TY  - JOUR
A1  - Richter, L.
A1  - Wichern, M.
A1  - Grömping, Markus
A1  - Robecke, U.
A1  - Haberkamp, J.
T1  - Ammonium recovery from process water of digested sludge dewatering by membrane contactors
JF  - Water Practice and Technology
N2  - Membrane contactors are a promising alternative for nitrogen removal and recovery from process water compared to other physicochemical and biological sidestream treatment processes. Münster wastewater treatment plant (WWTP) is the first municipal WWTP in Germany operating a full-scale membrane contactor system to improve the nitrogen elimination and recovery efficiency. Factors influencing the operation and membrane performance are investigated in an accompanying research project. Additional operational aspects of the applied membrane modules are investigated in detail using a bench-scale membrane contactor. First results of the full-scale application demonstrate a high nitrogen removal efficiency of >95%.
Y1  - 2020
U6  - https://doi.org/10.2166/wpt.2020.002
SN  - 1751-231X
VL  - 15
IS  - 1
SP  - 84
EP  - 91
PB  - IWA Publishing
CY  - London
ER  - 
TY  - JOUR
A1  - Schopen, Oliver
A1  - Narayan, Sriram
A1  - Beckmann, Marvin
A1  - Najmi, Aezid-Ul-Hassan
A1  - Esch, Thomas
A1  - Shabani, Bahman
T1  - An EIS approach to quantify the effects of inlet air relative humidity on the performance of proton exchange membrane fuel cells: a pathway to developing a novel fault diagnostic method
JF  - International Journal of Hydrogen Energy
N2  - In this work, the effect of low air relative humidity on the operation of a polymer electrolyte membrane fuel cell is investigated. An innovative method through performing in situ electrochemical impedance spectroscopy is utilised to quantify the effect of inlet air relative humidity at the cathode side on internal ionic resistances and output voltage of the fuel cell. In addition, algorithms are developed to analyse the electrochemical characteristics of the fuel cell. For the specific fuel cell stack used in this study, the membrane resistance drops by over 39 % and the cathode side charge transfer resistance decreases by 23 % after increasing the humidity from 30 % to 85 %, while the results of static operation also show an increase of ∼2.2 % in the voltage output after increasing the relative humidity from 30 % to 85 %. In dynamic operation, visible drying effects occur at < 50 % relative humidity, whereby the increase of the air side stoichiometry increases the drying effects. Furthermore, other parameters, such as hydrogen humidification, internal stack structure, and operating parameters like stoichiometry, pressure, and temperature affect the overall water balance. Therefore, the optimal humidification range must be determined by considering all these parameters to maximise the fuel cell performance and durability. The results of this study are used to develop a health management system to ensure sufficient humidification by continuously monitoring the fuel cell polarisation data and electrochemical impedance spectroscopy indicators.
KW  - PEM fuel cell
KW  - Electrochemical impedance spectroscopy
KW  - Relative air humidity
KW  - Active humidity control
KW  - Impedance analysis
Y1  - 2024
SN  - 0360-3199 (print)
U6  - https://doi.org/10.1016/j.ijhydene.2024.01.218
SN  - 1879-3487 (online)
VL  - 58
IS  - 8
SP  - 1302
EP  - 1315
PB  - Elsevier
CY  - Amsterdam
ER  -