(289b) Transient Behavior of Dead-End Filtration at Low Solids Concentration

The Hanford Site’s Direct Feed Low-Activity Waste process performs a pretreatment step prior to planned vitrification in the Low-Activity Waste (LAW) Facility at the Hanford Waste Treatment and Immobilization Plant. The pretreatment is performed by the Tank Side Cesium Removal (TSCR) system, which prepares LAW for vitrification by removing solids and cesium-137. The solid removal step is conducted by dead-end filtration are operated in parallel: one is actively processing while the other is flushed and put on standby. Thus, the filters periodically restart from a flushed state when the system swaps between them.

Significant transient behavior has not been observed in the deployed TSCR system to date; however, test data collected at multiple scales using the same filter media Time dependence manifests as pressure drop increases required to maintain the target throughput, and in some cases, this occurs shortly after filtration begins. In the future, the TSCR filters may experience feeds with enough solids to experience some transience and anticipating/understanding the behavior would be helpful to guide operations. To that end, test data sets collected with actual and simulated waste are used to investigate fluid and operating parameters that affect transient behavior and examine the impact of filter configuration and scale.