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1.
Sci Total Environ ; 804: 149965, 2021 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-34508937

RESUMO

Ammonium removal in wastewater treatment plants demands large quantities energy input, such as aeration for wastewater and the addition of organics for nitrate reduction. Anaerobic ammonium oxidation coupled to Fe(III) reduction, called Feammox process play a crucial role in natural nitrogen cycle, which has been rarely investigated in the field of wastewater treatment. Besides, Iron-reducing bacteria (FeRB) as function bacteria of Feammox could transfer electrons to iron oxide by oxidizing organics. The possibility of anaerobic ammonium removal coupled with organics should be investigated to assess the potential of Feammox process for conventional wastewater treatment. In this study, five Fe(III) compounds, Fe2O3, Fe3O4, Fe(OH)3, Citrate-Fe and pyrite were supplemented to investigate the effect of iron oxides on ammonium removal in serum bottles with working volume of 100 mL. It was found that ammonium removal efficiency of the Fe2O3 group was the highest. To simulate wastewater treatment process in sewage treatment plant, three Up-flow anaerobic sludge blanket reactors with volume of 250 mL adding Fe2O3 were applied with influent of ammonium and carbon sources. It was found that the organics significantly inhibited the ammonium removal by Feammox process. This was attributed to that carbon sources and ammonium could be used as electron donors for Fe(III) reduction. In addition, this nitrogen removal was also likely related with the iron cycle, i.e., Fe(III) reduction with ammonium oxidation and Fe(II) oxidation with nitrate/nitrite reduction. This study provides a promising alternative technology for anaerobic ammonium removal in wastewater treatment. Optimizing nitrogen removal and carbon sources applied in conventional wastewater plants are required in future.

2.
Sci Total Environ ; 751: 141703, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32882553

RESUMO

Ammonium removal in wastewater treatment plants requires a large number of energy input, such as aeration and the addition of organics. Alternative, more economical technologies for nitrogen removal from wastewater are required. This study comprehensively investigated the feasible of microbial electricity coupled with Fe(III) reduction promoting the anaerobic ammonium removal. It was found that electrostimulation coupled with Fe(III) reduction (bioelectrochemical systems-Fe(III) (BES-Fe(III)) reactor) enhanced the anaerobic ammonium removal by 50.38% and 38.8% compared with the BES reactor and Fe(III) reactor, respectively. The ammonium removal rate reached the highest value of 80.62 ± 0.26 g N m-3·d-1 in the Fe(III)-BES reactor comparable to conventional wastewater treatment plants (WWWTPs). The improvement of ammonium removal might be the synergistic effect of BES and Feammox process on reaction process and microorganisms. Firstly, the addition of Fe2O3 could improve the electrochemical characteristics by enriching iron-reducing bacterial (FeRB). Secondly, the improved ammonium removal could be due to nitrite generated from Feammox process driving the anodic ammonium oxidation. Additionally, the ammonium removal improvement might be the effect of BES on the Fe2+ leaching so as to accelerate the Fe (II)/Fe(III) cycle. In agreement, higher abundance of FeRB and iron-oxidizing bacteria was detected in the Fe(III)-BES reactor. This study provides a lower energy consumption and operational cost technology compared with the conventional partial nitrification/denitrification, which was more than 800 times less than for the conventional wastewater treatment.


Assuntos
Compostos de Amônio , Terapia por Estimulação Elétrica , Anaerobiose , Reatores Biológicos , Desnitrificação , Compostos Férricos , Nitrogênio/análise , Oxirredução , Águas Residuárias
3.
Huan Jing Ke Xue ; 32(4): 1020-6, 2011 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-21717742

RESUMO

Poly-beta-hydroxybutyrate (PHB) could be efficiently accumulated under optimized conditions in a sequencing batch moving bed biological reactor (SBMBBR), and a high performance of denitrifying phosphorus removal in the reactor could be achieved by coupling with a two-sludge system. Denitrifying phosphorus removal achieved the highest efficiency under influent COD of 200 mg/L, neutral pH and stirring speed of 80 r/min. The removal rates of phosphorus, NO3(-)-N and NO2(-)-N reached 83.7%, 81.4% and above 100%, respectively. High biomass in the SBMBBR is one of keys to improve the performance in removal of nitrogen and phosphorus. When the SBMBBR was conducted under a two-sludge system, stable and high performance was obtained. Removal rates of phosphorus and TN reached 89.2% and 84.5% under the influent COD of 140-170 mg/L and TN of 34-42 mg/L, respectively. In the process, phosphorus content in excess sludge approached to that in the feeding, and other path of phosphorus removal was not found.


