Environmental Engineering (General Engineering) (SSC JE)

The lead effects most commonly encountered in current populations are neurological effects in children and cardiovascular effects (e.g., high blood pressure and heart disease) in adults, lead is persistent in the environment and accumulates in soils and sediments through deposition from air sources, direct discharge of waste streams of water bodies, mining and erosion.

Aeration–It is a physical treatment process in which air is thoroughly mixed with water-a technique effective for removing dissolved gases and highly volatile odours compounds. One of the most common uses of aeration is for necessary to clarify the water.
• Aeration in water treatment can be accomplished using spray nozzles, cascade systems, multiple-tray aerators, diffused air aerators and mechanical aerators.

Biological oxygen demand (BOD) – BOD is amount of oxygen required to decay a certain amount of organic matter.
• As micro organism decompose organic matter, they up all the available oxygen.
Organic matter + O₂ → Newcells + CO₂ + H₂O + etc.
• BOD of safe drinking water must be zero.
• But, when BOD value reaches 5 mg/l. The water is doubtful in purity.

Sluice valve– These valves are provided to regulate the flow of water through the pipe where it is essential to divide the main line into several section.
• These valves are usually placed at the summits of the pressure conduit, where pressure is low.

The source of lead in urban atmosphere is road traffic almost 80-90% of all lead emissions into the atmosphere are caused by road traffic in the urban atmosphere.

The noise level decrease with distance following inverse law
• The inverse square law state that for every doubling of the distance from the sound source in a free field situation- the sound intensity will diminish by 6 decibelsWhere,
R= Distance from the source.

Acidity is determined by measuring how much standard base must be added to raise the pH to specified value. Acidity is the net effect of the presence of several constituents, including dissolved CO₂, dissolved multivalent metal ions, strong mineral acids such as sulfuric, nitric and hydrochloric acids and weak organic acids such as acetic acid. Dissolved CO₂ is the main source of acidity in unpolluted waters.

Sulphur dioxide is a secondary pollutant. It can cause respiratory problems such as bronchitis and pulmonary emphysema can irritate your nose, throat and lungs.

It may cause coughing, wheezing,, phlegm and asthma attacks. Sulphur dioxide has been linked to cardiovascular disease. The national ambient air quality guide line for sulphur dioxide is 120 µg/m³ as a 24-hour average.

Chemcial oxygen demand (COD) – The organic matter present in waste water can be measured in a number of ways, volatile solids determination being a crude measure of organic matter.

• Organic matter is most often assessed in terms of oxygen required to completely oxides the organic matter to CO₂, H₂O and other oxidized speciceis.

Secondary pollutants–
• H2SO₄ (more toxic then SO₂↑)
• Ozone
• Peroxyacetyl-nitrate (PAN) etc.
• Photchemical smog

Primary pllutants–
• Sulphur dioxide • CO↑
• Nitrogen oxides NO and NO₂
• Lead
• Hydrocarbons
• Radio active substances etc.