Algae extracts as a sustainable nitrogencontaining fertilizer

The enormous increase in the world population will provoke an escalation in our overall consumption and demand for food and animal feed, which will eventually drain our limited resources. Therefore, increasing agricultural production in order to respond to the growth of the population is necessary.

However, it means an increase in the use of fertilizers as well. The widely applied Haber-Bosch method is a very important in nitrogen-containing fertilizers production. However, it is an energyconsuming process. Thus, the production of sustainable fertilizers is compulsory.

Microalgae grow predominantly in nutrient-rich water (e.g. wastewater). They could be used to recover the nutrients and to avoid the leaching of nutrients (e.g. phosphorous and nitrogen) to the groundwater. Afterward, due to the high nitrogen content and to close the nitrogen cycle, microalgae or its extract could be used as nitrogen-containing fertilizers. Moreover, subcritical water extraction is a ‘green’ and efficient approach to recover protein from microalgae cells. In this project, the potential of using algae extracts as a nitrogen-containing fertilizer was investigated. Due to its high protein content, Spirulina platensis was chosen in this work.