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Cyanide is a highly toxic compound which is Normally found in numerous industries, such as electroplating wastewater. Release of this compounds in to the Enviroment has a lot health hazards.The Purpose of this study is to Determine the efficiency of electrochemical oxidation method for Cyanide removal from industrial wastewaters. This study conducted in a pilot system experimentally .In this study the effect of pH, voltage and operation time on total cyanide removal from industrial wastewaters by Electrochemical Oxidation was investigated by applying a Stainless Steel as a Anode and copper as a cathode. The average percentage removal of cyanide was about 88 with SD=2.43. The optimal condition obtained at voltage of 9V and pH=13 and The operation time of 90 minutes. The volume of sludge which formed in this condition was about 20 percent of a one liter pilot reactor. The results statistically confirmed the significant relationship between input and cyanide concentration removal efficiency [p< 0.05], and confirmed The this confirmed The relation between cyanide and cyanat oxidation and hydroxyl ions consumption 1:2.[L.Szpyruowicz]. therefore the best pH is 12.5-13.5 by Considering the need of alkaline environment to remove cyanide
Sujet(s)
Techniques électrochimiques , Élimination des déchets liquides/méthodes , Rendement , Polluants chimiques de l'eauRÉSUMÉ
Neonatal sepsis is one of the common causes of neonatal mortality and morbidity. This study was aimed to evaluate the plasma interleukin-6 [IL-6] level as an early marker of neonatal sepsis. This study was conducted on 142 term neonates admitted to the neonatal intensive care unit of Kashan Shahid Beheshti hospital during 2010-11. The plasma IL-6 level of cases was determined using the electrochemiluminescence method. Ten icteric neonates with no signs or symptoms of sepsis were treated with phototherapy. Bactec blood culture was performed in 132 cases of suspected sepsis. Ten cases had positive blood culture and 122 negative blood culture with symptoms of sepsis. Then the levels of IL-6, in10 positive blood culture, 10 negative blood culture and another 10 cases with no symptoms of sepsis, were compared using Kruskal-Wallis test. Seventy-four cases were male and 68 were female. The incidence of neonatal sepsis was 7%. The most common bacterial agents were group B Streptococcus and Staphylococcus epidermidis. Tachypnea [35.9%] was the most common sign among the admitted neonates. The mean IL-6 level in the first [suspected sepsis with a positive blood culture], the second [suspected sepsis with a negative blood culture] and the control group [icteric neonates] were 1545.65, 14.79 and 11.04 micro g/dl, respectively [P=0.001]. The plasma IL-6 level can be a good predictor of early neonatal sepsis
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Background and aims: Crude oil is very complex composition with harmful effect in human health, such as carcinogenesis and blood dyscrasia. Because of the entry of relatively high volume of these compounds in aquatic environments, effective controlling is very important. The aim of this study was to investigate the effect of powdered activated carbon [PAC] for reducing the toxicity of crude oil in water
Methods: Water soluble fraction standard samples were prepared with one part crude oil in 9 part water. For toxicity test, different concentrations of crude oil water soluble fraction in water and larvae of rainbow trout were used. Before and after the addition of 10, 20, 40 and 60 mg/l powdered activated carbon, TOC and bioassay tests were performed. LC50 and evaluation of results was done with probit statistic program
Results: LC50 for samples 24, 48, 96 hrs after addition of different concentration of PAC were 94.8, 106.6, 117.8, 138.3 and 181.5 mg/l. Values of TOC for these samples was 44.81, 43.88, 38.16, 36.62 and 35.14 mg/l
Conclusion: The use of activated carbon reduced toxicity and TOC. With increase in the concentration of activated carbon, toxicity was decreased, but intensity of TOC removal wasn't similar to toxicity removal. Using of powdered activated carbon for treatment, in case of accidents and entering crude oil in drinking water supplies, can be considered
