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ORGANICS How do we catch and kill them ?. Organics 2 l W here do organics come from ? l W hat are they ? l H ow to measure them ? l W hat do they do to.

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Presentation on theme: "ORGANICS How do we catch and kill them ?. Organics 2 l W here do organics come from ? l W hat are they ? l H ow to measure them ? l W hat do they do to."— Presentation transcript:

1 ORGANICS How do we catch and kill them ?

2 Organics 2 l W here do organics come from ? l W hat are they ? l H ow to measure them ? l W hat do they do to a demin water plant ? l H ow is resin fouling affecting plant operation ? l W hat resins to use ? l H ow to prevent resin fouling ? l H ow to restore fouled resins ? ORGANICS AND ION EXCHANGE RESINS

3 Organics 3 ORIGIN OF ORGANIC MATTER l Organics are mainly found in surface water (rivers, lakes) VegetalsAnimals Domestic wasteIndustrial waste

4 Organics 4 l Principle Oxidise with potassium permanganate Boil in acidic conditions Titrate excess KMnO 4 l Procedure See notes l TOC vs COD TOC measured as mg of Carbon COD measured as Potassium Permanganate consumption v Very rough thumb rule: 1 mg/L TOC ~ 5.5 mg/L as KMnO 4 MEASUREMENT (KMnO 4 method) There is no direct relation between KMnO 4 and TOC measurement

5 Organics 5 l We dont guarantee a given degree of removal Resins are there to exchange ions, not organics (in industrial water treatment) l Usual degree of organic reduction WBA50 to 90 % SBA polystyrenic40 to 90 % SBA polyacrylic50 to 90 % REMOVAL FROM WATER

6 Organics 6 ELUTION OF ORGANICS (from resin) l WBA90 to 100 % l SBA type 150 to 90 % l SBA type 260 to 95 % l SBA Acryl90 to 100 % When elution (during regeneration) is less than 100 %, organics accumulate on resin This is Resin Fouling When elution (during regeneration) is less than 100 %, organics accumulate on resin This is Resin Fouling

7 Organics 7 Example of fouling l Water with 5 mg/L as KMnO 4 l SBA resin type 2 l Run length 100 Bed volumes (e.g. 1000 m 3, 100 m 3 /h) Organic load 100 x 5 = 500 mg KMnO 4 per L resin l Organic removal 50 % 5 mg/L in > 2.5 mg/L out 250 mg organics are picked up by resin in each run l Elution 80 % Only 0.8 x 250 = 200 mg are removed from resin 50 mg/L accumulate on resin in each run l After 200 cycles, resin contains 10 g/L of organics 5 mg/L 2.5 mg/L

8 Organics 8 Humic acid Humic acid structure proposed by Dragunov A typical decay product or building block is gallic acid:

9 Organics 9 NATURAL ORGANIC ACID (partial structure) Molecular mass 500 - 30 000

10 Organics 10 STRONGLY BASIC RESINS (partial structure) PolystyrenicPolyacrylic

11 Organics 11 ELECTROVALENT BONDING Attraction between cation & anion Anion resin Organic acid

12 Organics 12 VAN DER WAALS BONDING Attraction between aromatic rings Anion resin Organic acid

13 Organics 13 ADSORPTION OF THE ORGANIC ACID Combination of ionic and Van der Waals attraction Polystyrene anion resin Organic acid Polystyrene anion resin

14 Organics 14 FOULING OF RESINS l Regeneration breaks the ionic bonds It doesn't break the Van der Waals bonds l Acrylic resins are not aromatic ! Van der Waals forces are therefore weak l Acrylic resins don't get fouled Use Amberlite IRA458 or IRA478

15 Organics 15 HOW DOES FOULING GET NOTICED ? l NaOH is absorbed inside resin (on – COOH groups) l Rinse is long l Na leakage increases l SiO 2 leakage increases l Capacity decreases l Moisture content decreases Problems in plant operation Long rinse

16 Organics 16 FOULING INDEX l Example 1 Degassed water, 6 meq/L Tot Anions 12 mg/L KMnO 4 N = 12/6 = 2Moderate l Example 2 Undegassed, thin water, 1.5 meq/L 12 mg/L KMnO 4 N= 12/1.5 = 8Highly fouling l Example 3 High TDS water, 15 meq/L, 3 mg/L KMnO 4 N= 3/15 = 0.2Not fouling N = OM (mg/L as KMnO 4 ) Total Anions (meq/L)

