Maximizing the Potential of Electrodeionization: The Separative Bioreactor

Electrodeionization (EDI) is a separative process that is normally associated with the production of ultrapure water for the pharmaceutical and semiconductor industries due to its effectiveness in removing salts and other impurities from dilute aqueous streams. The process is usually carried out in a flow through system, often termed the EDI "stack." In these stacks, ion-exchange resins (formed of beads, like fine sand) are sandwiched between special membranes that enable the removal of charged particles via an applied electric field. Due to the fineness and fluidity of the resin beads, sealing the stack is very difficult and leakage, where the removed impurities recontaminate the purified stream, often occurs. This phenomenon has also limited the number of applications that EDI could be used for.

Argonne researchers set out to solve this problem and have developed a series of semi-rigid resin wafers that can be manufactured with different shapes, sizes and constituents. In effect - a customizable resin wafer can be designed, produced and used in an EDI stack without the usual leaking and sealing problems.

This development has allowed the Argonne researchers to combine the effectiveness of EDI contaminant removal with chemistry. For example, the novel EDI stack can be used to directly synthesize an organic ester from a lower alcohol and an organic acid. Another type of EDI stack can be used to concentrate and separate organic acids directly, without the need for neutralization.

Coupled with a bacterial strain producing a substance of interest, the new EDI stack provides a one-step process of product production and product capture. For example as the bacteria continue to grow, the growth media can be fed into the EDI stack for the removal of the product and the growth media can be recycled. This is particularly important if the substance being produced is toxic or inhibitory to the bacterial cells producing the product

The fact that this technology allows both the continuous bio-production and collection of a desired product has earned the technology its unique name, the Separative Bioreactor.

Patents and Published Patent Applications

Additional Information

Technology Fact Sheet (pdf)