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In this research, the continuously operated laboratory scale Kaldnes [k1] moving bed biofilm reactors [MBBRs] under partial nitrification-denitrification process were used for treatment of synthetic wastewater containing ammonium and glucose. The Anoxic and Aerobic reactors were filled to 40 and 50% [v/v] to attach and retain biomass with k1 biofilm carriers, respectively. The favorite internal recycle ratio and hydraulic residence time [HRT] to eliminate nitrogen compounds were 300% of inflow rate and 20 hours, respectively. Optimal dissolved oxygen [DO] was 1-1.5 mg/L in the aerobic reactor. No sludge was returned into the system and only an internal recycling was performed from aerobic to anoxic reactor. The results showed that the maximum and average specific nitrification rate [SNR] in the aerobic reactor were 49.4 and 16.6 g NOx-N/KgVSS.day, respectively and the maximum and average specific denitrification rate [SDNR] as 156.8 and 40.1gNOx-N/KgVSS.day in the anoxic reactor, respectively. The results also showed that it is possible to reach a stable partial nitrification with high ratio of NO2-N/NOx-N [80% to 85%] during high load ammonium and low DO concentration [<1.5 mg/L] in the aerobic reactor. During optimum conditions, the average removal efficiency of total nitrogen [TN], ammonia and soluble organic carbon [SCOD] occurred as 98.23%, 99.75% and 99.4%, respectively. This study showed that the partial nitrification/denitrification process in the moving bed biofilm reactors system has an acceptable performance for treatment of wastewater with high load of organic carbon and organic nitrogen compounds
Sujet(s)
Biofilms , Eaux usées , Nitrification , Dénitrification , Composés d'ammonium , GlucoseRÉSUMÉ
Today, due to health, environmental and economical problems, of chlorine application, UV radiation is better option than chlorine for disinfection of effluent. The aim of this study was disinfection of secondary effluent with UV radiation. Two types of UV disinfection system including low pressure [LP] and medium pressure [MP] was used to disinfection of Isfahan North Wastewater Treatment Plant [INWWTP] effluent without pretreatment. Single and combined lamps were operated to evaluate the removal of total and fecal coliforms [TC and FC], and fecal streptococcus [FS]. TSS, iron, hardness, UV absorption and transmittance were analyzed in order to observe the fouling of the quartz sleeves. After using LP lamp with dose of 161 mws/cm[2], TC and FC content was declined to standard level [1000 TC, and 400 FC/100ml]. In addition, disinfection with MP lamp was led to FS content of 400 MPN/100 mL. Combination of LP and MP, with dose of 460 mws/cm[2] could be met the environmental requirements of TC and FC, and the FS count was reached to 400 MPN/100 mL with dose of 237 mws/cm[2]. Maximum photo-reactivation percentage of coliforms after LP and MP lamps were appeared 15 and 3 percent respectively, while it was not observed for FS. High fluctuation in secondary effluent quality of INWWTP mainly TSS concentration was caused to decline of the UVT value. Therefore, disinfection of effluent by LP, MP and even combined both systems are not applicable in conventional UV dose. Hence, using advanced process unit before UV disinfection system is necessary for removal of TSS
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Purification de l'eau , Pollution de l'eau , Polluants de l'eau , Gestion des déchets , Désinfection , Élimination des déchets liquidesRÉSUMÉ
The sorption of cadmium and humic acids from aqueous solutions using surface-modified nanozeolite A has been investigated under various examination conditions. The morphology of untreated and treated nanozeolite was studied under scanning electron microscope and transmission electron microscope. Isotherms of cadmium adsorption onto surface-modified nanozeolite A were studied at different pH, solid to liquid ratio, adsorbate concentration and interaction time. Kinetic and equilibrium studies were conducted and the equilibrium data have been analyzed using Langmuir and Freundlich isotherm models. The study revealed that experimental results were in agreement with the Freundlich model. The Langmuir monolayer adsorption capacity was found to be 1666.67 g cadmium and 6.75 g humic acid per gram of modified nanozeolite A, which is higher than that of reported value for other zeolites. The sorption ability was enhanced by surface modification and reduction in size and enabled the zeolite to adsorb cadmium. The adsorption of cadmium and humic acid on nanozeolite was found to be the highest at pH 6 and 3, respectively. Results showed that solid to liquid ratio and pH are the most important factors for cadmium and humic acid removal, respectively. Effect of competitive ions was studied and results showed that there is no competition between cadmium and humic acid sorption and presence of these ions
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Substances humiques , Adsorption , SolutionsRÉSUMÉ
