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Liquid low and intermediateLiquid low and intermediate--level level

radioactive wastes treatment radioactive wastes treatment ––

the challenge for membrane methodsthe challenge for membrane methods

Grazyna Zakrzewska-Trznadel

Institute of Nuclear Chemistry and Technology, Institute of Nuclear Chemistry and Technology,

DorodnaDorodna 16, Warsaw, Poland.16, Warsaw, Poland.

Places of arising

Waste not deriving from nuclear activities

Decommissioning of nuclear facilities

Nuclear fuel cycleMining and milling

Fuel supplyManagement of spent fuel

Reactor operation/power generation

Production and use of radioisotopesRadioisotope productionRadioisotope applicationResearch activities

Origin and types of radioactive wastesOrigin and types of radioactive wasteOrigin and types of radioactive wastess

Origin and types of liquid radioactive wasteOrigin and types of liquid radioactive wastess

�� In Poland In Poland mainlymainly wastes from the production and application wastes from the production and application of radioisotopes, medium and lowof radioisotopes, medium and low––level, total specific activity level, total specific activity ofof γγ and and ββ emitters not higher than emitters not higher than 101077 Bq/dmBq/dm33

�� Classification of liquid radioactive wastes in Poland:Classification of liquid radioactive wastes in Poland:

LowLow--level: level: AAss<10<1044 Bq/dmBq/dm33

MediumMedium--level: level: 101044 <A<Ass< 10< 107 7 Bq/dmBq/dm33

HighHigh--level: level: AAss> 10> 107 7 Bq/dmBq/dm33

�� Liquid radioactive wastes may contain suspended matter, Liquid radioactive wastes may contain suspended matter, emulsions, detergents and ionic species. Most often present emulsions, detergents and ionic species. Most often present radioisotopes: radioisotopes: 3232P, P, 3535S, S, 5151Cr, Cr, 6060Co, Co, 6565Zn, Zn, 9090Sr, Sr, 9090Y, Y, 9595Zr, Zr, 9595Nb, Nb, 106106Ru, Ru, 121121Te, Te, 131131I, I, 133133Ba, Ba, 134134Cs, Cs, 137137Cs, Cs, 144144Ce and Ce and 152152--155155Eu. Eu.

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Radioactive wasteRadioactive wastess treatmenttreatment

Radioactive WasteProcessing PlantRepository

MEDICINE

INDUSTRY

SCIENCE

PROCESSES OF LIQUID RADIOACTIVE WASTE TREATMENT

EVAPORATION

•Thin-film evaporators

•Evaporators-dryers

•Vacuum evaporators-dryers

•Fluidised evaporators-dryers

EXTRACTION

•Organophosphoric extractants

•Tertiary amines

•Crown ethers

ELEKTROCHEMICAL

PROCESSES

•Electrolysis•Electroflotation

•Electroflocculation

•Electrodialysis

•Electroosmosis

•Electrochemical ion exchange

ION EXCHANGE

•Inorganic natural ion exchangers

•Organic natural ion exchangers•Modified natural ion exchangers

•Synthetic inorganic ion exchangers

•Synthetic organic ion exchangers

•Composite ion exchangers

•Ion-exchange membranes

BIOLOGICAL PROCESSES

•Bioaccumulation

•Biodegradation

•Biosorption

(bacteria, fungi, algae)

PRECIPITATION

•Lime-soda process

•Hydroxide processes•Oxalate precipitation

•Phosphates precipitation

•Cyanoferrates

precipitation

•Tetraphenylborates

precipitation

Methods of liquid radioactive Methods of liquid radioactive wastewastess processingprocessing

Nuclear Technologies –Membrane Processes

�� Membrane processes Membrane processes are the latest achievements of the are the latest achievements of the technology offering the attractive solutions in the field of efftechnology offering the attractive solutions in the field of effective ective and selective separationand selective separation;;

�� All technical solutions introduced into nuclear industry have toAll technical solutions introduced into nuclear industry have to fulfil fulfil high standards of securityhigh standards of security,, apart from technical and economic apart from technical and economic criteriacriteria;;

�� Involve effective and selective separation methods and nonInvolve effective and selective separation methods and non--conventional processesconventional processes;;

�� Apply the tools derived from new achievements of science and Apply the tools derived from new achievements of science and technology stimulating their further developmenttechnology stimulating their further development..

