Environmental Engineering (Part-2) (General Engineering) (SSC JE)

As per CPCB Noise limits in industrial, commercial, residential and silence zones area as follows–

When chlorine gas on being passed through slaked lime at high temperature (400ºC) give bleaching powder.

Ca (OH)₂ + Cl₂ → CaO Cl₂₀ + H₂

• Bleaching powder used in the paper & textile industries.
• Most commonly used for bleaching powder as disinfectant that's used to make drinkable water.

Anaerobic treatment of sewage–Anaerobic treatment process require less energy for its operation than the aerobic treatment process.

• In this treatment requires fewer nutrients because less biomass is produced. • In this process requires smaller reactor volume as it can handle higher volumetric loading rates.
• Anaerobic process produces a biogas, consisting of methane, carbon dioxide, hydrogen sulphide and tracers of other contaminant gases.

Ozone is the structural modification of oxygen is an air pollutant in the lower atmosphere but beneficial in the upper atmosphere.

• Ozone in the upper atmosphere forms a protective layer around the earth and protects from sun's ultraviolet rays.

• Ozone at the ground level is an air pollutant causing negative effects to human and environmental health.

Mercury is a highly toxic element that is found both naturally and as an introduced contaminant in the environment.

• Its toxic effects depend on its chemical form and the route of exposure, methyl mercury is the most toxic form.

• It affects the immune system, alters genetic and enzyme systems and damages nervous system.

• Most toxic form of mercury in water is H₃ – Hg⁺

• Pollutants like phenol and mercury can removed from water by filtration process.

Afforestation is the process of planting trees in regions that haven't had any tree cover in the recent post in order to build a forest.

• Afforestation in deserts in difficult because of low rainfall.

• Afforestation, reforestation and other forms conservational forestry methods are often though to be used for stopping the effects of climate change by reducing atmospheric carbon.

Socket and spigot joint–In this joint, spigot is the male part and socket is the female part of joint. Socket and spigot is part of cotter joint, the spigot end goes inside the socket end and the gap is filled by jute yarn. It is mostly use in pipe fittings.

Hydraulic pipe joint–Pipes carrying fluids very high pressure are using hydraulic joint. In this joint, pipe machined to the correct size and joined by two bolts.

Screwed union joint–This joint used in galvanised iron pipes.

CO₂ levels increases around earth, the amount of dissolved CO₂ also increases, which increases the amount of carbonic acid therefore decreasing the pH.

• As raindrop falls through the air, CO₂ molecules interact creating carbonic acid in the rain drops, which lowers the pH value of 5.65 at 20ºC.

• The strong acid likes like sulphuric acid (H₂SO₄) and nitric acid (HNO₃) dissolved or formed in rainwater dissociate or release hydrogen ions thereby increasing the acidity in rain drops.

Permissible limit of fluoride content in drinking water is taken as 1.5 mg/l.

• When fluoride content increases from 1.5 mg/l then it affects the teeth in discoleration of teeth.
• If fluoride content greater than 5 mg/l, its causes deformation of bones or called as bone flourosis.
• But 1 mg/l of fluoride is required to prevent the dental cavity and helps in the formation of growth of permanent teeth.

The hardness that is equivalent to alkalinity is known as carbonate hardness.

Carbonate hardness – It is equal to the total hardness or alkalinity whichever is less.

Non-carbonate hardness – It is the total hardness in excess of the alkalinity. If alkalinity is equal to or greater than total hardness. Then there is no noncarbonate hardness.