Maximum Concentration Of SO2 Research Articles

Similar experimental study on diffusion and distribution of diesel exhaust in confined space of a coal mine.

In the confined space of the underground coal mine, which is dominated by transportation lanes, explosion-proof diesel-powered trackless rubber-wheeled vehicles are becoming the main transportation equipment, and the exhaust gas produced by them is hazardous to the health of workers and pollutes the underground environment. In this experiment, a similar test platform is built to study the effects of wind speed, vehicle speed, and different wind directions on the diffusion characteristics of exhaust gas. In this paper, CO and SO2 are mainly studied. The results show that the diffusion of CO and SO2 gas is similar and the maximum SO2 concentration only accounts for 11.4% of the CO concentration. Exhaust gas is better diluted by increasing the wind speed and vehicle speed, respectively. Downwind is affected by the reverse wind flow and diffuses to the driver's position, which is easy to cause occupational diseases. When the wind is a headwind, the exhaust gases spread upwards and make a circumvention movement, gathering at the top. When the wind speed and vehicle speed are both 0.6m/s, the CO concentration corresponds to the change trend of the Lorentz function when the wind is downwind and the CO concentration corresponds to the change trend of the BiDoseResp function when the wind is headwind. The study of exhaust gas diffusion characteristics is of great significance for the subsequent purification of the air in the restricted mine space and the protection of the workers' occupational health.

Dispersion of SO2 emissions in a gas refinery by AERMOD modeling and human health risk: a case study in the Middle East

ABSTRACT This study aimed to model the dispersion of emitted SO2 from stacks and flares in one of the largest Gas Refinery Companies in the Middle East . Pollutant emission coefficients and air pollution’s various sources contributions were determined based on the collected data after measuring SO2 concentrations in a fixed monitoring station (stack) and across different distances from it for a year. The SO2 release pattern was simulated, and annual pollutant concentrations in average periods of 1-hr and 24-hr were predicted using AERMOD 8.9.0. The maximum simulated ambient SO2 were 27,447 and 4592 µg/m3 in average sampling times of 1-hr and 24-hr, respectively. The hazard quotient of 95% percentile for children, teenagers, and adults due to inhalation of SO2 was more than one.The maximum concentration of SO2 in the 1-hour and 24-hour period in the study area was higher than the amount introduced by Iran’s clean air standard and the WHO standard.

Analysis of The Effect of Deforestation Rates on Air Pollution Concentration and Land Surface Temperature Using Landsat-8 Imagery with Google Earth Engine (Case Study: East Kalimantan Province, 2019-2020)

The increase in population triggers an increase in deforestation rates. According to data from Ministry of Environment and Forestry, East Kalimantan’s highest deforestation rate reached 54.8 thousand hectares in 2018-2019. This study analyzed the effect of deforestation rates on air pollutant concentrations (SO2 and NO2) and land surface temperature (LST) in East Kalimantan in 2019-2020 with Google Earth Engine (GEE) platform using Landsat 8 Level 2 surface reflectance imagery. The TIR channel was converted into brightness temperature which further used as the input in LST estimation using Mono-Window Algorithm, SO2 estimation using Hasan Algorithm (2014), and NO2 estimation using Alseroury Algorithm (2015). During 2019-2020, the average LST value was 24.2 °C, which was increased by 2.0 °C from the previous year. The maximum NO2 concentration was 189.771 g/m3. The annual average NO2 concentration increased by 0.757 g/m³ from the previous year. The maximum concentration of SO2 was 0.521 ppm. The annual average SO2 concentration increased by 0.011 ppm from the previous year. To determine the effect of deforestation rates on the concentration of SO2, NO2 and LST, the Pearson correlation test was carried out. The correlation coefficient between deforestation rates and SO2 is R = 0.949 (very strong correlation); correlation coefficient between deforestation rates and NO2 is R = 0.889 (very strong correlation); and the correlation coefficient between the deforestation rates and the LST is R = 0.887 (very strong correlation). This shows that the higher deforestation rates, will caused in the higher concentration of SO2, NO2, and LST.

