Which of the following statement (s) is/are correct regarding advantage of recirculation in a high rate trickling filter:
1. It helps to analyze the variations in strengths and flow of sewage applied to filter.
2. It enables higher hydraulic loading on the filter.
3. It provides longer contact period of applied sewage with the bio-film on media thereby accelerating the oxidation process.
4. Size of primary sedimentation tank is decreased.
5. It reduces odour in the effluent.
Question 2
Match List-I with List-II and choose the correct option using the codes given below:
List – I (Treatment unit)
p. Activated sludge
q. Oxidation pond
r. Septic tank
s. Trickling filter
List – II (Biological agent)
1. Aerobic bacteria (suspended Culture)
2. Anaerobic bacteria (Attached culture)
3. Anaerobic bacteria
4. Facultative bacteria
Codes:
Question 3
The MLSS concentration in the aeration tank of extended aeration activated sludge process is 4000 mg/l. If one litre of sample settled in 30 minutes and the measuring cylinder showed a sludge volume of 200 ml, then the sludge volume index would be nearly:
Question 4
An activated sludge plant treating a flow of 25 litre/sec has an aeration basin volume of 450 m3 and operates with a MLVSS concentration of 3250 mg/l. Sludge with a SVSS content of 15000 mg/l is wasted at a rate of 35 m3/day. Calculate the sludge age?
Question 5
Septic tank is
Question 6
Which of the following is NOT the correct advantage of an oxidation Ditch:
Question 7
What is the order of BOD5 removal efficiency of a septic tank for isolated houses?
Question 8
The different actions that take place in anaerobic decomposition process are the following:
a) Alkaline fermentation
b) Acid fermentation
c) Acid regression
d) Methane formation
What is the correct sequence of occurrences of these actions from earlier to later?
Question 9
In a sludge digestion tank, the gas that mainly evolves is
Question 10
Consider the following statements: 1) If sludge contains large amount of organics then its digestion is carried out aerobically. 2) When the sludge is digested anaerobically its volume reduces to 1/3 of the original volume.
