Motivation of phosphorus recovery in sewage treatment plants:
This is how CalPrex® works:
A mesophilic anaerobic pre-acidification prior to digestion allows a good return of the phosphate. In the centrate, which contains soluble phosphates, the precipitation of the phosphate as brushite takes place under slightly acidic conditions and addition of Ca (OH)2.
After the brushite removal the reacted centrate is recombined with cake and sent to the methane digester or, if available, to a hydrolysis process.
Benefits of CalPrex® process: