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1.
Int J Phytoremediation ; 26(5): 608-617, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-37705149

RESUMEN

Polycyclic aromatic hydrocarbons (PAHs) are a serious threat to the health of the environment. This study investigated the potential of Azolla filiculoides for the uptake, accumulation, and biodegradation of phenanthrene and pyrene. A- filiculoides plants were treated with 10 and 30 mg L-1 concentrations of phenanthrene and pyrene for the experimental duration of ten days. Phenanthrene and pyrene concentrations were measured using the high-performance liquid chromatography (HPLC) technique. Identification of the intermediate by-products resulting from the biological degradation of PAHs was performed by gas chromatography-mass spectrometry (GC/MS). The quantities of phenanthrene and pyrene in the ten-day treatments with 10 and 30 mg L-1 were 0.007 and 0.011 mg g-1 FW, and 0.048 and 0.079 mg g-1 FW, respectively. The growth parameters in the plants such as fresh weight, dry weight and RFN as well as the content of photosynthetic pigment of the plant decreased significantly compared to the control sample (p < 0.05). Ten compounds were identified from the plant tissue during the decomposition of pyrene and phenanthrene, and none of the PAHs were identified in the aquatic environment. Therefore, the use of A-filiculoides for phytoremediation of water resources contaminated with PAHs is an effective and promising method.


This study estimated the efficiency of Azolla filiculoides phytoremediation in the uptake, accumulation and biodegradation of phenanthrene and pyrene in polluted waters as a total of 100%. High accumulation of pyrene and phenanthrene in the plant tissue decreased plant growth and the number of photosynthetic pigments. GC-MS analysis, identified ten by-products resulting from the degradation of pyrene and phenanthrene in A-filiculoides plant tissue. HPLC analysis showed that there are no substances of PAHs in the water environment.


Asunto(s)
Fenantrenos , Hidrocarburos Policíclicos Aromáticos , Contaminantes del Suelo , Biodegradación Ambiental , Contaminantes del Suelo/metabolismo , Fenantrenos/análisis , Fenantrenos/metabolismo , Pirenos/metabolismo , Hidrocarburos Policíclicos Aromáticos/análisis , Plantas/metabolismo
2.
J Environ Health Sci Eng ; 20(1): 241-249, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35669797

RESUMEN

Background and aim: The approach of food storage, especially cereals and basic human food sources, has long been considered as a problem to combat storage pests. the use of plant compounds has been suggested by researchers as an alternative to phosphine in the fight against pests.In this study, four plants such as Aesculushippocastanum, Thymus daenensis, Artemisia abrotanum and Chrozophoratinctoria were evaluated based on their deadly and repellent properties of pests and insectsconsidering Iranian medicine sources. Materials and methods: First, plant extracts were prepared by ethanol solvent method and then, their lethal and Anti-feeding experiments were performed on rice insects (Sitophylusoryzae) in standard laboratory conditions. Results: Extracts of Thymus daenensis, Aesculushippocastanum, Artemisia abrotanum and Chrozophoratinctoria were estimated to be 553.2, 753.6, 878.3 and 987.3 mg / ml effective dose, respectively.The results showed that Thymus daenensis extract with 90.33% with lower concentration compared to Aesculushippocastanum, Artemisia abrotanum and Chrozophoratinctoria extracts has the highest lethal effect against S. oryzae. Also in Anti-feedingtest, Thymus daenensis extract showed the highest Anti-feedingeffect in comparison with Aesculushippocastanum, Artemisia abrotanum and Chrozophoratinctoria extracts, respectively. Conclusions: The use of plants in the control against storage pests such as rice weevils will have favorable environmental results, human health and less storage is dangerous.

