PNNL

Abstract

The present experimental work was performed in order to investigate media performance in both cross-flow and dead-end filtration on 9 L of Hanford tank AP-107 supernatant. Media grades 0.1 and 5 were tested for each the cross-flow filter (CFF) and dead-end filter (DEF). The CFFs were tested in the cells unit filter (CUF) system in recycle mode and the DEFs (in-line and disc) were used to dewater the feed. Visual inspection of the feed material indicated essentially no settled insoluble solids in the feed material. The 5 micron grade cross flow filter produced stable filter fluxes while the flux for the 0.1 micron grade material steadily decayed. The 5 media grade BDEF (backpulsed dead-end filter) was effective at removing solids from the AP-107 feed and when backpulsed, fully restored the filter flux, indicating that the solids did not irreversibly foul the filter. The 0.1 media grade DEF was used to filter the final 2 liters of AP-107 feed drained from the CUF and collect solids on the filter media. Additional DEF filtering was performed on 4 L of BDEF permeate in order to assess whether small particles that cause fouling in the 0.1 media grade filter passed through the 5 media grade filter. There was no indication of fouling and limited solids were observed on the filter. A direct comparison of filtration rates between the 0.1 and 5 media grade filters for both the CFF and DEF showed the 5 media grade filter flux was, on average, 200 times higher than the 0.1 media grade filter while still effectively filtering the solids.