Let´s talk dirty: recover nutrient from fecal sludge and municipality organic waste into high-quality fertilize


I have been dealing with shit for almost 2 years now. Yes, the literal shit. It is a part of my master thesis that I conducted in collaboration with the International Water Management Institute, Sri Lanka and Ruhr Universität Bochum, Germany. The project is Co-composting of Solid Waste and Fecal Sludge for Nutrient and Organic Matter Recovery. 

What is the challenge?

The current linear approach to agriculture removes important nutrients from the soil, passes them through a value chain and discards them in a way that can lead to unproductive soil and negative environmental impacts. Most importantly, increasing demand on chemical fertilizer has become a problem especially because many key resources have finite reserves, and some case such us Phosphorus, there is no synthetic alternative.

Meanwhile at the other end,

The city keeps generating waste, both human waste and organic waste. Nitrogen, Phosphorous, and Potash are some of the essential nutrients for the plant. Along with organic matter and Carbon, these nutrients can be found in human waste and organic waste. If recover properly, human excreta from a city with 1 million residents can produce around 1,200 tons N year-1, 170 tons P year-1 and 330 tons K year-1.

How it works,

In Sri Lanka where this project was conducted, there is no proper centralized wastewater treatment. For a developing country, it's simply not applicable due to high investment and operational cost. So, affordable and low tech treatment process would be an appropriate solution.

Co-composting fecal sludge with organic waste from municipality is the most feasible solution. Why co-composting? Even though fecal sludge contains high valuable nutrients, composting it alone won't assure the complete pathogen destruction since its too little organic content. Co-composting fecal sludge with rich carbon material such us organic waste (food scrap, food waste, agriculture waste) is necessary to achieve the thermophilic condition.

The thermophilic condition produces biological heat which enables complete pathogen destruction. The result is high-quality fertilizer which can be enriched with additional nutrient or biochar for carbon sink.

This technology can be replicated, especially for the area where a centralized wastewater treatment plant still lacking.

The benefit

  • A new business opportunity
  • Considering its raw material, farmers can have affordable fertilizer
  • Improve the health condition


What’s is now?

I am currently still working on this project. I am working on bringing it out of the laboratory to a start-up. I have participated in some pitching competition to gain feedback from experts and of course for the seed funding. The most current one is The Falling Walls Lab in Berlin where I become a finalist.

I am so looking forward to a fruitful discussion on this topic!

Below are some related publication;

Co-composting of Solid Waste  and Fecal Sludge for Nutrient and Organic Matter Recovery 

Business Models for Fecal Sludge Management


Comments (2)

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What can go wrong?
Vanessa Leslie Bolivar Paypay
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  • Hi Fadli! i went through your article. I guess composting sounds a solution they could adopt and could be successful among local farmers. However, did you evaluate the nutrient's balance of the final product? in case of Germany for example composting and later one the use of the product as fertlizer had led in the past to an unbalance of nutrient concentration in soil and water, ending the situation with high amounts of phosphorus or nitrogen (in form of nitrates) in the water. Therefore, Germany has now one of the highest concentration of nitrates in water in Europe and also eutrophication problems, from that time to now in some regions like mine Baden Wuttember it is currently forbiden to spread the manure directly to the land (even if pathogens are killed). I can guess Sri Lanka may not have the problem Nitrogen or Phosphorus surplus due to unbalanced fertilization, however i guess it is important to take into account.

    Fadli Fadli
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  • Yes, I did an analysis on the physical, biological, and chemical properties of the end product. Nutrient content, especially NPK is the main factor to determine the quality of the products. Therefore, we have post-treatment which adding enrichment to the composting product. This enrichment could be additional nutrient (NPK) from mineral fertilizer or biochar as a carbon sink.