3.
J Environ Health Sci Eng ; 20(1): 219-225, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35669812

RESUMEN

Purpose: Nosocomial infections can be transmitted by contaminated hospital surfaces with resistant pathogens. Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen that causes public healthcare issues. Conventional sanitation is not efficiently contributing to removing resistant pathogens. Bacteriophages suggest safe and specific decontamination. Bacteriophages are a promising alternative strategy to chemical biocides. This research aimed to evaluate the potential of phage in controlling P. aeruginosa in infected hard surfaces. Methods: Bacteriophage was isolated from hospital wastewater. The efficiency lytic activity of phage against P. aeruginosa was assessed on various infected hard surfaces as plastic and ceramic. 50 µl of the phage lysate (2 × 1012 PFU/mL) and 50 µl of 70% Ethanol solution separately were spread on the different infected surfaces. After 15 min, 1, 3, 6, and 24 h, surfaces were directly sampled by contact plates. The bacterial load was evaluated by enumerating plate CFU. Results: Cystoviridae phages with titer (2 × 1012 PFU/mL) efficiently can reduce P. aeruginosa on contaminated surfaces. The treated surfaces with 70% Ethanol solution and phage showed an evident drop in bacterial cell number. Conclusions: Bacteriophages can be used as a new option for the development of biological products aimed at the control and deletion of pathogens on contaminated hard surfaces.

4.
J Environ Health Sci Eng ; 19(2): 1623-1633, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34900293

RESUMEN

PURPOSE: The existence of parasite agents in natural organic fertilizers can lead to health problems and infection transmission. The aim of the present study was to survey the parasites' population reduction during the vermicomposting of the mixtures of municipal sewage sludge (SS) and cow dung (CD) using E. fetida earthworms. METHODS: The vermicomposting process was performed by using earthworms of E. fetida species. The composting process was conducted in 27 pilots for 3 months. The identification and counting of the parasites' population were carried out by Mac Master Slide, according to Bailenger method. RESULTS: The results indicated that the type and number of parasite elements decreased with increasing vermicomposting time. The cumulative removal percent of parasites for sewage sludge (96.10%) was more than the SS + CD (93.65%) and CD (92.93%) treatments. The results showed that after 90 days of vermicomposting, the highest cumulative reduction in the number of parasites was obtained for the treatments with 40 earthworms (98.48%), while the corresponding value for the treatments without earthworms was (88.66%). The statistical analysis indicated that in terms of the parasite's population, a significant difference was observed for the three kinds of compostable materials (P < 0.05), however, this difference was not significant for the three levels of the earthworms (P > 0.05). CONCLUSION: The results showed that the mixture of sewage sludge and cow dung in combination with sawdust could lead to greater and faster reduction in the parasite's population. In addition, the bio-transformed product can be used as useful manure.

5.
Environ Technol ; 42(1): 100-113, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31107636

RESUMEN

The aim of this study is tracing seasonal variability of total organic carbon (TOC), trihalomethanes (THMs) and haloacetic acids (HAA5) as disinfection by-products (DBPs) in drinking water sources and the distribution system in the north of Iran. The results showed that the concentrations of TOC were within the range of 0.013-1.42 mg/L. In addition, the results showed that most of the water sources had nearly the same concentration level (i.e. <1 mg/L), with the exception of one peak for groundwater source and middle drinking water distribution system in the city of Sari (1.42 mg/L) and Babol (1.37 mg/L). It was demonstrated that brominated HAA (MBAA) presented the highest concentration in the Sari City (17.3 µg/L) followed by the City of Behshahr (8.9-11.19 µg/L). The Babol City showed the highest concentration of chlorinated HAA (22.403 and 22.503 µg/L for DCAA and TCAA, respectively). Among the different compounds of THMs, the concentration of CHBr3 was nearly in the same order of magnitude in the cities of Sari, Babol and Behshahr for both spring and summer seasons. The brominated THM (BDCM) concentrations were also high (14.7 µg/L) in the Behshahr City. The results of independent t-test indicated that the seasonal (spring and summer) difference was statistically significant in the case of temperature and TTHM (p < 0.05). Furthermore, total HAA5 ≤ 60 µg/L and THM ≤100 µg/L in all the considered cities over the period of the study. The TTHMs concentration was 56 µg/L in treating surface water (TSW) source in the summer season at the Sari city.


