Layer-by-layer modification of membranes for resource recovery

Remmen, Kirsten Maria; Wessling, Matthias (Thesis advisor); Sudhölter, Ernst (Thesis advisor); Wintgens, Thomas Josef (Thesis advisor)

Aachen (2019, 2020)
Dissertation / PhD Thesis


Phosphorus (P) is a critical raw material with finite availability. Despite the clear need for phosphorus recovery from waste sources such as sewage sludge, most currently available recovery processes are not yet economically feasible. In this thesis, novel Layer-by-Layer (LbL) nanofiltration membranes are applied to recover phosphorus from sewage sludge ash leached by acids. An optimization of LbL membranes is performed to achieve superior phosphorus yields and permeabilities compared to conventional membranes, leading to a more environmentally friendly and economically feasible process. The performance of the membranes are tuned to achieve desired retention values by adapting the coating procedure and used materials. Initial stability tests and upscaling into larger membrane modules demonstrate the viability of the modification approach. The application of Layer-by-Layer membranes in an acidic environment is extended to pickling acid purification and the recovery of rare earth elements from hydrochloric acid, demonstrating the versatility of Layer-by-Layer membranes.