DISPERSION OF SO2 AND NO2 EMITTED BY AUXILIARY BOILER OF PT KMI METHANOL INDUSTRIAL USING THE GAUSSIAN PLUM MODEL AERMOD IN BONTANG CITY EAST KALIMANTAN INDONESIA

The petrochemical industry PT Kaltim Methanol Industri Bontang City, uses auxiliary boilers with natural gas fuel and is connected to the stack to emit pollutants into the atmosphere. The objectives of this study are SO2 modeling with a radius of 5 kilometers and modeling of NO2 with a radius of 10 kilometers from the emission source. Modeling using AERMOD software, AERMET Software, and Aermap ArcGIS Software. The wind rose in the dominant research area from the southwest and northeast directions. Dispersion of SO2 and NO2 decreases according to the distance. The increase in concentration occurred in areas that experienced elevation increases, in Teluk Pandan District with a distance of about 10 kilometers northwest with an elevation of about 100 meters above sea level, and part of the West Bontang District with a distance of about 5 kilometers to the southwest with an elevation of about 90 meters above sea level. The maximum concentration of SO2 at the receptor was 6.2631 μg/m3 on hourly modeling, 0.58132 μg/m3 on modeling per 24 hours, and 0.0317 μg/m3 on annual modeling. The maximum NO2 concentration at the receptor was 1.96781 μg/m3 on hourly modeling, 0.18089 μg/m3 on hourly modeling, and 0.01002 μg/m3 on annual modeling. The distribution of pollutants based on hourly modeling per 24 hours is spreading in all directions and irregularly while for annual modeling it tends to spread towards the southwest and northeast according to the wind rose.Keywords: AERMOD, Emissions, Modeling, Air Dispersion, Auxiliary boiler

Assessment the impact of different fuels used in cement industry on pollutant emissions and ambient air quality: a case study in Egypt

This study aims to assess the impact of using different fuels in Egyptian Titan Alexandria Portland Cement Company on emissions and concentrations of pollutants (Total suspended particles (TSP), nitrogen dioxide (NO2‎), and sulfur dioxide (SO2)) and their influence on ambient air quality during the period 2014–2020 using AERMOD dispersion model. The results showed that changing the fuel from natural gas in 2014 to coal mixed with alternative fuels (Tire-Derived Fuel (TDF), Dried Sewage Sludge (DSS), and Refuse Derived Fuels (RDF)) in 2015–2020 caused fluctuating variations in pollutant emissions and concentrations. The highest and lowest maximum concentrations of TSP occurred in 2017 and 2014 respectively, where the TSP is positively correlated with coal, RDF, and DSS and negatively correlated with natural gas, diesel, and TDF. Also, the lowest and highest maximum NO2 concentrations were detected in 2020 and 2016 followed by 2017 respectively, where NO2 is positively correlated with DSS and negatively correlated with TDF and varies with diesel, coal, and RDF. Moreover, the maximum concentrations of SO2 were the lowest in 2018 and highest in 2016 followed by 2017 because of its considerable positive correlation with natural gas and DSS and negative correlation with RDF, TDF, and coal. Generally, it was found that increasing the percentage of TDF and RDF with decreasing the percentage of DSS, diesel, and coal will reduce pollutant emissions and concentrations and enhance ambient air quality.

Environmental Health Risk Assessment of Air Pollutants in Online Motorcycle Taxi Drivers in the Special Capital Region of Jakarta

