Recovering Phosphorus from Wastewater

May 2019

Phosphorus is essential for plant growth and food production, but reserves of the raw material are limited – and demand is rising. At present, Germany imports all the phosphorus it needs, including the roughly 170,000 tons spread on fields each year as fertilizer.

However, the German government has stipulated that beginning in 2029 phosphorus must be recovered from wastewater and fed back into the economic cycle. For example, treatment plants for population equivalents greater than 100,000 will have to do so beginning in 2029, and those for population equivalents greater than 50,000 beginning in 2032. And the first municipal disposal company to do so will be that of the city-state of Hamburg. On March 1, the foundation stone was laid for a unique phosphorous recycling plant. It will use the so-called TetraPhos process to economically and efficiently recover up to 7,000 tons of high-purity phosphoric acid each year from sewage sludge ash when it enters operations in 2020.

The plant is being built by the water company Hamburg Wasser and the recycling service provider Remondis as part of a project being funded by the Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU). “Building the phosphorus recycling plant is an important project for Hamburg as a seat of innovation,” said Hamburg Mayor Dr. Peter Tschentscher. “The recovery process reduces environmental pollution and makes a valuable raw material available again.”

Phosphorus sulphide molecule model © Pixabay/ Wikimedialmages