Which of the following statements are true in the context of sludge in wastewater treatment?

1.Sludge management is one of the easiest tasks of wastewater treatment plants

2.There is high water content and poor dewaterability in sludge management

3.There are usually strict regulations for sludge reuse or disposal

A1, 2 and 3

B2 and 3 ✓ Correct

C1 and 3

D1 and 2

Correct answer: (B) 2 and 3

Explanation

Sludge management is marked by high water content, poor dewaterability and strict rules for reuse or disposal.

Statement 1 is wrong because sludge handling is among the hardest, not the easiest, tasks of a treatment plant.

Statement 2 is right because sludge holds much water and drains poorly, making it bulky to treat.

Statement 3 is right because reuse or disposal of sludge is tightly regulated for safety.

Dewatering and stabilisation are therefore major cost centres in treatment.

Treated sludge, or biosolids, can sometimes be applied to land as fertiliser.

Want more like this? Create a free account to practise a full test, track your progress, and get spaced-repetition review.