skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: PERFORMANCE IMPROVEMENT OF CROSS-FLOW FILTRATION FOR HIGH LEVEL WASTE TREATMENT

Abstract

In the interest of accelerating waste treatment processing, the DOE has funded studies to better understand filtration with the goal of improving filter fluxes in existing cross-flow equipment. The Savannah River National Laboratory (SRNL) was included in those studies, with a focus on start-up techniques, filter cake development, the application of filter aids (cake forming solid precoats), and body feeds (flux enhancing polymers). This paper discusses the progress of those filter studies. Cross-flow filtration is a key process step in many operating and planned waste treatment facilities to separate undissolved solids from supernate slurries. This separation technology generally has the advantage of self-cleaning through the action of wall shear stress created by the flow of waste slurry through the filter tubes. However, the ability of filter wall self-cleaning depends on the slurry being filtered. Many of the alkaline radioactive wastes are extremely challenging to filtration, e.g., those containing compounds of aluminum and iron, which have particles whose size and morphology reduce permeability. Unfortunately, low filter flux can be a bottleneck in waste processing facilities such as the Savannah River Modular Caustic Side Solvent Extraction Unit and the Hanford Waste Treatment Plant. Any improvement to the filtration rate would lead directlymore » to increased throughput of the entire process. To date increased rates are generally realized by either increasing the cross-flow filter axial flowrate, limited by pump capacity, or by increasing filter surface area, limited by space and increasing the required pump load. SRNL set up both dead-end and cross-flow filter tests to better understand filter performance based on filter media structure, flow conditions, filter cleaning, and several different types of filter aids and body feeds. Using non-radioactive simulated wastes, both chemically and physically similar to the actual radioactive wastes, the authors performed several tests to demonstrate increases in filter performance. With the proper use of filter flow conditions and filter enhancers, filter flow rates can be increased over rates currently realized today.« less

Authors:
; ;
Publication Date:
Research Org.:
SRS
Sponsoring Org.:
USDOE
OSTI Identifier:
1001427
Report Number(s):
SRNL-STI-2010-00486
TRN: US1100363
DOE Contract Number:
DE-AC09-08SR22470
Resource Type:
Conference
Resource Relation:
Conference: Waste Management 2011
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; ALUMINIUM; CAPACITY; CLEANING; FILTRATION; FLOW RATE; IRON; MORPHOLOGY; PERMEABILITY; POLYMERS; PROCESSING; RADIOACTIVE WASTES; SHEAR; SLURRIES; SOLVENT EXTRACTION; START-UP; SURFACE AREA; WASTE MANAGEMENT; WASTE PROCESSING; WASTES

