experimental analysis were carried out on gas discharged from petroleum industry in. Kaduna State, Nigeria to determine the concentration of NO, CO, SO2 and.
AU J.T. 9(3): 172-174 (Jan. 2006)
Urban Air Pollution by Process Industry In Kaduna, Nigeria A.S Abdulkareem and A.S Kovo Chemical Engineering Department, Federal University of Technology Minna, Nigeria
Abstract In the developing countries, it is a known fact that most of the cities are highly polluted. The major sources of pollutant come from process industries. In this paper, experimental analysis were carried out on gas discharged from petroleum industry in Kaduna State, Nigeria to determine the concentration of NO, CO, SO2 and hydrocarbon contents of the exhaust gas. Samples of air were collected at distances of 20m, 60m, 80m and 100m away from the flare point. Results obtained revealed that the concentrations of the pollutant are unacceptable compared to the Federal Environmental Protection Agency set limit. The dispersion pattern of pollutants showed that the extent of spreading is dependent on nearness to the source of flare. Keywords: Pollutants, concentration, NO, CO, SO2, FEPA.
crops and acute toxicological effect in human resulting in death. Therefore, the aim of this paper is to investigate urban air pollution by process industries in Kaduna State, Nigeria, in order to offer suggestion in prevention of discharge into the atmosphere.
Introduction Air pollution is considered a major problem in the major cities of the world. As this danger looms on the developed countries of the world, Africa can only be described as operational disaster areas. Kaduna State in Nigeria is an industrialized city as a result of number of process industries cited there. Pollution if not properly controlled could endanger the lives of the inhabitants living in it. The principal sources of emission in Kaduna State are refinery, transportation (combustion of fuel), incinerators, refuse burning, etc. The major pollutants are gases and particulate matters. Gases such as oxide of sulphur, nitrogen and carbon, ammonia and hydrocarbons predominate Other pollutants are particulate matters such as smoke, dust, fog, mist, etc. (Perry, 1984). The debilitating effect of the pollutants on the various lives present in the environment cannot be overemphasized. These effects include decolouration of building, thereby disfiguring structure and reduce their aesthetic appeal; impairment of visibility normally caused in the air, death and stunted growth of
Methodology In this research work, air samples were collected at various distances away from the flare stack to determine the concentrations of pollutants in the flared gas. The samples for the work were collected from a petrochemical industry in Kaduna State, Nigeria. Determination of Sulphur Dioxide The technique used in the determination of sulphur dioxide (SO2) is the electrochemical method. In this method, SO2 gas was allowed to diffuse through a semi-permeable membrane and a thin electrolyte layer to get absorbed at the sensing electrode where it is proportional to the SO2 concentration.
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Determination of Carbon Monoxide
Results
The non-dispersive infrared spectrophotometer is the standard method used for the determination of carbon monoxide. The method allows continuous analysis based on the capacity of carbon monoxide do absorb infrared radiation. The concentration of CO was determined using this method.
The results of concentration of pollutants with respect to distance from the stack used for flaring gaseous pollutants are given in the table below.
Determination of Nitrogen Oxides
20 40 60 80 100 FEPA limit
Distance (m)
The method used for the determination of nitrogen oxide is the phenol disulphuric acid method. The stack gas is drawn into a collection flask, evacuated previously to the vapour pressure of the absorbing solutions. The absorbing solution consists of 3% hydrogen peroxide and 0.14 sulphuric acid. The presence of hydrogen peroxide causes the oxide of nitrogen (except nitrous oxide) to get oxidised to nitric acid. Analysis is carried by reacting the liquid with phenol disulphone acid, whish is subsequently treated with ammonium hydroxide to obtain a yellow compound. The intensity of the colour is read using a spectrophotometer.
