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1.
Chemosphere ; 262: 127567, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32755692

RESUMO

Acid mine drainage (AMD) is recognized as a challenge encountered by mining industries globally. Cyclic mineralization method, namely Fe2+ oxidation/mineralization-residual Fe3+ reduction-resultant Fe2+ oxidation/mineralization, could precipitate Fe and SO42- present in AMD into iron hydroxysulfate minerals and greatly improve the efficiency of subsequent lime neutralization, but the current Fe0-mediated reduction approach increased the mineralization cycles. This study constructed a bacteria-driven biomineralization system based on the reactions of Acidithiobacillus ferrooxidans-mediated Fe2+ oxidation and Acidiphilium multivorum-controlled Fe3+ reduction, and utilized water-dropping aeration and biofilm technology to satisfy the requirement of practical application. The resultant biofilms showed stable activity for Fe conversion: the efficiency of Fe2+-oxidation, Fe-precipitation, and Fe3+-reduction maintained at 98%, 32%, and 87%, respectively. Dissolved oxygen for Fe-oxidizing bacteria growth was continuously replenished by water-dropping aeration (4.2-7.2 mg/L), and the added organic carbon was mainly metabolized by Fe-reducing bacteria. About 89% Fe and 60% SO42- were precipitated into jarosite mineral after five biomineralization cycles. Fe was removed via forming secondary mineral precipitates, while SO42- was coprecipitated into mineral within the initial three biomineralization cycles, and then mainly precipitated with Ca2+ afterwards. Fe concentration in AMD was proven to directly correlate with subsequent lime neutralization efficiency. Biomineralization for five cycles drastically reduced the amount of required lime and neutralized sludge by 75% and 77%, respectively. The results in this study provided theoretical guidance for practical AMD treatment based on biomineralization technology.


Assuntos
Ferro/análise , Poluentes Químicos da Água/análise , Acidiphilium , Acidithiobacillus , Ácidos , Bactérias/metabolismo , Biodegradação Ambiental , Biomineralização , Compostos de Cálcio , Compostos Férricos , Ferro/metabolismo , Minerais , Mineração , Óxidos , Sulfatos , Poluentes Químicos da Água/metabolismo
2.
Chemosphere ; 262: 127904, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32799153

RESUMO

Manganese accumulated in corrosion scales on drinking water distribution systems (DWDSs) can be released into bulk water, causing discolouration and thereby leading to customer concerns about drinking water quality. A static release experiment was conducted on iron pipe scales under three different temperatures, pH values, alkalinity values, sulfate (SO42-) concentrations, and disinfectants to study the separate effect of these factors on Mn release from pipe scales under stagnant conditions. Results showed that more Mn was released from corrosion scales under the conditions of lower pH, lower alkalinity, higher temperature, and higher SO42- concentrations. Three commonly used disinfectants, sodium hypochlorite (NaClO), chlorine dioxide (ClO2), and monochloramine (NH2Cl) were found to inhibit the release of Mn from iron corrosion scales, with the ranked order of inhibitory effect of ClO2≈NaClO > NH2Cl under the same CT (product of disinfectant concentration and contact time) value. The orthogonal experimental results indicated that SO42- and alkalinity had extremely significant effects on the release of Mn from pipe scales, while pH and disinfectant type had a significant impact on the release of Mn from pipe scales. Thus, the SO42- concentration and alkalinity of the bulk water should be determined to avoid excessive release of Mn into drinking water. However, further investigation of the effect of disinfectants on Mn release in DWDSs is necessary. This research helps establish a systematic understanding of the influential factors in Mn release from pipe scales into bulk water, as well as their significant relationships.


Assuntos
Água Potável/química , Manganês/análise , Poluentes Químicos da Água/análise , Compostos Clorados , Corrosão , Desinfetantes/análise , Concentração de Íons de Hidrogênio , Ferro , Óxidos , Sulfatos/análise , Temperatura , Qualidade da Água , Abastecimento de Água
3.
Environ Monit Assess ; 192(12): 751, 2020 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-33156467