Asunto(s)
Desinfectantes , Agua Potable , Contaminantes Químicos del Agua , Purificación del Agua , Ciudades , Desinfección , Sequías , Irán , Estaciones del Año , Trihalometanos/análisis , Contaminantes Químicos del Agua/análisis
6.
J Hazard Mater ; 405: 124185, 2021 03 05.
Artículo en Inglés | MEDLINE | ID: mdl-33189473

RESUMEN

This study investigates the mineralogy, micro-morphology, chemical characteristics and oxidation toxicity of respirable dusts generated in underground coal mines. The active sampling was applied to collect airborne particulates with aerodynamic diameter <4 µm (PM4) at depth greater than 500 m from earth surface. The average mass concentration of PM4 was extremely higher than recommended values. QXRD and FESEM-EDS analyses were applied to study the micro-mineralogy and micro-morphology of respirable dusts. The chemical analysis by ICP-MS revealed an enrichment of V, Cr, Cu, Zn, As, Ag, Cd and Sb in respirable dust compared with the background environment and world coals. The EPA's health risk model showed that the health risk posed by Cr and Co in all workplaces exceeded the acceptable risk value for human health. The synthetic respiratory tract lining fluid (RTLF) model was utilized to achieve a novel insight into the toxicity of respirable coal dust. The result showed an overall depletion of lung surface antioxidants with the decreasing trend of ascorbic acid > reduced glutathione >> urate, implying low- to medium level of oxidative stress. The result of this study can be applied globally by decision-makers to decrease hazardous exposure of mine workers to respirable dust.


Asunto(s)
Minas de Carbón , Exposición Profesional , Carbón Mineral , Polvo/análisis , Humanos , Especies Reactivas de Oxígeno , Medición de Riesgo
7.
J Environ Health Sci Eng ; 18(2): 1083-1097, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33312626

RESUMEN

The aim of this study was to evaluate the efficiency of photocatalytic ozonation process using graphene-dioxide titanium nanocomposite in removing Pentachlorophenol (PCP) from aqueous solutions. In this study, nanocomposites with graphene to TiO2(G/T) ratios of 1:10 and 1:20 were synthesized by hydrothermal method, and its characteristics were assessed using various analyses, SEM, XRD, FTIR, TEM, BET and TGA. In this process, the effects of parameters including O3 concentration (0.25-1.25 mg/L), nanocomposite concentration (50-500 mg/L), initial PCP concentration (10-100 mg/L), and time (10-60 min), were studied. The results showed that PCP removal efficiency was increased by decreasing solute concentration. Increasing nanocomposite dose to 100 mg/L was led to an increase in efficiency (99.1%), but then a decreasing trend was observed. Increasing the concentration of ozone, up to specific value, also enhanced the efficiency but then had a negative effect on process efficiency. Furthermore, the optimum ratio of the catalyst was determined to be 1:20. The highest efficiency of the process for initial pentachlorophenol concentration of 100 mg/L was obtained 98.82% in optimum conditions (catalyst dose of 100 mg/L and 60 min). It is concluded that the photocatalytic ozonation process using graphene-dioxide titanium nanocomposite had the highest efficiency in removal and mineralization of PCP.

8.
9.
J Microbiol Methods ; 167: 105736, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31626893

RESUMEN

In the present study, SiO2-TiO2 hybrid nanomaterial and zeolite-TiO2 (Z-TiO2) composites were synthesized by the sol-gel method. Then, the antibacterial activity of the above-mentioned synthesized materials, SiO2 and zeolite (Z) was investigated by the disk diffusion method using Echerichia coli and Enterobacter aerogenes as test microorganisms. All the materials showed antibacterial activity against E. coli with 7.2, 10.7, 3.5 and 8.2 mm of inhibition zone for SiO2-TiO2 hybrid nanomaterial, SiO2, zeolite and Z-TiO2 composite, respectively. However, none of them showed antibacterial activity against E. aerogenes. The obtained results pointed out that these natural-based materials (i.e. Z, SiO2, Z-TiO2 and SiO2-TiO2), known to be noncarcinogenic and nontoxic, can be used as disinfectants against E. coli (an important indicator of the bacteriological quality of water) as safe and eco-friendly alternatives to chlorine.