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Examples of membrane installations Examples of membrane installations operated around the Worldoperated around the World

� Chalk River Laboratory (Canada) – mixed radioactive wastes (MF, spiral wound and tubular RO modules)

� Sellafield (G.B.) – UF installation for removal of actinides and dewatering of radioactive sludge

� Nuclear Power Plant in Paks (Hungary) – boric acid recovery (ultrafiltration, polysulfone membranes)

� Harwell (G.B.) – separation of the precipitate from water after flocculation (ultrafiltration)

� Hanau (Germany) – processing of low-level liquid wastes from fuel production plant (ultrafiltration)

� Cadarache Nuclear Research Centre and Harwell – UF-complexation

� Nuclear power stations in USA, e.g. Nine Mile Point, Wolf Creek, Comanche Peek, River Bend, Salem, Seabrook, Callaway, Diablo Canyon – RO or UF

� Bruce Nuclear Power Station in Canada – RO, UF - aqueous wastes from steam generator chemical cleaning

� ANSTO, Australia - RO

Application of reverse osmosis for Application of reverse osmosis for treatment of radioactive wastes treatment of radioactive wastes

Pilot plant experiments at Radioactive Waste Processing Plant Pilot plant experiments at Radioactive Waste Processing Plant in in SwierkSwierk, Warsaw, Warsaw

TheThe reasonsreasons for application of reverse osmosis:for application of reverse osmosis:

�� Large amount of small ions in the liquid waste from nuclear centLarge amount of small ions in the liquid waste from nuclear centres res and hospitals; and hospitals;

�� The necessity of integration of RO installation with an evaporatThe necessity of integration of RO installation with an evaporator or (the initial concentration of radioactive species before an (the initial concentration of radioactive species before an evaporation or final polishing of the condensate polluted evaporation or final polishing of the condensate polluted bybyradioactive compounds).radioactive compounds).

REVERSE OSMOSISREVERSE OSMOSIS

Pilot plant experiments: RO installation Pilot plant experiments: RO installation (Radioactive Waste Processing Plant in (Radioactive Waste Processing Plant in SwierkSwierk))

Retentate Permeate

Total salinity, [g/dm3]

250 0,1

Specific activity, [kBq/m3] 107 (0,3 Ci/m3) <10 (ββββ i γγγγ)<1 (αααα)

REVERSE OSMOSISREVERSE OSMOSIS

Model SU-720R Model SU-810

Membrane

type

Cross linked fully

aromatic polyamide

composite

Cross linked fully

aromatic polyamide

composite

Elementconfiguration

Spiral wound Spiral wound

Salt Rejection 99.7%* 99.4%**

Product flowrate

20.0 m3 /day* 4.0 m3 /day**

*Test conditions: Pressure: 15 bar

Temperature: 25oCFeed concentration: 1500ppm (NaCl)Brine flow rate: 80 dm3 /min

pH: 6.5

**Test conditions: Pressure: 55 bar

Temperature: 25oCFeed concentration: 3.5% NaClBrine flow rate: 20 dm3 /min

pH: 6.5

44444444

REVERSE OSMOSISREVERSE OSMOSIS

Waste tank, 8m3

Pressure pump

I stage

III stage

II stage

prefilter

Intermediate tank, 2.5m3

Feed

Product

concentrate

brine

Pressure pump Circulation pump

Circulation pump

PilotPilot--plant experiments: removal of plant experiments: removal of radioactive compoundsradioactive compounds

2200

12,3

7000

2200

10,4

3,9

23

3,9

7000

16000 16000

1

10

100

1000

10000

100000

I stage II stage III stage total unit

Bq/dm3

feed

permeate

concentrate

REVERSE OSMOSISREVERSE OSMOSIS

Advantages of use of RO:Advantages of use of RO:

�� Total removal of dissolved matter (ions) Total removal of dissolved matter (ions)