RESUMO

Besides causing acidification, acid sulfate (AS) soils contain large nitrogen (N) stocks and are a potential source of N loading to waters and nitrous oxide (N2O) emissions. We quantified the stocks and flows of N, including crop yields, N leaching, and N2O emissions, in a cultivated AS soil in western Finland. We also investigated whether controlled drainage (CD) and sub-irrigation (CDI) to keep the sulfidic horizons inundated can alleviate N losses. Total N stock at 0-100 cm (19.5 Mg ha-1) was smaller than at 100-200 cm (26.6 Mg ha-1), and the mineral N stock was largest below 170 cm. Annual N leaching (31-91 kg N ha-1) plus N in harvested grain (74-122 kg N ha-1) was 148% (range 118-189%) of N applied in fertilizers (90-125 kg N ha-1) in 2011-2017, suggesting substantial N supply from soil reserves. Annual emissions of N2O measured during 2 years were 8-28 kg N ha-1. The most probable reasons for high N2O emission rates in AS soils are concomitant large mineral N pools with fluctuating redox conditions and low pH in the oxidized subsoil, all favoring formation of N2O in nitrification and denitrification. Although the groundwater level was higher in CD and CDI than in conventional drainage, N load and crop offtake did not differ between the drainage methods, but there were differences in emissions. Nitrogen flows to the atmosphere and drainage water were clearly larger than those in non-AS mineral soils indicating that AS soils are potential hotspots of environmental impacts.


Assuntos
Nitrogênio , Solo , Agricultura , Monitoramento Ambiental , Fertilizantes , Finlândia , Óxido Nitroso/análise , Sulfatos
4.
Water Sci Technol ; 82(7): 1404-1415, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33079719

RESUMO

In this study, peroxydisulfate (PDS) was successfully activated by UV-irradiation for the degradation of paracetamol (PCT) frequently detected in the environment. Results showed that increasing the initial PDS concentration from 5 to 20 mM promote the removal of PCT from 49.3% to 97.5% after 240 min of reaction time. As the initial PCT concentration increased from 0.066 to 0.132 mM, the degradation efficiency of PCT decreased from 98% to 73% after 240 min of reaction time, while the optimal pH was found to be 6. It is apparent that the degradation rate of PCT was favored by the lamp power regardless of the initial PCT concentration, for 0.132 mM of PCT, the degradation efficiency increased from 73% to 95% when the lamp power increased from 9 to 30 W, respectively. The kinetic of degradation of the PCT was described by a pseudo-second order kinetic model. The model obtained by central composite design led to the following optimal conditions for PCT degradation: 0.132 mM initial PCT concentration, 20 mM PDS dose, pH solution 6 and lamp power 30 W led to the removal of 92% of PCT at 25 °C within 240 min of reaction time.


Assuntos
Acetaminofen , Poluentes Químicos da Água , Cinética , Sulfatos , Raios Ultravioleta , Poluentes Químicos da Água/análise
5.
Huan Jing Ke Xue ; 41(10): 4626-4635, 2020 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124395

RESUMO

The degradation of emerging pollutant artificial sweetener sucralose (SUC) using UV/persulfate (UV/PS). The effects of several process parameters, including UV light intensity, PS dosage, pH, and anion concentration, were also investigated. The degradation products and their toxicity during the UV/PS process were further analyzed and evaluated. It is reported that, compared with single UV or PS, the degradation of SUC by UV/PS was more obvious. The degradation rate constants increased with an increase in the light intensity and PS dosage. The SUC degradation could be improved under neutral conditions. The background ions NO3- and HCO3- could inhibit the degradation process, while Cl- and SO42- ions could accelerate the process. Sixteen intermediate products were identified using high-resolution mass spectrometry (HRMS) and GC-MS. Hydroxylation, oxidation, ether cracking, and other reactions were involved. A degradation path was further proposed. Moreover, luminescent bacteria toxicity test and ECOSAR prediction showed that the intermediates with higher toxicity could be produced during UV/PS, which could pose a potential threat to the ecological environment.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Cinética , Oxirredução , Sacarose/análogos & derivados , Sulfatos , Raios Ultravioleta , Água , Poluentes Químicos da Água/análise
6.
Huan Jing Ke Xue ; 41(9): 4133-4140, 2020 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124295