Asunto(s)
Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Desinfectantes/farmacología , Nanocompuestos/química , Nanopartículas/química , Antibacterianos/química , Enterobacter aerogenes/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Dióxido de Silicio/farmacología , Titanio/farmacología , Zeolitas/farmacología
10.
RSC Adv ; 9(29): 16496-16508, 2019 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-35516408

RESUMEN

CoFe3O4 nanoparticles supported on multi-walled carbon nanotubes (MWCNTs-CoFe3O4) were synthesized by the co-precipitation method as a novel catalyst for degradation of diclofenac (DCF). The comparative experiments indicated that MWCNTs-CoFe3O4 has a better catalytic activity in degradation of DCF and activation of peroxymonosulfate (PMS) compared to other catalytic systems. This can be attributed to the interaction of MWCNTs with CoFe3O4 in accelerating the absorption process and activating the PMS (E a = 22.93 kJ mol-1). The removal efficiencies of DCF and total organic carbon (TOC) were 99.04% and 50.11%, under optimum conditions, e.g., pH of 7, PMS dosage of 4 mM, DCF concentration of 30 mg L-1, catalyst dosage of 500 mg L-1, and reaction time of 120 min. The oxidation of DCF was fitted by the pseudo-first-order kinetic model and the constant rate was increased by increasing the pH, temperature, dosage of PMS and catalyst. The production of reactive species was studied using scavengers such as TBA and ethanol and the results showed that sulfate radical is the reactive species responsible for the degradation of DCF. The MWCNTs-CoFe3O4 catalyst showed high stability and reusability based on five successful repeated reactions, X-ray diffraction and energy dispersive X-ray spectroscopy analysis. Based on the intermediates detected by gas chromatography-mass spectrometry (GC-MS), the possible pathways for DCF catalytic oxidation were proposed. The results explained that the PMS/MWCNTs-CoFe3O4 system is a promising method for treating DCF solution due to high efficiency, good reusability of catalyst and greater PMS activation.

11.
J Environ Health Sci Eng ; 17(2): 767-777, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32030150

RESUMEN

BACKGROUND: Different bulking agents are used in the compost of dewatered sludge (DWS). The aim of this study has been using of indigenous bulking agents (IBAs) in the enhancing of the DWS class of municipal wastewater from class B to class A and complementary stabilization of it for production of green manure in Sari city, Iran. METHODS: Three IBAs including the Saccharum Wastes (SW), Citrus Purning Wastes (CPW) and Phragmites Australis (PA) from eight IBAs were selected to be compared with the sawdust (SD) that was as a control bulking agent. Five turned windrow piles were constructed on a full scale and on base of optimal C/N equal 25.All experiments were performed on the base of the standard methods on initial mix and final compost. RESULTS: Among five windrow piles, P5 was been the best pile with a weighting ratio of DWS to IBAs (DWS: SW: CPW: PA) equal 1: 0.2: 0.24: 0.28. Pile P1 with weighting ratio DWS: SW equal 1: 0.6, Pile P3 with weighting ratio DWS: PA equal 1: 0.84, Pile P2 with weighting ratio DWS: CPW equal 1: 0.73 and Pile P4 with weighting ratio DWS: SD equal 1: 0.57 were placed in the next rounds. The results showed that the class of DWS enhanced to Class A for about 80 to 97 days and complementary stabilization of DWS by IBAs was done well and produced green manure in term of organic matter, potassium, germination index, PH, C/N and electrical conductivity had reached to the Grade 1 of Iran's manure 10716 standard and in term of phosphorus and moisture had reached to the Grade 2 of this standard. Also heavy metals were below the maximum permissible of standards. CONCLUSION: Using of IBAs, had a higher efficiency than the control bulking agent (sawdust) in enhancing sludge class and its stabilization, so that using of them in combination (mix of IBAs) had the highest efficiency and respectively, Saccharum Wastes (SW), Phragmites Australis (PA), Citrus pruning wastes (CPW) were placed in the next round, and sawdust was placed after them. By adding suitable IBAS, with an optimal ratio in turned windrow method, the class of DWS of sari WWTP enhanced to Class A and complementary stabilization of DWS has been well done and the produced green manure has been reached to agricultural standards and can be safely used in agriculture.

