Efficiency of advanced oxidation and hydroxyl technology in methyl terciary – butyl ether (MTBE)

زمینه و هدف: فرآیندهای اکسیداسیون پیشرفته بعنوان روش های سریع و موثر برای تصفیه دامنه وسیعی از آلایندهای آلی مقاوم به اثبات رسیده است. هدف از این تحقیق آزمایش استفاده از O3 در ترکیب با یونهای هیدروکسیل (pH بالا) بعنوان تسریع کننده واکنش ها برای تجزیه MTBE در فاضلاب های صنعتی و آبهای آلوده به آن بود. روش مطالعه: در این مطالعه که از نوع نیمه تجربی می باشد: اثر O3 در ترکیب با یونهای هیدروکسیل (pH بالا) بعنوان تسریع کننده واکنش هایی که منجر به تولید رادیکال های هیدروکسیل می شوند برای تجزیه متیل ـ ترشیاری ـ بوتیل اتر ( MTBE) در فاز مائی مورد آزمایش قرار گرفت. تمامی واکنش ها در داخل یک راکتور ستونی حبابی نیمه پیوسته نسبت به جریان ازن و پیوسته نسبت به MTBE رخ داد. در این تحقیق اثر pH و زمان واکنش و میزان ازن مورد نیاز برای رسیدن به تجزیه کامل MTBE در غلظت ثابتی از ازن و در پنج pH مختلف (10،5/10،11،5/11 و 12) به مدت 100 دقیقه برای هر pH مورد آزمایش قرار گرفت. نتایج: آزمایش نشان داد که 5/11=pH، نسبت Intermediates / MTBE º=0.60 v/mM بود که در مقایسه با نزدیکترین نسبت بعد از آن ( مربوط به 11pH=) به میزان20% بیشتر است.کمترین زمان و ازن مورد نیاز برای تجزیه 90% هر مول از MTBE که به ترتیب معادل 70دقیقه و 3/5 مول بود در 5/11pH= رخ داد. آزمایشات انجام شده برای تعیین میزان MTBE حذف شده به سبب فراریت به هوا نشان داد که این میزان در مدت 100 دقیقه در pH های مختلف 5/19-11% بود. آزمایشات نشان داد که در سطح خطای 5% هیچگونه رابطه معنی داری بین میزان MTBE حذف شده از محیط بدلیل فراریت به هوا و pH محیط در محدوده pH های 12-10 وجود ندارد. نتیجه گیری: MTBE یک ترکیب سنتزی است که حتی در فرآیندهای اکسیداسیون پیشرفته نسبتا در مقابل تجزیه از خود مقاومت نشان می دهد ولی با ادامه اکسیداسیون به طور کامل قابل تجزیه است. بهترین pH برای تجزیه MTBE به وسیله واکنش های رادیکال 5/11 است

Hopkins Syndrome in a 14-Year-Old Boy; a Case Report

Hopkins syndrome (HS) is a flaccid paralysis resembling poliomyelitis that has been seen in some children who are recovering from an acute episode of asthma. This syndrome should be suspected based on clinical findings even before the occurrence of characteristic breathing patterns and epilepsy. We report a 14-year-old boy who had experienced an episode of HS

Twenty-three unsolved problems in hydrology (UPH) – a community perspective

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focussed on process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come

Comparison of the Effects of Atorvastatin, Hyaluronic Acid and Oxidized Cellulose (Interceed) on Reducing Intestinal Adhesions Postoperative after Open Abdominal Surgery in Animal Models: effects of atorvastatin, hyaluronic acid and oxidized cellulose on intestinal adhesions