17 Organics 17 ORGANIC LOAD l Example 1 6 meq/L Tot Anions, 12 mg/L KMnO 4 Assume a capacity of 0.6 eq/L for SBA alone BV treated = 1000 x 0.6/6 = 100 Organic load = 100 x 12 mg = 1.2 g/L R as KMnO 4 l Example 2 Thin water, 1.5 meq/L, 12 mg/L KMnO 4 Assume a capacity of 0.6 eq/L for SBA alone BV treated = 1000 x 0.6/1.5 = 400 Organic load = 400 x 12 mg = 4.8 g/L R as KMnO 4 The definition of Organic Load: Quantity of organics going through the resin Not quantity removed by the resin The definition of Organic Load: Quantity of organics going through the resin Not quantity removed by the resin

18 Organics 18 l New Example High TDS water, 15 meq/L, 30 mg/L KMnO 4 Combination WBA / SBA WBA cap 1.0 eq/L, ionic load 10 meq/L > 100 BV treated SBA cap 0.5 eq/L, ionic load 5 meq/L > 100 BV treated Each litre of WBA gets 24 mg x 100 BV = 2.4 g as KMnO 4 WBA picks up about 60% of organics lets through 40% SBA gets 0.4 x 30 = 12 mg/L H2O Each litre of SBA gets 12 mg x 100 BV = 1.2 g as KMnO 4 ORGANIC LOAD (cont.) 2.5 mg/L Org 12 mg/L Ions 5 meq/L WBASBA Org 30 mg/L Ions 15 meq/L Cap 1.0 eq/LCap 0.5 eq/L

19 Organics 19 RESISTANCE TO FOULING Resin N maxmax load g/L R as KMnO 4 Amberjet 4200 Cl 32 Amberjet 4400 Cl 21 Amberjet 4600 Cl 64 Amberlite IRA402 Cl 32 Amberlite IRA405 Cl 105 Amberlite IRA410 Cl 64 Amberlite IRA458 Cl 158 Amberlite IRA478RF Cl 1512 Amberlite IRA900 Cl 63 Amberlite IRA910 Cl 104 Amberlite IRA96 1212 Amberlite IRA67 2025 Amberlite IRA70RF 1820 Resin N maxmax load g/L R as KMnO 4 Amberjet 4200 Cl 32 Amberjet 4400 Cl 21 Amberjet 4600 Cl 64 Amberlite IRA402 Cl 32 Amberlite IRA405 Cl 105 Amberlite IRA410 Cl 64 Amberlite IRA458 Cl 158 Amberlite IRA478RF Cl 1512 Amberlite IRA900 Cl 63 Amberlite IRA910 Cl 104 Amberlite IRA96 1212 Amberlite IRA67 2025 Amberlite IRA70RF 1820

20 Organics 20 Organic SCAVENGER (organic trap) l Is used to protect demin plant Reduction of organic load on WBA and SBA l Today, not much used Acrylic resins used instead in the demin line

21 Organics 21 SCAVENGER RESINS l Resin choice Polystyrenic macroporous Amberlite IRA900 Cl Polyacrylic macroporous Amberlite IRA958 Cl l Regeneration 2 BV of a 10% NaCl + 2% NaOH solution Sizing : So that organic load is about 10 g/L as KMnO 4 10 to 30 BV/h l Efficiency Organic removal 50 to 90% Composition of feed water to demin plant is changed (more Cl, less HCO 3 and SO 4 )

22 Organics 22 WBA resins help ! l Combine WBA macroporous resin with SBA WBA protects SBA l Combine styrenic and acrylic matrix e.g. IRA96 + IRA458 l 3-compartment Amberpack ® anion column Compartment 1 designed as integrated organic trap. Use reverse flow regeneration for WBA WBA 1 WBA 2 SBA IRA96RF IRA458RF Amberlite

23 Organics 23 DETERGENTS l Detergents are particularly harmful to anion resins They cause irreversible fouling (they can practically not be removed) Example : ABS (Alkylbenzene sulphonates) l Best bet : Acrylics (again !)

24 Organics 24 HOW TO LIMIT FOULING l Good pre-treatment Flocculation Chlorination Scavenger resins l Membrane filtration Ultrafiltration Reverse osmosis l Good resin selection Acrylic SBA Use a WBA to protect SBA l Limit loading Short runs Use more resin (dilution) l Regenerate more efficiently Increase NaOH level Hot NaOH (type 1 only!) l Regular de-fouling treatment (see next slide)

25 Organics 25 RESTORING RESIN QUALITY l Best cure : alkaline brine treatment Solution of 10 % NaCl + 2 % NaOH See details in the notes l Acid treatment (useful when iron is complexed with organics) Treatment with 10% HCl See details in the notes After treatment, check resin rinse

26 Organics 26 Thank you!


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