Turning Human Waste to Fertilizer: An African Solution

By David South, Development Challenges, South-South Solutions

SOUTH-SOUTH CASE STUDY

While South Africa has been free of the racist Apartheid regime since the mid-1990s, the expected boost to living standards for the majority black population has not been as widespread and as quick as many had expected.

One important aspect of lifting living standards is making sure the entire population has access to adequate sanitation and hygiene services. Another is making sure they have access to adequate and healthy food sources. A bright idea based on intensive research is meeting both goals in an innovative way.

According to the Council for Scientific and Industrial Research (http://www.csir.co.za/), some 11 million South Africans have received access to basic sanitation services since 1994 – but 13.3 million still lacked basic sanitation services by 2008.

The Water Research Commission (WRC) (http://www.wrc.org.za/) believes there is a crisis with South Africa’s toilet pit latrines, which are quickly filling up past their original design capacity. WRC’s solution is to turn the human faeces or faecal sludge deposited in pit latrines into fertilizer for farming and agriculture. The Water Research Commission is advocating using the fertilizer either for fruit trees or for trees that will be turned to income sources like paper and fuel.

The WRC’s project and series of experiments are called “What happens when pit latrines get full?”

“Only one third of municipalities have a budget to maintain on-site sanitation,” WRC researcher and scientist David Still told Inter Press Service (IPS). “If pits fill up, all the hard work that was done to address the sanitation backlog will be wasted. Why not use faecal sludge to address the growing problem of food insecurity by planting fruit trees? Or use the sludge to cultivate trees for fuel or paper production?”

Human faecal sludge contains a variety of nutrients, such as nitrogen, phosphates and potassium. The WRC estimates the average person excretes enough human faecal sludge per year to fertilize 300 to 400 square metres of crops.

The big reason people are reluctant to use human waste as fertilizer is because of the pathogens it contains. Spreading this on edible crops is dangerous and it is also a risk to groundwater when it leaches in to the soil.

The WRC conducted research on two sites: Umlazi and Karkloof, both in KwaZulu-Natal, South Africa. They used property owned by the South African Paper and Pulp Industry (SAPPI) and the local municipality.

The first step in the experiments was to bury the sludge in pits and plant crops on top of it. The pathogens were contained using this method and in time died off.

The test trenches were 0.75 metres in depth and filled with different quantities of sludge. Two control sites did not use faecal sludge. The scientists found the sites where the human waste was used saw plant growth and volume increase by “as much as 80 per cent.”

They then tested for pathogens in the soil. This included looking for the eggs of the large roundworm (http://www.nhs.uk/conditions/Roundworm/Pages/Introduction.aspx), a parasite whose presence would be harmful to humans. The site was tested over a period of 30 months, but none could be found.

Tests for microbes at the Umlazi site also found none. The plants were found to have healthy dark green leaves and the trees grew larger with the sludge present.

Researchers also monitored the groundwater around the sites. They found in flat ground and sandy soil there was no impact. In the site with sloping and shallow soil, small increases in nitrate were observed in the groundwater after rainfall.

They concluded the best place to apply this technique is in places that are flat and where the soil is deep.

One local resident, Lindiwe Khoza, was selected to be part of the test. Citrus and peach trees were planted on top of the buried sludge.

She told IPS: “The fruit grows much faster and it seems to be tastier and juicier than fruit bought at supermarkets. We now enjoy fruit from our own garden.”

WRC’s clever solution to these twin problems could help make life much more pleasant in communities still grappling with poor hygiene services, while dramatically improving the health of crops and their yields.

Resources

1) World Bank guide to pit latrines. Website: http://water.worldbank.org/shwresource-guide/infrastructure/menu-technical-options/pit-latrines

2) A video on how to construct a ventilated pit latrine. Website: http://www.youtube.com/watch?v=n4yfAyhiV74

3) A Practical Guide for Building a Simple Pit Latrine: How to Build Your Latrine and Use It Hygienically, for the Dignity, Health, and Well Being of Your Family. Website: http://www.crsprogramquality.org/publications/2011/9/13/a-practical-guide-forbuilding-a-simple-pit-latrine-how-to-b.html

4) The Control of Pathogens from Human Waste and their Aquatic Vectors by L. E. Obeng. Website: http://www.jstor.org/discover/10.2307/4312882?uid=3738032&uid=2129&uid=2&uid=70&uid=4&sid=21100919752851

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