RESUMO

Naphthalene sulfonic acid is widely used in the industry. In this study, H acid (1-amino-8-naphthol-3,6-disulfonic acid) was selected as the characteristic pollutant, and the alkali-activated, thermally-activated, and alkali-heat-complex activated persulfate (PS) degradation of H acid was analyzed. The effects of other factors on complex activation were discussed. The experimental results showed that with the addition of calcium oxide from 0 to 1250 mg ·L-1, the H acid removal rate increased from 42.5% to 82.8% after 100 min of reaction. The removal rate of H acid in thermal activation is positively correlated with temperature. The removal rate of H acid at 65℃ is 77.5%, and the apparent activation energy is 37.85 kJ ·mol-1. Although composite activation speeds up the reaction rate, rapid degradation of PS at high temperatures caused the degradation of H acid to be worse than single thermal activation. The change in PS concentration did not significantly improve the removal rate of H acid, and the inorganic anion CO32- was not conducive to the removal of H acid. Compound activation is not ideal for the mineralization of H acid, and the removal rate of TOC is only 16%. GC-MS identified the degradation product of H acid as terephthalic acid, indicating that phthalic anhydride may be formed after the naphthalene ring is opened.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Naftalenos , Oxirredução , Sulfatos
7.
mBio ; 11(5)2020 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-33109768

RESUMO

The reproducibility of adaptive evolution is a long-standing debate in evolutionary biology. Kempher et al. (M. L. Kempher, X. Tao, R. Song, B. Wu, et al., mBio 11:e00569-20, 2020, https://doi.org/10.1128/mBio.00569-20) used experimental evolution to investigate the effect of previous evolutionary trajectories on the ability of microbial populations to adapt to high temperatures. Despite the divergence caused by adaptation to previous environments, all populations reproducibly converged on similar final levels of fitness. Nevertheless, the genetic basis of adaptation depended on past selection experiments, reinforcing the idea that previous adaptation can dictate the trajectories of later evolutionary processes.


Assuntos
Bactérias , Sulfatos , Bactérias/genética , Reprodutibilidade dos Testes , Temperatura
8.
Chemosphere ; 261: 127844, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113647

RESUMO

Biochar supported nanosized iron (nFe(0)/BC) was synthesized and used as a persulfate (PS) activator to degradation tetracycline (TC). The influence of the initial pH values, PS and nFe(0)/BC dosage, initial TC concentration, and coexist anions were investigated. In the nFe(0)/BC-PS system, TC could be effectively removed at various pH values (3.0-9.0). The degradation efficiency of TC (100 mg/L) was 97.68% using nFe(0)/BC (0.4 g/L) and persulfate (1 mM) at pH 5.0. Coexisting ions (HCO3- and NO3-) had an inhibitory effect on TC degradation. The removal of TC could be fitted by a pseudo-second-order model. Electron-Spin Resonance (ESR) analysis and scavenging tests suggested that sulfate radicals (SO4·-) and hydroxyl radicals (HO·) were responsible for TC degradation. Details of the advanced oxidation process (AOP)-induced degradation pathways of TC were determined based on liquid chromatography mass-spectrometry (LC-MS) analysis. The nFe(0)/BC could still maintain 86.38% of its original removal capacity after five cycles. The findings of this study proved that nFe(0)/BC can be applied to activate PS for the treatment of pollution caused by TC.


Assuntos
Carvão Vegetal/química , Ferro/química , Nanopartículas/química , Compostos de Sódio/química , Sulfatos/química , Tetraciclina/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Radical Hidroxila/química , Modelos Teóricos , Oxirredução , Águas Residuárias/química
9.
Am J Vet Res ; 81(11): 837-877, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33107745

RESUMO

OBJECTIVE: To compare the pharmacokinetics of cefquinome sulfate in ducklings and goslings after IV or IM administration of a single dose. ANIMALS: 216 healthy Muscovy ducklings (Cairina moschata) and 216 healthy Sichuan white goslings (Anser cygnoides). PROCEDURES: Ducklings and goslings were each randomly assigned to 3 groups (n = 72/group) that received a single dose (2 mg/kg) of injectable cefquinome sulfate administered IV or IM or of injectable cefquinome sulfate suspension administered IM. Blood samples were collected at various points after drug administration (n = 6 birds/time point). Plasma cefquinome concentrations were measured by high-performance liquid chromatography with UV detection, and pharmacokinetic parameters were calculated with a 2-compartment model method. RESULTS: After IV injection, mean distribution half-life of cefquinome was longer in goslings (0.446 hours) than in ducklings (0.019 hours), whereas volume of distribution at steady state was greater (0.432 vs 0.042 L/kg) and elimination half-life was slower (1.737 vs 0.972 hours). After IM administration of injectable cefquinome sulfate, bioavailability of the drug was higher in goslings (113.9%) than in ducklings (67.5%). After IM administration of injectable cefquinome sulfate suspension, bioavailability was also higher in goslings (123.1%) than in ducklings (96.8%), whereas elimination half-life was slower (6.917 vs 1.895 hours, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: In goslings, IV administration of cefquinome resulted in slower distribution and metabolism of the drug than in ducklings and IM administration resulted in higher bioavailability. The delayed-release effect of the injectable cefquinome sulfate suspension when administered IM was observed only in goslings.