Distance (m) 20 40 60 80 100 FEPA limit
Determination of Hydrocarbons The total hydrocarbon content is determined by the flare ionization technique. The sample is injected into the flame created by burning hydrocarbon in either air or oxygen. When hydrogen alone burns, relatively few ions are generated but when hydrocarbon is present, the flame produces a complex ionization in which a large number of ions are present. An electric field is set up in the vicinity of the flame by making the burner jet positive with respect to a wire loop. The electric field induces ion migration in such a manner that a small ionization current is established between the electrodes, and this current is proportional to the concentration of the ion in the flame.
Concentration of pollutants (mg/m3) NO CO Hydro SO2 3 (mg/m ) (mg/ (mg carbon /m3) (mg/m3) m3) 0.096 1.12 14.64 0.282 0.093 1.06 13.21 0.221 0.091 1.04 12.63 0.182 0.086 1.02 11.21 0.18 0.084 0.04 11.18 0.12 0.0620.05 11.43 0.16 0.093 Concentration of pollutants (mg/m3) NO (mg/ SO2 CO Hydro 3 m) (mg/ carbon (mg/ m3) (mg/m3) m3) 0.098 1.11 14.63 0.312 0.095 1.04 13.41 0.294 0.092 0.92 12.82 0.227 0.091 0.87 11.75 0.198 0.087 0.05 11.49 0.170 0.0620.05 11.45 0.160 0.093
Discussion Man’s activity has reached a level at which there effects are global in nature. The natural system, i.e. the atmosphere, land and sea as well as life’s and plant are being disturbed. It is obvious that some trace of CO, NO, SO2 and HC gases have increased during the last century. This is a result of continued global industrial growth and development considering the serious deteriorations of the basic characteristics of the environment as a result of harmful pollutant released into the air, it has become necessary to seriously consider environmental management as a priority project if improved quality of life for all living is to be guaranteed. 173
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the month of July are 0.312, 0.294, 0.227, 0.198 and 0.170 mg/m3, which are above the value allowed by FEPA.
From the experiment value shown in table 3.1 and 3.2, the concentration of polluted in air varies from month to month. These values are as a result of gas flared and wind speed. It could be observed from the result that the concentration of NO decrease from 0.096 to 0.084 mg/m3 and 0.098 to 0.087 mg/m3. For both results, the distance increases from 20m to 100m respectively. The concentration of NO at 20m away in table 3.1 and 40m away in table 3.2 is higher than that of FEPA (federal environmental protection agency) while that obtained at a distance of 40m in table 3.1 is at maximum concentration allowed by FEPA. The concentration of NO obtained at distance of 60, 80 and 100m (0.091, 0.086 and 0.084 mg/m3) away from the flare point are within the range allowed by FEPA (0.062-0.093 mg/m3) in table 3.1. This could be attributed to complete combustion of gases and low efficiency of the stack (Bassel, 1981). The concentration of SO2 obtained with respect to distances of 20, 40, 60, 80 and 100m away from the gas flaring point are 1.02, 1.06, 1.04, 0.08 and 0.04 mg/m3 for month of June 2003 and for July 2003. The concentrations of SO2 are 1.11, 1.04, 0.92, 0.87 and 0.05 respectively. It is only the concentration obtained at a distance of 100m that is within the standard set by FEPA. The dispersion is low compared to that obtained for NO. The concentration of CO obtained at distance 20, 40, 60, 80 and 100m away from the point of gas flaring are 14.64, 13.21, 12.63, 11.21 and 11.18 mg/m3 respectively as shown in table 3.1. The concentration obtained at distances of 20, 40 and 60m are above that allowed by FEPA. The concentrations of CO in table 3.2 are completely out of range from the standard. This reveals that there is incomplete combustion in the flare. The concentration of hydrocarbon obtained for distances of 20, 40, 60, 80 and 100m away from the gas flaring point for the month of June 2003 are 0.282, 0.221, 0.182, 0.18 and 0.12 mg/m3. Those of
Conclusion The pollutants (NO, CO, SO2 and HC) released by petrochemical industry located in Kaduna State, Nigeria are dispersed (decreasing in concentration) with respect with distances away from the flare. The data obtained on the concentration of pollutant with respect to distances show that the concentrations exceed the Federal Environmental Protection Agency limit.
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