type of the smoke. The rate of change in smoke transmittance from fast to slow is: polyvinyl chloride (PVC), polystyrene (PS), wood, and styrene butadiene rubber (SBR), respectively. With an external potential of 4 kV, PVC smoke reaches the safe threshold after 12.1 s, while SBR smoke achieves it in just 4.9 s. Analysis of the microscopic morphology of agglomerates with scanning electron microscopy (SEM) reveals that particle size distribution is an important factor affecting electric agglomeration elimination. This is because larger initial particles carry a greater charge, enabling the formation of larger agglomerates for more efficient removal. This study provides theoretical guidance for the practical application of electric agglomeration in eliminating smoke particles.</p>","PeriodicalId":12009,"journal":{"name":"Environmental Technology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142282402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-21DOI: 10.1080/09593330.2024.2405945
Jigang Zhang, Zijun Liu, Kun Cheng, Lianqin Jia, Kuihua Han
Hydrogen fluoride (HF) corrosion of boiler water-cooled wall pipes at high temperature hinders the co-disposal of fluorinated hazardous wastes and coal by combustion. In this paper, common water-cooled wall pipes (15CrMoG and 20G) were utilized to perform gaseous HF corrosion experiments at high temperature on a horizontal tube furnace. The effects of temperature on HF corrosion of different water-cooled wall pipes in 0.2% HF were investigated. Corrosion kinetics curve was obtained by calculating the mass increase due to corrosion. The microscopic morphology and physical phase composition of water-cooled wall pipes after HF corrosion were analyzed. The corrosion resistances of the two water-cooled wall pipes decrease with increasing the temperature. The corrosion weight gain curves of 15CrMoG and 20G at 550 ℃ are ΔW1.9144 = 0.2100t and ΔW1.8356 = 0.1344t, respectively. The average corrosion rates of 15CrMoG and 20G are 0.0177 and 0.0125 mg/(cm2·h), respectively. The corrosion resistance of 15CrMoG is superior compared to 20G. The HF corrosion at high temperature consists of non-alternating fluorination and oxidation of the metal matrix. This study is of great significance for the protection of boilers with HF corrosion at high temperature.
{"title":"Experimental study on high temperature gaseous hydrogen fluoride corrosion of boiler water-cooled wall pipes.","authors":"Jigang Zhang, Zijun Liu, Kun Cheng, Lianqin Jia, Kuihua Han","doi":"10.1080/09593330.2024.2405945","DOIUrl":"https://doi.org/10.1080/09593330.2024.2405945","url":null,"abstract":"<p><p>Hydrogen fluoride (HF) corrosion of boiler water-cooled wall pipes at high temperature hinders the co-disposal of fluorinated hazardous wastes and coal by combustion. In this paper, common water-cooled wall pipes (15CrMoG and 20G) were utilized to perform gaseous HF corrosion experiments at high temperature on a horizontal tube furnace. The effects of temperature on HF corrosion of different water-cooled wall pipes in 0.2% HF were investigated. Corrosion kinetics curve was obtained by calculating the mass increase due to corrosion. The microscopic morphology and physical phase composition of water-cooled wall pipes after HF corrosion were analyzed. The corrosion resistances of the two water-cooled wall pipes decrease with increasing the temperature. The corrosion weight gain curves of 15CrMoG and 20G at 550 ℃ are Δ<i>W</i><sup>1.9144 </sup>= 0.2100<i>t</i> and Δ<i>W</i><sup>1.8356 </sup>= 0.1344<i>t</i>, respectively. The average corrosion rates of 15CrMoG and 20G are 0.0177 and 0.0125 mg/(cm<sup>2</sup>·h), respectively. The corrosion resistance of 15CrMoG is superior compared to 20G. The HF corrosion at high temperature consists of non-alternating fluorination and oxidation of the metal matrix. This study is of great significance for the protection of boilers with HF corrosion at high temperature.</p>","PeriodicalId":12009,"journal":{"name":"Environmental Technology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142282400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}