The Lippeverband together with the Emschergenossenschaft as German waterboards treat waste water from about 3.6 Mio. people in the Emscher-Lippe-Region. The sewage sludge evolving at the 59 waste water treatment plants mostly gets incinerated. Two incineration plants in Bottrop and Lünen produce about 66.000 t sewage sludge ashes. This offers great opportunities to recover Phosphorus from these ashes.
To find the best technology provider the Lippeverband organized a European tendering procedure. In this, REMONDIS Aqua convinced with its TetraPhos® process. This process recovers the Phosphorus contained in sewage sludge ashes by chemical leaching and subsequent purification. Final product is a high quality phosphoric acid (brandname REPACID®). During the process, by products evolve: metal salts can be used as precipitants for P elimination on waste water treatment plants; ash residue and gypsum can be used by the building materials industry.
In the framework of Phos4You it was investigated if the TetraPhos® process is suitable to recover P from the sewage sludge ashes in the Emscher-Lippe-Region. These ashes have a relatively low P load (below 6% P). After adaptation to the characteristics of the Emscher-Lippe-ashes, the TetraPhos® process showed good results: At the REMONDIS Aqua pilot plant in Werdohl-Elverlingsen, stable operation of the process and achievement of Phosphorus recycling rates constantly exceeding 85% was demonstrated for a prolonged period of time.
This is very promising for the involved water boards. Next steps will be working on the economic efficiency with rising the P load of the ashes to some percentage points.
Read more about the P recovery technologies in the Phos4You factsheets, see section "project documents".
Below: The REMONDIS Tetraphos® Demonstrator, copyright: REMONDIS Aqua