1. How we are trying to
“Stop Soil Wasting Away”
13
th
June 2014
A Case Study – a Flexigester in Malawi
by
Dr John Mullett and Lynn McGoff

2. Content of presentation
SOWTech will present a case study of new equipment which
is designed to make returning human and animal waste back
to the soil both safe and affordable
Loss of soil fertility is threatening food security in the global
south. Chemical fertilisers alone will not be the long term
solution.
To grow food we need fertile soils. The difference between
fertile soil and dirt is organic matter and its associated “bugs”
The return of waste to the soil is the only way in which we
will stop soil fertility being lost

3. SOWTech = Sustainable OneWorld Technologies
A community interest company founded to share the
problem and opportunity of organic waste treatment in
low-income countries
We have experience and expertise gained in working in
the organic waste treatment field over the last 30 years
Designed and built
Composting and Anaerobic Digestion projects
ranging from 5 – 40,000 t/a
Project experience worldwide including many
counties in Europe, Ghana, Malawi, India and
Thailand.
We also have a track record of innovative and value
engineering development
enclosed composting, low visual impact AD,
ozone based odour control

4. What does SOWTech do
We design and develop equipment in partnership with others
for the treatment of organic waste and the production of
fertiliser and renewable energy in low income countries
We have developed a digester which can process animal,
human and vegetable wastes
Its unique features are “flat-pack design” for easy
transportation and rapid deployment
The unit cost of the item will be low enough for widespread
application

5. What is Anaerobic Digestion
The natural process which occurs
when organic wastes break down in
the absence of air.
Methane and Carbon dioxide gas
(Biogas) are generated in this
process. The plant material changes
into a nutrient rich natural fertiliser.
The natural fertiliser returns nutrient
and organic matter to soil.
The process of decomposition
reduces the number of pathogens in
the material to make the reuse of the
waste safer.
The biogas can be used as a
renewable fuel.

6. Case Study:
Namisu Orphanage, Malawi
Objective:
To demonstrate the potential of
a Flexigester for emergency
sanitation applications, such as
flood relief and refugee camps
Sponsor:
International Federation of the
Red Cross & Red Crescent
Location:
Orphanage near Blantyre
Malawi, funded by Aquaid
Lifeline

10. Photo taken beginning
of April – 2 months after
installation
Flexigester inflated as it
is producing biogas
Now receiving human
waste from the latrine
block, animal waste and
waste cooking water

12. Note the inflated
transportable gas bag in
the background

16. Added nutrients means better yields
The usual crop produced
locally – no fertiliser
The crop which can be
achieved with fertiliser

17. Sustainable Soil Management
Wherever soil is used for food production, there is a net
loss of nutrients and organic matter from the soil
Chemical fertiliser can replace the plant nutrients, but
they do not replace the organic matter
Without organic matter in soils, they lack biomass and
are unable to retain nutrients and moisture for plants to
use
Declining levels of soil organic matter is not restricted
to the global south, but deforestation for fuel, lack of
organic fertiliser use, and more intensive land use is
generating a problem
This is exacerbated by climate change related
increases in heavy rainfall, erosion and unpredictable
growing seasons

18. Why chemical fertilisers will not
solve the problem
Those who grow most of the food, which supports the population in
emerging economies, cannot afford to buy enough chemical fertilisers
now. Subsistence farming, which is 80% of agricultural production in
Africa, does not generate the cash needed to buy fertiliser.
The chemical fertilisers are not going to get cheaper in the future. The
relative costs of chemical fertilisers will continue to rise because:
Nitrogen fertiliser is made from fossil fuel gas
Phosphates are mined and demand is predicted to outstrip
supply with significant price rises expected.
Fertiliser in Africa can be between 5 to 6 times more expensive than
Europe due to transport costs, import taxes, and lack of economies of
scale.
Central government subsidies in emerging economies are short term
and usually unsustainable political expedients

19. So what is the answer
We must find ways to return the sources of plant nutrients
and soil conditioning materials back to the land used by
farmers in emerging economies
This will be through “fertiliser factories” which harness local
wastes resources and turn them into soil supporting inputs.
If we do not nurture all the worlds soils through better waste
management we will be guilty of wasting the very soil itself....

20. So what are we seeking to achieve
To develop the Flexigester as a fertiliser factory to enable
communities to capture and treat organic wastes in a safe
and hygienic way
To make the technology affordable
To gain widespread distribution and application
To drive towards new products and processes which
enhance the ability of low income farmers to maximise
production of food in a sustainable way

21. Fertile soils puts food on

22. “We need to
feed the soil...
if we expect it to
feed the people”
JAJM
Thank you for your attention
Dr John Mullett
www.sowtech.com
johnajmullett@gmail.com
077 026 79191