Using ultraviolet irradiation for removal of malathion pesticide in water

Organophosphorus pesticides are one of the most consumable poisons. Such poisons can enter water sources by different routes. Since consuming some drinking water containing an amount of poison higher than the standard level, causes undesirable effects on human health. This research aimed to study the effectiveness of eliminating malathion from water by ultraviolet irradiation [UV] mercury lamp with a medium pressure. In this experimental- applied study, variants of initial pHs and initial concentrations and exposure times were investigated. Initial concentrations of malathion were 0.5, 1 and 2 mg/l. The samples were then exposed to UV irradiation interruptedly the time periods of 10, 20, 30, 40, 50 and 60 minutes. The UV lamp used in the reactor was medium pressure [irradiation intensity= 200 W/m[2]]. The amounts of malathion were determined before and after the irradiation by HPLC instrument. Moreover, the results obtained from the study were analyzed using SPSS software and ANOVA and t-test statistical trials. The minimum reduction occurs at 10 min [%46] and the maximum reduction in 60 min [% 87.25] [P < 0.05]. In addition, the effectiveness of irradiation process decreases with increasing the poison concentration [P < 0.001]. However, the efficiency of the process increases with pH increase. The results show the most effectiveness were achieved at 60 min and 0.5 mg/l and pH= 9. Therefore, the application of UV reactors could be considered as an appropriate method

[Bioassay for toxicity assessment of zinc oxide and titanium oxide to escherichia coli ATCC 35218 and staphylococcus aureus ATCC 25923 bacteria]

This study was conducted to investigate the toxicity of Titanium Oxide [TiO2] and Zinc Oxide [ZnO] nanoparticles as two of most widely used nanoparticles. The result of this study can help to designing environmental standard and legislations for nanoparticles. Different concentrations of nano ZnO and TiO2 nanoparticles were added to nutrient Agar culture media. Then, definite numbers of Escherichia coli and Staphylococcus aureus bacteria were added to culture media and inhibition of these bacteria growth was measured in comparison to controls. Obtained data were analyzed to determine nanoparticles' EC50 and NOEC [No Observed Effect Concentration] using SPSS ver.16 and Probit standard test. 24-hours EC50 of nano ZnO using E. coli and S. aureus determined to be 5.47 mg/L and 2.38 mg/L respectively. In addition, 24-hours EC50 of nano TiO2 using E. coli and S. aureus determined to be 5366 mg/L and 3471 mg/L respectively. In the case of ZnO nanoparticles, no observed effect concentration determined to be 1.15 and 3.28 mg/L for E. coli and S. aureus respectively and in the case of TiO2 nanoparticles no observed effect level determined to be 1937 and 1184 mg/L for E. coli and S. aureus respectively. This study showed that acute toxicity of nano ZnO is by farmore than that of nano TiO2. Regarding the EPA acute toxicity criteria, nano ZnO is categorized as moderately toxic and nano TiO2 is categorized as practically non toxic. Hence, regarding the acute toxicity, in recommending exposure criteria and environmental disposal standards, compared to nano TiO2, nano ZnO requires more attention

Trace analysis of xylene in occupational exposures monitoring

Determination of organic pollutants usually requires extraction of the pollutants from samples, using hazardous solvent. Solid phase micro-extraction [SPME] is a solvent-free equilibrium extraction method, in which, proper calibration can allow quantitative measurements of organic pollutants at a very good sensitivity without the use of any organic solvent. Because individual VOCs are generally present in urine only at trace levels, a sensitive and accurate determination technique is essential. This study describes the optimization of headspace solid phase micro-extraction [HS-SPME] followed by gas chromatography equipped with flame ionization detector [GC-FID] for xylene in spiked urine. Through this investigation, the parameters affecting the extraction and GC determination of xylene, including extraction time, temperature, desorption temperature, desorption time, salt addition, sample pH, sample volume and sample agitation were studied. An optimized headspace extraction was carried out at 30°C for 6 min in presence of 0.2 gml-1 of NaCl in the sample solution. Desorption of the xylene was carried out for 60 sec. at 250°C. The optimized procedure was also validated with three different pools of spiked urine samples and showed a good reproducibility over six consecutive days as well as six within-day experiments. In this study, the accuracy, linearity, and detection limits were also determined. The HS-SPME-GC-FID technique provided a relatively simple, convenient, practical procedure, which can be successfully applied for determination of xylene in spiked urine when an occupational exposure monitoring is required

