19 i Lewatit FO 36 Presentation for Customers Short

5/27/2018 19 i Lewatit FO 36 Presentation for Customers Short

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Arsenic Removal from PotableWater with Lewatit FO 36

- Summary of Current Status ofProduct and Process Development-

Dr. Stefan Neumann

Manager Technical Marketing, Ion Exchange Applications

12_10_2011


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Application of Ion Exchangers in Potable Water PurificationDr. Stefan Neumann, September 20072

Content

1. Basics / Arsenic in the Environment/ Mechanism of As-Adsorption

2. Effect of Water Constituents on Arsenic Uptake3. Regeneration Procedure

4. Treatment of Spent Regenerant Solution

5. NSF Certificate

6. Summary


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1. Basics


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Arsenic can occur in ground- and surface water by

dissolution of minerals from subterranean strata

anthropogenic origin

mining / ore smelting operations

wood preservatives

agricultural pesticides

semiconductor material

anti termite treatment

Problem- / Task DescriptionArsenic - RemovalAs O

-O

-O

OH

AsO

-O

-O

OH

AsO

-O

-O

OH

Constant consumption of Arsenic loaded water is pathogen

Arsenicosis, the arsenic related disease include:

- changes in skin colour, formation of hard patches

- skin, bladder, kidney, lung, liver and colon cancer

- damage of genetic material through genotoxicity

- type 2 diabetes & vascular disease

- diverse other non-cancerous health effects.

Incidences of cancer per 10,000 people, depending on arsenic

concentration in drinking w ater

4 612

247

11

23

45

59

18

36

4

7

14

27

0

20

40

60

80

100

120

140

MCL 3 ppb MCL 5 ppb MCL 10 ppb MCL 20 ppb

Lung Cancer (Males)

Lung Cancer (Females)

Bladder Cancer (Males)

Bladder Cancer (Females)

Occurence of arsenic contaminatedgroundwater all over the world:

Incidences of cancer per 10,000 people, depending on arsenic

conentrationtion in dringking water


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Problem- / Task DescriptionArsenic - RemovalAs O

-O

-O

OH

AsO

-O

-O

OH

AsO

-O

-O

OH

since 2011 (?)5Sweden

50China

since 199310WHO conductance

state: 200250India

state: 200250Bangladesh

state: 200250Chile

since 1943 /since 2006

50 / 10USA

since 199810EU Directive 98/93/CE

before 1996 /

since 199640 / 10Germany

Point of timeMarginal value(g / l)

Country

Limits for arsenic concentrations by country:

10 since 2009


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Arsenic - RemovalAs O

-O

-O

OH

AsO

-O

-O

OH

AsO

-O

-O

OH

Product-Description

Lewatit FO36 development product

type: hybride of weakly basic resin + FeO(OH)

CH2-N(CH3)2 FeO(OH)


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-O

-O

OH

AsO

-O

-O

OH

AsO

-O

-O

OH

Lewatit FO36

Product Properties

Mean bead size: 0.35 mm

Uniformity coefficient: 1.1

Density: 1.25 g/ml

Bulk density: 0.65 g/mlWater retention: 53 58 wt. %

Iron content based on dry weight: 15%

Porosity (Hg-porosity method): 811 mm/g

BET surface: 102 m/g

Surface charge: not measured


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-O

-O

OH

AsO

-O

-O

OH

AsO

-O

-O

OH

Reaction-Scheme

Fe

OOH

OOH

OOH

OOH

+ As

O

-O

-O

OHFe

OOH

O

O

OOH

+ 2 OH-

+ 2 OH-, - HAsO42-

Regeneration:

As

O

O

O

OH

Exhaustion:


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-O

-O

OH

AsO

-O

-O

OH

AsO

-O

-O

OH

Reaction-Scheme

Two species of arsenic can be present in groundwater:

As(V) As(III)

AsO

-O

-O

OHAs

HO

HO

OH

- negatively charged anion

under neutral pH conditions

- can be removed wi th

Strong base anion exchanger (SBA)

and selective hybride adsorber (ASHA)

- neutrall (non)charged molecule

under neutral pH conditions

- can not be removed by strong base

Anion exchanger (SBA). Adsorption

only possible on selective hybride adsorber (ASHA)


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2. Effect of Water Compositionon Operating Capacity


