Three basic processes are involved in the overall anaerobic digestion of sewage sludge following any of the sequence :
MH SET - 2018, SET Exam - 2018,
Answer: A
The sequence is Hydrolysis → Fermentation → Methanogenesis.
Anaerobic digestion of sludge begins with hydrolysis, in which enzymes break proteins, fats and carbohydrates into soluble molecules. In fermentation (acidogenesis and acetogenesis), bacteria turn these into volatile fatty acids, acetate, hydrogen and carbon dioxide. Finally, in methanogenesis, archaea convert acetate, or hydrogen and carbon dioxide, into methane.
Each step depends on the product of the step before, so the order cannot change. Fermentation cannot precede hydrolysis, since the polymers must first be broken down, and methanogenesis, which needs the products of fermentation, must come last.
Please log in or register to report this question.