The saying ‘we are what we eat’ is only part of the story. What we eat is what we excrete, and this means plant nutrients. Human excreta contain the same nitrogen, phosphorus and potassium (N-P-K) as the fertilisers used to produce the food consumed (Winker et al., 2009). However, human excreta are considered unwanted waste throughout the world, creating humanitarian and environmental problems (Baum et al., 2013). In order to replace the nutrients removed from the fields during harvesting, more fertilisers are manufactured in industrial processes that are contributing to environmental changes at global level (Rockström et al., 2009). Recycling human excreta back to agricultural fields would reduce the current dependence on fossil fuel-derived fertilisers (Ramírez & Worrell, 2006). It would also improve crop yields in e.g. sub-Saharan Africa, where fertiliser application is low (FAO, 2015), and protect marine ecosystems in the Baltic Sea by limiting the flow of excess nutrients to surface waters (Rockström et al., 2009).
Category: English
The Road to Large-scale Implementation of Source-separation?
Within our research group we are working with several methods for returning nutrients from food and wastewater to agriculture. Source separation of waste flows can make for simpler treatment and higher quality of the recovered products. However, the use of source separation systems is far from wide spread. Trying to understand why this is the case and what can be done to increase source separation is also part of our research focus. And we are not alone in looking for opportunities to transition our waste systems into something more sustainable. A recent popular science article in the magasin Extrakt, sponsored by the Swedish Research Council Formas, featured an interview with Jennifer McConville on what is needed to implement these systems at a large scale.
What do farmers in South India think of human urine as a fertiliser?
Technological advances in the sanitation sector have made it feasible to safely recycle human wastes to agricultural areas to use as fertilisers. From a social science perspective, these developments open up a new array of questions: for instance, are farmers be willing to handle and use such fertilisers? How do farmers perceive such materials – as wastes or valuable products? What factors shape these perceptions and subsequent attitudes towards these practices?
Foto: Feng Zhong (CC BY-NC-ND 2.0)