12.
Artículo en Inglés | MEDLINE | ID: mdl-29234499

RESUMEN

Disinfection by-products (DBPs) have heterogeneous structures which are suspected carcinogens as a result of reactions between NOMs (Natural Organic Matter) and oxidants/disinfectants such as chlorine. Because of variability in DBPs characteristics, eliminate completely from drinking water by single technique is impossible. The current article reviews removal of the precursors and DBPs by different membrane filtration methods such as Microfiltration (MF), Ultrafiltration (UF), Nanofiltration (NF) and Reverse Osmosis (RO) techniques. Also, we provide an overview of existing and potentially Membrane filtration techniques, highlight their strengths and drawbacks. MF membranes are a suitable alternative to remove suspended solids and colloidal materials. However, NOMs fractions are effectively removed by negatively charged UF membrane. RO can remove both organic and inorganic DBPs and precursors simultaneously. NF can be used to remove compounds from macromolecular size to multivalent ions.

13.
Data Brief ; 15: 127-132, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28975144

RESUMEN

Fluoride concentrations in drinking water were analyzed relative to air temperature data collected in different provinces of Iran. Determining suitable concentrations of fluoride in drinking water is crucial for communities because of the health effects of fluoride on humans. This study analyzed fluoride concentrations in drinking water from selected Iranian provinces. The data were derived mainly from a detailed literature review. The annual mean maximum temperatures (AMMTs) were collected from a popular website that maintains records of daily ambient temperature measurements for the last five years (2012-2016). Using regional ambient temperatures, the optimal value of fluoride in drinking water for each province was calculated by the Galgan and Vermillion formula. These optimal fluoride concentrations in drinking water for different Iranian regions were calculated to be 0.64-1.04 mg F/L. Most of the selected provinces were found to have acceptable concentrations of fluoride, except for Alborz, Khuzestan, and Hormozgan, which reported concentrations of 0.66, 0.66, and 0.64 mg/L, respectively.

14.
Water Sci Technol ; 74(9): 2021-2035, 2016 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-27842022

RESUMEN

In this study, eucalyptus bark and Crataegus oxyacantha core-based activated carbon were synthesized and their morphological features characterized by scanning electron microscopy and Fourier transform infrared spectroscopy techniques. The efficiency of synthesized adsorbents in removal of methylene blue (MB) from aqueous solution was investigated in a series of batch experiments. Furthermore, the influences of various experimental factors involving the contact time, the initial dye concentration, the adsorbent dosage, and the pH of the dye solution were investigated. The point of zero charge (pHpzc) of the applied adsorbents was also determined. In addition, the experimental data were expressed by Langmuir, Freundlich and Tempkin isotherms and pseudo-first order and pseudo-second order kinetic models. Adsorption equilibrium of the two adsorbents was reached within 1 h for MB concentrations of 20 to 100 mg/L. The equilibrium data obtained at optimum conditions of MB sorption by eucalyptus bark activated carbon and Crataegus oxyacantha core activated carbon were best fitted to Tempkin and Langmuir isotherm models, respectively. Besides, it was revealed that the adsorption rate follows a pseudo-second order kinetic model. From the findings of this study, it can be postulated that these adsorbents could be of great potential as a new class of adsorbents for organic dye removal from polluted water.


Asunto(s)
Carbón Orgánico/química , Crataegus/química , Eucalyptus/química , Azul de Metileno/química , Corteza de la Planta/química , Adsorción , Colorantes/química , Concentración de Iones de Hidrógeno , Cinética , Microscopía Electrónica de Rastreo , Soluciones , Espectroscopía Infrarroja por Transformada de Fourier , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos
15.
Environ Sci Pollut Res Int ; 23(21): 21846-21860, 2016 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-27525742

