Published on March 05, 2024
Pilot plant for phosphorus recovery
In order to meet the goals of sustainable environmental and resource protection more effectively than before, cities and municipalities will have to recover the vital raw material phosphorus from sewage sludge in future. With this obligation introduced by the German government, sewage treatment plant operators are under pressure to implement a concept for phosphorus recovery by 2023 and its realization by 2029. In addition to phosphorus recovery from wastewater treatment plants, nutrient removal from agricultural wastewater streams in connection with soil and groundwater protection is another important task in sustainable environmental and resource protection. Farm fertilizers in particular, such as liquid manure, slurry, manure, bark mulch and fermentation residues, have high nutrient contents, which have led to restrictions in their application in recent years. Nutrient removal from farm manure enables greater application of the available farm manure and also produces a storable fertilizer product.
Open framework for action
The German government's "Sewage Sludge Ordinance" does not describe a mandatory procedure for phosphorus recovery and therefore leaves room for the use or development of innovative technologies. One possibility is the P-Roc process (Phosphorus Recovery by Crystallization) developed and patented at KIT, with which the Competence Centre for Material Moisture (CMM) has been active in research and application since 2006. The CMM is based at the Institute of Concrete Structures and Building Materials (IMB) at KIT. To date, the researchers have gained extensive experience in dealing with various types of wastewater, for example from the food industry, sewage treatment plants and agriculture.
Leading by example
In order to support wastewater treatment plant operators in implementing the legislative obligation, the cooperation partners in the project will jointly commission a pilot plant. In addition to reliable upscaling for continuous operation, the mobile pilot plant also offers the opportunity to serve as a demonstration plant for interested sewage treatment plant and biogas plant operators. In the project, CMM is responsible for monitoring the construction, the preliminary tests on a laboratory scale to determine the necessary operating resources and the operation of the pilot plant. Geltz is supplying the pilot plant, instructing the personnel and providing support for conversions and retrofits. ISU mbH is responsible for project management and reporting and is involved in discussions on achieving the benchmarks and any necessary process engineering modifications. The Institute for Meteorology and Climate Research – Atmospheric Aerosol Research (IMK-AAF) at KIT provides administrative support for the project.
From plant engineering to granulate
In spring 2024, the dimensions of the pilot plant will be determined and construction will begin. The pilot plant will then be used at a bio-digestion plant in Hesse to remove nutrients from the fermentation residue liquid produced during the dewatering of the fermentation residue so that more fermentation residue liquid can be spread and a storable mineral fertilizer can be produced at the same time. The production of a mineral fertilizer in granulate form saves storage capacity at the plant, as less digestate liquid has to be stored. An application in the municipal wastewater sector, in which a municipality in the district of Aschaffenburg has expressed interest, is planned for fall 2024 in order to treat the sludge water from the dewatering of the digested sludge. With upstream sewage sludge disintegration, the nutrients can be converted into a soluble form and thus be available for subsequent recovery using the P-RoC process. For KIT and its cooperation partners, the construction of the pilot plant is an example of the successful transfer of research into application.
comments about this article
No comments