�� High DFHigh DF

�� VRCVRC ca.10ca.10--1515

�� WellWell-- developed method, elaborated in technical scale developed method, elaborated in technical scale

�� Its suitability for liquid radioactive wasteIts suitability for liquid radioactive wastess treatment treatment

was verified in industrial scalewas verified in industrial scale

REVERSE OSMOSISREVERSE OSMOSIS

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Enhanced ultrafiltrationEnhanced ultrafiltration

+

Dispersed sorbent or

complexing agent

Sorption or complexation

Multi-component solution

Membrane filtration

The component retained by

the membraneThe component passing through

ULTRAFILTRATIONULTRAFILTRATION

� High chemical resistance (in full range of pH), stability of operation with organic

solvents, resistance to ionising radiation;

� High temperature resistance, the possibility of washing at high temperatures,

with strong cleaning solutions;

� Resistance to compression, sterilizable by steam;

� Easy cleaning minimises to exploitation costs: increases output and decreases

energy consumption.

Application o ultrafiltration for liquid radioactive Application o ultrafiltration for liquid radioactive waste treatment: waste treatment: ceramicceramic membranesmembranes

ULTRAFILTRATIONULTRAFILTRATION

The goal of the studies:The goal of the studies:

�� Enhancement of the treatment efficiency by Enhancement of the treatment efficiency by

application of hybrid process UF/complexation; application of hybrid process UF/complexation;

increase of installation outputincrease of installation output

�� Testing of ceramic membranesTesting of ceramic membranes

ULTRAFILTRATIONULTRAFILTRATION

Application of ultrafiltration for liquid Application of ultrafiltration for liquid radioactive wasteradioactive wastess treatmenttreatment

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P1

F1

25 l

F1

UF standUF stand

The study of influence of membrane characteristics and process parameters:

�� the type of the membrane (pore size and cut-off)

� pH ,

� the type of complexing agent, its concentration and molecular weight

�Alkali metal concentration, total salinity, etc.

ULTRAFILTRATIONULTRAFILTRATION

The influence of complexing

agent on retention of Co2+ ions,

MEMBRALOX® 50 nm,

CCo= 0.1 g/dm3, CL= 0.2 g /dm

3

The influence of pH on retention

and decontamination of 60Co,

MEMBRALOX 50nm, PEI 0,1

1

10

100

0,00 2,00 4,00 6,00 8,00 10,00 12,00

pH

DF

DF R

ULTRAFILTRATIONULTRAFILTRATION

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

1

retention factor

ultrafiltration

PAA, weak

crosslinking/UF

INSTAR AS (MW = 15

000)/UF

PAA (Mw=25 000)/UF

PEI/UF

NaPAA-30000/UF

pH~6-7

Advantages of UFAdvantages of UF

� Low pressures applied: <10 bar, high permeate flux;

� Effective method for separation of colloids and suspended solids;

� For ionic species high efficiency achieved in hybrid processes;

� Easy to combine with sorption or complexation – selectivity of the hybrid process;

� Inorganic membranes available;

� Well-developed method.

�� MnMn 98%98%

�� Fe Fe 98.6%98.6%

�� Cu Cu 92.4%92.4%

�� Ni Ni 91.5%91.5%

�� Zn Zn 94.7%94.7%

�� Mg(2+)Mg(2+) 67%67%

�� Ca(2+)Ca(2+) 58%58%

�� SO4(2SO4(2--)) 22.6%22.6%

Retention of metals and bivalent ionsRetention of metals and bivalent ions

ULTRAFILTRATIONULTRAFILTRATION

1 10 100 1000

1

2

3

4

5

6

7

DF

Am-241

Eu-152

Eu-154

Co-60

Cs-137NaPAA-1200

NaPAA-8000

NaPAA-15000

NaPAA-30000

4g/l

8g/l

PEI

CoCF/PEI

(total salinity ≈≈≈≈ 1g/dm3, specific radioactivity ≈≈≈≈200kBq/dm3, ≈≈≈≈68% Cs-137) MEMBRALOX ® 15nm