Introduction: Online motorcycle taxi drivers spend most of their time outside as either driving or waiting for their customers. Therefore, chances of exposure to various air pollutants are higher and may cause various health problems, especially the respiratory problems. Methods: This is a descriptive study that used the Environmental Health Risk Analysis method to estimate the Risk Quotient (RQ) from exposure to PM10, SO2, CO, O3, and NO2 in drivers. The RQ was calculated based on exposure concentrations from the Special Capital Region of Jakarta Environment Agency; daily working hours, working days in a year, and working period obtained from interviews; additionally, body weight measurement, reference concentration (RfC), and the default value of inhalation intake were also collected. The population of this study was adult online motorcycle taxi drivers who operate around areas which become the air quality measurement stations in the Special Capital Region of Jakarta with a total sample of 81 people. Results and Discussion: The RQ for all minimum, average, and maximum concentrations of SO2, CO, and NO2 were <1. While for the average and maximum concentrations of PM10 and the maximum concentration of O3, the RQ was >1. The safe concentrations, work duration, and the number of working days also surpassed the maximum safety limit levels. Conclusion: PM10 and O3 ambient exposures are categorized unsafe for drivers. Environmental health efforts are necessary to reduce the concentration of air pollutants, and the guidelines to reduce pollutants exposure should be provided for drivers.

Hazardous Gas Analysis during Fire Investigation

Various types of hazardous substances are generated at fire scenes. Firefighters usually use the self-contained breathing apparatus (SCBA) during firefighting; however, SCBA is very inconvenient to use in other works (e.g., fire investigation and fire scene commands). Therefore, firefighters can be exposed to numerous chemicals. In this study, concentrations of hazardous gases were measured by utilizing gas analyzers with seven sensors during fire investigations. Six fire investigators measured the concentrations of hazardous gases directly as they worked. This included capturing the maximum concentrations of SO2 at seven places, HCHO at 29 places, NO2 at one place, HCN at 13 places, and CO at two places where the concentration exceeded the short-term exposure limit (STEL). When reconstruction experiments were performed, the maximum allowable concentrations for most hazardous chemicals fell below the STEL approximately 90 min after the fire occurrence. Therefore, we determined that fire investigators should wear proper respiratory protective equipment when working.

Short-term air pollution events in the Atacama desert, Chile

An evaluation of the concentrations of PM10, PM2.5, SO2, CO, NO2, O3 and meteorological variables recorded between 2013 and 2016 at three continuous monitoring stations in the urban area of Calama (located in the hyper-arid desert from the Atacama) is presented. The results indicated that the recorded concentrations of PM10, PM2.5, and SO2 exceeded the World Health Organization (WHO) daily and annual guidelines throughout the years studied. The diurnal variability of PM10 and PM2.5 concentrations showed that two maxima occurred during mornings and nights, while SO2 concentrations showed a single acute maximum at noon. The relationship between the wind regime in the area and the concentrations of PM10 and PM2.5 implied significant contributions from sources located at the west end of the city: industrial sources (local mining industry) and natural sources (the Atacama desert) during warmer seasons, while local urban sources (vehicles and residential heating) became more relevant during cooler seasons. Maximum SO2 concentrations were connected to changes in the local wind patterns (east to west) that occur around noon in Calama. These changes determined that the emissions from the copper extraction and smelting operations (located north of Calama) could have been transported into the urban area, therefore causing the deterioration of its air quality that is perceived by the local population. No significant trends for SO2 and O3 concentrations were observed during 2013–2016, while an increase of 8.8% year−1 for CO, and a reduction of 5% year−1 for the other pollutants studied was observed.

Dispersion Model Evaluation of SO2 Emission From Stack in Oil Refinery Plant Using AERMOD 8.9.0

Background: In the operation of oil refineries, one of the main pollutants in stack emission is SO2. Dispersion modeling is a necessary tool for simulation of air pollutant concentration, which is the main part of urban air quality management. Objectives: The ability of air quality models is well established where sufficient input data are available. The present study is performed to assess the SO2 emission from the Tehran oil refinery. Methods: The release pattern of SO2 was simulated by the AERMOD model in the desired zone, with an area of 25 × 25 km2. Modeling was run in the 1, 3, 8, and 24 average times for two warm and cold seasons. Predicted and observed pollutant concentrations were compared for validation of the results by the EPA statistical index. Four receptors were selected to compare the predicted and observed values. Results: Correlation coefficient values for SO2 were 0.92 and 0.95 for the warm and cold seasons, respectively. The maximum concentration of SO2 was on the local scale of 25 × 25 km2. Conclusions: The results showed that modeling is appropriate for conducting point sources in the oil refinery. 1 and 24 h averaging time from the model for SO2 concentrations were lower than standard levels; therefore, in the study area, the AERMOD model performance for prediction of SO2 concentrations was acceptable. Although most of the measurements were lower than standard values, due to the possibility of air pollution transmission to the urban area, their control should be considered.

