Path to Quality Water

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Eustace Rose
7 years ago
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Today s Agenda Different Coagulate Treatments (Alum & Alchlor) Chemistry of these coagulants Raw water quality Variability Problems Solutions

1 Today s Agenda Different Coagulate Treatments (Alum & Alchlor) Chemistry of these coagulants Raw water quality Variability Problems Solutions Coagulant performance Sludge Compliance with a Quality Control system - ADWG Summary and Questions Path to Quality Water A L C H LO R G O L D 1

2 COAGULANT TREATMENTS FEATURES ALUM - Aluminium Sulphate Al 2 (SO 4 ) 3 Alumogen used by the Egyptians. ALUM liquid Al 2 (SO 4 ) 3.18 H 2 O A conc. H 2 SO 4 + Al(OH) 3 (Aluminium hydroxide) B conc. H 2 SO 4 + Bauxite ore Highly acidic Sulphate based system Overdosing produces an earthy taste in potable water Forms very wet sludge releases Al - toxic Promotes algae growth in the treatment plant Carried through to sewerage system A L C H L O R G O L D 2

3 COAGULANT TREATMENTS FEATURES Alchlor - Aluminium Chlorohydrate Al 2 (OH) 5 Cl Originally deodorant antiperspirant (12% Al 2 O 3 ) astringent 23% Al₂O₃ (PAC23) standard grade for water treatment. ALCHLOR 25% Al₂O₃ - greater concentrate - higher charge Prehydrolysed low ph impact Small to no ph adjustments Forms crystalline sludge which holds aluminium in the matrix A L C H L O R G O L D 3

4 Chemistry of Treatments ALUM NON-polymerised aluminium Sulphate AI 2 (SO 4 ) 3.18 H 2 0 2Al(OH) 3 PAC 23 Polymeric Standard (ACH 23% Al ) Al 13 O 4 (OH) 24 (H 2 O) Keggin Ion Structure Al 13 Typical Dose Rates at 100 NTU (mg/l) ALUM PAC 23 ACH Gold Alchlor Gold ACH Highly Polymeric high MW (ACH 25 + % Al 2 O 3 ) Al 30 O 8 (OH) 56 (H 2 O) Positive Charge + Al species present upon equilibrium A L C H L O R G O L D 4

5 QUALITY OF WATER WHERE DO COAGULANTS FIT? Membrane Removal Coagulation range Natural Settling SALTS BACTERIA ALGE SUGAR VIRUS PROTOZOA SAND PHENOLS CLAY SILT PAPER FIBRE µm REVERSE OSMOSIS NANOFILTRATION CENTRAFUGATION COAGULATION/FLOCCULATION ION EXCHANGE SEDIMENTATION ADSORPTION ULTRAFILTRATION MICROFILTRATION DEPTH FILTRATION SCREENING Expensive Cheap Free ALCHLOR GOLD 5

6 ALCHLOR VS. ALUM DOSAGE Coagulant Dosage Turbidity (NTU) ALCHLOR GOLD 6

7 ALUMINIUM RESIDUAL SOLUBILITY ADWG Aluminium Ceiling mg/l Aim mg/l is potable water ph A L C H L O R G O L D 7

8 COMMON PROBLEMS WITH RAW WATER Issues ALUM (steps to treat) ACH (steps to treat LOW ALKALINITY LEVELS 1. Raise Alkalinity with Lime 2. Adjust ph to H₂SO₄ 3. Floc with Alum 4. Raise ph to Floc with higher gold dose or raise alkalinity and floc. 2. Adjust ph to approx 7.5 if necessary. HIGH MANGANESE LEVELS HIGH TURBIDITY LEVELS LOW TURBIDITY LEVELS < 5 NTU 1. Remove manganese with KMnO 4 Oxidation above ph 8 2. Readjust ph to Floc with ALUM 4. Raise ph to ph with Lime or Soda Ash adjustment to compensate for the ALUM high dose Acidity. ( mg/l) 2. Adjust ph to ph 2. Adjust ph to 7.5 with Soda Ash 1. Remove manganese with KMnO 4 by oxidation at ph above 8 2. Floc 3. Readjust ph if nessesary 1. Floc at 7.5 ph ( 20 to 60 mg/l) 1. Floc at ph 7.5 using <1 mg/l of polymer ALCHLOR GOLD 8

9 SLUDGE REMOVAL ALUM 2-5 times the level of sludge Toxic to plant life Sulphate - amorphous Sludge is water rich and acidic Alchlor Gold ¼ the sludge produced Non Toxic to plant life Chloride crystaline Sludge dries to friable soil A L C H L O R G O L D 9

