Variant – 23

1. Wet dust removal equipment

The dust removal equipment available may be divided into two large groups: Dry dust removal equipment and wet dust removal equipment. For both groups: A few representative examples will be discussed.

In wet dust removal equipment, the dust particles are captured by liquid drops introduced into the gas stream. The gas pollution problem is converted into a liquid pollution problem. This is acceptable when the volume of the contaminated water is small and when a waste water treatment plant is available.

There is a great variety of wet dust scrubbers available. Only three examples are selected for a brief discussion:

1. Packed column scrubber.

2. Vortex scrubber.

3. Venturi scrubber.

In the packed column scrubber, the water is distributed over the surface of various types of small packing elements and flowing downwards. The gas moves counter currently through the porous layer of packing elements, changing its flow direction according to the arrangement of the elements. Because of the inertia forces the particles, particularly the coarser ones, do not follow the gas flow, and impinge on the liquid surface.

In the vortex scrubber, the water drops are produced by the gas stream and carried into the vortex channel. The dust particles are captured during the period of drop movement inside the vortex channel. The efficiency of dust collection by drops depends on the relative velocity between drops and dust particles.

The Venturi scrubber is the most efficient wet dust scrubber. The water is introduced into the throat of the Venturi scrubber and there dispersed by the high-velocity gas steam. The pressure drop of the gas on its way through the Venturi scrubber is very high.

2. Soil protection and their rational use

Protecting the quality of our soils is as important as protecting the air we breathe and the water we drink. Protecting soil is critical to protecting our ecosystems and our ability to raise crops or maintain a backyard garden.

Soil quality can be a measure of soil productivity. Soil quality can also be linked to water quality.

Specifically, soil quality is “The capacity of soil to function within ecosystem boundaries to sustain biological productivity, maintain environmental quality, and promote plant and animal health.”

Soil quality focuses not just on characteristics such as nutrient availability and total organic matter levels, but also focuses on overall soil biological activity, organic matter content, water infiltration, and soil structure.

Protecting and enhancing soil quality is accomplished through the use of soil conservation efforts; Best Management Practices for fertilizers and pesticides; and the proper use, handling and storage of agricultural chemicals, fertilizers, manures and soil amendments.

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3. Dynamic parameters of community

Dynamic parameters of community reflect the processes proceeding in the community for certain time interval. The basic parameters from them: birth rate, death rate, growth rate of the community.

Birth rate is a number of the new species who have appeared in the community for a time unit in the result of breeding.

There are the maximal and actual birth rates. The maximal birth rate is a maximal realization of a birth opportunity in the absence of limiting factors of environment. Actual birth rate is a real realization of the birth opportunity.

Death rate (velocity of the death rate) is a number of the species who have lost in the community for a time unit (from predators, illnesses, an old age and other reasons). Death rate is a size return to the birth rate.

Rate of a growth community is a change of the community number in unit of time. Rate of a growth community can be positive, zero and negative. It depends on parameters of birth rate, death rate and migration (immigrations and emigrations). The rise (profit) of number occurs in the result of the birth rate and immigration of species, and reduction (loss) of number is in the result of the death rate and emigration of species.