Sewage sludge is commonly used on agricultural land as a sustainable and renewable source of fertiliser throughout European countries, in part due to EU directives that promote the diverting of sewage sludge away from landfill and incineration and towards energy production and agriculture.
This EU directive led to the spread of the unintended consequence.
the team estimate that microplastics removed from raw sewage at wastewater treatment plants go on to make up roughly 1% of the weight of sewage sludge, which is commonly used as a fertiliser on farms across Europe.
This case illustrates the potential unintended consequences from attempting to do good.
This is a classic example of how progress traps occur.
Capturing nutrients in waste water closes a nutrient waste loop and seems a good example of applying circular economy thinking.
HOWEVER, at the time the decision was made to process sewage sludge into fertilizer ignored the relationship of sludge to microplastics was unknown or insufficiently explored. After the decision was made, the practice was adopted across many countries in the EU. After years of practice, the new knowledge reveals that there has been years of silent microplastic contamination. To fix the solution will require another solution, perhaps even more complex..
This illustrates the danger of applying circular economy techniques when the waste stream is not fully characterized.
Peccia, J., Zulli, A., Brackney, D. E., Grubaugh, N. D., Kaplan, E. H., Casanovas-Massana, A., Ko, A. I., Malik, A. A., Wang, D., Wang, M., Weinberger, D. M., & Omer, S. B. (2020). SARS-CoV-2 RNA concentrations in primary municipal sewage sludge as a leading indicator of COVID-19 outbreak dynamics. MedRxiv, 2020.05.19.20105999. https://doi.org/10.1101/2020.05.19.20105999
Kaplan, Edward H, Dennis Wang, Mike Wang, Amyn A Malik, Alessandro Zulli, and Jordan H Peccia. ‘Aligning SARS-CoV-2 Indicators via an Epidemic Model: Application to Hospital Admissions and RNA Detection in Sewage Sludge’. Preprint. Infectious Diseases (except HIV/AIDS), 29 June 2020. https://doi.org/10.1101/2020.06.27.20141739.