Assuntos
Carbono/isolamento & purificação , Nitrogênio/isolamento & purificação , Fósforo/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Aerobiose , Anaerobiose , Reatores Biológicos/microbiologia , Carbono/análise , Desnitrificação , Hidroxibutiratos/química , Poliésteres/química
4.
Sheng Li Xue Bao ; 63(1): 55-61, 2011 Feb 25.
Artigo em Chinês | MEDLINE | ID: mdl-21340435

RESUMO

The present study was aimed to investigate the effect of hypoxic training on mitochondrial antioxidants and activities of respiratory chain complexes in mitochondria of skeletal muscle in rats. Forty healthy male Wistar rats were randomized to 5 groups (n=8): living low-training low (LoLo), living high-training high (HiHi), living high-training low (HiLo), living low-training high (LoHi), and living high-exercise high-training low (HiHiLo). All the animals were subjected to 5-week training in normoxic (atmospheric pressure=632 mmHg, altitude of about 1 500 m) or hypoxic environment (atmospheric pressure=493 mmHg, simulated altitude of about 3 500 m). Before exhaustive running, the animals stayed in normoxia for 3 d. Skeletal muscles were prepared immediately after exhaustive running. Muscle mitochondria were extracted by differential centrifugation. Spectrophotometric analysis was used to evaluate activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA) level and respiratory chain complex (C) I-III activities in muscle homogenate and mitochondria. Results showed that SOD, GSH-Px, CAT activities and MDA level in skeletal muscle homogenate in HiHi and HiHiLo groups were significantly increased (P<0.05 or P<0.01) compared with those in LoLo group. Muscle mitochondrial MDA level in HiHi and HiHiLo groups was significantly lower (P<0.01), while activities of SOD, GSH-Px and CAT were remarkably higher (P<0.01) than those in LoLo group. Meanwhile, C I-III activities in HiHi and HiHiLo groups were increased significantly (P<0.01), and C II activity in HiLo group also was increased remarkably (P<0.01) compared with those in LoLo group. These results suggest that HiHiLo might be an ideal hypoxic training mode.


Assuntos
Adaptação Fisiológica/fisiologia , Hipóxia/fisiopatologia , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Esforço Físico/fisiologia , Altitude , Animais , Antioxidantes/metabolismo , Complexo I de Transporte de Elétrons/metabolismo , Glutationa Peroxidase/metabolismo , Hipóxia/metabolismo , Masculino , Músculo Esquelético/fisiologia , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismo
5.
Huan Jing Ke Xue ; 31(5): 1233-8, 2010 May.
Artigo em Chinês | MEDLINE | ID: mdl-20623857

RESUMO

The heat and ferrous ion-activated sodium peroxydisulfate (PDS) for the oxidation of 4-chlorophenol (4-CP) was investigated. These processes are based on the generation of sulfate radicals, which are powerful oxidizing species found in nature. The effects of temperature, pH, the initial concentrations of Fe (II), PDS and citric acid on the degradation efficiencies of 4-CP were studied. The results show that the degradAtion efficiency of 4-CP is significantly enhanced as temperature increases. The degradation efficiencies of 4-CP are 2.5% and 43.5% within 4 h at 30 degrees C and 50 degrees C, respectively. Moreover, 4-CP is degraded completely at 60 degrees C. The degradation efficiency of 4-CP follows the order: pH 4.0 > pH 7.0 > pH 10.0. In the PDS/Fe (II) system, ferrous ion played an important role in generating sulfate radicals at ambient temperature. The optimum experimental condition is established and the addition of probe compounds proves the formation of sulfate radicals. Furthermore, the iron availability in the aqueous solution is manipulated with the optimum amount of citric acid, as a chelating agent. The degradation efficiency of 4-CP is 50.9% in the PDS/Fe (II)/citric acid system, which is superior to 43.5% at 50 degrees C under the same initial concentration of PDS.


