pH Effects of Anion ResinpH Effects of Chloride Form Anion ...

Bill Koebel, May 2014

pH Effects of Chloride Form Anion ResinsPresented to Eastern Water Quality Association

• Alkalinity

• Arsenic

• Nitrate

• Sulfate

• Tannins

• Perchlorate

• Uranium

• Chromate

Contaminants

• Standard SBA

• Standard SBA

• Selective or Standard

• Standard SBA

• Selective

• Selective

• Standard SBA

• Selective or Standard

Type of Anion Resin

• Alkalinity

• Arsenic

• Nitrate

• Sulfate

• Tannins

• Perchlorate

• Uranium

• Chromium

• Tiny plastic beads that have been chemically activated

• They are manufactured products that are made from petrochemical based monomers

Ion Exchange Today

Make the Beads

• Mix Styrene with Divinyl Benzene (Crosslinkage)

• Suspension Polymerization

• No Water Content

• Neither Cation or Anion resin

• Beads are called co-polymer

Anion Resins

• Swell the co-polymer• Chloromethylation – prepares the resin for adding the functional groups• Amination – adds the amine functional groups

• Why it smells like fish• Properties

• About 27,000 grains per cu. ft.• 55% moisture content• 44 pounds per cu. ft.• 93%+ whole beads

Material Properties

• Size between 16 to 50 U.S. Mesh

• Resistance to fracture

• Insoluble

• Permanently attached sites

• High capacity for ions

• Temperature effects negligible

Common Anions

Sulfate SO4-

Nitrate NO3-

Chloride Cl-

Bicarbonate HCO3-

Silica SiO2

pH Concerns

• Anionic softening removes carbonates/bicarbonates as well as the contaminant of concern.

• Without bicarbonates present in the water, pH decreases

• Relationship of CO2 + HCO3- + CO3-2 + OH-

• Percentage of which of species dependent on pH in water

pH vs Alkalinity RelationshipForms of inorganic carbon at different pH levels

0

25

50

75

100

4 5 6 7 8 9 10 11 12 13

FreeCO2 HCO3- FreeCO3-2

Arsenic & Nitrate Removal by Type 2 Anion ResinCo-flow 15 lbs NaCl/cu.ft. @ 5% Brine

0

125

250

375

500

Gallons per cubic foot0 750 1,500 2,250 3,000

PPM Cl (L) PPM HCO3 (L) PPM SO4 (L) PPB AS +5 (R) PPM NO3 - N (R)

Curve run out past exhaustion to show dumping Reference: RTC: 8948

Arsenic & Nitrate Removal by Type 2 Anion ResinpH Change during service cycle

0

75

150

225

300

Gallons per cubic foot0 750 1,500 2,250 3,000

PPM HCO3 (L) PH (R)

Reference: RTC: 8948

What Else Do I Need to Know?

• TDS or conductivity• Sulfate• Nitrate• Chloride• Alkalinity• Silica • pH

pH to M-Alk/CO2 RelationshippH

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

pH to M-Alk/CO2 Ratio [meq/meq].01 .1 1 10 100

Calculating pH Drop

• Use Chart to calculate CO2 from influent chemistry• Use of influent pH and Alkalinity data

• Reduce alkalinity by 95% to assume worse case

• Determine ratio with low alkalinity and CO2 content• 5% of original alkalinity and influent CO2

• Use chart to see what the new ratio yields for pH

• Piece of cake!!!

Calculating pH Drop Volume

• Dealkalization Calculation for Standard SBA:• Formula: (175,000* ppm Alkalinity/TDS) / ppm Alkalinity

• Example: (175,000 * 200/400) / 200 = 437.5 Gallons/Cuft

Now you can determine the pH drop and for how long!

pH Correction Methods

• Product water can be buffered by addition of soda ash (Na2CO3) to the salt tank• 1 lb of soda ash to 9 lbs of salt

• Media neutralizer post anion unit • Calcite, Corosex, etc.

• Soda Ash or Caustic Soda (NaOH) Liquid feed post anion unit

THANK YOU

Bill Koebel

p. 412-716-7921 e. [email protected]

Eastern Regional Sales Mgr