Open Positions

The effort for phosphorus (P) recovery from sewage sludge is high, because phosphorus is transferred within the wastewater treatment into the sewage sludge mostly by precipitation with iron or aluminum salts to protect the receiving water and needs to be recovered subsequently from the sewage sludge in a multi-stage process. This process starts with the dissolution of phosphorus bound in the sewage sludge, subsequent complexation or precipitation of interfering ions like iron and renewed precipitation and crystallisation of the phosphorus in form of plant-available fertilizer.

Influences on these phosphorus precipitation and recovery steps are manifold. Technologies used for P-elimination as well as the type and composition of the sewage sludge have a significant influence on the P-recovery steps. The precipitation and crystallisation of struvite as a possible product of P-recovery depends on numerous factors, such as the pH value of the solution, the saturation, the molar ratios of various ions, the stirring speed, the temperature and the presence of foreign ions. Yet these influences are not clearly understood. 

Thus the most important scientific questions of this PhD project will be:

-  Which boundary conditions in the real wastewater system influence the efficiency of phosphorus recovery and the product quality?
-  Which steps in the process chain determine the recovery rate and product composition most strongly?
-  What are the interdependencies between phosphorus elimination, sludge treatment and phosphorus recovery?
-  How can suitable conditions be set in the operation of a sewage treatment plants to reach high phosphorus recovery with high product quality while minimising the use of chemicals? 
-  Can generally valid statements on the behaviour of complex wastewater treatment systems be derived from these investigations? 
-  What differences are there to highly simplified systems?

Requirements for applicants:

-  Excellent Master degree (M.Sc.) in civil  or environmental engineering or related subjects
-  Knowledge of wastewater treatment and sludge treatment
-  A goal-oriented way of working and a high degree of creativity, initiative and proactivity 
-  Interest in complex and interdisciplinary issues
-  In-depth academic English experience and willingness to learn German (for non-German speaking persons)

Application:

You can send applications for this topic to Prof. Dr.-Ing. Heidrun Steinmetz: heidrun.steinmetz[at]rptu.de