Test: Sludge Thickening, Sludge Dewatering - Civil Engineering (CE) MCQ

Explanation: The design solid surface loading during a gravity thickening process in an activated sludge plant lies between 25 to 30 kg/m²/day.

Explanation: Potassium, Phosphorous and Nitrogen are found in municipal sewage having maximum plant nutrient concentration of 3.3% of total municipal waste as nitrogen.

Explanation: In pressure type flotation device, 3-5kg/cm² pressure is applied to the sludge thickening process.

Explanation: The range of design Hydraulic loading rate of the gravity thickener is 20-25m³/m²/day.

Explanation: The process involved in sludge thickening are gravity thickening, air flotation and centrifugation.

Explanation: When the thickened sludge, solid concentration is between 7-9, the type of sludge obtained from gravity thickner is activated.

Explanation: The process used for drying of sludge is multiple effect evaporation, rotary dryer, spray dryer and flash dryer.

Explanation: In the centrifugation process, the force is applied so that rotation of sludge takes place which helps in the dewatering of sludge.

Explanation: Acid fermentation is a sludge digestion process and composting, heat drying and incineration are the methods of disposal of dewatered sludge.

Explanation: Good amount of dried solids is produced by drying bed process and they are commonly used in the sludge dewatering process due to their low cost and better efficiency.