Removal of airborne hexavalent chromium using alginate as a biosorbent

Airborne hexavalent chromium has been classified as a human respiratory carcinogen and long term exposure has been known to cause ulceration and perforation of the nasal septum, bronchitis, asthma, and liver and kidney damage. Chromium electroplating plants are the major sources of atmospheric chromium and packed-bed scrubbers are the common control devices used to reduce emission of chromic acid mist from electroplating bathes. The feasibility of a new method to remove this pollutant using alginate beads as a biomass derivative was investigated by one factor at a time approach and Taguchi experimental design. Polluted air with different chromium mist concentrations [10-5000 micro g/m3] was contacted to alginate beads [3.3-20 g/L], floating in distilled water with adjusted pH [3-7], using an impinger at different temperatures [20 and 35°C], and various velocities [1.2 and 2.4 m/s]. Although there were no statistical significant differences between factor levels, the higher ions removal efficiencies were achieved at lower levels of air velocities, pollution concentrations, higher levels of pHs, temperatures, and sorbent concentrations

Prevalence of rotavirus, adenovirus, and astrovirus infections among patients with acute gastroenteritis in, Northern Iran

The aim of the study was to determine the incidence of non-bacterial acute gastroenteritis associated with diarrheal diseases in Mazandaran Province, northern Iran. A total of 400 symptomatic cases from patients with acute gastroenteritis from Mazandaran Province in Iran were screened using EIA method for the presence of rotavirus, adenovirus and astrovirus during 2005-2006. Chi-square tests were used for testing relationships between different variables. Rotavirus, adenovirus and astrovirus were detected in 62%, 2.3%, and 3% of samples, respectively. The maximum rate of rotaviruses was detected in the<1-year-old age group, while minimum rate was found in the 10 years and older age group. Astrovirus and adenovirus were detected predominantly in the 2-5-year-old age group of children, with a prevalence of 8.3% and 3.5% respectively. All studied viral gastroenteritis peaked in the winter, and minimum rate were found in summer. Our statistical analyzes indicated that viral gastroenteritis, especially Rota-viral, had the highest number of occurrences in colder seasons notably in winter and more frequently were observed among younger children

Determinants number of cigarette smoked with Iranian adolescents: a multilevel zero inflated poisson regression model

The present study was conducted to know about the association between amount of smoking and mental health plus demographic factors in the Iranian adolescents. Data of this research was drawn from the National Health Survey in Iran from April 1999-March 2000. All 1745 adolescents aged 15-20 yr that were residence in the eight northwest provinces of Iran, were included in this study. In order to evident zero-inflation and because of sampling design, multilevel zero-inflated Poisson [ZIP] regression applied for analysis of data. We analyzed data with programs written with s-plus. Zero-inflated part of ZIP model shows that gender of female effects to increase the chance of "not to smoke cigarette at all" [P< 0.001] and older adolescents are less at risk of smoking than younger [P= 0.036]. It also shows that, unemployed [P= 0.028] and Housewife [P= 0. 003], adolescents are more at risk of smoking compare with student adolescents. Under Poisson part of this model, depression [P= 0.012] and gender of female [P< 0.001] are indirectly associated with number of cigarette smoked per day by adolescents. Among adolescent smokers, males smoke more number of cigarettes than females, younger teenager are more at risk of being a smoker than older ones and dropping out of high school is an important risk factor for smoking. We did not find any relation between mental disorders and being a smoker while we did for the relation between Number of Smoked Cigarette [NSC] and depression

[Design, construction and performance of chromium mist generator]

The chromium mist generator is an essential tool for research and for making evidence-based recommendations in evaluating air pollution and its control systems. The purpose of this study was to design and construct a homogeneous chromium mist generator and to look at the effects of factors such as sampling height and distance between samplers in side-by-side sampling on the chromium mist sampling method. First we developed a mist generator, using a chromium electroplating bath in pilot scale. Concentrations of CrO3 and sulfuric acid in plating solution were 125 g L-1 and 1.25 g L-1, respectively. To set up permanent air sampling locations, a Plexiglas cylindrical chamber [75 cm height, 55 cm i.d] was installed as the bath overhead. Sixty holes were made on the chamber in 3 rows [20 in each row]. The distance between rows and holes was 15 and 7.5 cm, respectively. Homogeneity and the related factors were studied using a side-by-side air sampling method. Forty-eight clusters of samples were collected on polyvinyl chloride [PVC] filters contained in sampling closed-face cassettes. Cassettes were located 35, 50, and 65 cm above the solution surface with < 7.5 and/or 7.5-15 cm distance between heads. All samples were analyzed by the NIOSH method 7600. ANOVA tests showed no significant differences between locations in side-by-side sampling [P=0.82] or between different sampling heights or sampler distances [P=0.86 and 0.86, respectively]. However, there were notable differences between means of coefficients of variation [CV] in various heights and distances. We conclude that the most chromium mist homogeneity could be obtained at a height of 50 cm from the bath solution surface and with a distance of < 7.5 cm between samplers

Removal of airborne hexavalent chromium mist using chitosan gel beads as a new control approach

Airborne hexavalent chromium is a known human respiratory carcinogen and allergen. Many workers are exposed to hexavalent chromium in various processes which chromium electroplating plants are the most common. In this study, the feasibility of a new control approach to remove this pollutant using chitosan beads as a biosorbent was investigated. Hexavalent chromium sorption was studied relative to pH, pollution concentration, sorbent concentration, temperature, and air velocity using one factor at a time approach and Taguchi experimental design. Polluted air with different chromium mist concentrations [10-5000 micro g/m[3]] was contacted to chitosan beads [3.3-20 g/L], floating in distilled water with adjusted pH [3-7], using an impinger at different temperatures [20 and 35 °C], and various velocities [1.12 and 2.24 m/s]. The ANOVA test result showed that, there were statistical significant differences between factor levels except optimized pH levels. The higher ions removal efficiencies were achieved at lower levels of air velocities, pollution concentrations, and higher levels of solution pH values, temperatures, and sorbent concentrations