In secondary treatment mainly settled sewage flows to an aerobic biological treatment stage where it comes into contact with micro-organisms which remove and oxidise most of the remaining organic pollutants.

Correct Option: D

In secondary treatment mainly settled sewage flows to an aerobic biological treatment stage where it comes into contact with micro-organisms which remove and oxidise most of the remaining organic pollutants.

BOD is a measure of organic matter present in water. It refers to amount of O₂ consumed by microbes to decompose all the organic matter in 1 L of water at 20°C for 5 days. The greater the BOD of waste water, more is its polluting potential.

Correct Option: A

BOD is a measure of organic matter present in water. It refers to amount of O₂ consumed by microbes to decompose all the organic matter in 1 L of water at 20°C for 5 days. The greater the BOD of waste water, more is its polluting potential.

The step taken by Government of India to control air pollution include compulsory PUC (pollution under control) certification of petrol driven vehicles which tests for carbon monoxide and hydrocarbons.

Correct Option: A

The step taken by Government of India to control air pollution include compulsory PUC (pollution under control) certification of petrol driven vehicles which tests for carbon monoxide and hydrocarbons.

The central pollution control board (CPCB), statutory organisation, was constituted in September, 1974 under the water (Prevention and Control of Pollution) Act 1974. Further, CPCB was entrusted with the powers and functions under Air (prevention and control of pollution) Act, 1981. It serves as a field formation and also provides technical services to the Ministry of Environment and Forest, of the provisions of the Environments (protection) Act, 1986. Principal functions of the CPCB, as spelt out in the water (prevention and control of pollution) act, 1974, and the Air (prevention and control of pollution) Act, 1981.
(i) to promote cleanliness of streams and wells in different areas of the states by prevention, control and abatement of water pollution.
(ii) to improve the quality of air and to prevent, control or abate air pollution in the country. According to CPCB, 2.5 or less particulate size in diameter (in micrometers) of the air pollutants is responsible for greatest harm to human health.

Correct Option: A

The central pollution control board (CPCB), statutory organisation, was constituted in September, 1974 under the water (Prevention and Control of Pollution) Act 1974. Further, CPCB was entrusted with the powers and functions under Air (prevention and control of pollution) Act, 1981. It serves as a field formation and also provides technical services to the Ministry of Environment and Forest, of the provisions of the Environments (protection) Act, 1986. Principal functions of the CPCB, as spelt out in the water (prevention and control of pollution) act, 1974, and the Air (prevention and control of pollution) Act, 1981.
(i) to promote cleanliness of streams and wells in different areas of the states by prevention, control and abatement of water pollution.
(ii) to improve the quality of air and to prevent, control or abate air pollution in the country. According to CPCB, 2.5 or less particulate size in diameter (in micrometers) of the air pollutants is responsible for greatest harm to human health.

In recent years, the increases in toxic substances of NO_x and/or SPM (Suspended Particulate Matter) from vehicles come to be serious problem. About the correlation between the traffic volume in our model and the real volume, we obtained the correlation coefficient of 0.74. Simultaneously, we got the result that the concentration of NO_x was approximately 70 to 230 ppm. That of SPM was approximately 40 to 100 µg/m³.

Correct Option: B

In recent years, the increases in toxic substances of NO_x and/or SPM (Suspended Particulate Matter) from vehicles come to be serious problem. About the correlation between the traffic volume in our model and the real volume, we obtained the correlation coefficient of 0.74. Simultaneously, we got the result that the concentration of NO_x was approximately 70 to 230 ppm. That of SPM was approximately 40 to 100 µg/m³.