Bio-digester toilets are hailed as a solution to many of our problems. Which of the following statements about bio-digester toilets is correct?

1. They use aerobic bacteria
2. They require no or very low maintenance
3. They use less water

Select the correct statement using the codes given below.
a) 1 and 2 only
b) 1 and 3 only
c) 2 and 3 only
d) 1, 2 and 3

Ans- [ C]

Explanation– Biodigester toilets use anaerobic bacteria like Clostridium and Methanosarcina. Anaerobic bacteria don’t need oxygen to carry out biochemical reactions. They were found in Antarctica when DRDO sent scientists  under India’s 13th Antarctic Mission in 1994 to look for microorganisms that can break down excreta. This was required for the military posted in higher altitude snow covered areas where deep pits were dug out and all excreta was collected. Afterwards it was dropped in plains or incinerated which required labor, cost and did pollution. Biodigester solved all this problem.

Excreta or faecal matter contains carbohydrates, protein and fats. In the first step, bacteria converts them into simple sugars, amino acids and fatty acids. In the next step, these break to form carbonic acid, alcohols, hydrogen and water. In the third step, acetic acid, hydrogen and carbon dioxide is formed and finally methane, carbon dioxide and water are formed. Methane can be used for cooking while water for irrigation. These series of stepss are called as- hydrolysis, acidogenesis, acetogenesis and methanogenesis.

These toilets don’t require any sewerage system and once bacteria are embedded in biodigesters, they can work for very long time without maintenance.

Hence statement 2 and 3 are correct.

You can see biodigester toilet below in image.

Biodeigester