Assuntos
Clorofenóis/isolamento & purificação , Compostos Ferrosos/química , Compostos de Sódio/química , Sulfatos/química , Poluentes Químicos da Água/isolamento & purificação , Biodegradação Ambiental , Clorofenóis/química , Ácido Cítrico/química , Temperatura Alta , Concentração de Íons de Hidrogênio , Oxirredução , Poluentes Químicos da Água/química
6.
Huan Jing Ke Xue ; 31(2): 379-84, 2010 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-20391706

RESUMO

To elucidate the roles of humic acids (HAs) and iron on the environmental fate and transport of organic pollutants in natural water, the interactions of HAs with Fe(III) were characterized by Fourier transform infrared spectroscopy (FTIR) spectra, Ultraviolet-visible (UV-vis) spectra and fluorescence spectra, indicating the formation of HAs-Fe(III) complex. Electron paramagnetic resonance (EPR) spectra show *OH radicals are generated and can participate in the photoreaction in solutions containing HAs, Fe(III) and HAs-Fe(III) complex. Under Xe lamp irradiation (lamda >290 nm), the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D), as a kind of herbicide, followed the pseudo-first-order reaction kinetics. The pseudo-first-order rate constant of 2,4-D photodegradation with the presence of only 2,4-D (2 mg x L(-1)) was 0.007 h(-1). In the presence of HAs (5 mg x L(-1)), Fe(III) (0.2 mmol x L(-1)) and HAs-Fe(III) complex, the rate constants of 2,4-D degradation were 0.004, 0.034 and 0.046 h(-1), respectively. It was interesting to note that in the existence of HAs, 2,4-D photodegradation was inhibited. While in the presence of Fe(III), 2,4-D photodegradation was enhanced. Furthermore, in the coexistence of HAs and Fe(III), HAs-Fe(III) complex showed better increased effect on the photodegradation of 2,4-D than Fe(III) alone.


Assuntos
Ácido 2,4-Diclorofenoxiacético/química , Compostos Férricos/química , Substâncias Húmicas , Fotólise , Poluentes Químicos da Água/química , Ácido 2,4-Diclorofenoxiacético/isolamento & purificação , Ácido 2,4-Diclorofenoxiacético/efeitos da radiação , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/efeitos da radiação
7.
Huan Jing Ke Xue ; 31(3): 720-4, 2010 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-20358833

RESUMO

Xe lamp was employed to simulate the sunlight as light source to study the direct photolysis of three kinds of phenolic pollutants under different pH values. The effects of the dissociation on their photolysis were investigated, and a calculation method and a forecasting model for the photolysis rate constants under the situation of dissociation and non-dissociation of phenolic pollutants were established. The experiment results showed that the photolysis rate constant of pentachlorophenol (PCP) increased from 25.30 x 10(-4) min(-1) to 82.90 x 10(-4) min(-1) when pH value varied from 4.0 to 9.0, and that of nitrophenol (PNP) decreased from 11.90 x 10(-4) min(-1) to 3.18 x 10(-4) min(-1) Similar to the PNP, the photolysis rate constant of phenol decreased from 32.50 x 10(-4) min(-1) to 13.40 x 10(-4) min(-1) with the pH value increased from 4.0 to 11.0. From analysis of the results, a power function relationships between the total photolysis rate constants (K) and dissociation degrees (alpha) of these three phenolic compounds could be established. If alpha had been determined, the dissociation and non-dissociation species photolysis rate constants could be calculated by the tangent equation of the power function. The effect of dissociation on the photolysis should be mainly attributed to the formation of the negative oxygen ions, which led to the changes of the activities of benzene ring and substituent groups. These results will provide theoretical references to further understand environmental behaviors of phenolic compounds in natural waters.


Assuntos
Nitrofenóis/isolamento & purificação , Pentaclorofenol/isolamento & purificação , Fenol/química , Fotólise/efeitos da radiação , Poluentes Químicos da Água/isolamento & purificação , Nitrofenóis/química , Pentaclorofenol/química , Fenol/isolamento & purificação , Luz Solar , Poluentes Químicos da Água/química
8.
Huan Jing Ke Xue ; 31(10): 2360-4, 2010 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-21229746

