Hollow Fiber Membrane Contactors (HFMC) were evaluated at bench-scale to recover the remaining ammonia from the anaerobic membrane bioreactor permeate.
The technology works as follows: the ammonia rich effluent and an acid solution (is this case a sulphuric acid solution) are recirculated through the membrane contactor. The ammonia passes through the hydrophobic membrane from the ammonia rich effluent to the acid solution, and reacts there to form ammonium salts. Ammonium salts are a valuable product as they can be applied as fertilizers for the agriculture.
The experiments were performed in batch and with two types of effluents coming from the previous treatment step:
- Permeate coming from the anaerobic membrane bioreactor (AnMBR) treating liquid digestate from the organic fraction of municipal solid waste (OFMSW) from Ecoparc 2 and
- Permeate coming the AnMBR treating a mixture of 50% of liquid digestate from OFMSW and 50% landfill leachate
The ammonia removal/recovery rate obtained with membrane contactors was high for both types of effluents (>99%), but membrane fouling and scaling decreased the ammonia mass transfer coefficient by around 35% after two removal cycles in batch mode. pH adjustment to 12 before experiments promotes the precipitation of compounds, thus increasing fouling and scaling phenomena. The membrane contactor pilot that is currently under construction will include a filtration pre-treatment in order to remove suspended solids and colloidal matter after pH adjustment to protect the membrane contactors from fouling and scaling.
Further progress is expected during next weeks. Don’t forget to visit the project website, social media and subscribe to the project newsletter to be aware of the last updates of the project.
