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The painting “The Alchemist in Search of the Philosopher's Stone” (1771) by Joseph Wright of Derby depicts the discovery of the element phosphorus by German alchemist Hennig Brand in 1669. Source: Wikipedia (Public Domain)
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Phosphorus Recycling from Sewage
Scientists at the KIT have further developed a process to regain phosphorus from sewage. A pilot plant now has taken up operation at the sewage plant of the city of Neuburg in Bavaria.
Phosphorus is a vital element in the energy metabolism not only of plants but also of animals and humans. The easily exploitable phosphorus deposits will last for approximately another 100 years only and the stock exchange prices have already considerably increased over the past few years. Therefore, it is interesting not only from an environmental point of view but also commercially rewarding to develop new recycling processes. The aim is to extract part of the phosphorus from sewage and to generate a raw phosphate substitute as a reuseable product. To this end, KIT researchers from the Competence Centre for Material Moisture (CMM) headed by Dr Rainer Schuhmann refined the P-RoC process (Phosphorus Recovery from Wastewater and Process Water by Crystallisation). With this procedure, phosphate dissolved in the wastewater phase can be recovered as a phosphorus-containing product via crystallisation on calcium-silicate-hydrate phases (CSH). "This simple and effective principle", explains Schuhmann, "produces a product that can be absorbed by plants and, for instance, can be used directly as a fertilizer without any further processing." The companies Cirkel GmbH & Co. KG in Rheine and the HeidelbergCement AG are cooperation partners in this project. The pilot phase in Neuburg can be finalised in about half a year. Subsequently, the efficiency and economic viability of the P-RoC process will be assessed. "Then we will know, whether 20, 30 or an even greater percentage of the approximately 30 tonnes of phosphorus accruing each year can be recovered from the Neuburg sewage", says Schuhmann.
