UPSC Prelims 2015 Question:

With reference to bio-toilets used by the Indian Railways, consider the following statements:

1. The decomposition of human waste in the bio-toilets is initiated by a fungal inoculum. 
2. Ammonia and water vapour are the only end products in this decomposition which are released into the atmosphere.
   
   

Which of the statements given above is/are correct?

Explanation: 

• Bio-toilet consists of an easy-to-install super-structure, a multi-chambered matrices bio-tank that holds the bacterial culture and supports the treatment of human waste. The system doesn’t need any external energy for treatment, rather gives out pathogen-free effluent water that is apt for gardening and similar purposes; and biogas that could be used for cooking or heating.
  
  
• The bio-digester tank in every bio-toilet is filled with inoculums containing four types of bacteria. The indigenously developed ‘anaerobic bacteria’ converts human waste into water and bio-gases. It is not fungal inoculum. So, statement 1 is not correct.
  
  
• The water trap system in the toilet prevents air from getting into the tank, the human waste is processed by anaerobic bacteria in seven chambers in the tank. The bio gas so produced is mainly Methane and Carbon Dioxide. Ammonia and water vapour are not the only end products. So, statement 2 is not correct.
  
  

Therefore, option (4) is the correct answer.

Subject: Environment | Waste Management