Assuntos
Patos , Gansos , Animais , Antibacterianos , Área Sob a Curva , Disponibilidade Biológica , Cefalosporinas , Meia-Vida , Injeções Intramusculares/veterinária , Injeções Intravenosas/veterinária , Sulfatos
10.
Water Sci Technol ; 82(8): 1676-1686, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33107861

RESUMO

In this paper, wasted copper tailings (CT) were used to activate persulfate (PS) to degrade azo dye methyl orange (MO). The results show that a large amount of FeS2 contained in CT can slowly release Fe2+ in the aqueous solution to activate PS to generate reactive oxygen species to degrade MO. When the dosage of CT and PS was 2 g/L and 3 mM respectively, the MO degradation efficiency of 20 mg/L in the CT/PS system was 96.52% within 60 min. At the same time, it is found that CT has a certain adsorption capacity for MO, and the intra-particle diffusion model can well describe the adsorption process of MO by CT. The effects of related reaction parameters (CT dosage, PS dosage, initial MO concentration and solution pH) on MO degradation in CT/PS system were investigated. Compared with the direct addition of an equal amount of Fe2+ as in the CT/PS system, for homogeneous activated PS to degrade MO (Fe2+/PS), the results showed that the degradation efficiency of Fe2+/PS system for MO was lower than that of CT/PS system due to excessive Fe2+ consumption of SO4·-. By comparing the Fe2+ and Fe3+ concentrations in the two systems, it was found that the CT/PS system could maintain a low Fe2+ concentration during the reaction process, and the Fe2+ released by CT could be used by PS to degrade MO more efficiently. The free radical scavenging experiments showed that the reactive oxygen species in the CT/PS system was mainly SO4·-. This study not only proposed a new CT utilization approach, but also solved the problem of reduced degradation efficiency of organic pollutants caused by excessive Fe2+ in the Fenton-like reaction.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Compostos Azo , Cobre , Ferro , Oxirredução , Sulfatos
11.
Chemosphere ; 254: 126869, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957283

RESUMO

This paper presents the results of Co(II) and Ni(II) extraction from model and real solutions using bis(2,4,4-trimethylpentyl)phosphinic acid (i.e. Cyanex 272) that are in agreement with waste-to-resources approach, i.e. the recovery of valuable components from wastes. The results from this study shows that, extraction using Cyanex 272 is an efficient method to recover Co(II) selectively from sulfate electrolytes obtained from the leaching of steel scraps of aircraft engines. The highest selectivity value (∼160) of Co(II) extraction over Ni(II) was obtained at a pH of 4.8, the lowest selectivity value (∼30) was observed at a pH of 5.5, while above this value the selectivity only increased slightly with increasing pH. A pH of 5.2 was selected as a compromise between Co(II) selectivity and Ni(II) amount in the organic phase. The essence of the investigation is to propose important parameters to extract Co(II) from real leach solutions, and to further recover valuable Co(II) from the loaded organic phase by stripping with 1 M H2SO4, thus producing an electrolyte of Co(II) for electrowinning - a possible alternative route for resource recovery. Small volume of the stripping phase (w/o = 1:5) used in this study, lead to an enrichment of sulfate electrolyte in Co(II), resulting in ∼50 g/dm3 of Co(II) in the solution, which is a great advantage of the approach proposed. Such a solution is a valuable source for the electrowinning of metallic cobalt, which can be used for the production of steel alloys, Li-ion batteries or catalysts.


