Positive Energy WasteWater Treatment by Anaerobic Membrane Bioreactor – BaMAn

BàMAn is a project of applied research which global objective is to prove that the original coupling of G-AnMBR and Degassing Membrane makes possible a positive energy DWWT. Objectives also involved building a base of fundamental knowledge of this innovative technology with a better understanding of membrane fouling and transfer mechanisms in order to optimize this new AnMBR process.

We confirm that Anaerobic Membrane Bioreactors (AnMBRs) can:
• Retain anaerobes bacteria completely (Hydraulic and Solid Retention Time (HRT and SRT) are uncoupled in AnMBR) and work with high loading capacity,
• Produce excellent permeate qualities (in terms of suspended solids, organic matter and microorganisms) thanks to ultrafiltration (UF) membranes,
• Keep the content of nutrients of the influent available for its recovery or direct reuse.
• Recover energy content of organic matter in form of methane, suitable for being used as source of energy, e.g. heat and electricity.
• Reduce Green House Gas (GHG) emissions by saving energy consumption and producing CH4 suitable for being used as energy source,
The scientific program was designed so as to find answer to the following scientific locks:
• What are the key operating conditions and parameters in AnGS activities and G-AnMBR fouling mitigation?
Temperature and loading rate are key parameter for AnGS methane production
G-AnMBR fouling is difficult to mitigate thanks to granular fluidization because of the high energy needed to fluidize the granular material
• Does AnGS have the potential to ensure satisfactory methane production from DWW in psychrophilic temperatures?
Yes. We habe observed really important methane production in our lab-scale units, even at 25°C, thanks to a sufficient period of acclimatization.
• Can membrane degassing recover the totality of dissolved methane?
95 to 97% of dissolved methane could be removed from the AnMBR permeate thanks to membrane degassing unit.

• WP4 “Coupling G-AnMBR with degassing membrane for continuous process operation and optimization” is a 20-months task dedicated to the demonstration of the combined processes at lab-scale (definition of optimum operation strategies for DWWT). The results of WP1, 2 and 3 have been used to define the optimal operating conditions tested in this WP. The pilot-scale unit has been designed and manufactured in IEM. The effect of the hybrid process on the improvement of the net biogas production is under investigation. Influence of operating conditions applied to the G-AnMBR on the membrane fouling and production of gaseous methane and recovery of dissolved methane is studied. The global synergetic efficiency of the combined process will be optimized in order to integrate appropriately the two operations in the treatment line depending on the feeding conditions.
• WP 5 “Energy balance, Life Cycle Assessment and Cost/Benefit Analysis” goal is to prove the sustainability, feasibility and energetic efficiency of G-AnMBR combined to degassing membrane to boost carbon recycling into energy. Energy balance, Life cycle assessment and Cost/benefits analysis will be conducted in collaboration with a specialized research team (Ligia Barna, LISBP, INSA Toulouse) with data obtained from BàMAn lab-scale experiments and modelling (WPs 1, 2, 3 and 4).

• Anjum, F., Khan, I. M., Kim, J., Aslam, M., Blandin, G., Heran, M., & Lesage, G. (2020). Trends and progress in AnMBR for domestic wastewater treatment and their impacts on process efficiency and membrane fouling. Environmental Technology & Innovation, 101204. doi.org/10.1016/j.eti.2020.101204

• Heran Marc, Lesage Geoffroy, Zaviska François. Membranes et procédés biologiques : de la STEP vers la STAtion de Récupération des Ressources des eaux usées. Francofilt 22 au 25 /09/2019. Hammammet. Tunisia.

Nowadays, water scarcity and quality are big challenges facing humanity in many places around the world. In order to adequately respond to this growing problem, new ways of domestic wastewater (DWW) management can be open up. Indeed, by applying appropriate treatment, DWW can be an alternative resource of water, energy and nutrients. Wastewater Treatment Plants (WWTPs) have even been rebranded as Water Resource Recovery Facilities (WRRFs) to recognize and reinforce the significant resource recovery potential that exists in wastewater streams.
In this regards, anaerobic digestion process is proving to be a sustainable solution to DWW management by transforming organic carbon into biogas (methane) which could be used as an energy source.
Since this last decade, anaerobic membrane bioreactors (AnMBRs) have gained particular interest for mainstream treatment of municipal wastewater. This is mainly due to its competitive advantages compared to conventional anaerobic treatment systems and aerobic MBRs (i.e., bioenergy production, quality effluent, low sludge disposal, high loading capacity, nutrient recovery, footprint efficiency, lower energy requirements, possibility of co-treating food waste and decentralized operation) (Galib et al., 2016; Pretel et al., 2016).
However, membrane fouling has remained as one of the most challenging issues impeding the progress of AnMBRs (Saleem et al., 2016), especially when high biomass concentration is used. Moreover, although well designed anaerobic Membrane Bioreactors (AnMBRs) are able to effectively treat DWW at psychrophilic temperatures (10–30 °C), lower temperatures increase methane solubility leading to lower net energy production.
Thus, innovative fouling control, optimization of biogas production as well as recovery methods for dissolved methane need to be investigated to develop more efficient and sustainable AnMBRs.
• Granular anaerobic membrane bioreactor (G-AnMBR), a hybrid anaerobic biotechnology that incorporates the granular technology with membrane based separation offer promising approach to the conventional AnMBR in terms of fouling mitigation (Chen et al., 2016).
• Degassing membrane module used for degasification of the mixed liquor is a promising technology for improving methane recovery of the AnMBR process for treating low-strength wastewater at low temperature (Luo et al., 2014; Bandara et al., 2011 and 2012).
This project is based on the combination of Granular Anaerobic Membrane Bioreactor (G-AnMBR) with degassing membrane to achieve the development of a neutral or even positive energy domestic wastewater treatment while increasing efficiency of the global process in term of treated water productivity and quality.
BàMAn is a project of applied research which global objective is to build a base of fundamental knowledge pertaining to the coupling of degassing membrane and G-AnMBR and better understand membrane fouling and transfer mechanisms for optimizing the AnMBR process and prove that this technology makes possible a positive energy wastewater treatment.
The advances of BàMAn would be: (1) the development of a first French expertise on G-AnMBR combined to membrane degassing; (2) fundamental understanding of fouling reduction mechanisms in G-AnMBR and biogas recovery optimization; (3) combining mass transfer and biological mechanisms with fouling models in the G-AnMBR/membrane degassing system; (4) prove the potential of positive energy wastewater treatment by performing an energetic analysis, a life cycle assessment and a cost/benefit analysis.