Geocycle and Holcim Start Pilot Project to Recover Phosphorus From Sewage Sludge

Geocycle and the LafargeHolcim innovation center in Lyon (F) are working together on various approaches to remove phosphorus from sewage sludge. By 2022, Geocycle will use more than 170,000 tons of dried sewage sludge at European cement plants.

An industrial pilot project for phosphorus recovery from sewage sludge is being developed in close cooperation with Holcim cement plant in Untervaz, Switzerland. The first pilot tests are planned for spring 2021.

There are two main processes for recovering phosphorus from sewage sludge: the thermal and the wet phase process. In Untervaz, the team is working on the development of the thermal process in which the dry sewage sludge is gasified at 1000 °C. Biomass is chemically converted into energy-rich syngas and separated from phosphorus, which precipitates with the ash.

While syngas replaces traditional fuels in cement production and thus cuts CO₂ emissions, phosphorus ash produced in the process can be used as a fertilizer. The phosphorus contained in Swiss sewage sludge could replace 60 % of the imported phosphorus. Geocycle and Holcim are working flat out to offer Geocycle customers a sustainable solution so that they can comply with the Swiss ordinance on phosphorus recovery by 2026.