Group turns human waste into fertiliser

Sanergy has been installing toilets in slums while turning this human waste into organic fertiliser

In Summary

• In many slums, waste is unsafely managed and is causing environmental pollution

• Environmental organisation has stepped in to provide latrines and make use of waste

A child jumps over a sewer line in Kibra slum
A child jumps over a sewer line in Kibra slum

The world celebrated World Toilet Day on Thursday under the theme, ‘Sustainable sanitation and climate change’. It came as the population in Kenyan slums is rapidly growing. This means the amount of solid waste generated will continue to grow as well.

With most slums having outdated and over-capacity landfill spaces, waste is unsafely disposed of/managed and is causing environmental pollution.

It is estimated that about 1 million people die every year due to sanitation-related illnesses.


Amid efforts to mitigate the situation, Sanergy has been installing toilets in slums while turning this human waste into organic fertiliser.

In the past five years, Sanergy has placed over 3,500 sanitation facilities across 11 informal settlements within Nairobi. They include Mukuru kwa Njenga, Mukuru kwa Reuben, Mukuru Kayaba, Viwandani, Kiambiu, Makadara, Mathare and Kamukunji.

These facilities are run by over 2,000 entrepreneurs, called ‘Fresh Life Operators’, who provide safe sanitation access to over 140,000 urban residents every day.

Its communication manager Sheila Kibuthu said the enterprise developed a sustainable circular economy approach designed to address three critical challenges, including access to safe and dignified sanitation for residents living in urban non-sewered areas, such as the low-income informal settlements.

Another focus is on the unsafe disposal of sanitation and other solid organic waste and the lack of quality agricultural inputs for most Kenyans, who rely on agriculture for their livelihoods. 

Their model consists of building and distribution of high quality, cost-effective container-based sanitation units called Fresh Life. Then there is professional collection and removal of all sorts of organic waste (sanitation waste from the Fresh Life Toilets, agricultural waste, and market/kitchen waste).

This is followed by safe transportation to their large-scale recycling factory, and finally treatment and re-purposing to agricultural inputs and energy.

“Every year, we safely remove, treat and convert 12,000Mt of waste, producing high-quality products which include agricultural inputs (organic fertiliser, insect-based protein for animal feed) and clean energy,” Kibuthu said.

The project was inspired by the challenges slum dwellers face. She said many organisations have their focus on toilets without proper management of the waste.

“Sewers are expensive to build. Nairobi has about 5 million people, depending on outdated infrastructure that has been outpaced by the population. Though there are several pit latrines in these slums, this again is where unsafe management happens,” she said.

One of the operators empties the toilet
One of the operators empties the toilet


The organisation builds efficient toilets and gives out to individuals interested to operate them. The individuals in return pay a monthly fee of Sh850, while charging Sh10 for those accessing the facilities.

Those who instal the toilets for non-commercial use also pay a monthly fee of Sh850. The container-based toilets have no sewer attached to it. They are designed using urine-diverting technology, where a scot plate is used to separate solid and liquid waste at the source.

After one relieves themselves, they sprinkle sawdust instead of flashing with water. The operators then will replace the containers every day and transport the waste using hand carts to a consolidation site, where it is transferred to large cartridges and transported to Machakos for recycling.

The main end products include organic fertiliser, manufactured through thermophilic composting, and insect-based animal protein, through the rearing of Black Soldier Fly larvae.

These agricultural inputs sold to farmers in Kenya help tackle food security issues and increase farmers’ incomes. Over the last two years, Sanergy has sold over 600Mt of organic fertiliser to farmers, who are seeing an overall 30 per cent increase in their crop yield.

In 2019, Sanergy treated 12,000T of waste and is scaling to have the capacity for processing 70,000T of waste per year in 2020.

It also operates a transfer station for waste from pit latrines and oversees a community-based coalition of manual pit emptiers, serving an additional 30,000 people in Mukuru Kwa Njenga.

Edited by T Jalio