GATE 2025 Environment Quiz 14

Assertion (A): - Composting is basically a treatment method for inorganic waste from a community

Reason( R): - In the incineration method of refuse disposal, the refuse is burn off and the volume is much reduced.

If ‘d’ is the depth of flow at partial flow, ‘D’ is the diameter of sewer line and ‘α’ is the central angle subtended by partially filled section then which of the following expression is NOT correct:

If the average discharge in a sewer is 7500 m³/day then which of the following statement(s) is/are correct.

1. Minimum daily sewage flow is taken as 5000 m³/day

2. Minimum hourly sewage flow is taken as 2500 m³/day

3. Design sewage flow is taken as 0.26 m³/sec

Statement (I): Digestion of sludge is not required when secondary treatment of sewage is done in oxidation ditches.

Statement (II): Oxidation ditch admits an extended aeration process.

ASP is used to treat a waste water flow of 2MLD having BOD₅ of 250 mg/lit. The biomass concentration in the aeration tank is 2500 mg/lit and the concentration of biomass leaving the system is 80 mg/lit, the aeration tank has a volume of 200m³.

A sanitary landfill has an available space of 12.5 ha for the dumping of solid waste. On average, 640 m³ of solid waste is dumped at the site 5 days per week. This waste is compacted to twice its delivered density. If a landfill is to be designed for 10 years, the average depth of the landfill required is :