Reuse of faeces and urine from ecological sanitation
Practical Action
Heat Treatment/Composting – High temperature is one of the most reliable methods of
reducing pathogen content, thermophilic composting is one method of ensuring high
temperatures. Although many toilets are described as composting they do not actually
maintain these conditions which require good management to hold a temperature of > 50 ºC
for > 1 week (WHO, 2006) (despite this the storage conditions can still render faeces safe).
Faeces can also be solar heated whilst composting to increase the temperature. Composting is
best applied as a secondary large scale treatment process where it can be adequately
managed. Small scale composting needs further evaluation.
Alkaline Treatment – This can take place using either ash and lime or urea. Ash and lime can
be added at a household facility level to provide a primary level of treatment, raising the pH
above 9 will assist die off in combination with storage. Further benefits include reduced
smell, reduction of flies (as material covers faeces) and assistance in moisture content
reduction. 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) (Schönning and Stenström, 2004). Urea is an
additive used for elevating the pH level of faeces, it can also add to the fertilizer value. It is
generally accepted as a method for larger scale secondary treatment when professionals can
handle the chemicals.
Incineration – This process is accepted to be for larger scale secondary treatment when it
needs to be assured that no pathogens remain, the resulting ash will have a lower nutritional
value as the nitrogen is lost. Moving the waste to incineration will pose a health risk to
workers. Further evaluation of incineration in practice still needs to take place.
Practical guidelines for application
The following practical recommendations should be followed when applying faeces to land,
treatment processes may allow survival of some pathogens and precautions should be taken
(Slob, 2005):
personal protective equipment such as gloves and washing of equipment and hands
should be practiced;
a period of one month should be observed between fertilizing and harvesting, allowing
further die off of pathogens whilst the material is on the crops;
large levels of phosphorous in faeces make this a good indicator for application rates,
more detailed information can be found from EcoSanRes (n.d:b);
equipment for sanitised material should not be used for un-sanitized material;
faeces should be worked into the soil to minimise exposure to humans or animals;
crops that are consumed raw (except fruit trees) should not be fertilized with faecal
material;
faeces should be buried deep, but not below the rooting depth of the crop; and
faeces should be added to soil before planting of crops.
Following these guidelines will minimise the risk of disease transmission. Four separate
methods to apply faeces are suggested by Slob (2005):
ploughing with tractor or animal drawn;
burying faeces under a layer of plain soil forming a bed;
placing faeces into channels and covering with unmixed soil; and
placing into holes close to where crops will be planted and covering with soil.
Storage
Stored material should be kept dry before use, this could be achieved by elevating and
covering the material. Animals and children should not be allowed access to the stored
material, simply fencing off the area can achieve this.
Alternative use for faeces
If use of faeces in agriculture is not culturally acceptable the material could be mixed with
animal manure and added to a bio-gas digester, although this technology is yet to prove very
reliable. If responsibly handled, faeces can also be buried in shallow pits and a tree planted
4