Citation Formats

Duignan, M., Nash, C., and Poirier, M. PERFORMANCE IMPROVEMENT OF CROSS-FLOW FILTRATION FOR HIGH LEVEL WASTE TREATMENT. United States: N. p., 2011. Web.
Duignan, M., Nash, C., & Poirier, M. PERFORMANCE IMPROVEMENT OF CROSS-FLOW FILTRATION FOR HIGH LEVEL WASTE TREATMENT. United States.
Duignan, M., Nash, C., and Poirier, M. Wed . "PERFORMANCE IMPROVEMENT OF CROSS-FLOW FILTRATION FOR HIGH LEVEL WASTE TREATMENT". United States. doi:. https://www.osti.gov/servlets/purl/1001427.
@article{osti_1001427,
title = {PERFORMANCE IMPROVEMENT OF CROSS-FLOW FILTRATION FOR HIGH LEVEL WASTE TREATMENT},
author = {Duignan, M. and Nash, C. and Poirier, M.},
abstractNote = {In the interest of accelerating waste treatment processing, the DOE has funded studies to better understand filtration with the goal of improving filter fluxes in existing cross-flow equipment. The Savannah River National Laboratory (SRNL) was included in those studies, with a focus on start-up techniques, filter cake development, the application of filter aids (cake forming solid precoats), and body feeds (flux enhancing polymers). This paper discusses the progress of those filter studies. Cross-flow filtration is a key process step in many operating and planned waste treatment facilities to separate undissolved solids from supernate slurries. This separation technology generally has the advantage of self-cleaning through the action of wall shear stress created by the flow of waste slurry through the filter tubes. However, the ability of filter wall self-cleaning depends on the slurry being filtered. Many of the alkaline radioactive wastes are extremely challenging to filtration, e.g., those containing compounds of aluminum and iron, which have particles whose size and morphology reduce permeability. Unfortunately, low filter flux can be a bottleneck in waste processing facilities such as the Savannah River Modular Caustic Side Solvent Extraction Unit and the Hanford Waste Treatment Plant. Any improvement to the filtration rate would lead directly to increased throughput of the entire process. To date increased rates are generally realized by either increasing the cross-flow filter axial flowrate, limited by pump capacity, or by increasing filter surface area, limited by space and increasing the required pump load. SRNL set up both dead-end and cross-flow filter tests to better understand filter performance based on filter media structure, flow conditions, filter cleaning, and several different types of filter aids and body feeds. Using non-radioactive simulated wastes, both chemically and physically similar to the actual radioactive wastes, the authors performed several tests to demonstrate increases in filter performance. With the proper use of filter flow conditions and filter enhancers, filter flow rates can be increased over rates currently realized today.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 12 00:00:00 EST 2011},
month = {Wed Jan 12 00:00:00 EST 2011}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • A full-scale modular solid/liquid separation (SLS) system was designed, fabricated, installed, and successfully deployed for treatment of liquid low-level waste from the Melton Valley Storage Tanks (MVSTs) at Oak Ridge National Laboratory (ORNL). The SLS module, utilizing cross-flow filtration, was operated as part of an integrated tank waste pretreatment system (otherwise known as the Wastewater Triad) to remove suspended solids and prevent fouling of ion-exchange materials and heat exchange surfaces. The information gained from this testing was used to complete design specifications for the full-scale modular SLS system in May 1997. The contract for detailed design and fabrication of themore » system was awarded to NUMET in July 1997, and the design was completed in January 1998. Fabrication began in March 1998, and the completed system was delivered to ORNL on December 29, 1998. Installation of the system at the MVST facility was completed in May 1999. After completing an operational readiness assessment, approval was given to commence hot operations on June 7, 1999. Operations involving two of the eight MVSTs were performed safely and with very little unscheduled downtime. Filtration of supernatant from tank W-31 was completed on June 24, 1999 and W-26 processing was completed on August 20, 1999. The total volume processed during these two campaigns was about 45,000 gal. The suspended solids content of the liquid processed from tank W-31 was lower than expected, resulting in higher-than-expected filtrate production for nearly the entire operation. The liquid processed from tank W-26 was higher in suspended solids content, and filtrate production was lower, but comparable to the rates expected based on the results of previous pilot-scale, single-element filtration tests. The quality of the filtrate consistently met the requirements for feed to the downstream ion-exchange and evaporation processes. From an equipment and controls standpoint, the modular system (pumps, valves, sensors, monitors, controls, shielding, and containment) functioned very well during each campaign. Evaluation of the Endress+Hauser Promass 63F Mass Flowmeter (a secondary objective of the project) indicated reasonably accurate and reliable performance. This instrument was installed on the feed pipeline for the SLS system, and it provided very accurate mass flow and density data, and reasonably accurate solids content data. Near the end of tank W-31 processing, the solids content of the feed to the SLS system increased to a very high concentration. This behavior was caused by the increased mixing of liquid and sludge phases within MVST Tank 31 as the level of liquid being decanted from the tank approached the level of the settled sludge. The physical properties of the heavy sludge caused some difficulties in draining and flushing of the system. Other minor equipment problems were encountered, but none resulted in significant downtime or safety issues. Operational data collected during the campaign were useful in evaluating the performance of the system. The 50-ft{sup 2} cross-flow filter was designed to provide filtrate at the rate of 1 to 5 gal/min (flux range of 0.02 to 0.1 gal min{sup -1} ft{sup -2}) of filtrate, and actual production was between 0.6 and 8.0 gal/min (flux range of 0.012 to 0.16 gal min{sup -1} ft{sup -2}). Additional operating data will be needed, however, to assess the long-term performance of the system with wider variations in the composition of the tank waste feed. The SLS will be employed in further processing campaigns during FY 2000, and more performance data will be collected.« less
  • This paper discusses the results of a cross-flow filter in a pilot-scale experimental facility that was designed, built, and run by the Experimental Thermal Fluids Laboratory of Savannah River Technology Center.
  • The Savannah River Site has 23 Type 3 high-level radioactive waste tanks, each with a storage capacity of 1.3 million gallons. These tanks contain nearly 9 million gallons of precipitated salt. To immobilize the waste, the salt is dissolved through water addition, followed by precipitation of the radionuclides through the addition of sodium tetraphenylborate. This precipitate is then concentrated and washed to remove sodium through cross-flow filtration. This waste pretreatment process started radioactive operation in late 1995. During the normal plant operation, the cross-flow filtration system (consisting of two 216-square-foot filter elements) maintains a constant filtrate production rate. This objectivemore » is achieved by allowing the operating pressure to increase to maintain a constant filtrate production rate. A maximum pressure differential limit of 40 psig has been imposed on this system. When this maximum is approached, a high-energy backpulse of filtrate removes foulant from the surface of the filter, thereby restoring the filter flux. This laboratory work examined two key aspects of the anticipated facility operating conditions: the efficacy of using pressure differential to control filtrate production rates and the risk posed to filter performance associated with pore plugging of the filter immediately following the backpulse. Tests used simulated tetraphenylborate precipitate and a bench-scale cross-flow filtration unit consisting of two parallel filter units each 4 feet in length. Tests used slurries containing between 1 and 10 wt% tetraphenylborate to cover the anticipated range of operation. Data collected included both initial flux-decline measurements and steady-state filtrate production measurements. Analysis of these data indicates, for the more dilute slurries, pressure was an effective tool in controlling filtrate flux. However, as the slurry became more concentrated, the ability to manipulate filtrate flux by pressure greatly diminished. Analysis of the initial filtrate decline data using first-principle models indicates that the primary mechanism for decreasing filter flux involved development of a surface cake. Given the operating constraints of the facility, these results provide guidance for future filtration operation.« less
  • This report discussed results of tests which investigated filter performance with slurry containing simulated Tank 8F Sludge at concentrations between 0.044 wt percent and 4.80 wt percent. Testing used a slurry containing 3.5 wt percent Tank 8F simulated sludge and a target concentration of 0.06 weight percent MST.
  • Document of cross-flow filtration tests performed using supernatant from Tanks 37H and 44H, MST, and sludge from any of three waste tanks.