RESUMO

The effects of influent nitrate concentration and its adding modes on denitrifying phosphorus removal in a wastewater with low carbon (COD = 200 mg/L) using a sequencing batch moving bed biofilm reactor (SBMBBR) operated under anaerobic-anoxic conditions was investigated. After the domestication, the percentage of denitrifying phosphorus removing bacteria (DPB) in all phosphorus removing bacteria(PB) increased from 15.7% to 71.3%, indicating that DPB was enriched. Concentration of the influent nitrate had a significant effect on the treatment. At the influent nitrate concentration of 30 mg/L, i. e., C/N = 6.7 : 1, COD, PO4(3-) -P and NO3(-) -N removal increased to 97.8%, 82.0% and 81.2%, respectively, showing an efficient treatment under this low carbon. When the influent nitrate was less or more (20 and 40 mg/L), phosphorous uptake observed was insufficient in the anoxic stage, and poly-beta-hydroxybutyrate (PHB) increased from 2.2 mg/g MLSS in the initial anaerobic stage to 5.1 mg/g MLSS and 3.5 mg/g MLSS, respectively, affecting phosphorous release in the next period. Adding nitrate in one time, two times or continuous mode had little effect on the denitrifying phosphorus removal, but affected the removal rate in the initial anoxic stage.


Assuntos
Bactérias Anaeróbias/metabolismo , Nitratos/isolamento & purificação , Fósforo/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Anaerobiose , Biofilmes , Reatores Biológicos/microbiologia , Carbono/química , Desnitrificação
9.
Huan Jing Ke Xue ; 30(2): 557-62, 2009 Feb 15.
Artigo em Chinês | MEDLINE | ID: mdl-19402515

RESUMO

The advantage of rapid, selective and simultaneous heating of microwave heating technology was taken to remediate the crude oil-contaminated soil rapidly and to recover the oil contaminant efficiently. The contaminated soil was processed in the microwave field with addition of granular activated carbon (GAC), which was used as strong microwave absorber to enhance microwave heating of the soil mixture to remove the oil contaminant and recover it by a condensation system. The influences of some process parameters on the removal of the oil contaminant and the oil recovery in the remediation process were investigated. The results revealed that, under the condition of 10.0% GAC, 800 W microwave power, 0.08 MPa absolute pressure and 150 mL x min(-1) carrier gas (N2) flow-rate, more than 99% oil removal could be obtained within 15 min using this microwave thermal remediation enhanced by GAC; at the same time, about 91% of the oil contaminant could be recovered without significant changes in chemical composition. In addition, the experiment results showed that GAC can be reused in enhancing microwave heating of soil without changing its enhancement efficiency obviously.


Assuntos
Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodos , Micro-Ondas , Petróleo/efeitos da radiação , Poluentes do Solo/efeitos da radiação , Poluentes do Solo/química , Difusão Térmica
10.
Chemosphere ; 75(3): 405-9, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19135701

RESUMO

Perfluorooctane sulfonate (PFOS) was evaluated alone and in binary mixtures with pentachlorophenol, atrazine and diuron, respectively to investigate the effects of interactions between PFOS and other compounds on the growth rate in Scenedesmus obliquus. Single application of PFOS showed no inhibition on the growth of S. obliquus below 40 mg L(-1), whereas PFOS acting with pentachlorophenol resulted in higher algal growth inhibition in comparison with pentachlorophenol alone. A maximum increase of 45% in the growth inhibition was observed at a pentachlorophenol concentration of 2.56 mg L(-1) together with a PFOS concentration of 40 mg L(-1). On the contrary, the algal growth inhibition of atrazine and diuron was depressed by PFOS. Furthermore, cell uptake was examined to gain some insights into the mechanisms of the effects of PFOS on the toxicity of the other compounds. Cell uptake of pentachlorophenol increased while that of atrazine and diuron was reduced in cells that have been exposed to PFOS. The effects of PFOS on the toxicity of pentachlorophenol, atrazine and diuron were possibly related to the influence of PFOS on the cell uptake of these hydrophobic compounds. Results suggested that PFOS influenced the cell uptake and toxicity of structurally different compounds in dissimilar manners and potentially increased the accessibility and toxicity of more hydrophobic compounds to algal cells.