This study investigates the anaerobic treat ability of reactive Red2 in an anaerobic/aerobic sequential process. Laboratory scale anaerobic baffled reactor and fixed activated sludge reactor were operated at different organic loadings and hydraulic retention times. The effects of shock dye concentration on the chemical oxygen demand and color removal efficiencies were investigated in the anaerobic baffled reactor. The effect of hydraulic retention time on the color and chemical oxygen demand removal efficiencies were also investigated in the aerobic reactor. The studies were carried out in continuous mode and the effluent of the anaerobic baffled reactor was used as feed for the fixed activated sludge reactor. Chemical oxygen demand removal efficiency of 54.5% was obtained at HRT =1 day in the anaerobic reactor. The average color removal was 89.5%. Chemical oxygen demand removal efficiency of 69% was obtained at HRT =7 h in the aerobic fixed activated sludge reactor. A slight decrease of the color was also observed in the aerobic reactor. This investigation has shown that successful treatment of a highly colored wastewater is possible in the anaerobic baffled reactor. Also the results showed that, anaerobic biological system has higher efficiency in dye removal than fixed activated sludge system, while aerobic system has higher efficiency in chemical oxygen demand removal comparing with the anaerobic baffled reactor
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Triazines , Eaux d'égout , Amines biogènes , Purification de l'eau , Agents colorantsRÉSUMÉ
In present study, degradation of p-chlorophenol using several oxidation systems involving advanced oxidation processes such as ultraviolet/H[2]O[2], microwave/H[2]O[2] and both in the absence of hydrogen peroxide in batch mode by photolytic pilot plant and modified domestic microwave oven was evaluated. The oxidation rate was influenced by many factors, such as the pH value, the amount of hydrogen peroxide, irradiation time and microwave power. The optimum conditions obtained for the best degradation rate were pH=7 and H[2]O[2] concentration of 0.05 mol/L for ultraviolet/H[2]O[2] system and pH=10.5, H[2]O[2] concentration of about 0.1 mol/L and microwave irradiation power of about 600W for microwave/H[2]O[2] system at constant p-chlorophenol concentration. The degradation of p-chlorophenol by different types of oxidation processes followed first order rate decay kinetics. The rate constants were 0.137,0.012,0.02 and 0.004/min[1] for ultraviolet/H[2]O[2], microwave/H[2]O[2], ultraviolet and microwave irradiation alone, respectively. Finally a comparison of the specific energy consumption showed that ultraviolet/ H[2]O[2] process reduced the energy consumption by at least 67% compared with the microwave H[2]O[2] process
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Micro-ondes , Rayons ultraviolets , Peroxyde d'hydrogène , Élimination des déchets liquidesRÉSUMÉ
Although Iran is known as an iodine sufficient area, congenital hypothyroidism [CH] is prevalent. Because iodine excess can contribute to hypothyroidism we evaluated the role of iodine excess and ID in the etiology of CH. In a cross sectional study UICs [Urine Iodine Concentration] in newborns with CH as well as UIC and MIC [Milk Iodine Concentration] of their mothers were compared with a control group. After acid digestion of urine samples milk samples, iodine concentrations were determined by the Sandell-Kolthoff method. Chi-square and Wilcoxon, and Pearson correlation tests were used for statistical analysis. A P value less than 0.05 was considered statistically significant. The median of MIC of CH [n=68] and healthy subjects [n=179] was different [210 vs. 170 micro g/L respectively, P<0.05]. However the median of UIC in neonates and those of mother's of CH and healthy subjects were not different statistically [305 vs. 300 micro g/L and 150 vs. 130 micro g/L respectively, P>0.05]; 71.2% and 46.7% of mothers of hypothyroid and healthy subjects had MICs above 180 micro g/I [iodine excess] respectively [p=0.002]. Based on the higher levels of MIC in mothers of CH neonates, iodine excess could be a possible risk factor for CH. Since however comparison of UIC between the control and neonate groups showed no differences, further investigations are needed to facilitate deeper insight into and clarification of the etiology of CH
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Humains , Iode/urine , Iode/composition chimique , Iode/déficit , Études transversales , Tests de sensibilité microbienne , Nouveau-néRÉSUMÉ
