List of top Environmental Engineering Questions asked in GATE Civil Engineering

A water treatment plant treats 25 MLD water with a natural alkalinity of 4.0 mg/L (as CaCO₃). It is estimated that, during coagulation of this water, 450 kg/day of calcium bicarbonate (Ca(HCO₃)₂) is required based on the alum dosage.
Consider the atomic weights as: Ca-40, H-1, C-12, O-16.
The quantity of pure quick lime, CaO (in kg) required for this process per day is _____ (rounded off to 2 decimal places).

A circular settling tank is to be designed for primary treatment of sewage at a flow rate of 10 million liters/day. Assume a detention period of 2.0 hours and surface loading rate of 40000 liters/m²/day. The height (in meters) of the water column in the tank is __________ (rounded off to 2 decimal places).

An organic waste is represented as C₂₄₀O₂₀₀H₁₈₀N₅S.
(Atomic weights: S-32, H-1, C-12, O-16, N-14).
Assume complete conversion of S to SO₂ while burning.
SO₂ generated (in grams) per kg of this waste is _______ (rounded off to 1 decimal place).

Which one of the following products is NOT obtained in anaerobic decomposition of glucose ?

Activated carbon is used to remove a pollutant from wastewater in a mixed batch reactor, which follows first-order reaction kinetics.
At a reaction rate of 0.38 /day, the time (in days) required to remove the pollutant by 95% is ______ (rounded off to 1 decimal place).

The primary air pollutant(s) is/are

The following table gives various components of Municipal Solid Waste (MSW) and a list of treatment/separation techniques.

Component of MSW	Treatment/separation technique
P - Ferrous metals	i - Incineration
Q - Aluminum and copper	ii - Rapid composting
R- Food waste	iii - Eddy current separator
S-Cardboard	iv - Magnetic separator

The CORRECT match is 

The number of degrees of freedom for a natural open channel flow with a mobile bed is