Practical lesson # 1

Paracelsus, a famous physician in the sixteenth century, stated, thаt almost any substance may be either beneficial or harmful to man, depending on the amount used and the way it is combined with other substances.

Some of the important pollutants found in the air are listed in the table 2. These pollutants are emitted by natural sources or they are due to man*s activity, i.e., they are emitted by anthropogenic courses. According to table 1 emissions from anthropogenic sources are almost negligible when compared with emissions from natural sources. The differences in emissions from natural and anthropogenic sources and their relative importance can best be explained by the following equation:

M_E=m_E*A_E

M_E is the mass flow rate of the emitted pollutant, m_E (kg|m2) is the specific mass flow rate, that is the mass flow rate per unit emission area of the emitted pollutant, and A_Eis the emission area. Natural emissions are in the most cases characterized by very small specific mass flow rates of the pollutants and by very large emission areas. Typical sources of anthropogenic emissions are chimneys. Chimneys of industrial plants are in general rather high so that emissions from these sources are not very important for the pollution of the biosphere close to the surface of the earth.

Energy conversion: power plants, all fire stations in industry and in private households.

Chemical industry: all industries based on chemical conversion of matter.

Traffic: road traffic, rail road traffic, shipping, air traffic.

GCC: glass, ceramics, cement and allied industries.

According to the information given one may gain the impression that air pollution is a purely quantative problem. In a certain way, this impression is correct because, as Paracelsus already noted, that is the quantity of a substance that makes a pollutant. The danger, however, is not only related to the mass of a pollutant. It may, for example, happen that a great mass of dust is far less dangerous than a very small one, if the great mass of dust consists of particles with a diameter of about 1 mm, while the small mass of dust consists of particles with diameter of only 1 µm. The small dust particles will get easily into the respiration system of man and cause well known health problems.

Table 1

Plants and factories	Dust	Sulphur
Thermal power station	42,5	58.6
Ferrous metallurgy	25,6	17,6
Non-ferrous metallurgy	2,8	18,5
Industry of build	27,4	-
Chemical and oil processing	1,7	5,3

There are inconstancy natural impurity and anthropogenic pollutions. Effluents of the industrial factories, motor transport, products of incomplete combustion and waste of burning are related to the anthropogenic impurities.

Effluents of industrial factories.

The main sources of atmospheric pollutions are steam power plant (29 % pollutions), plants of ferrous and nonferrous metallurgies (24 and 10,5%), petroleum chemistry industry (15,5%), factory of building materials (8,1 %), chemical industry (1,3 %), motor transport (13,3%). In the cities the share of motor transport is 60-80%.

The main components of effluents are dioxide sulphur, oxide of carbon and dust. Distribution of share of dust and sulphur dioxide, ejected in the atmosphere by the different factories are following.

Ferrous metallurgy is the source of effluents in the atmosphere of carbon oxide, manganese, Mn, small compound of arsenic, As, antimony, Sb, lead Pb, mercury Hg (quicksilver) steam and other.

Effluents of ferrous metallurgy contain arsenic, lead and other. Oil production, oil processing and petroleum chemical industries are source such pollutions as hydrocarbons, acid impurities and solid particles.

Coal industry ejected in the atmosphere sulphur dioxide, carbon oxide, products of sublimation of resinous substances.

Дата добавления: 2015-10-29