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Relative uptake of arsenic by LEWATIT FO 36 in the presence of a selection of co-occurring ions

(Results obtained by shaking tests with 0.3 g of resin, 250 ml of solution, start conc. of As = 11 ppm )

0

0,2

0,4

0,6

0,8

1

1,2

0,01 0,1 1 10 100 1000 10000

molar ratio (c co-occurring)/(c arsenic) at start

(Asuptakeu

nderco-occuringio

ns)/(as

uptakeblank)

PO4

SiO2 PH = 3.5

NaCl

HCO3

SiO2 pH=7

selectivity series: HAsO42- = HPO42- > HSiO3- > HCO3- >>

Cl-pH-dependency: influence of HSiO3

- disappears at low pH !

Relative

Arsenic

Adsorp

tion


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-O

-O

OH

AsO

-O

-O

OH

AsO

-O

-O

OH

Operative Results

0,00

0,02

0,04

0,06

0,08

0,10

0,12

0,14

0 10000 20000 30000 40000 50000 60000 70000 80000 90000

throughput (BV)

Aseffluentconce

ntration(ppb)

ipilot plant product

tested with

portable water

pilot plant product

tested with

demi water

first production lot

tested with

demi water

arsenic feed concentration = 100 ppb

pilot plant product

tested with pottable

water


tested with demin

water

pilot plant product

tested with

demin water

0,00

0,02

0,04

0,06

0,08

0,10

0,12

0,14

0 10000 20000 30000 40000 50000 60000 70000 80000 90000

throughput (BV)

Aseffluentconce

ntration(ppb)

ipilot plant product

tested with

portable water

pilot plant product

tested with

demi water


tested with

demi water

arsenic feed concentration = 100 ppb

pilot plant product

tested with pottable

water


tested with demin

water

pilot plant product

tested with

demin water

BP1 BP2BP3

operating capacities

at 10 ppb @ outlet 1 column

achieved

in the three experiments were:

1.9 g/l at break through point 1(BP1)

5.8 g/L at break through point 2 (BP2)

8.5 g/L at break through point 3 (BP3)

FO36

(ppm)

-> how to explain different

results ?

-> what makes the difference

between tap water and

demin water?

-> influence of water

ingredients ?

tap-water

demin-water

Filtration test to remove As (V) with LEWATIT FO 36 from tap waterand from demineralised water

(Linear velocity: 25 BV/h, As, feed concentration 100 ppb in all experiments, tap water analysis: 160 ppm

bicarbonate, 50 ppm chloride, 13 ppm sulfate, 6 ppm of silica as SiO2, 100 ppb of fluoride, 60 ppb of phosphorus

and TOC < 1 ppm ))


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-O

-O

OH

AsO

-O

-O

OH

AsO

-O

-O

OH

Field Test Studies

0

1

2

3

4

5

6

7

8

9

10

10 100 1000 10000

As conc. in feed of filter (ppb)

ope

rating

capacity

(g

Asperlitre

ofadsorb

er)

Operating Capacities (OCs) of 40 field studies with complex water composition

Variations within that range mainly depend on water composition

severe operating conditions

moderate operating conditions

severe operating conditions

FO 36 shows typical behavior in l ine with the other adsorbers

moderate operating conditions


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3. Regeneration Procedure


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Different Regeneration + Conditioning Methods in Comparison

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12

Number of Adsorption Cylce (Adsorption + Regeneration)

AsAds

orptionperShakingTest(

regen + store 1 day under agitation in NaCl soln. by controlling pH @ 4,5 (Lot CHN10014)

regen + store 1 day under agitation in soln NaCl by controlling pH @ 4.5 (lot CHK 20004)

regen + keep one day under agitation in demin w ater by controlling pH @ 4.5 (lot

CHN10014)

regem + store 1 to 5 day w ithout agitation in NaCl under controlling pH @ 4.5

re en w ithout conditionin


-O

-O

OH

AsO

-O

-O

OH

AsO

-O

-O

OH Regeneration Tests

(shaking test series 13)

agitation during conditioning makes the difference !

in the latest test series adsorption could be kept > 90% over 8 cycles

NaCl is not necesserily required to be present in conditioning solution

mass transport effects seem to be important during conditioning


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-O

-O

OH

AsO

-O

-O

OH

AsO

-O

-O

OH Regeneration Tests

(Shaking Tests)

If conditioning (pH adjustment in NaCl solution)

is carried out through 24 hours at permanent agitation of

the liquid phase the fate of capacity can becompletely avoided.

