Management of biological sewage sludge: Fertilizer nitrogen recovery as the solution to fertilizer crisis

In the current situation of a serious raw material crisis related to the disruption of supply chains, the bioeconomy is of particular significance. Rising prices and the problem with the availability of natural gas have made N fertilizers production very expensive. It is expected that due to natural gas shortages, conventional production of nitrogen fertilizers by chemical synthesis will be hindered in the coming season. An important alternative and an opportunity to solve the problems of fertilizer nitrogen availability are biological wastewater treatment plants, which can be treated as a renewable biological nitrogen mines. Sewage sludge (including activated sludge) contains up to 6-8% DM. N. Considering the quantity of sewage sludge generated in wastewater treatment plants, it can become an important raw material for the sustainable production of organic-mineral fertilizers from renewable resources available locally, with a low carbon footprint. Furthermore, the sewage sludge management method should take nitrogen retention into account and should not allow the emission of greenhouse gases containing nitrogen. This article analyzes the technological solutions of nitrogen recovery for fertilization pur-poses from biological wastewater treatment plants in the context of a new and difficult resource situation. Conventional and new nitrogen recovery methods were analyzed from the perspective of the current legal sit-uation. An attempt was made to evaluate the possibility of implementing the assumptions of the circular economy through the recovery of renewable nitrogen resources from municipal wastewater treatment plants.

Automated summary

In the current serious raw material crisis, the bioeconomy is particularly significant. Biological wastewater treatment plants can serve as renewable biological nitrogen mines to solve the problem of nitrogen fertilizer availability. Sewage sludge can be used as a local renewable resource for sustainable production of organic-mineral fertilizers with a low carbon footprint. Nitrogen retention and greenhouse gas emissions should be taken into account in sewage sludge management.