Question

In which process, waste material is burnt in absence of oxygen?

• A. Incineration
• B. Pyrolysis
• C. Gasification
• D. Composting

Hint:

Remember the key difference in oxygen requirements: Incineration = excess oxygen; Gasification = limited oxygen; Pyrolysis = no oxygen. Composting is a biological, not thermal, process.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The question asks to identify the thermal waste treatment process that specifically involves heating in the complete absence of oxygen.

Step 3: Detailed Explanation:
\[\begin{array}{rl} \bullet & \text{(A) Incineration: This is the combustion of waste material in the presence of a sufficient amount of oxygen.} \\ \bullet & \text{(B) Pyrolysis: This is a process of thermal decomposition of organic material at elevated temperatures in the complete absence of oxygen. It produces solid (char), liquid (pyrolysis oil), and gaseous products.} \\ \bullet & \text{(C) Gasification: This process converts carbonaceous materials into a synthesis gas (syngas) by reacting the material at high temperatures with a controlled, limited amount of oxygen and/or steam. It is not a completely oxygen-free process.} \\ \bullet & \text{(D) Composting: This is a biological process in which microorganisms decompose organic waste in the presence of oxygen (aerobic decomposition).} \\ \end{array}\]

Step 4: Final Answer:
Pyrolysis is the process where waste material is burnt (thermally decomposed) in the absence of oxygen.