Abdominal adhesions are considered as an important problem in abdominal surgery. In this study we compared the effectiveness of atorvastatin, hyaluronic acid and interceed (oxidized cellulose) in prevention of postoperative intestinal adhesions. A total of 40 Wistar-albino rats were randomly divided into 5 groups: Group 1 (Sham); Group 2 (Control or Adhesion induction); Group 3 (Adhesion induction + hyaluronic acid); Group 4 (Adhesion induction + oxidized cellulose); and Group 5 (Adhesion induction + atorvastatin). A same experimental method of cecal abrasion and ligature was used to produce adhesions in all rats. Fourteen days after adhesions formation, animals were killed and adhesions were scored according to macromorphological characteristics and adhesion-carrying tissues under standard histologic examination. Inflammation,vascularization and fibrosis in granulation sites were graded in all samples. Adhesion scores in all experimental groups were slightly lower than control group. Group 3 had the lowest mean adhesions score (1.18 ± 1.24) based on surgeon observation. The mean of adhesion score in Group 3 (1.18 ± 1.24) was significantly lower than that in Group 4 (3.43 ± 0.53) (p=0.004). Group 5 showed the lowest mean adhesions score on pathological examination (5.62 ± 3.73). The mean of adhesion total score in Group 3 was slightly lower than that in other groups; however, this difference was not significant. Hyaluronic acid, oxidized cellulose, and atorvastatin are effective in treatment and prevention of intestinal adhesions during open abdominal surgery. Although hyaluronic acid was slightly more effective, further studies are needed to evaluate the effect of combination therapy with these agents

Enhancement of the Biodegradability of Methyl tert- Butyl Ether (MTBE) by Advanced Oxidation

The effectiveness of ozone treatment for improving the biodegradability of recalcitrant pollutants has been proved by investigating the ozonation reaction of Methyl tert-Butyl Ether (MTBE) as a bioresistant gasoline oxygenate. Laboratory scale experiments have been carried out at room temperature by bubbling for 120 minutes ozonated air (3.4 ppm/min) into 3 liter of an alkaline (pH=11.5) aqueous solution (100 mg/L) of MTBE. The experimental results indicated that during the ozonation, complete MTBE degradation occurs in 100 minutes and after this time, ozone consumption goes on very slowly. At the end of the ozonation, after 100 minutes, the initial value of COD (256 mg O2/L) is 98 and corresponds to a relative removal of about 62%. As for MTBE solution biodegradability expressed as (BOD5) / (COD) ratio, during the first 90 minutes, its value regularly increases from lowest 0.01 up to a maximum of 0.68 that corresponds to an ozone consumption of 1.25 mg per each mg of COD initially present in the solution. The research showed that partial degradation of MTBE in the advanced oxidation processes results an increase in its biological degradation. But more oxidation results lower  (BOD5) / (COD) ratio. Also the research showed that for idealization of the chemical oxidation conditions of MTBE, it needs to decrease COD to 46-68% before the biological degradation. The experimental results for determining the rate of MTBE removal due to stripping showed that about 14% of MTBE strips out after an hour of sparging with oxygen gas. The fraction of MTBE oxidized and/or striped increases to about 28% (in pH=7) and 70% (in pH=11.5) with ozonation over the same time period

Investigation of Anaerobic Fluidized Bed Reactor Aerobic Mov-ing Bed Bio Reactor (AFBR/MMBR) System for Treatment of Currant Wastewater

Background: Anaerobic treatment methods are more suitable for the treatment of concentrated wastewater streams, offer lower operating costs, the production of usable biogas product. The aim of this study was to investigate the performance of an Anaerobic Fluidized Bed Reactor (AFBR)-Aerobic Moving Bed Bio Reactor (MBBR) in series arrangement to treat Currant wastewater.Methods: The bed materials of AFBR were cylindrical particles made of PVC with a diameter of 2-2.3 mm, particle density of 1250 kg/m3.The volume of all bed materials was 1.7 liter which expanded to 2.46 liters in fluidized situation. In MBBR, support media was composed of 1.5 liters Bee-Cell 2000 having porosity of 87% and specific surface area of 650m2/m3.Results: When system operated at 35 ºC, chemical oxygen demand (COD) removal efficiencies were achieved to 98% and 81.6% for organic loading rates (OLR) of 9.4 and 24.2 g COD/l.d, and hydraulic retention times (HRT) of 48 and 18 h, in average COD concentration feeding of 18.4 g/l, respectively.Conclusion: The contribution of AFBR in total COD removal efficiency at an organic loading rate (OLR) of 9.4 g COD/l.d was 95%, and gradually decreased to 76.5% in OLR of 24.2 g COD/l.d. Also with increasing in organic loading rate the contribution of aerobic reactor in removing COD gradually decreased. In this system, the anaerobic reactor played the most important role in the removal of COD, and the aerobic MBBR was actually needed to polish the anaerobic treated wastewat