Exploring the potential for ammonia recovery from wastewater with bipolar membrane electrodialysis
Project lead
Dr Sebastien Allard, sebastien.allard@csiro.au
Lead researchers
Sebastien Allard
Ruth Dominguez
Challenge
Ammonia (NH3) has recently been recognised as a suitable renewable energy carrier.
Ammonia can be found in wastewater due to the decomposition of nitrogenous organic matter from sewage and farmland drainage. Recovering NH3 from wastewater is potentially more energy efficient than conventional NH3 production using the Haber-Bosch process. It is also more energy efficient to produce hydrogen from NH3 than by water electrolysis.
What we are doing
This project will evaluate the technical feasibility of recovering NH3 from wastewater using bipolar membrane electrodialysis (BPMED), and determine the achievable NH3 recovery and energy efficiencies.
A proof-of-concept BPMED prototype allowing efficient recovery of NH3 from a wastewater treatment stream was developed.
Bipolar membrane electrodialysis (BPMED) stack design
We will evaluate the effects of different process parameters and BPMED configurations on the efficiency of NH3 recovery and a range of pre-treatment options (e.g. biogas sparging, struvite precipitation, membrane filtration unit) to reduce fouling on the membranes based on the wastewater quality. We will also thoroughly assess the energy efficiency of the process.
Recovering ammonia from wastewater could have the following impacts:
- contribute to making wastewater treatment operations energy self-sufficient and thus potentially reduce wastewater treatment costs.
- help to establish a sustainable NH3/H2 energy industry based on circular economy principles.
- improve national fuel security from fuel recovered from local waste streams.
- reduce greenhouse gas emissions (N2O) as compared to removing NH3 through aerobic NH3 oxidation and anoxic denitrification.
- provide NH3 for transport fuel for car or trucks used by water treatment operators, or as a chemical feedstock, contributing to green-house gas reduction.
- improve the quality of treated wastewater effluent through effective NH3 recovery from wastewater.
Outcomes to date
Initial results indicate that BPMED allows ammonium to be removed from water and to simultaneously produce concentrated dissolved NH3 (ammonium hydroxide), without using chemicals, only electricity. BPMED was found to be a reliable technology with 85 to 91% nitrogen recovery. However, wastewater typically has high levels of inorganic anions and cations (calcium, magnesium, bicarbonate and phosphate) and organics; as a result, there is potentially a serious risk of membrane fouling and decreased separation efficiency as well as reduced membrane life. Further research is currently being undertaken to investigate these issues.
Lessons learned
The lab scale unit was successfully developed and proved to be efficient in recovering NH3. Upscaling will present new challenges and more possibilities for potential industrial applications.
Project finish date
August 2025