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FAECAS TO FERTILISER
Goto Technical details of treatment of faecus
Factors that affect the survival of micro-organisms in the environment
Temperature  AT 55-65 degree Celsius most types of  pathogens (except bacterial spores) will  die within hours
pH  AT pH 12 inactivation of microorganisms
 is rapid
Ammonia  Addition of ammonia will inactivate the
 Pathogens in excreta
Dryness  Dryness will reduce the number of
 pathogens since it is unfavorable
Solar Radiation  The survival time of pathogens on soil and
  crop surfaces will be reduced by UV
  radiations
Other organisms  Different types of pathogens affect other
 by predation, release of antagonistic
 substances or competition for nutrients

Nutrients
Competition with other organisms may limit the ability of faecal bacteria to reproduce and survive
Oxygen  Since most enteric bacteria are anaerobic,
  they are likely to be out-competed by  other organisms in an aerobic environment
After collecting the human waste, the first task before us is to destroy the harmful bacteria and pathogens. The Pathogens such as protozoa and viruses will decrease naturally since they are not able to multiply outside the host, but bacteria may continue to multiply or get destroyed depending on the conditions heat, pH, moisture, solar radiation/UV-light, nutrient availability and presence of other micro-organisms.

Treatment of Faeces
There are two ways of converting waste to manure: Desiccating or dehydrating and Composting. In extreme case, incineration is also used.

De-water ( Dehydration)

Given the above factors, the first step is to reduce the amount of water in the excreta. In most pit latrines, the chamber is made porous, to filter out water, and dry up the excreta. The faecus is also contained in the chamber for sometime, till its pathogen content is reduced. The higher the quantity of water, the more time this process takes. This means that the design of the pit should be such that it can filter out the water, as well as contain the faecus, and ensure that it does not become a breeding ground for mosquitoes and new pathogens. 

Alkaline treatment : Adding ash or lime after defecation will lower the moisture content and to raise the pH and ammonia level, thus creating unfavourable conditions for pathogens. This also reduces odour and the risk of attracting flies.

At least 1 – 2 cups (200-500 ml) of ash and/or lime should be added after each defecation (or enough to cover the faeces). Urea is an additive used for elevating the pH level of faeces. It also adds to the fertilizer value. A pH of over 9 for at least 6 months will kill most pathogenic organisms. At a higher pH, the drying time period can be reduced. The product from a dehydration process is a kind of mulch, rich in humus, carbon, fibrous material, phosphorous and potassium. It should be stored, sun-dried or composted in order to kill off all pathogens.

 

Secondary Treatment:

Secondary treatment of faeces may be required to make human faeces safe enough to return to the soil. Secondary treatment includes high temperature composting, chemical addition of urea and longer storage times.
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