During the last decade, there has been a concern about the relation between aluminum residuals in treated water and Alzheimer disease, and more interest has been considered on the development of natural coagulants such as chitosan. Chitosan, a natural linear biopolyaminosaccharide, is obtained by alkaline deacetylation of chitin. The present study was aimed to investigate the effects of alum as coagulant in conjunction with chitosan as coagulant aid on the removal of turbidity, hardness and Escherichia coli from water. A conventional jar test apparatus was employed for the tests. The optimum pH was observed between 7 to 7.5 for all turbidities. The optimum doses of alum and chitosan when used in conjunction, were 10mg/L and 1mg/L, 5mg/L and 0.5mg/L, and 5mg/L and 0.5mg/L in low, medium and high turbidities, respectively. Turbidity removal efficiency was resulted between%74.3 to%98.2 by alum in conjunction with chitosan. Residual Al[+3] in treated water was less than 0.2 mg/L, meeting the international guidelines. The results showed that turbidity decrease provided also a primary Escherichia coli reduction of 2-4 log units within the first 1 to 2 hr of treatment. Hardness removal efficiency decreased when the total hardness increased from 102 to 476mg/L as CaCO3. At low initial turbidity, chitosan showed marginally better performance on hardness, especially at the ranges of 100 to 210 mg/L as CaCO3. In conclusion, coagulant aid showed a useful method for coagulation process. By using natural coagulants, considerable savings in chemicals and sludge handling cost may be achieved
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Purification de l'eau/méthodes , Alun , Coagulants , Escherichia coli , Rendement , DuretéRÉSUMÉ
Nitrification, the oxidation of ammonia tp nitrate catalyzed by bacteria, is a key part of global nitrogen cycling. In the first step of nitrification, chemolithoautotrophic ammonia oxidizers transform ammonia to nitrite, which is subsequently oxidized to nitrate by nitrite-oxidizing bacteria. This process can be affected by several factors. In this study the effect of influent COD/N ratio on nitrification rate in a bench-scale biological reactor was investigated. Experiments were carried out using synthetic wastewater. The initial ammonium concentration was 25 mg NH[4]-NL[-1]. The effect of COD/N ratio between 10.0l +/- 0.083 and 24.08 +/- 0.22 gCODgN[-1] on nitrification rate were investigated by varying the COD loading supplied to the reactor. From the results obtained in this study it is found to be in the range of 10.01 +/- 0.083 to 14.15 +/- 0.17 gCODgN[-1], there is a direct relationship between COD/N ratio and nitrification rate. However, more than 14.15 +/- 0.17 up to 24.08 +/- 0.22 gCODgN[-1] was found to exhibit an indirect relationship between the ratio and rate
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This study determined the types, patterns and prevalence of congenital malformation among the offspring of consanguineous and nonconsanguineous parents. In this prospective study of 3529 neonates delivered alive during a 1-year period, 109 had congenital malformations [3.09/1000 live births]. The rate of congenital malformation was 2.0% among neonates from nonconsanguineous marriages and 7.0% from consanguineous marriages. The most common malformations were genitourinary [32.1%], musculoskeletal [22.0%] and cardiovascular [14.7%]. Of the total malformed infants, 8.3% died within the neonatal period. Male infants were at greater risk for birth malformations. A history of congenital malformation was more common in siblings of consanguineous than nonconsanguineous marriages
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Humains , Femelle , Mâle , Consanguinité , Répartition par sexe , Études prospectives , Malformations/épidémiologieRÉSUMÉ
Neonatal bacterial sepsis is one of the major cause of morbidity and mortality in neonates. This retrospective study was performed to determine the incidence of bacterial sepsis with focus on Gram negative organisms in neonates admitted at Beheshti Hospital in Kashan, during a 3-yr period, from September 2002 to September 2005. Blood culture was performed on all neonates with risk factors or signs of suggestive sepsis. Blood samples were cultured using brain heart infusion [BHI] broth according to standard method. From the 1680 neonates 36% had positive blood culture for Pseudomans aerugi-nosa, 20.7% for Coagulase negative Staphylococci, and 17% for Klebsiella spp. Gram-negative organisms accounted for 72.1% of all positive cultures. The overall mortality rate was 19.8% [22/111] of whom 63.6% [14/22] were preterm. Pseudomona aeruginosa and Klebsiella spp. showed a high degree of resistance to commonly used antibiotics [ampicillin, gentamicin] as well as third generation cephalosporins. Continued local surveillance studies are urged to monitor emerging antimicrobial resistance and to guide interventions to minimize its occurrence