ALTERNATIVE METHODS OF SULFUR DIOXIDE USED IN WINE PRODUCTION

Sulfur dioxide (SO2) is the most common additive used in winemaking for many years. This compound is important for wine producers and consumers due to its antiseptic and antioxidant properties. However, excessive sulfites caused some symptoms such as a headache, nausea, stomach irritation and respiratory distress in asthmatic patients. Additionally, excessive SO2 in winemaking process leads to organoleptic changes of final product. For these reasons, the maximum SO2 concentrations allowed in wines were gradually reduced. In the wine industry it is essential to reduce or even eliminate SO2 especially in the production of organic wines. These obstacles lead to requirements of new healthier and safety strategies for reduction of SO2. Up to know have been discussed the priorities of SO2 used in wine making. Recently some authors evaluated studies with chemical and non-thermal alternatives of SO2. Some other authors reviewed the side effects of SO2 used in wines, but none of them have comprised the effects of new techniques in grape, must, wine and pomace. This review discussed effects of different alternatives (thermal, non-thermal, chemical and natural additives) techniques demonstrated in grape, must, wine and pomace as possible alternative to SO2 in comprehensive manner. The antioxidant, antimicrobial and sensory properties of tannin, oak and vine shoot extracts are also discussed as new alternatives of SO2. The studies demonstrated that SO2 could be lowered and even changed by using the development of new methods.

Use of dispersion model and satellite SO2 retrievals for environmental impact assessment of coal-fired power plants

The aim of this study is to investigate the impact of ten proposed plants along with three operating plants in Çanakkale province of Turkey where the proposed plants are within very close proximity. The province has the highest capacity of the planned plants and the region is also of interest due to its history, tourism and agriculture potential. Current SO2 pollution was assessed using ground observations and satellite retrievals where the impact of plants was better captured by satellite retrievals.Individual and cumulative impact from proposed and operating plants was simulated by CALPUFF for 2014. The study domain was 150 × 150 km2, with 1 × 1 km2 cell size. The effect of changing meteorological inputs and domain size were investigated with simulations. Three cases were performed using meteorological inputs: from one surface and one radiosonde station (Case 1), 22 surface and one radiosonde station (Case 2), and 22 surface and two radiosonde stations (Case 3).Case 2 and 3 resulted in higher concentrations and showed larger affected regions than case 1 in all simulations. The cumulative impact of proposed plants indicated national annual and daily limit values were exceeded in Case 2 and 3. Hourly limit values were exceeded in all three cases.Simulations for two selected proposed plants were assessed for plant impact area given in environmental impact area reports. Results indicated the plant impact areas cannot be sufficient to determine the maximum SO2 concentrations in some cases and using single meteorology station data cannot represent the study area, especially regions with complex terrain and land-sea interactions such as Çanakkale province. Cumulative impact can be underestimated due to small size of plant impact areas not including other plants. Lastly satellite retrievals are better capturing the pollution than air quality monitoring stations which are strongly affected by meteorology.