RESUMEN

The photocatalytic degradation of furfural in aqueous solution was investigated using N-doped titanium dioxide nanoparticles under sunlight and ultraviolet radiation (N-TiO2/Sun and N-TiO2/UV) in a lab-scale batch photoreactor. The N-TiO2 nanoparticles prepared using a sol-gel method were characterized using XRD, X-ray photoelectron spectroscopy (XPS), and SEM analyses. Using HPLC to monitor the furfural concentration, the effect of catalyst dosage, contact time, initial solution pH, initial furfural concentration, and sunlight or ultraviolet radiation on the degradation efficiency was studied. The efficiency of furfural removal was found to increase with increased reaction time, nanoparticle loading, and pH for both processes, whereas the efficiency decreased with increased furfural concentration. The maximum removal efficiencies for the N-TiO2/UV and N-TiO2/Sun processes were 97 and 78 %, respectively, whereas the mean removal efficiencies were 80.71 ± 2.08 % and 62.85 ± 2.41 %, respectively. In general, the degradation and elimination rate of furfural using the N-TiO2/UV process was higher than that using the N-TiO2/Sun process.


Asunto(s)
Furaldehído/química , Nanopartículas del Metal/química , Titanio/química , Catálisis , Espectroscopía de Fotoelectrones , Luz Solar , Rayos Ultravioleta , Contaminantes Químicos del Agua/química
16.
Environ Monit Assess ; 187(11): 682, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26452506

RESUMEN

In this study, multi-walled carbon nanotubes were functionalized by L-cysteine to show the kinetic and isotherm modeling of Cd (II) ions onto L-cysteine functionalized multi-walled carbon nanotubes. The adsorption behavior of Cd (II) ion was studied by varying parameters including dose of L-MWCNTs, contact time, and cadmium concentration. Equilibrium adsorption isotherms and kinetics were also investigated based on Cd (II) adsorption tests. The results showed that an increase in contact time and adsorbent dosage resulted in increase of the adsorption rate. The optimum condition of the Cd (II) removal process was found at pH=7.0, 15 mg/L L-MWCNTs dosage, 6 mg/L cadmium concentration, and contact time of 60 min. The removal percent was equal to 89.56 at optimum condition. Langmuir and Freundlich models were employed to analyze the experimental data. The data showed well fitting with the Langmuir model (R2=0.994) with q max of 43.47 mg/g. Analyzing the kinetic data by the pseudo-first-order and pseudo-second-order equations revealed that the adsorption of cadmium using L-MWSNTs following the pseudo-second-order kinetic model with correlation coefficients (R2) equals to 0.998, 0.992, and 0.998 for 3, 6, and 9 mg/L Cd (II) concentrations, respectively. The experimental data fitted very well with the pseudo-second-order. Overall, treatment of polluted solution to Cd (II) by adsorption process using L-MWCNT can be considered as an effective technology.


Asunto(s)
Cisteína/química , Nanotubos de Carbono/química , Adsorción , Cadmio/química , Restauración y Remediación Ambiental/métodos , Cinética , Modelos Químicos
17.
Artículo en Inglés | MEDLINE | ID: mdl-24693863

RESUMEN

Many organic hazardous pollutants such as bisphenolA (BPA) which are toxic and not easily biodegradable can concerns for environmental pollution worldwide. The objective of this study was to examine whether Azolla Filiculoides is able to remove BPA from aqueous solutions. In this study, the Azolla with different biomass (0.3, 0.6, 0.9, 1.2 g) has been cultured in solution that was contained 5, 10, 25 and 50 ppm BPA. Samples were collected every 2 days from all of containers. The analytical determination of BPA was performed by using of DR4000 uv-visible at λmax = 276 nm. The results indicated that Azolla has high ability to remove BPA from aqueous solutions. The BPA removal was 60-90%. The removal efficiency is increasing with decreasing of BPA concentration and increasing of biomass amount and vice versa. The removal efficiency was more than 90% when BPA concentration was 5 ppm and amount of biomass was 0.9gr. It is concluded that Azolla able remove BPA by Phytodegradation from the aqueous solutions. Since conventional methods of BPA removal need to high cost and energy, phytoremediation by Azolla as a natural treatment system can decrease those issues and it can be a useful and beneficial method to removal of BPA.