Assuntos
Cobalto/química , Modelos Químicos , Níquel/química , Ácidos Fosfínicos/química , Fontes de Energia Elétrica , Lítio , Sulfatos
12.
Chemosphere ; 258: 127288, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947659

RESUMO

The discharge of toxic elements from tailings soils in the aquatic environments occurs chiefly in the presence of indigenous bacteria. The biotic components may interact in the opposite direction, leading to the formation of a passivation layer, which can inhibit the solubility of the elements. In this work, the influence of jarosite on the bio-immobilization of toxic elements was studied by native bacteria. In batch experiments, the bio-immobilization of heavy metals by an inhibitory layer was examined in the different aquatic media using pure cultures of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. A variety of analyses also investigated the mechanisms of metals bio-immobilization. Among different tests, the highest metal solubility yielded 99% Mn, 91% Cr, 95% Fe, and 78% Cu using A. ferrooxidans in 9KFe medium after ten days. After 22 days, these percentages decreased down to 30% Mn and about 20% Cr, Fe, and Cu, likely due to metal immobilization by biogenic jarosite. The formation of jarosite was confirmed by an electron probe micro-analyzer (EPMA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The mechanisms of metal bio-immobilization by biogenic jarosite from tailings soil confirmed three main steps: 1) the dissolution of metal sulfides in the presence of Acidithiobacillus bacteria; 2) the nucleation of jarosite on the surface of sulfide minerals; 3) the co-precipitation of dissolved elements with jarosite during the bio-immobilization process, demonstrated by a structural study for jarosite. Covering the surface of soils by the jarosite provided a stable compound in the acidic environment of mine-waste.


Assuntos
Compostos Férricos/química , Substâncias Perigosas/análise , Sulfatos/química , Acidithiobacillus , Acidithiobacillus thiooxidans , Bactérias , Substâncias Perigosas/toxicidade , Metais Pesados , Minerais , Solubilidade , Sulfetos/química , Difração de Raios X
13.
Food Funct ; 11(9): 7415-7420, 2020 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-32966484

RESUMO

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread around the world at an unprecedented rate. In the present study, 4 marine sulfated polysaccharides were screened for their inhibitory activity against SARS-CoV-2, including sea cucumber sulfated polysaccharide (SCSP), fucoidan from brown algae, iota-carrageenan from red algae, and chondroitin sulfate C from sharks (CS). Of them, SCSP, fucoidan, and carrageenan showed significant antiviral activities at concentrations of 3.90-500 µg mL-1. SCSP exhibited the strongest inhibitory activity with IC50 of 9.10 µg mL-1. Furthermore, a test using pseudotype virus with S glycoprotein confirmed that SCSP could bind to the S glycoprotein to prevent SARS-CoV-2 host cell entry. The three antiviral polysaccharides could be employed to treat and prevent COVID-19.


Assuntos
Antivirais/farmacologia , Betacoronavirus/efeitos dos fármacos , Feófitas/química , Polissacarídeos/farmacologia , Rodófitas/química , Pepinos-do-Mar/química , Animais , Antivirais/química , Betacoronavirus/fisiologia , Infecções por Coronavirus/virologia , Humanos , Pandemias , Pneumonia Viral/virologia , Polissacarídeos/química , Tubarões , Sulfatos/química , Internalização do Vírus/efeitos dos fármacos
14.
Chemosphere ; 254: 126899, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957294

RESUMO

In this study, the reduction of iron-carbon internal electrolysis was reinforced by persulfate for p-nitrophenol removal. The effects of persulfate dosage, initial pH and iron-carbon mass ratio were comprehensively studied in batch experiments. In the system of iron-carbon internal electrolysis coupled with persulfate, the iron-carbon internal electrolysis and persulfate had a significant mutual influence, exhibiting a wide range of pH in the treatment process. Moreover, the coupled system also showed the remarkable removal and degradation efficiency of p-nitrophenol according to the contrast experiments. The satisfactory results should be attributed to the potential reduction of iron-carbon internal electrolysis, which was stimulated by persulfate to transform the nitro group to the amine group, accompanying the subsequent oxidation. Furthermore, persulfate possessed the ability that the dynamically destructive effect on external and internal of Fe0 and the scavenging action on activated carbon, effectively strengthening the potential energy for release and transfer of reductive substances. Both HO• and SO4•- as the main free radicals were formed to mineralize the intermediates in the coupled system. These findings indicate that the system of iron-carbon internal electrolysis coupled with persulfate can be a promising strategy for the treatment of the toxic and refractory wastewater.