The impact of power plant emission variability and fuel switching on the air quality of Kuwait

Power plant emissions have a significant impact on air quality, and a frequent assumption made in estimating impacts is to assume annual or monthly average emission rates. This study investigates the impact, on predicted ambient concentrations, of assuming annual average emissions, compared to resolving emissions on an hourly basis (base case). A case study of emissions from power plants in Kuwait, for the year 2014, is presented. In Kuwait, power plants operate on a mix of natural gas, gas oil, crude oil, and heavy fuel oil, and the type of fuel used varies on an hourly basis. Because of this fuel variability, a fuel switching strategy was also simulated in this work, replacing high sulfur fuels with natural gas during hours with high predicted SO2 concentrations. Emissions estimates were combined with an air quality dispersion model to simulate the temporal variability and spatial dispersion of sulfur dioxide (SO2) and nitrogen dioxide (NO2) in Kuwait, for a one-year episode. The results indicate that emission averaging and fuel switching operations result in lower area-wide annual maximum SO2 concentrations compared to the base case (1747 μg/m3, 1063 μg/m3, 616 μg/m3 for base case, annual average emissions and fuel switching scenarios, respectively). The number of receptor sites recording daily exceedances of the SO2 standard for annual average emissions were one seventh of those predicted for hourly averaged emissions and 92% lower for the fuel switching scenario. For NO2, while the overall number of exceedances of air quality criteria was much lower than for SO2, the numbers of exceedances were also predicted to be lower using annual averaged emissions compared to the base case. These results document the importance of using emission estimates that capture hourly variability over annually averaged emissions, particularly in locations such as Kuwait where multiple fuels are used in power production.

Particulate matter tolerance of plants (APTI and API) in a biodiversity hotspot located in a tropical region: Implications for eco-control

Air pollutants such as particulate matter (PM10 and PM2.5), nanoparticles, micropollutants, magnetic particles, oxides of sulfur as well as nitrogen, and ground-level ozone pose serious threats to human health and vegetation, especially crops and forests. To this end, Air Pollution Tolerance Indices (APTI) are of paramount importance as they help study effects/interactions of air pollution on plants, with possible eco-control implications for environmental management. The present study measured the APTI of certain common roadside plant species in India (at sites E and NE) to assess the impact of air pollutant and particulate matter concentrations on their biochemical/physiological parameters. The maximum concentrations of SO2, NO2, and suspended particulate matter (SPM) were found at site E during the study period of November 2011 to February 2012. APTI, ascorbic acid, and relative water content (RWC) were higher at site E compared to NE, whereas total chlorophyl content and pH were lower at site E, which was characterized by manmade roadside plantations and more industrial sites unlike the biodiversity-rich site NE. Thus, although both sites E and NE grew common plants, they showed variations in physiology as well as stress tolerance indices. Henceforth, screened potent plants from this study may be used to investigate plant-PM interactions, resulting effects/tolerance, with possible implications for environmental/air pollution amelioration, namely, assisting eco-sustainable strategies for particulate pollution control.

Volcanogenic SO2, a natural pollutant: Measurements, modeling and hazard assessment at Vulcano Island (Aeolian Archipelago, Italy)

Sulfur dioxide (SO2) is a major component of magmatic gas discharges. Once emitted in the atmosphere it can affect the air and land environment at different spatial and temporal scales, with harmful effects on human health and plant communities.We used a dense dataset of continuous SO2 flux and meteorological measurements collected at Vulcano over an 8-year period spanning from May 2008 to February 2016 to model air SO2 concentrations over the island. To this end, we adopted the DISGAS (DISpersion of GAS) numerical code coupled with the Diagnostic Wind Model (DWM). SO2 concentrations in air were determined for three different SO2 emission rates: a reference SO2 flux of ∼18 t/d (the median of more than 800 measurements), an enhanced SO2 flux of 40 t/d (average of all measurements plus 1 σ), and a maximum SO2 flux of 106 t/d (maximum value measured in the investigated period). Maximum SO2 concentrations in air were estimated at the crater, near the high-T fumarole field that is the source of the gas, and ranged from 2000 ppb to ∼24,000 ppb for the reference flux, from 2000 ppb to 51,000 ppb for the enhanced flux and from 5000 ppb to 136,000 ppb for the maximum flux, with peak values in limited areas at the bottom of the crater. These concentrations pose a hazard for people visiting the crater, for sensitive individuals in particular. Based on estimated SO2 concentrations in air, we also consider the phytotoxic effects of SO2 on local vegetation.