Improving efficiency of disinfection of water for non-contact UV system

The goal was to upgrade and/or uprate the traditional non-contact array by producing few modifications in the configuration of this model in order to maximize light receiving of water from the UV lamp and a better disinfection. An innovative non-contact model was made with a design based on irradiation of water, which was flowing as two thin waterfalls around a UV lamp in order to have direct germicidal rays from all positions of the lamp. By this water circulating and traditional water flow in an ordinary canal below the lamp, UV light would reach every drop of water effectively. Another model which had been studied was a simple stair type design in which a bare lamp was fixed over the shiny steel steps. Results of water disinfection in two flow rates of 12 and 24 L/min were compared with traditional design at exactly similar conditions. Disinfection in this new model produced more reduction in fecal coliforms concentration than the traditional array and the inactivation efficiency was specified to be 3.65 log reduction compared to 2.93 log, in the turbidity of 0.5 NTU. Besides, this new model was quite capable in disinfection of water with high turbidities up to 20 NTU. The reduction in disinfection efficiency at higher flow rates for new model was much less than traditional array. Results of water disinfection in the simple stair type were not wonderful and even it was less satisfactory compared to traditional model. The reason is that the flow of water was not set parallel to the length of the lamp

[Optimization of solid phase micro-extraction [SPME] for monitoring occupational exposure to ethyl benzene]

Analytical methods for volatile organic compounds [VOCs] in different samples need extraction of compounds by applying hazardous solvents. Solid phase micro-extraction [SPME] is a solvent-free equilibrium extraction method in which proper calibration can allow quantitative determinations of VOCs at a very good sensitivity without the use of any organic solvent. VOCs are generally present in urine only at trace levels therefore a sensitive procedure is needed for their trace determinations. Throughout this study headspace solid phase micro-extraction [HS-SPME] was followed by GC-FID for ethyl benzene in spiked urine was optimized. In this study the parameters influencing SPME and gas chromatography of ethyl benzene including extraction time temperature desorption temperature desorption time salt addition sample pH sample volume and sample agitation were investigated. Extraction procedure was performed at 30°C for 6 min using 0.2 gmL[-1] of NaCl in the sample solution. The sample volume and sample pH were optimized at 5 ml and 7 [neutral pH] respectively. Desorption of the ethyl benzene was carried out for 60 sec. at 250°C. The method was also validated with three different spiked urine samples and illustrated an appropriate reproducibility over six consecutive days as well as six within-day experiments. During this investigation parameters of accuracy linearity and detection limits of the procedure were also evaluated. The developed method of HS- SPME-GC-FID proved to be a simple convenient and practical procedure and was successfully used for measuring of ethyl benzene in spiked urine

[UV-lamp intensity determination without use of radiometer]

Measurement of light intensity is a recommended practice for insuring the delivery of required germicidal dose in disinfection operations by UV lamps. Use of sensitive to light chemicals which is the base of actionometeric methods could be considered as a suitable manner for estimating the intensity of UV lamp in circumstances that special radiometers are not available. lodide-iodate mixture was used as an actinometer for this study. The light intensities of a UV lamp [LP 25W] were first determined by a special UVC radiometer at certain distances from the lamp. Then the test of determining the suitable period of time for irradiation of actinometer was accomplished. Finally the color changes of iodide - iodate solutions at the predetermined distances were evaluated at the wavelength of 352 nm. The latter analysis can be done by a common [visible] spectrophotometer. Results indicated that use of this actinometer is more suitable at the distances of 35 to 60 cm from the center of the lamp bulb, since iodode-iodate solution has a detectable color change at this range of distance in one minute irradiation which may be considered as a reasonable time for actionmeteric operations. Although all kinds of actinometers should not be regarded as precise as special radiometers and there would be need to use pure chemicals for actinometeric determination of light intensity, it can be claimed that the recommended procedure in this study which is the newest actinometeric method can be used in acceptable evaluation of UV intensity with least difficulty in providing necessary instruments

[Results of neuro-endoscopic pituitary surgery in 26 patients with pituitary adenoma]

Endoscopic surgery of pituitary adenoma is a rapidly developing surgical procedure in the field of neurosurgery, with known limitations and advantages. The aim of this study was to evaluate the results of this technique for treatment of a group of patients with pituitary adenoma. In the present study, 26 patients with the diagnosis of pituitary adenoma, who were considered for endoscopic operation between 2002-2005 in Sina and Amir Alam hospitals, were included. The following data were registered: age, sex, symptoms of disease, findings of neurological exam, adenoma type [functional versus non-functional], treatment outcome and complications of the procedure and duration of hospital stay. Twenty six patients [14 male and 11 female] included in the study. Most of them were in the 3-6 decades of life. They included 11 non-functional adenoma, 9 GH-producing adenomas, 3 ACTH secreting adenomas and 3 cases with prolactinomas. Seven patients had complications of the operation [reversible in 6 patients and fatal in 1] and 6 of them had recurrence of the tumor during the 2-year follow up. Endoscopic surgery is an invaluable method for treatment of pituitary adenoma, and factors such as decreased complications and duration of hospital stay further adds to its popularity

