Phosphorus is indispensable for agriculture and industry, yet it is a scarce, strategically critical raw material. Europe has hardly any natural phosphate deposits of its own and is almost entirely dependent on imports. This dependency involves significant risks: geopolitical uncertainties, strong price fluctuations and quality issues caused by contaminated imported phosphates. Against this background, the recovery of phosphorus from domestic secondary resources is becoming increasingly important.
This is exactly where the LeachPhos process, developed and patented by AIK Technik AG, comes into play. It enables the efficient recovery of phosphorus from sewage sludge ash from mono-incineration plants – a material stream with typical phosphorus contents of around 8 percent. LeachPhos is a practical example of urban mining and a functioning circular economy.
The wet-chemical process is based on targeted acid leaching of the ash under moderate, stable process conditions. Extraction rates of over 80 percent can be achieved. In the final recovery stage, a fine, light-colored phosphate product with excellent plant availability is produced, which can be used directly as fertilizer or as an intermediate product for industrial applications. Approximately 50 to 70 kilograms of phosphorus can be recovered from one metric ton of sewage sludge ash.
The technical maturity of the process was demonstrated early on under real conditions. As early as 2013, AIK Technik AG successfully operated a pilot plant in Bern operated over an extended period, treating up to 300 kilograms (660 lbs) of sewage sludge ash per hour. The insights gained were incorporated directly into the further development of the LeachPhos process.
A particular advantage of LeachPhos is its technical simplicity. It deliberately avoids high-temperature processes and complex specialized equipment, relying instead on robust, proven industrial components. This significantly reduces investment and operating costs, making LeachPhos a particularly attractive economic proposition compared to thermochemical alternatives. Furthermore, modular integration of the process into existing plants and efficient continued use of existing infrastructure are possible.
With LeachPhos, AIK Technik AG demonstrates how technical expertise, economic efficiency, and environmental responsibility can be successfully combined, making a decisive contribution to the long-term securing of one of the most important raw materials of our time.