Also a resin that is already showing severe disturbtion of

adsorption capacity can be repaired by this treatment

Mass transfer process that is enhanced by agitat ion seems

to play an important role here

pH adjustment in NaCl removes alkalinity from the resin and at the

same time seems to positively influence the surface morphology of

the resin (chrystallization state / surface charge ,,,,)


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Regeneration / Conditioning ProcedureStep 1. Backwash Lewatit FO36 with tap water for 30 min to remove suspended particles

and to loosen bed

Step 2. Pump 2 BV of a solution containing both: 20 g/L of NaOH and

20 g/L of NaCl over the fi lter at a flowrate of 4 BV/h

Step 3. Collect this solution in the spent regenerant treatment tank T1*

Step 4. Wash the fi lter with 4 BV of softened water

Step 5. Send the spent washing water in tank T1*

Step 6. Fill tank T2 with tap water

The water volume should be equivalent to 2 BV of the Lewatit FO 36 filter bed.

Step 7. Circulate the water over the resin in upflow mode,

whereby filter bed is fluidized, switch on agitator of tank T2

Step 8. After 10 min of pumping switch on pH control system

adjusted at a pH of 4.5. Use 10 % HCl as feed for the pH-controlStep 9. Let the system recycle for around 24 hours. PH at the end should be around

pH = 4.5 4.0

Step 10. Release water from T2 into waste channel or reuse for next conditioning step

Step 11. Wash filter bed with 5 BV of tap water, release spent rinse water to waste channel

-> Filter is now ready for next cycle

*) Treatment of spent regenerant + rinse water collected in tank T1 is described

on slide 5


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Principal Plant Concept (Regeneration + Waste Treatment)

C

MQICpH

M

QICpH

T1T2

Sludge disposal

Supernatant water disposal

20 g/L NaCl + 20 g/L NaOH

Softened water

2BV

4 BV

Tap water

Backwash and 2nd rinse water disposal

Conditioning agent disposal

30 % HCl

20 % NaOH

FeCl3

PE P1

P2

P3

P4


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Remarks on Plant Design1. As an option regenerant solution required in step 1 can be prepared in

tank T2

2. For steps 2 and 4 softened water has to be used as a base, otherwise there is the danger

of CaCO3 precipitation

3. Tank 1 to be designed with a filling volume of 7 BV related to the resin volume in one column.

Tank 2 to be designed with a filling volume of 2BV in case option 1 is

chosen.

4. For backwash (step 1) and condition ing o f Lewatit FO 36 use 4 m/h linear velocity

5. Spent backwash water (from step 1) as well as spent cond itioning water (from step 10)can be discharged into sewage system since the arsenic content is very low.

Same for supernatant water from precipitation.

But this has to be checked with local authoriti es

6. Thickened sludge from arsenic precipitation in T2 (see waste water treatment) to be discharged

to landfil (-> check with local authorit ies). If required, further dewatering in filter press or

other filtration device to be planned.

7. Tank T1 to be equipped with blade agitator and tank T2 to be equipped with propeller agitator

8. Dosage Pumps P1, P2 and P3 to be designed for slow flow rates to gi ve pH adjustment enough

response time


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4. Spent regenerant andwaste water treatment


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Co-Precipitation of Iron and Arsenate

Fe3+ + 3 OH- Fe(OH)3

Fe3+ + AsO43- FeAsO4

Treatment of spent regenerant is based on the following chemical reactions:

Precipitation of arsenate and arsenite by iron salts is a conventional

technique.Rest concentrations of > 0.5 ppm in mother liquor after precipitation is possible.

Precipitaiton reaction is similar to the removal of phosphate from water.


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Step 1: Homogenize spent regenerant (from step 3) and rinse water (from step 5) mixture in tank T1

Step 2: Acidify water mixture. Add hydrochloric acid until pH is down at pH < 3

Step 3: Add FeCl3 by 5 times of the stoichiometric amount related onAs present in the solution

(Therefore FeCl3 can be added as a solid or as a concentrated solution)

Completely dissolve FeCl3 and homogenize the solut ion.