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Humains , Infections bactériennes à Gram positif/épidémiologie , Nouveau-né , Facteurs de risque , Mortalité infantile , Sepsie/traitement médicamenteux , Sepsie/étiologie , Études rétrospectives , Multirésistance bactérienne aux médicamentsRÉSUMÉ
Thermophilic aerobic digestion [TAD] is a possible alternative for rapid sludge degradation and producing Class A biosolids. Aeration rate and detention time are two of the important parameters in TAD processes due to rapidly growing thermophilic bacteria population, limited solubility of oxygen at high temperatures and the need to prevent cooling of TAD process. Also the current knowledge and understanding of dewatering TAD biosolids are limited and incompelet.The objectives of this study were to investigate the effects of various aeration rates and detention time on some characteristics of mixed sewage sludge. Four glass-cylindrical digesters with 7 liters of sludge in each, placed in a water bath and were operated at 55 ?C with the aeration rates of 2.14, 3.00, 3.86 and 4.71 volume of air per volume of sludge per hours. It was found the increase in aeration rate decreased the required detention time in order to meet the Class A sludge regulations to reduce vector attraction. The values of Oxidation-Reduction Potential [ORP] were changed from negative values to positiv ones and the values of pH were increased from around neutral to slightly basic, but this increases were occured at different detention times. TAD affected dewaterability of mixed sewage sludge and produced biosolids with higher specific resistance to filtration [lower dewaterability] than undigested sludge. Thermophically digested sludge has a good setteling behavior and air drying on sand bed
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Gestion des déchets , Chauffage , Oxydoréduction , Concentration en ions d'hydrogèneRÉSUMÉ
Anaerobic digestion is among the oldest processes used for stabilization of solid and biosolids. In this survey 12 samples were taken from the digested anaerobic sludge of Isfahan and ShahinShahr WWTP and total solids, volatile solids, total coliform, fecal coliform, Salmonella and viable parasite ova tests were done. Results were compared with the 503 sections of the 40 CFR regulation of the US EPA .The result showed that the average reduction rate was 30% for volatile solids, 4.5x107 MPN/g. dry solids [DS] for total coliform, 5.6x106MPN/g.DS for fecal coliform, 24MPN/4g.DS for Salmonella, and 27 number/4g.DS for viable parasite ova of digested anaerobic sludge in Isfahan. In Shahinshahr WWTP, the average of reduction was 39% in volatile solids, 2.13x 107MPN /g.DS in total coliform, 1.16x106 MPN /g.DS in fecal coliform ,11 MPN/4g.DS in Salmonella and 16 number/4g.DS for viable parasite ova of digested anaerobic sludge . Therefore the digested sludge in Isfahan did not meet the requirements of pathogen reduction in class A and B as well as the reduction requirements for vector attraction, while the digested sludge in ShahinShahr met the requirements of pathogen reduction in class B and vector attraction. So, agricultural use of digested sludge should be made by limiting the kind of crops as well as controlling the harvesting time. The results from the two anaerobic digesters of Isfahan and Shahin Shahr showed that there was a significance correlation between the reduction of volatile solids with total coliform, fecal coliform and Salmonella [P<0.05, r>0.9], while there was no significance correlation between the reduction of volatile solids and viable parasite ova
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Toxicity evaluation is an important parameter in wastewater quality monitoring as it provides the complete response of test organisms to all compounds in wastewater. The water flea Daphnia magna straus is the most commonly used zooplankton in toxicological tests. The objective of this study was to evaluate the acute toxicity of effluents from different units of Isfahan Wastewater Treatment Plant [IWTP]. The samples were taken from four different physical and biological units. The acute toxicity tests were determined using Daphnia magna. The immobility of Daphnia was determined after 48h. Toxicity results showed that 48h-LCq and ATU values for raw wastewater were 30% [v/v] and 3.33, respectively. It was also found that LC50 values after 48 h for preliminary, primary, and secondary effluents were 32%, 52% and 85% [v/v], respectively. The ATU values for these effluents were 3.1, 1.9, and 1.8, correspondingly. The efficiency levels of preliminary, primary, and secondary units for removal of toxicity were found as 6%, 38.9% and 8%, in that order. Overall, the present investigation indicated that toxicity removal by up to 50% might be achieved in IWPT. Based on the obtained results and regarding the improvement of water quality standards, coupled with public expectations in Iran, it is necessary to consider more stringent water quality policies for regular monitoring and toxicity assessment