Assuntos
Ácidos Alcanossulfônicos/toxicidade , Clorófitas/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Fluorcarbonetos/toxicidade , Ácidos Alcanossulfônicos/farmacologia , Atrazina/farmacologia , Atrazina/toxicidade , Permeabilidade da Membrana Celular , Clorófitas/crescimento & desenvolvimento , Clorófitas/metabolismo , Diurona/farmacologia , Diurona/toxicidade , Relação Dose-Resposta a Droga , Poluentes Ambientais/farmacologia , Fluorcarbonetos/farmacologia , Interações Hidrofóbicas e Hidrofílicas , Pentaclorofenol/farmacologia , Pentaclorofenol/toxicidade
11.
Huan Jing Ke Xue ; 29(6): 1743-8, 2008 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-18763533

RESUMO

Pd/CeZr/TiO2/Al2O3 wire-mesh honeycomb catalyst was prepared by sol-gel and impregnation. Furthermore, selective catalytic reduction of NOx over Pd/CeZr/TiO2/Al2O3 wire-mesh honeycomb catalyst with propylene under lean burn condition was studied. The effects of the concentration of tetra-n-butyl titanate and dipcoat cycles on TiO2 washcoat were studied by SEM, and the effects of Pd concentration, O2 concentration and gas velocity on catalytic activity were investigated. The experimental results showed that the TiO2 washcoat on wire-mesh support is even and crack-free when the support is impregnated in 20.0% tetra- n-butyl titanate sol for 2 cycles. The NOx conversion decreases with Pd concentration increase. When Pd concentration is 0.23%, NOx conversion is highest. NOx conversion increases with oxygen concentration increase in the range of 1.5%-6.0%. However, when oxygen concentration is higher than 6.0%, NOx conversion decreases with increasing oxygen concentration. The NOx conversion decreases with gas velocity increase and its effect is severer at high temperature than low temperature.


Assuntos
Óxido de Alumínio/química , Óxidos de Nitrogênio/química , Titânio/química , Catálise , Cério/química , Oxirredução , Oxigênio/química , Paládio/química
12.
Huan Jing Ke Xue ; 28(11): 2484-7, 2007 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-18290470

RESUMO

The effect of two kinds of temperature conditions (14 degrees C +/- 1 degrees C and 24 degrees C +/- 1 degrees C) on the removal of phosphorus and nitrogen were studied in a sequencing batch moving bed biofilm reactor (SBMBBR). The experiments were performed at the concentrations of COD, nitrogen and phosphorus in the feed fixing at about 450 mg/L, 40 mg/L and 10 mg/L, respectively. The results indicated that under the two temperatures the phosphorus release amounts were 54.7 mg/L, 19.7 mg/L, and the phosphorus removals were 98.3%, 83.4%, and the total nitrogen removals were 87.8%, 98.4%, respectively. It found that PAOs (phosphorus-accumulating organisms) predominated in the biomass and the nitrifying level was low at the lower temperature. However, with increase of temperature, PAOs were no longer the predominant microbial species and the total nitrogen removal efficiency increased. A denitrifying phosphorus experiment was carried out under the mode of anaerobic/anoxic in the SBMBBR after 3 months anaerobic/oxic operation. The results showed the ratio of denitrifying phosphorus removal to total phosphorus removal was about 80%.


Assuntos
Reatores Biológicos/microbiologia , Nitrogênio/metabolismo , Fósforo/metabolismo , Eliminação de Resíduos Líquidos/métodos , Anaerobiose , Biofilmes , Nitratos/metabolismo , Nitrogênio/isolamento & purificação , Fósforo/isolamento & purificação , Temperatura
13.
J Environ Sci (China) ; 17(3): 433-6, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16083118

RESUMO

A novel process, microwave assisted catalytic wet air oxidation (MW-CWO), was applied for the degradation of H-acid (1-amino-8-naphthol-3, 6-disulfonic acid) in aqueous solution. Ni-loaded granular activated carbon (GAC), prepared by immersion-calcination method, was used as catalyst. The results showed that the MW-CWO process was very effective for the degradation of H-acid in aqueous solution under atmospheric pressure with 87.4% TOC (total organic carbon) reduction in 20 min. Ni on GAC existed in the form of NiO as specified by XRD. Loss of Ni was significant in the initial stage, and then remained almost constant after 20 min reaction. BET surface area results showed that the surface property of GAC after MW-CWO process was superior to that of blank GAC.


Assuntos
Carvão Vegetal/química , Micro-Ondas , Naftalenossulfonatos/química , Níquel/química , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Adsorção , Catálise , Oxirredução , Eliminação de Resíduos Líquidos/instrumentação , Purificação da Água/instrumentação
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