18.
J Environ Health Sci Eng ; 11(1): 35, 2013 Dec 19.
Artículo en Inglés | MEDLINE | ID: mdl-24355262

RESUMEN

This paper reviews both heterotrophic and autotrophic processes for the removal of nitrate from water supplies. The most commonly used carbon sources in heterotrophic denitrification are methanol, ethanol and acetic acid. Process performance for each feed stock is compared with particular reference nitrate and nitrite residual and to toxicity potential. Autotrophic nitrate removal has the advantages of not requiring an organic carbon source; however the slow growth rate of autotrophic bacteria and low nitrate removal rate have contributed to the fact that relatively few full scale plants are in operation at the present time.

19.
Iranian J Environ Health Sci Eng ; 9(1): 3, 2012 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-23369204

RESUMEN

Advanced oxidation processes like Fenton and photo-Fenton have been effectively applied to oxidize the persistent organic compounds in solid waste leachate and convert them to unharmful materials and products. However, there are limited data about application of Fenton-like process in leachate treatment. Therefore, this study was designed with the objective of treating municipal landfill leachate by Fenton, Fenton-like and photo-Fenton processes to determine the effect of different variables, by setting up a pilot system. The used leachate was collected from a municipal unsanitary landfill in Qaem-Shahr in the north of Iran. Fenton and Fenton-like processes were conducted by Jar-test method. Photo-Fenton process was performed in a glass photo-reactor. In all processes, H2O2 was used as the oxidant. FeSO4.7H2O and FeCl3.6H2O were used as reagents. All parameters were measured based on standard methods. The results showed that the optimum concentration of H2O2 was equal to 5 g/L for the Fenton-like process and 3 g/L for the Fenton and photo-Fenton processes. The optimum ratio of H2O2: Fe+2/Fe+3 were equal to 8:1 in all processes. At optimum conditions, the amount of COD removal was 69.6%, 65.9% and 83.2% in Fenton, Fenton-like and photo-Fenton processes, respectively. In addition, optimum pH were 3, 5 and 3 and the optimum contact time were 150, 90 and 120 minutes, for Fenton, Fenton-like and photo-Fenton processes, respectively. After all processes, the biodegradability (BOD5/COD ratio) of the treated leachate was increased compared to that of the raw leachate and the highest increase in BOD5/COD ratio was observed in the photo-Fenton process. The efficiency of the Fenton-like process was overally less than Fenton and photo-Fenton processes, meanwhile the Fenton-like process was at higher pH and did not show problems.

20.
Water Res ; 43(13): 3270-80, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19520413

RESUMEN

This study demonstrates the removal efficiency and the permeate flux behavior during cross-flow nanofiltration (NF) of aqueous solutions of five pharmaceutically active compounds (PhACs). Cephalexin, tetracycline, acetaminophen, indomethacin and amoxicillin were used as models of PhACs, and alginate was selected as model of natural organic matter (NOM). Two commercial composite NF membranes (SR2 and SR3) with different characteristics were used. The highest rejection was observed for tetracycline, i.e., 75-95% for membrane SR 2 and 95-100% for membrane SR 3, while the rejection was least for acetaminophen (32-36% for SR2 and 52-59% for SR3). As the pH of acetaminophen solution was increased (from 6 to 9) the rejection would increase. Changes of ionic content (from 10 to 20mM) lead to increase (from 89 to 93% for SR 3) or decrease (from 100 to 91% for SR2) of cephalexin rejection depending on the membrane used. The permeate flux would decrease with decreasing the pH solution and increasing ionic strength. The addition of alginate in the feed stream decreased the permeate flux, with lower reduction for SR3, and increased the PhAC rejection except for acetaminophen and amoxicillin. Both size and Donnan exclusions seemed to occur, and the effect of Donnan exclusion was more pronounced for the NF membrane having larger effective pore size (SR2).


Asunto(s)
Residuos de Medicamentos/química , Ultrafiltración/métodos , Contaminantes Químicos del Agua/química , Acetaminofén/análisis , Acetaminofén/química , Alginatos/química , Amoxicilina/análisis , Amoxicilina/química , Cefalexina/análisis , Cefalexina/química , Residuos de Medicamentos/aislamiento & purificación , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Cinética , Permeabilidad , Preparaciones Farmacéuticas/análisis , Preparaciones Farmacéuticas/química , Ultrafiltración/instrumentación , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua
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