Civil aviation impacts on local air quality: A survey inside two international airports in central Italy

The results of air quality monitoring carried out over several years (2008–2012) in two international airports near Rome (labelled as A and B) are reported and discussed. Airport A serves regular flights, airport B operates low-cost flights and, during the period investigated, had about 17% of airport A aircraft traffic load.Diffusive sampling of gaseous species (NO2, SO2, BTX and O3) was performed at several sites inside the airports. During 2012 the investigation was improved by including PM10 and polycyclic aromatic hydrocarbons (PAHs). Higher concentrations of NO2 (+18%) and lower of SO2 (−20%) were found at airport B, compared to A, over the whole period investigated. The maximum concentrations of SO2 were measured in 2011 at both airports (13.4 μg/m3 and 10.8 μg/m3 respectively for A and B), despite the decrease of aircraft traffic load recorded. Statistical analysis of PM10 data showed that there was no significant difference between the average concentrations measured at the two airports (25.7 μg/m3 and 27.4 μg/m3 for A and B respectively) and among the sites investigated. The concentration of PAHs at airport B (4.3 ng/m3) was almost twice that of airport A (2.2 ng/m3), though the respective percentages of compounds were similar.Airport B seemed to be negatively influenced by its surroundings, in particular by vehicular traffic flows of two major roads, whereas airport A was positively influenced by the proximity to the seaside. PCA data analysis showed that airport A sites are differently impacted by the LTO flight phases according to their position, whereas at airport B it was impossible to find similar relationships.

Study of ignition, combustion, and production of harmful substances upon burning solid organic fuel at a test bench with a vortex chamber

Results of investigation of furnace processes upon burning of pulverized fuel at a test bench with a power of 5 MW are presented. The test bench consists of two stages with tangential air and pulverized coal feed, and it is equipped by a vibrocentrifugal mill and a disintegrator. Such milling devices have an intensive mechanical impact on solid organic fuel, which, in a number of cases, increases the reactivity of ground material. The processes of ignition and stable combustion of a mixture of gas coal and sludge (wastes of concentration plant), as well as Ekibastus coal, ground in the disintegrator, were studied at the test bench. The results of experimental burning demonstrated that preliminary fuel grinding in the disintegrator provides autothermal combustion mode even for hardly inflammable organic fuels. Experimental combustion of biomass, wheat straw with different lignin content (18, 30, 60%) after grinding in the disintegrator, was performed at the test bench in order to determine the possibility of supporting stable autothermal burning. Stable biofuel combustion mode without lighting by highly reactive fuel was achieved in the experiments. The influence of the additive GTS-Powder (L.O.M. Leaders Co., Ltd., Republic of Korea) in the solid and liquid state on reducing sulfur oxide production upon burning Mugun coal was studied. The results of experimental combustion testify that, for an additive concentration from 1 to 15% of the total mass of the burned mixture, the maximum SO2 concentration reduction in ejected gases was not more than 18% with respect to the amount for the case of burning pure coal.

Impact of Air Pollutant on Human Health in Kushtia Sugar Mill, Bangladesh

The study dealt with the concentration of air pollutants emitted from Kushtia sugar mills in Jagati region of Bangladesh in order to evaluate their impact on human health. The dispersion of air pollutants from sugar mill's chimney was obtained through point source Gaussian dispersion model. The air pollutants were monitored during winter season in 2011- 2012. A questionnaire survey was randomly carried out in a small scale at the study area. The result showed that the maximum concentration of SO2, NOx and PM10 were 28.837 µg/m 3 , 76.177 µg/m 3 and 380.339 µg/m 3 respectively. The particulate matter (PM10) concentration was found to be very high whereas sulfur dioxide (SO2) and nitrogen oxide (NOx) concentrations were low at the study area. The calculated value of air pollution index (API) was 88.18 which indicate that heavy air pollution can predispose individuals to heart and lung disease in the study area people. This study revealed that the concentration of particulate matter found in Kushtia sugar mill had exceeded the minimum level according to the WHO standards. The high concentration of PM10 is suggested to affect human health and environmental conditions in the study area.