Assuntos
Carvão Vegetal/química , Eletrólise/métodos , Ferro/química , Nitrofenóis/análise , Sulfatos/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Modelos Teóricos , Nitrofenóis/química , Oxirredução , Águas Residuárias/química , Poluentes Químicos da Água/química
15.
Water Sci Technol ; 82(2): 315-329, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32941173

RESUMO

Reuse of wastewater, as well as recovery of valuable, toxic or harmful products in industrial discharges, still represents an important issue, not only because it reduces the effect on receiving water bodies, but also because of the economic resources it represents for industry itself. In this research, in situ regeneration of Mn2SO4 is evaluated, for its reuse as the main raw material in the original process of a fungicide plant. The regeneration is evaluated by selective recovery of Mn2+, Zn2+ and SO4= present in the wastewater produced by the industrial plant, and utilizing nanofiltration, electro-electrodialysis and chemical precipitation as separation alternatives. Each alternative was designed and evaluated technically and economically through simulations in Aspen Plus®, with data and information of the real process supplied by the company. Because zinc concentration is relatively low, its selective recovery was not attractive. The resulting Mn2SO4 solution and treated water quality in conventional alternatives were significantly poor with high costs. In contrast, nanofiltration and electro-electrodialysis alternatives generate water and by-products of higher quality and reuse potential with significantly lower costs. However, their viability depends on the membrane performance. The results were satisfactory, but future experimental studies are required to optimize the alternatives and define the correct pretreatment process.


Assuntos
Praguicidas , Purificação da Água , Compostos de Manganês , Sulfatos , Eliminação de Resíduos Líquidos , Águas Residuárias
16.
Water Sci Technol ; 82(1): 185-193, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32910802

RESUMO

Orange G (OG), a typical azo dye in textile wastewaters, has been the subject of intense investigations. This study investigated oxidative degradation of OG in aqueous solution by persulfate (PS) activated with pyrite. A complete destruction of OG was achieved within 60 min in the pyrite/PS system. Lower solution pH, smaller pyrite particles and higher pyrite dosage was beneficial for OG degradation. Higher PS concentration was also in favour of OG degradation, but excess PS would decrease the removal efficiency of OG. The addition of HCO3- and H2PO4- but Cl- had inhibitory effects on the destruction of OG. The results of quenching experiments and electron paramagnetic resonance tests proved that SO4•- and •OH were the dominant reactive species responsible for OG degradation in the pyrite/PS system. The azo bond, naphthalene ring and benzene ring of OG were all destroyed by the generated reactive species. The mineralization rate of OG reached 34.4% after 60 min of reaction. This work will provide information for understanding azo dye degradation by pyrite activated PS.


Assuntos
Compostos Azo , Sulfatos , Ferro , Estresse Oxidativo , Sulfetos
17.
Bioresour Technol ; 318: 124096, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32932117

RESUMO

Nitrate removal from low carbon water is a problem in the water treatment, especially in the presence of high sulfate. In this work, an up-flow three-dimensional biofilm electrode reactor (3D-BER) was established to remove nitrate and sulfate from low organic carbon water. Results indicated that sulfate negatively affected nitrate removal. Moreover, high electric current and short hydraulic retention time deteriorated the performance of nitrate and sulfate removal. When the influent of SO42- was 150 mg/L, the removal efficiency of NO3--N and SO42- was 88.49 ± 4.5% and 29.35 ± 5.5%, respectively. The high-throughput sequencing revealed that denitrifying bacteria dominated in the lower part of the reactor while sulfate reducing bacteria dominated in the upper part of the reactor. It was speculated that oxidation products of sulfide could serve as supplementary electron donors to enhance nitrate removal in the 3D-BER.


Assuntos
Reatores Biológicos , Nitratos , Biofilmes , Desnitrificação , Eletrodos , Sulfatos
18.
Chemosphere ; 254: 126851, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957275