77777777

Application of membrane distillation for liquid Application of membrane distillation for liquid radioactive waste treatmentradioactive waste treatment

TheThe reasonreason for application of for application of MD:MD:

The possibility of utilisation of lowThe possibility of utilisation of low--enthalpy heat enthalpy heat sources, e.g. waste heat discharged by nuclear power sources, e.g. waste heat discharged by nuclear power plantsplants

MEMBRANE DISTILLATIONMEMBRANE DISTILLATION

� Laboratory units: flat sheet membranes, capillary modules BFMF (EuroSep) and frame-and-plate modules (Sartorius)- polyolefine membranes

� Pilot plant, spiral-wound module G-4.0-6-7 (SEP Gesellschaft fur TechnischeStudien, Entwicklung, Plannung mbH) – PTFE membrane

P

P

P

MEMBRANE DISTILLATIONMEMBRANE DISTILLATIONConcentration of liquid radioactive waste by Concentration of liquid radioactive waste by

membrane distillationmembrane distillation

MD pilot plantMD pilot plant

PTFE PTFE membranemembrane::

r: 0,2 r: 0,2 µµmm

εε: 80%: 80%

Moduł MD

MEMBRANE DISTILLATIONMEMBRANE DISTILLATION

O vera ll d im ens ions φφφφ x h : 0 .45 m x 0 .62 m

E ffe ctive su rface a rea : 4 m 2

Vo lum e f low o f feed s tream s: 300 - 1500

dm 3/hD istilla te f lux : 10 - 60 dm 3/hRecomm ended feed s tream

tem pera tu re: 60 - 80 oCAverage ene rg y consum ption

per 1m 3 o f d is tilla te : ~ 600 kW h th

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Radioactive solution treatment by MD Radioactive solution treatment by MD methodmethod

1E1

1E2

1E3

1E4

1E5

Bq/l

mikroS/cm

0 5 10 15 20 25 30 czas [h]

Cond.R Cond.D Radioactiv.R Radioactiv.D

1E4

1E2

Sklad:

Co-60, Zn-65, Ag-110m, In-114m,

Ba-133, Cs 134, Cs-137

La-140, Tm-170, Ir-192, Hg-203

MEMBRANE DISTILLATIONMEMBRANE DISTILLATION

Advantages of MDAdvantages of MD� Retention of all dissolved substances;

� High DF;

� High concentration attained;

� Good chemical resistance of membranes (PTFE);

� High pressures are not applied;

� Economic for power conventional and nuclear stations.

1.00E+01

1.00E+02

1.00E+03

1.00E+04

1.00E+05

A [Bq/dm3]

1 1.657 3.4247 5.7013 8.4674 VRC=Vo/VR

retentate permeate

EV

MD

feed

concentrate

retentate

distillatedistillate

MD

MD

RO

feed distillate

retentate

concentrate

permeate

retentate

UF

MD

UF

water

complexingagent

concentrate for cementation

retentate

permeate

permeate

comlexing agent after regeneration

MEMBRANE DISTILLATION MEMBRANE DISTILLATION ––hybrid systemshybrid systems

Process Advantages Disadvantages

Reverse osmosis • Removes dissolved salts

• DF 100-1000 • VRF 100-1000 • Economical • Established for large scale operation

• High pressure system, limited by osmotic pressure

• Non-backwashable, subject to fouling

Ultrafiltration • Separation of dissolved salts from particulate and colloidal material

• Inorganic membranes available with good chemical and radiation stability can also operate at elevated temperatures

• Pressure<1 MPa

• Fouling - need for chemical cleaning or backflushing

• Organic membranes subject to radiation damage

Microfiltration • Low pressure operation (100-150 kPa)

• High recovery (99%)

• Excellent pre-treatment stage for RO

• Inorganic membranes available • Low fouling when air backwash is employed

• Backwash frequency can be quite high; depends on solids content of waste stream

Membrane distillation

• Removes all dissolved salts, very high DF

• Non-pressure driven operation • Economical for nuclear industry • Good chemical and radiation resistance of membranes

• Only for non-volatile compounds solutions

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Thank you!