Relation between Mortality Rate and Air Pollutant Concentrations in Mashhad, 2007-2009

Background and purpose: Air pollution has been known as one of the most effective factors on cardiovascular, pulmonary and infectious diseases. This study aims to determine the relation between mortality rate and air pollution in Mashhad during 2007-2009. Materials and Methods: Data of air pollution, mortality rate and geographic factors were collected during 2007-2009 and analyzed. Mortality rate, the average PSI of individual pollutants , temperature and moisture were weekly measured and the diagrams were then drawn according to the methods of statistical correlation and regression analysis of air pollution and mortality rate. Results: According to the findings, there was no significant relation between CO and mortality rate, but the other pollutants played a significant role in this regard. The maximum correlation was obtained for SO2 and O3 in the concentrations of 0.936 and 0.154 ppm, respectively, but in the final model for all pollutants and weather variables, only PSI for O3, season and humidity showed significant change. Conclusion: O3 has increased during three years of research and has been the leading cause of death among the pollutants. Most deaths occurred in cold seasons. Among all pollutants, the maximum concentration of SO2 was in winter and the maximum concentration of O3 was in spring and summer 2009. [*Alidadi H. Shakeri M.T. Hossein zadeh H. Noorani A. The Relation between Mortality Rate and Air Pollutant concentrations in Mashhad, 2007-2009. IJHS 2013; 1(2):68-74] http://jhs.mazums.ac.ir

Utilization of simulated flue gas for cultivation of Scenedesmus dimorphus

Effects of flue gas components on growth of Scenedesmus dimorphus were investigated and two methods were carried out to eliminate the inhibitory effects of flue gas on microalgae. S. dimorphus could tolerate CO2 concentrations of 10–20% and NO concentrations of 100–500ppm, while the maximum SO2 concentration tolerated by S. dimorphus was 100ppm. Addition of CaCO3 during sparging with simulated flue gas (15% CO2, 400ppm SO2, 300ppm NO, balance N2) maintained the pH at about 7.0 and the algal cells grew well (3.20gL−1). By intermittent sparging with flue gas controlled by pH feedback, the maximum biomass concentration and highest CO2 utilization efficiency were 3.63gL−1 and 75.61%, respectively. These results indicated that S. dimorphus could tolerate high concentrations of CO2 and NO, and the methods of CaCO3 addition and intermittent sparging have great potential to overcome the inhibition of flue gas on microalgae.

Identifying Effective Variables Using Mutual Information and Building Predictive Models of Sulfur Dioxide Concentration with Support Vector Machines

Sulfur dioxide (SO 2 ) is an issue of increasing public concern due to its recognized adverse effects on human health. Therefore, accurate SO 2 prediction models are very important tools in developing public warning strategies. The goal of this study is to identify the relevance of meteorological and air pollutant variables using a classical and widely used measure of dependence, Shannon's Mutual Information (MI), and to build an accurate SO 2 prediction model using the relevant variables as inputs. Specifically, features ranked by MI measure are tested on how much joint predictive power they have of the target using a popular machine learning tool, support vector machines (SVM), and in comparison to multilayer perceptron (MLP), which is the most commonly used machine learning tool in previous studies for the prediction and analysis of air pollutants. It was found that the SVM model gave a higher correlation coefficient (r) and less root mean squared error (RMSE) than MLP for both test and validation sets. The predictive model used 6 input variables for both data sets as the relevant features for maximum SO2 concentration prediction at time t+1, which are the average SO2, maximum SO2, outdoor temperature (OT), average nitrogen dioxide (NO2), average ozone (O3), and average wind speed at time t. The results of this study indicate that MI can be used efficiently in determining the importance of input variables in the prediction of SO2 concentration and SVM is a popular machine learning tool well suited for use in air pollution modeling.