RESUMO

In this study, daily PM2.5 mass and chemical composition were measure in Lin'an Reginal Background Station, Yangzte River Delta, from March 1, 2018, to February 28, 2019. Organic matter (OM) was found to be the most dominant component in four seasons. The proportions of nitrate in PM2.5 presented dramatically lowest in warm seasons but highest in winter, indicating that NO3- was maily driven by thermodynamics. Regional transportation in winter plays a strong impact on PM2.5 concentration, which showed the highest average mass of 60.1 µg m-3. Sulfate occupied a significant portion of PM2.5 in summer (19%), followed by spring (17%), fall (15%), and winter (12%), respectively, suggesting photochemical processes may play a dominant role in the sulfate formation. Secondary inorganic aerosol (SIA) was the dominant component (70%) in the highest polluted periods (PM2.5 > 75 µg m-3), whereas OM decreased into the lowest fraction (22%) of PM2.5. Nitrate was the most important component in SIA in the highest polluted periods with regarding winter. Source apportionment results shown that winter haze was likely strongly dominated by SIA, which was mainly affected by air masses from the North China Plain and Shang-Hangzhou direction. PM2.5 is known to play an important role in sunlight absorption and reversing to human health, continuous observation on PM2.5 species in a background site can help us to evaluate the control policy, and promote our insights to lifetime, formation pathways, health effects of PM2.5.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Material Particulado/análise , Rios/química , Aerossóis/análise , China , Humanos , Óxidos de Nitrogênio/análise , Estações do Ano , Sulfatos/análise
19.
Ecotoxicol Environ Saf ; 202: 110921, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800256

RESUMO

Jarosite is one of the iron oxyhydroxysulfate minerals that are commonly found in acid mine drainage (AMD) systems. In natural environments, phosphate and sulfate reducing bacteria (SRB) may be coupled to jarosite reduction and transformation. In this research, the effect of phosphate on jarosite reduction by SRB and the associated secondary mineral formation was studied using batch experiments. The results indicated that Fe3+ is mainly reduced by biogenic S2- in this experiment. The effect of PO43- on jarosite reduction by SRB involved not only a physico-chemical factor but also a microbial factor. Phosphate is an essential nutrient, which can support the activity of SRB. In the low PO43- treatment, the production of total Fe2+ was found to be slightly larger than that in the zero PO43- treatment. Sorption of PO43- effectively elevated jarosite stability via the formation of inner sphere complexes, which, therefore, inhibited the reductive dissolution of jarosite. At the end of the experiment, the amounts of total Fe2+ accumulation were determined to be 4.54 ± 0.17a mM, 4.66 ± 0.22a mM, 3.91 ± 0.04b mM and 2.51 ± 0.10c mM (p < 0.05) in the zero, low, medium and high PO43- treatments, respectively, following the order of low PO43- treatment > zero PO43- treatment > medium PO43- treatment > high PO43- treatment. PO43- loading modified the transformation pathways for the jarosite mineral, as well. In the zero PO43- treatment, the jarosite diffraction lines disappeared, and mackinawite dominated at the end of the experiment. Compared to PO43--free conditions, vivianite was found to become increasingly important at higher PO43- loading conditions. These findings indicate that PO43- loading can influence the broader biogeochemical functioning of AMD systems by impacting the reactivity and mineralization of jarosite mineral.


Assuntos
Bactérias/metabolismo , Compostos Férricos/química , Fosfatos/química , Sulfatos/química , Adsorção , Biodegradação Ambiental , Compostos Ferrosos , Ferro/química , Compostos de Ferro/química , Minerais , Mineração , Oxirredução
20.
Bioresour Technol ; 317: 124017, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32822894

RESUMO

The sludge flotation and washout are frequently observed in anaerobic sulfidogenic reactor. This challenge raised the interests of re-thinking/re-designing of a compact and low-flotation bioreactor. The present study investigated to understand the temporal dynamics of microbial community and granular sludge properties in a pneumatic-mixing reactor treating sulfate-laden wastewater. The findings revealed that the reactor performance and sludge properties were dynamically changed and correlated over long-term run. In the bioreactor, a rarer type of sulfate reducing bacteria (genus Clostridium XVIII) was remarkably enriched (~30% abundance). The Clostridium XVIII-mediated COD removal (92.7 ± 3.9%) was further confirmed via mass balance which demonstrated the growth rate of total active biomass and sulfate-reducing active biomass were 19.95 and 6.0 mg-COD/Linfluent respectively. The PICRUSt data suggested that i) high abundance of carbohydrate metabolism and S-reductase enzymes enriched, and ii) energy metabolism enzymes decreased which implies that the new SRB communities are more energy-efficient than conventional ones.


Assuntos
Esgotos , Águas Residuárias , Anaerobiose , Bactérias , Reatores Biológicos , Clostridium , Sulfatos , Eliminação de Resíduos Líquidos
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