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Ammonia is a colorless, toxic, reactive and corrosive gas with a sharp odor. It is irritating to the skin, eyes, nose, throat, and lungs. Ammonia gas occurs in the environment naturally and is emitted by many industries and, therefore, its control is essential. Biofiltration is a new emerging technology that is being used as a control procedure. This study evaluates the use of a mixture of compost, sludge, and pieces of PVC as biofilter media to remove ammonia gas. The study investigates the effects of parameters such as inlet concentration, accumulation time, and depth of filter media to evaluate the removal efficiency. A laboratory scale biofilter column was built and operated to investigate the removal of ammonia from a waste gas stream. The findings indicate that for inlet concentrations of 236 ppm, and ammonia loading of less than 9.86 g-NH3/m3.h at empty bed residence time of 1 min, an ammonia removal efficiency of more than 99.9% was obtained. The acclimation period of the bacteria was 10 days. The average pressure drop during measurement was 4.44 mm H2O. The study also revealed that for concentration levels of 99, 211, and 236 ppmv, biofilter media depths of 40, 80, and 120 cm will be required, respectively. The results obtained in this study indicate that the biofiltration system composed of compost in the mixture of sludge and smashed polyvinyl chloride as biofilter media is an efficient method for the removal of ammonia from waste gas streams. It is also found that the optimum depth of biofilter media depends on the inlet concentration of ammonia
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Background: the purpose of this study was to evaluate the influence of different concentrations of erythromycin on the anaerobic treatment of a synthetic pharmaceutical wastewater in an Anaerobic Sequencing Batch Reactor [ASBR]
Methods: a laboratory-scale ASBR was used to treat a synthetic substrate mixture representing pharmaceutical wastewater. The ASBR was operated with increasing organic loading rates until stable removal efficiencies were reached at a loading rate of 3 g COD L-1 d-1. At that point the reactor was exposed to low [1 mg/l] and subsequently, to high [200 mg/l] concentrations of the antibiotic erythromycin
Results: the effect of addition of erythromycin on the microbial community and the development of antibiotic resistance were evaluated based on overall reactor performance and using specific methanogenic activity [SMA] tests. It was found that the addition of erythromycin resulted in a reduction of biogas production and COD removal efficiency by 5 to 10%. As expected based on the reactor performance, biogas. production in SMA tests using the synthetic substrate mixture was only slightly affected by the presence of erythromycin. When sludge from ASBR that had been exposed to erythromycin for 47 days was used for SMA tests, the concentration of butyric acid was inhibited to a lesser extent
Conclusion: the reduction of 5 to 10% in biogas production and COD removal efficiency indicate that a substantial fraction of the microbial populations in the ASBR was resistant to the antibiotic. The conversion of butyric acid was inhibited when erythromycin was present, suggesting that fatty acid-beta oxidizing bacteria were sensitive to the antibiotic
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Sludges are stabilized to reduce pathogens, eliminate offensive odors and inhibit, reduce or eliminate the potential for putrification. In this study, stabilization of municipal wastewater sludge with and without earthworms [Eisenia fetida] was tested in a pilot study. The earthworms were fed at the optimum level of 0.75 kg-feed/kg-worm/day. Decomposition and stabilization of wastewater sludge occurred both in the presence and in the absence of earthworms during 9 weeks but the process was accelerated in their presence. Phosphorus content increased in the sludge with earthworms but decreased in it without them. Nitrogen content in the resulting vermicompost showed no difference with its quantity in the original substrate while it increased in the control treatment