[Investigating the Efficiency of Biological Filters for Ammonia Removal]

Ammonia removal from air to prevent severe damage to the environment and living organisms is very important. Biofiltration is an efficient, easy, cost-effective, and environmentally friendly process for degradation of ammonia from waste air. The aim of this study is to investigate the efficiency of biological filtration using a compost and scallop bed for ammonia removal. According to the ammonia removal method a column with 14cm inner diameter and 45cm height made from transparent Plexiglas was used. The column was filled up to 25 cm with compost and scallop [with a scallop: compost ratio of 1:4]. In this study, performance of the biofilter was studied under 10 different flow rates [1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 lit/min] and 5 different concentrations [0-20, 20-40, 40-60, 60-80 and 80-100 ppm] at a temperature of 25 degrees Celsius. The results of this study showed that efficiency is decreased when the flow rate or concentration is increased because the microbial population is reduced. The efficiency was reduced by 84.6-98.2 percent. Maximum efficiency occurred at a 0.19g/[m[3].h] loading rate. Efficiency was in 0-20 concentration intervals at a flow rate of 1 lit/min and at an Empty Bed Residence Time [EBRT] of 240 seconds. The results show that a biofilter with a compost and scallop bed is efficient for ammonia removal from air. Results can be optimized in the design and operation of biological systems to be used in the industrial control of ammonia gas.

Air pollution and low birth weight: a historical cohort study from Tehran

This historical cohort study was designed to clarify the association between air pollution and low birth weight [LBW] amongst women referred to Tehran hospitals in 2007. In total, 225 eligible pregnant women who lived within 5 km of an air pollution monitoring station during their pregnancy were selected for the study. Data were collected via interview and hospital records. Exposure to each pollutant was estimated for each woman individually throughout her pregnancy and for each trimester. Exposures were modelled as categorical variables using inter-quartile ranges in a logistic regression model. The results showed a significant association between exposure to CO and LBW [OR = 2.08, 95% CI: 1.70-4.60], particularly during the second trimester [OR = 3.96, CI: 1.83-12.5. We conclude that exposure to air pollution during pregnancy may be associated with LBW

Determination of air pollution monitoring stations

Swelling urban populations and increasing number of industry and especially automobiles in and around cities have resulted in adverse effect on human health. One of the most important things regarding air pollution in these days is that the number of motor vehicles has increased, and the resulting problems of new types of air pollution on large scale need to be emphasized in large cities. The groundwork for this study is based on collecte d data, specific studies regarding to use passive tube sampling techniques and geo-statistic mapping tools. The low cost and easy operation of the diffusive sampling technique makes it an ideal tool for large scale air pollution surveys with a high spatial resolution. Finally, we used Kriging method to draw air pollutions maps related to NO2 and SO2 measurements in Shiraz city. These maps conducted us to find number of air pollution monitoring stations. Results show that we need 2 traffic, 3 urban, 1 suburban and 1 industrial station in Shiraz area. In fact, the proposed method in this study provides a useful tool that can be easily applied to other polluted cities. Meanwhile, it would become effective as well as the actual time required to implement them

[Alteration trend of carbon monoxide pollutant level and a review on managerial approaches of comprehensive plan for reducing the air pollution in Tehran city]

In order to evaluate the success rate of Comprehensive Plan for Reduction of Air Pollution [1999-2005] of Tehran city, this study was carried out to measure the levels of carbonmonoxide pollutant in this city during the execution of the mentioned plan. Data from Air Pollutants Measuring Stations in Tehran were analyzed using Excel software in which the daily levels of carbon monoxide were formerly extracted from 8-hour data and using daily rates, therefore, the relative monthly and annual rates were calculated. Studying the process of changes in carbon monoxide level in Tehran city, we may conclude that execution of this plan was not effective enough to reduce the level of CO pollutant to the extent expected. Nevertheless, due to the increasing trend in number of motor vehicles, [which are considered to be the main source for producing the CO in this city] it seems that it has, somehow, prevented the increase of this pollutant. Due to the increasing trend of CO production in Tehran city and consequent dissatisfaction from this trend, reviewing the "Comprehensive Plan for Reduction of Air Pollution" which has been executing since 2000, is of indisputable importance. This may provide us another apportunity to control the level of CO pollutant in the remained years of Plan [2006-2010]