Transition from pore fouling to cake filtration in high level waste dead end filtration

ABSTRACT

Treatment of radioactive waste at the Hanford site is dependent upon dead end filtration to prepare feed for ion exchange. Recent testing has indicated that the filter media that will be deployed for this treatment process is susceptible to depth fouling. A model was developed to understand the transition from pore fouling to cake filtration to provide insight into the planned operations of this facility. These results indicate that an initial transition takes place during which the filter is depth fouled. However, after the majority of the pores have been plugged the filter flux is governed by cake filtration on the surface of the fouled filter.

Graphical abstract

KEYWORDS:

• Dead end filtration
• filter fouling
• hanford tank waste
• depth fouling
• cake filtration

Disclosure statement

No potential conflict of interest was reported by the author(s).

Nomenclature

A available filter surface area (m²)

A₀initial filter surface area (m²)

DP pressure differential (Pa)

K_{c c}ake filtration resistance coefficient (s/m⁶)

K_{i r}esistance coefficient (m⁻³)

Q volumetric flow rate (m³/s)

Q_{B v}olumetric flow rate through the blocked filter media (m³/s)

Q_{cake v}olumetric flow rate through the filter cake (m³/s)

Q₀initial volumetric flow rate (m³/s)

R_{B r}esistance of the blocked filter media (m-1)

R_{m r}esistance of membrane (m⁻¹)

t time (s)

V volume filtered (m3)

V_{cake v}olume filtered through the blocked pores (m³)

Greek Letters

β blocking law exponent

μ viscosity (Pa s)

σ pore blocking parameter (m⁻¹)

Highlights

1. The 5-micron grade filter is susceptible to depth fouling during radioactive waste filtration.

2. A slow transition from depth fouling to cake filtration is observed with radioactive tank waste.

3. Cake that is formed is not susceptible to compression over current operating conditions.

4. Simulant testing was able to recreate fouling transition.

Notes

¹ The filter was cut approximately in half and a new non-porous end cap was welded on. The weld was inspected and approved prior to use.

Additional information

Funding

This work was supported by the