For a more resilient food system, look to nutrient recycling

Data suggests cities should look at more than food waste to achieve circularity


Can we, as a society, recycle the nutrients needed to grow our food? Sally Brown explores the question in a new article on BioCycle. Here are some fascinating facts from the piece:

  • Each person throws away more than 200 pounds of food waste each year in the U.S.
  • It takes about 14.5 pounds of nitrogen and 2.5 pounds of phosphorous to grow all of the non-animal related crops needed to feed each person per year.
  • If each person composted all their food waste, the resulting compost would have 1.3 pounds of nitrogen and 0.2 pounds of phosphorous each year. That’s less than 10% of the nitrogen needed to keep each person fed!
  • “Composting [food waste] is wonderful — you know I believe that,” Brown writes. “But in terms of nutrient capture, it is time to talk toilets.”
  • In contrast to food waste, the 14.5 pounds of nitrogen and 2 pounds of phosphorous in bodily waste generated by each person per year is very close to the nutrients needed to feed each person. As Brown phrases it, “Those numbers are remarkably close to the amount of N (14.5 pounds) and P (2 pounds) we need each year to grow food. And it all goes down the sewer.”
  • Municipal wastewater treatment plants capture a fraction of the nitrogen and phosphorous sent down the toilet via biosolids. Nonetheless, biosolids bring us much closer to nutrient self-sufficiency than food waste composting alone, and that is why wastewater treatment systems, biosolids, and land application can be keys to circularity.

If wastewater treatment plants are going to capture more of the nutrients we need to grow food, that will mean more biosolids. More biosolids will entail more beneficial use (like conversion to fertilizer, compost, or anaerobic digestion).

Denali is here to make it happen. We work with hundreds of municipalities across the U.S. to manage biosolids. Click here to learn more.

Photo caption: Pipes carry wastewater into a treatment plant. Research suggests that cities should harness the value of their wastewater by better utilizing biosolids in order to become more nutrient self-sufficient.