A.The gases produced in sludge digestion process, contain 75% methane
B.The gases produced in sludge digestion process, contain 75% carbon dioxide
C.Sludge digestion is carried out in sludge tank
D.The process of decomposing the organic matter under controlled anaerobic conditions, is called sludge digestion
Explanation: The correct answer is The gases produced in sludge digestion process, contain 75% carbon dioxide.
Submitted by: Academy of Pakistan