10 ADWG Compliance to Australian Drinking Water Standards 1. Safe drinking water is essential 2. ADWG provides a framework for good management practices 3. ADWG provides a basis for the supply of quality water to consumers Treatment goals Thresholds 4. ADWG request a QC for Coagulant A L C H L O R G O L D 10

11 ADWS GUIDELINES FOR SUPPLIERS NATA Certificates Numbered Tagged Valves on Delivery Tanker (Insurance for Authorities) Denoted on Delivery Dockets ALCHLOR GOLD 11

12 JAR TESTING Singularly, the most important test required for Flocculation Treatment! 1. To determine optimum parameters for your treatment plan. 2. Measure parameters a. Mix and contact times b. Dose rates c. Floc formation d. Settling times e. Sludge production 3. Use accurate Dosing Syringe! Eppendorf ALCHLOR GOLD 12

13 ECONOMICS OF RELATIVE COST A L U M Dosage 5-30 times higher Low to high Turbidity water Depends on water quality Alkali Addition needed for ph corrections Can typically take 2-3 operational steps A L C H L O R G O L D ¼ Dose rate of Alum Usually zero Alkali addition required. Most customers treat water in one operational step. Overall treatment cost includes more than just price per Kg of coagulant Cost per megalitre of water produced A L C H L O R G O L D 13

14 CASE STUDY ANALYSIS ALUM (Al 2 0 ACH (Al 2 0 Alchlor Gold (Al 2 0 Cost per kg $0.18 $0.80 $1.00 Dose kg/megalitre ( kg /day) 90 (3,600kg) 28 (1,040 kg) 16 (640 kg) Direct Cost /megalitre $16.20 $22.4 $16.0 Freight cost $60 per tonne $5.4 $1.68 $1.0 ph Active Zone to 9 5 to 9 Alkali ph 30 kg/megalitre Alkali $500/tonne (Soda Ash) $15.00 Not usually required Not required Total direct delivered cost per megalitre $36.6 $24.0 $17.0 Total annual floc 40 megalitre WTP $380,640 $249,600 $176,800 Incremental annual operating saving in operations High Turbidity Water Labour cost ph adjustment (4hrs/day@$40/hr = $160/day) $40, Sludge removal per annum $ (Alum =5 tonne /day ACH = 1.0 tonnes/day) $45/tonne $60,000 $12,000 $12,000 Total Annual WTP cost $480,640 $261,600 $188,800 Annual Net Savings 0 $219,040 $291,840 A L C H L O R G O L D 14

15 CASE STUDY ANALYSIS ALUM (Al 2 0 ACH (Al 2 0 ALCHLOR GOLD (Al 2 0 Cost per kg $0.18 $0.80 $1.00 Dose kg/megalitre ( kg /day) 38 ( 1,520kg) 15 (600 kg) 10 (400 kg) Direct Cost /megalitre $6.84 $12.0 $10.0 Freight cost $60 per tonne (Bulk) $2.28 $1.00 $0.60 ph Active Zone to 9 5 to 9 Alkali ph 30 kg/mega litre Alkali $500/tonne (Soda Ash) $5.0 Not usually required Not required Total direct delivered cost per mega litre $14.0 $13.0 $10.6 Total annual floc 40 mega-litre WTP $145,600 $135,200 $110,240 Incremental annual operating saving in operations Low Turbidity Water Labour cost ph adjustment (2 = $80/day) $20, Sludge removal per annum $ (Alum =2 tonne /day ACH = 0.5 tonnes/day) $45/tonne? $24,000 $5,800 $5,800 Total Annual WTP cost $190,000 $141,000 $ Annual net savings 0 $49,000 $74,000 A L C H L O R G O L D 15

16 SUMMARY 1. Coagulant efficiency and performance is dependent on water quality. 2. Jar testing is absolutely essential to operations 3. Some form of Drinking Water Guidelines should be followed. Targets Thresholds 4. Sludge removal and ph adjustments adds to operational costs 5. Price of treatment is: cost of water produced (Not $/kg of coagulant) ALCHLOR GOLD 16

17 Courtney Keep A L C H L O R G O L D 17

Water Softening for Hardness Removal. Hardness in Water. Methods of Removing Hardness 5/1/15. WTRG18 Water Softening and Hardness

Water Softening for Hardness Removal. Hardness in Water. Methods of Removing Hardness 5/1/15. WTRG18 Water Softening and Hardness Water Softening for Removal 1 in Water High concentration of calcium (Ca2+) and magnesium (Mg2+) ions in water cause hardness Generally, water containing more than 100 mg/l of hardness expressed as calcium