Bio-Digester Technology

Septic Tank:
In India, Septic Tank is a very commonly used product for storage and disposal of Human Faecal matter at places / sites that lack connection to main sewage pipes which normally are provided by local government bodies.

Sadly in our country, the sewerage network is missing and in fact most of our urban clusters lack 100% sewage connections thus leading to higher usage of Septic Tanks which is NOT an Eco Friendly Solution.

Since Septic Tanks require large drainfields to dispose of the sludge (Human Faecal Matter), they are not suitable for densely built cities and in fact pollute the environment.

Periodic preventive maintenance is required to remove solids (faecal matter) that remain and gradually fill the Septic Tank which reduces its efficiency and thus regular pumping out is a must to de-sludge the Septic Tank. If this is not done then the faecal matter (solids) escapes from the Septic Tank and clogs the drainage pipes / surrounding areas thus polluting and creating numerous health hazards.

Additives to improve the effluent quality from septic tanks, reduce sludge build-up and to reduce odors have been promoted by some manufacturers, however, these additives – which are commonly based on “effective micro-organisms” – are usually costly in the longer term and fail to live up to expectations of the users.

Disadvantages of a Septic Tank:

• Septic tanks do not treat the waste but only store it thus they basically just postpone the problem of treating the waste and act as containers of waste material.

• In many rural areas no proper equipment is available to pump out the waste matter from the septic tanks and many a times people manually clean the septic tanks which is tantamount to manual scavenging, a practice that is morally repugnant, dehumanising and against the law.

• The agencies that “clean” the septic tanks do not treat the waste – they just dump it in the water bodies or ditches, thus polluting the environment.

Environmental concerns due to Septic Tank Systems:

Odour and gas emissions:
Septic Tank systems typically generate hydrogensulphide, a pungent and toxic gas along with ammonia which is also generated due to breakdown of Nitrates and organic nitrogen compounds. Both these gas emissions are not desirable for human beings and for our environment.

Nutrients in the effluent
Septic tanks are ineffective at removing nitrogen compounds that have potential to cause algal blooms in waterways into which the septic tank dischargefinds its way. Furthermore the system keeps phosphates in a soluble and mobilized form which can trigger prolific plant growth including algal blooms which also include the blooms of the potentially toxic cyanobacteria.

Groundwater pollution
In urban areas with high population density, septic tank system pollutes the ground water beyond acceptable limits which in turn pollutes the food chain leading to health hazards.

Surface water pollution:
In areas adjacent to water bodies, septic tank systems pollute the water thus harming the marine life leading to lower harvest levels (less number of fishes in the water) and ecological destruction.

Health Hazards:
In India, the extensive usage of Septic Tanks along with Soak Pits / Leach Pits and Open Defecation has led to degradation of our environment posing serious health hazards.

The list of diseases that could be reduced with proper sanitation and hygiene practices is very long. For example, in India, 15 diseases have been listed which could be stamped out by proper sanitation practises.

1. Anaemia, malnutrition
2. Ascariasis (a type of intestinal worm infection)
3. Campylobacteriosis
4. Cholera
5. Cyanobacteria toxins
6. Dengue
7. Hepatitis
8. Japanese encephalitis(JE)
9. Leptospirosis
10. Malaria
11. Ringwormor Tinea (a type of intestinal worm infection)
12. Scabies
13. Schistosomiasis
14. Trachoma
15. Typhoid and paratyphoid enteric fevers

Polio is another disease which is related to improper sanitation and hygiene.

To counter the problems faced due to the above scenario, DRDO (Defence Research and Development Organisation), Ministry of Defence, Govt of India has developed and commercialised the Bio-Digester Technology for treatment of human faecal matter. Dr Lokendra Singh of DRDE, Gwalior is credited with the invention of this technology that was initially deployed in the Defence sector and now is being promoted under the SWACCH BHARAT MISSION program.

Bio-Digester Systems versus Septic Tank Systems

Source: DRDO