Phosphorus recovery from sewage sludge by nanofiltration in diafiltration mode

Abstract

Phosphorus containing mineral fertilizers are frequently used in agriculture. The global resources of phosphorus rock are limited, which makes the use of alternative phosphorus sources increasingly promising. In this work, a process for phosphorus recovery from sewage sludge was studied. The focus lies on a nanofiltration process for the removal of metals and heavy metals from the product stream. In all cases, it was shown that metals were almost entirely retained by the membrane, while phosphorus permeated to a high degree. The phosphorus yield could be improved significantly by approaching diafiltration conditions.