Next gen toilets
Found in the uninhabitable climes of Antarctica, psychrotrophic bacteria could be the answer to India’s sanitation problems. After successful experimentation in high altitude toilets used by defence personnel, the Defence Research and Development Organisation [DRDO] plans to use the bacteria to tackle the problem caused by open defecation in the country. It will also be put to use in Indian Railways.
India is home to 60 per cent of the world’s population that defecates in the open. This has serious health implications and is consequently a big economic burden. Open defecation causes numerous water-borne diseases like diarrhoea, which kills 5,00,000 children every year. ‘The treatment process in septic tanks attached to toilets also does not break down the waste completely,’ adds Lokendra Singh, director of life sciences division at DRDO. Thus, sulphuric acid is produced which causes foul smell. Only 33 per cent of toilets in the urban areas are connected to the sewerage system; sewage from the rest flows in open drains, causing river contamination, as per 2011 Census.
‘Biodigester toilets can free us from these problems,’ says Singh. The zero-waste biodigester technology breaks down human excreta into usable water and gas through an anaerobic process. It does not have any geographical or temperature limitation and also does away with the need to set up large sewerage networks. The experiments to develop bio-toilets were started by DRDO around 20 years ago. In areas like Ladakh, deep pits are dug for defecation. Once the tank is full it is emptied in fields. The waste has chances of mixing with melting snow that feed rivers downstream. In freezing conditions, the waste is collected and then incinerated which requires energy and labour. says Selvamurthy. DRDO then decided to send scientists to Antarctica under India’s 13th Antarctic Mission in 1994 to look for microorganisms that can break down excreta. ‘After screening we found a variety of psychrotrophic bacteria like Clostridium and Methanosarcina,’ he says. These bacteria can live in cold or in hot climate and feed on waste to survive.
The bacteria were then cultured in the DRDO lab in Gwalior and tested at various altitudes and temperatures. They worked in temperatures ranging from 0°C to 55°C. To use it in a toilet, a tank was fitted below the commode to collect the excreta. The tank made of cement had sheets with bacteria embedded in it and free-floating bacteria. The bacteria cannot move out of the sheets but can multiply. When human excreta comes in contact with bacteria, it gets converted into methane and water through a series of steps of anaerobic digestion.
Faecal matter is composed of carbohydrates, protein and fats. In the first step, they are converted 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. In the last step, methane, carbon dioxide and water are formed.
On arrangement with Down to Earth magazine.