Step 4: Slowly (within around half an hour) neutralize the solution with NaOH

Iron hydroxide will precipitate together with iron-arsenate

Step 5: Let the reaction complete within around 1 hour agitation at slow agitation

rates

Step 6: Add suitable anionic polyelectroly te (PE) to enforce flocculation.

Slow down agitator velocity to not destroy freshly formed flocs.

Operate agitator in maximum 3 minutes after addition of polyelectrolyte

has been completed.Step 7: Let the flocks settle down into the cone shaped bottom of the reaction tank T1.

Settling may take around one hour.

Step 8: Discharge the sludge into dedicated treatment or storage channels

(sludge can either be discharged as a liquid sludge or can be

discharged as fur ther dewatered sludge. Further dewatering can be

carried out by a filter press or a bag filter)

Step 9: Discharge clear supernatant water into sewage channel

-> General Remark:

Since regeneration of filt er is carried in several months distances the hereby

described procedure can be spread over weeks. Equipment design and procedure

to be designed according ly.

Spent Regenerant + Rinse Water Treatment

Procedure


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General remark on the waste water treatment

-> Since cycle time of filter exhaustion is several months there is a lot of time

available to carry out the treatment of the waste water.

-> E.g. Floccultation and Sedimentation can be carried out stepwise

with days or weeks in between.

-> Therefore thickening of sludge can be done with optimum results,even without polyelectrolytes

-> Also filtration can be done in a very slow mode with a very

primitive filtration device such as a bag filter (see next slide)


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Spent Regenerant

Treatment

View inside the precipitation

tank after decantation of clear water:

arsenic containing

iron oxide sludge is left on the

ground.

Filter bag to take up

the arsenic containing

iron hydroxide sludge.

Sludge in the filter

bag is drying out.

Example from a plant in the alpine mountains

where the spent regenerant is treated

on site next to the arsenic removal filters


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5. Potable Water Approval


26/31


Food ApprovalArsenic - RemovalAs

O

-O

-O

OHAs

O

-O

-O

OHAs

O

-O

-O

OH

http://nsf.org/Certified/PwsComponents/listings.asp?standard=061&company=1E960&


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6. Summary


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Summary (I)Arsenic - RemovalAs

O

-O

-O

OHAs

O

-O

-O

OHAs

O

-O

-O

OH

-> Lewatit FO 36 is a hybrid adsorber resin for selective arsenic adsorption (ASHA)

It can adsorb As(III) as well as As(V).

-> Adsorption of arsenic is independent from Sulfate, Chloride and Nitrate, butthere are negative effects in the presence of Silicate, Phosphate, Bicarbonate and

also there is an effect of pH at pH higher than 7

-> Operating capacities of 1 to 2.5 g/L can be achieved, depending on the operating

conditions

-> Uptake of arsenic is heavily inhibited at silicate concentrations of higher

than 50 mg/L. At 100 mg/L SiO2 the arsenic uptake is only 1/10 of the uptake

found with no Silicate.

-> For the case of high silicate concentrations the SBA-ASHA concept wasinvented by LANXESS. By util ization of a standard strong base anion exchanger (SBA)

in addition to the ASHA-filter the negative effects of SiO2 can be

suppressed.


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Summary (II)Arsenic - RemovalAs

O

-O

-O

OHAs

O

-O

-O

OHAs

O

-O

-O

OH

-> Regeneration possible without loss of capacity: Therefore after regeneration

conditioning treatment is required

-> 8 reference plants listed so far

-> NSF and WRAS approval certifies product for use in potable water treatment


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Disclaimer

This information and our technical advice whether verbal, in writing or by way of trials are given in good

faith but without warranty, and this also applies where proprietary rights of third parties are involved. Our

advice does not release you from the obligation to check ist validity and to test our products as to their

suitability for the intended processes and uses. The application, use and processing of our products and

the products manufactured by you on the basis of our technical advice are beyond our control and,

therefore, entirely your own responsibility. Our products are sold in accordance with the current version of

o u r G e n e r a l C o n d i t i o n s o f S a l e a n d D e l i v e r y .

LEWATIT and IONAC are registered trademarks of LANXESS AG

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19 i Lewatit FO 36 Presentation for Customers Short

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