Environmental Engineering (General Engineering) (SSC JE)

Cyclone separator – They create a dual vortex to separate course from fine dust.

• For the separation of dry dust of 10 to 100 µm size the cyclonic separator is used.
• Cyclone separator is a method of removing particulates from an air, gas or liquid stream, without the use of fitness through vortex separation.
• When removing particulate matter from liquid, a hydro cyclone is used, while from a gas cyclone is used.

A green house is a construction of transparent walls and roofs in cold countries to provide adequate heat to the soil and plant. The solar heat/energy penetrates the green house but is prevented from escaping and thus heat remains within the green house keeping it warm.

A similar process keeping the atmosphere warm is therefore, called the green house effect where mainly carbon dioxide entraps the in coming solar heat.

The major (GHGs) are listed–
(i) Carbon dioxide (CO₂) - 76%
(ii) Methane (CH₄) - 15%
(iii) Nitrous oxide (N₂O) - 6%
(iv) Chlorofluoro carbon (CFC) - 3%

A plant remained in the dark for several days and died because it could not photosynthesis. Photosynthesis is a photo-biochemical process that essentially requires sunlight to start the synthesis of ATP and NADPH that are further used for glucose production. So, when sunlight is absent these chemicals could not be made and the plants die without food.

Bio-chemical oxygen demand– If sufficient oxygen is available in waste water, the useful aerobic bacteria will flourish and cause the aerobic biological decomposition of waste water which will continue until oxidation is completed. The amount of oxygen consumed in this process is the BOD.

Human hearing audible sound pressure range from 20 µPa (hearing threshold) till 20 Pa (Pain threshold), the threshold of sound pressure that a normal healthy person can respond to is 0.00002 Pa.

The pre-industrial era occurs before the industrial revolution, societies were ruled over by hand tools instead of the modern and complex machinery we have today.

According to the National Oceanic and Atmospheric Administration (NOAA), the global average amount of carbon dioxide during the preindustrial era was about 280 parts per million (ppm).

The oxides of nitrogen at higher concentration levels affect a fabric resulting its colour to change from white to yellow. It is harmful lung irritant and can cause respiratory diseases in children.

Nitrogen dioxide can combine with water droplets/water vapour in the atmosphere and fall down in the form of acid rain.

In the stratosphere, continuous from 6 miles (10 km) to about 31 miles (50 km). Most commercial air planes fly in the lower part of the stratosphere.

Most atmospheric ozone is concentrated in a layer in the stratosphere, about 9 to 18 miles (15 to 30 km) above earth's surface. Ozone is a molecule that contains three oxygen atoms.

At any given time, ozone molecules are constantly formed and destroyed in the stratosphere. The ozone layer in the stratosphere absorbs a position of the radiation from the sun, preventing it from reacting the planets surface. It absorbs the portion of VV light called UVB.

• The ozone concentration found maximum at mid and decreases either side.