Assessment of inter-and intra-observer variability of the la classification for gerd

Los Angeles classification is widely adopted as a means of unifying endoscopic observation for GERD. We assessed the inter- and intra-observer variability of LA classification. Two-hundred fifty-four still images of the lower esophagus taken by an expert endoscopist [RM] were randomly selected and presented to 9 gastroenterologists [2 females, 6 experts, 3 trainees]. They were asked to report the images according to LA classification. After 2 weeks the images were re-ordered and the same people were asked to report them again. Kappa-statistics was calculated for intra- and inter-observer variability. Mean kappa for intra-observer agreement was 0.54 for experts and 0.55 for trainees [p = NS]. Mean intra-observer kappa was greater among females than males [0.70 vs 0.50 respectively, p=0.05]. Mean inter-observer kappa was 0.20 and 0.31 for experts and trainees respectively [p = NS]. Mean inter-observer weighted kappas were 0.25 and 0.07 [p = 0.007] for males and females respectively. Analyzing data for source of the discrepancy showed that the least reproducible reading was GERD-A both for intra- and inter-observer agreement calculations. According to our data, the LA classification, although a major advance in reporting GERD, has a poor to fair reproducibility. There was no difference between experts and trainees in using the LA classification. Females seem to be more consistent in their readings, but have less agreement with others. Despite the inherent short-comings of kappa statistics and the limitation caused by the possible quality of the still images, revision of the LA system seems to be advisable

Solid phase microextraction for trace analysis of urinary benzene in environmental monitoring

Conventional analytical method for organic pollutants in water requires extraction of the pollutants, using hazardous solvent. Solid phase microextraction is a solvent free equilibrium extraction method, in which, proper calibration can allow quantitative determinations of organic pollutants at a very good sensitivity without the use of any organic solvent. Because individual volatile organic carbons are generally exposed environmentally and present in urine only at trace levels, a sensitive and accurate determination technique is essential. So, this study describes the optimization of headspace solid phase microextraction [HS-SPME] followed by GC-FID for benzene in spiked urine. Through this investigations, the parameters affecting the extraction and gas chromatographic determination of analytes, including extraction time, temperature, desorption temperature, desorption time, salt addition, sample pH, sample volume and sample agitation were studied. An optimized headspace extraction was carried out at 30°C for 6 min in the presence of 0.2 g/mL of NaCl in the sample solution. Desorption of the analytes was carried out for 60 sec. at 250°C. The optimized procedure was also validated with three different pools of spiked urine samples and showed a good reproducibility over six consecutive days as well as six within-day experiments. The accuracy, linearity, detection limits were also determined. The headspace solid phase microextraction, GC-FID technique provides a relatively simple, convenient, practical procedure, which was here successfully applied to determine benzene in spiked urine

Biodegradation of MTBE by a microorganism consortium

Methyl Tert-Butyl Ether [MTBE] is one of the ether oxygenates which its use has been increased within the last twenty years. This compound is produced from isobutylene and methanol reaction that is used as octane index enhancer and also increases dissolved oxygen in gasoline and decreases carbon monoxide emission in four phased motors because of better combustion of gasoline. High solubility in water [52 g/L], high vapor pressure [0.54 kg/cm3], low absorption to organic carbon of soil and presence of MTBE in the list of potentially-carcinogens of U.S EPA has made its use of great concern. The culture media used in this study was Mineral Salt Medium [MSM]. The study lasted for 236 days and in three different concentrations of MTBE of 200, 5 and 0.8 mg/L. A control sample was also used to compare the results. This research studied the isolation methods of microbial consortium in the MTBE polluted soils in Tehran and Abadan petroleum refinery besides MTBE degradation. The results showed the capability of bacteria in consuming MTBE as carbon source. Final microbial isolation was performed with several microbial passages as well as keeping consortium in a certain amount of MTBE as the carbon source

Application of chlorine dioxide for secondary effluent polishing

There are still many difficulties for developing the projects of using treated effluents. In this study, the efficiency of chlorine deoxide in the process of preparing the effluent of Sahebgharanieh Plant of Tehran for reuse purposes has been determind. Major results are as follows: Total COD reductions resulted from effluent treatment by ClO[2] solutions having concentrations equal to 1/4, 1/2 and 1/1 of COD samples at one hour contact time have been about 42%, 49% and 59% respectively. Total suspended solids were also reduced by treatment with ClO[2] solutions having the certain concentrations mentioned, and the reductions were about 37% ,47% and 58% respectively. Besides total and fecal coliforms results indicated that ClO[2] apllied was quite efficient in effluent disinfection. The conclusion is that reasonable reductions would be expected in the amounts of remained major pollutants and so reuse applications for some non-potable purposes may become possible. The acidification of chlorite has been used for ClO[2] generation as it is better suited to small treatment systems