Agricultural development is an important measure toward ending global poverty and feeding a projected 10 billion people by the year 2050 (FAO, 2017). Estimated to account for one-third of the global gross domestic product (GDP), it is also crucial for economic growth. Among many factors that stimulate agricultural development, the affordable availability of effective fertilizers is pivotal. The global fertilizer demand for 2018 was forecasted to be 194 Mt and is projected to increase to 201 Mt by 2020 (FAO, 2015) and 263 Mt by 2050 (Alexandratos and Bruinsma, 2012). Europe has also followed the same trend of agricultural intensification and over the last few decades evolved to intensive plant production resulting in an increasing demand for mineral fertilizers. In 2016, the total production of mineral fertilizers in Europe reached 16.6 Mt, out of which 73% of the produced fertilizers comprised of nitrogen (N), 16% of potassium oxide (K2O) and 11% of phosphorus pentoxide (P2O5)(Fertilizers Europe, 2018).
Currently, the N used in fertilizers is synthesized via the fossil-fuel intensive Haber-Bosch process, whereas phosphorus (P) is mined from finite phosphate rock deposits that are largely concentrated in certain parts of the world like China, United States of America, Russia and Morocco among a few other places. Assessments on nutrient budgets also state a deficit in potassium (K) and indicate that a global doubling of potash fertilizer production would be required to balance inputs and offtake (Manning, 2010). Moreover, there is a looming threat of the depletion of the mineral reserves along with an increase in its price. The quality of the ores has been diminishing and geopolitical concerns further cast doubts onto its uninhibited supply (Coppens et al., 2016).
It is therefore inevitable to have alternative processes that can manufacture fertilizers and maintain food security in a sustainable manner. Implementation of nutrient recovery from different waste streams for the production of fertilizers would not only help in the management of excess biomass, but also enable the recycling of valuable nutrients that would otherwise end up being lost into the ecosystem. Moreover, it would form an important part of the circular economy concept which aims to keep resources in use for as long as possible, extract the maximum value from them whilst in use, then recover and regenerate products and materials at the end of each lifespan.
Despite the existence of market-ready recovery techniques, recycling derived fertilizers (RDFs) are not yet extensively used due to certain barriers like legal constraints on the raw materials used in RDFs, initial investment costs of recovery plants, lack of awareness amongst the different stakeholders involved, lack of product-safety guarantee and other product information, and unavailability of suitable application techniques. These barriers need to be overcome to attain a larger market for RDFs and the first step is to provide an inventory report on existing nutrient recovery techniques.
ReNu2Farm is an Interreg North West Europe (NWE) project that focusses on nutrient recycling and upscaling from pilot level to farms and fields. Its priority specific objective is to optimise the reuse of material and natural resources in NWE. One of the project tasks is to deliver an inventory report that represents an actualization on the progress of market-ready techniques, building on previous benchmark reports published under projects like ARBOR and BIOREFINE. The report at first briefly describes the three main biomass streams of focus for ReNu2Farm, and secondly elaborates on biomass processing and nutrient recovery processes.