Electro-osmotic membrane dewatering of biomass

The transition to bio-based materials and energy is essential to tackle climate change and reduce our reliance on fossil fuels. Industrial and academic efforts have paved the way for this transition, finding new ways to extract useful chemicals from the abundantly available and renewable biomass. However the moisture-rich biomass needs to undergo dewatering and drying as part of its processing cycle. Not only are these processes energy intensive, accounting for 15-25% of all energy used in the processing industry; they usually rely on fossil fuel enabled thermal dewatering. Reliance on inefficient and unsustainable unit operations hinders our ability to move towards a carbon-neutral process industry.

Over the years several alternative techniques have been utilized to dewater biomass process streams. Membrane dewatering is one such technique that has gained lots of traction in the last two decades as a sustainable alternative to thermal dewatering. Membrane dewatering of biomass usually relies on pressure and concentration gradient to separate the aqueous media from the dispersed biomass particles. However the non-selective nature of these driving forces can lead to membrane fouling, reducing its efficiency over long-term operations. Furthermore, membrane dewatering is suitable for diluted slurries and is ineffective for concentrated biomass slurries. These inefficiencies in membrane dewatering of biomass slurries force us to identify selective driving forces that can dewater and concentrate biomass more efficiently.

Solid particles dispersed in aqueous medium are known to have electrochemical interactions at the interface. Depending on the pH of the media, the solid particles develop surface charges of either a positive or negative nature. This induces the formation of an electric double layer (EDL) at the interface creating opposing charges at the surface and the surrounding aqueous media. Upon superimposing an electric field, we can selectively migrate the two phases in opposite directions, thereby separating the particles from the aqueous medium. The migration of charged particles is referred to electrophoresis, whereas migration of water relative to the stationary solid particles is referred to as electro-osmosis. The electro-osmotic phenomena is applicable to any system with distinct phases and an EDL formation at interphases, such as a wet membranes or a semi-dilute biomass slurry. In this project, we intend on identifying and characterizing the necessary process parameters that are essential to dewater semi diluted biomass streams using electro-osmosis.