The ALI residue created in bioreactors is known to be a cleaning challenge during cleaning activities. Bioreactors have a long incubation time (e.g., 3-10 days) and a high packed cell volume (PCV), which contributes to the residue buildup at the ALI and often represents a more difficult cleaning challenge than the bioreactor bulk liquid soil, i.e., bioreactor vessel surfaces that are submerged in soil during production. Therefore, any chemistry shown to be more effective at removing the bulk liquid bioreactor soil should be confirmed as also effective at removing the ALI residue.

The Hyde Analytical Laboratory was contracted to determine the effectiveness of using additives with the client’s current caustic cleaning agent when cleaning bioreactor residual soil. The evaluation was performed by assessing the cleanability of two soil types from the bioreactor: 1) directly spiking bioreactor liquid soil onto a coupon, which represents bioreactor vessel surfaces that are submerged in soil during production; and 2) ALI residue, which was provided for the study via client-provided baffles from a pilot-scale bioreactor that had the ALI residue present on the surface of the baffle.

Due to a limited number of replicates, i.e., baffles, with the ALI residue, initial screening of additive efficacy was first performed on the bulk bioreactor soil in form of spiking liquid soil onto a coupon. This provided directional data as to which additive would likely be more effective in removing the ALI residue. Additionally, it provided a comparison of cleaning challenge for the bulk bioreactor soil and ALI residue to determine if the ALI residue truly represents a greater cleaning challenge for this bioreactor process.