LIQUID / SOLIDS SEPARATION IN WASTEWATER TREATMENT ...

1 LIQUID / SOLIDS SEPARATION IN. WASTEWATER TREATMENT &. BIOSOLIDS DEWATERING. Chemical Products Lab Testing Plant Trials LIQUID / SOLIDS SEPARATION . APPLICATIONS. Influent Water Clarification Process Water Recycling Primary WASTEWATER Clarification Secondary Clarification Sludge Thickening Sludge Dewatering LIQUID / SOLIDS SEPARATION . UNIT OPERATIONS. Clarifiers (Many Types). WATER. Filters (Many Types). OR. WASTE Dissolved Air Flotation Units WATER Induced Air/Gas Flotation Units Belt Presses Centrifuges SLUDGE. Screw Presses DEWATERING. Plate and Frame Presses vacuum Filters ( rotary & Horizontal). LIQUID / SOLIDS SEPARATION . PRODUCT TYPES. Coagulants (+) Low Mol Wt Organic Inorganic Blended Flocculants (+ , - , 0 ) High Mol Wt Dry Emulsion Solution Oil- Oil-Free Flocculants COAGULANTS AND FLOCCULANTS. Act on Insoluble Particles in Water Oils, Grease, Blood, Insoluble Organics, Clay, Silicates, Metal Oxides/Hydroxides Dirt, Dust, Rust & Metal Filings Can Act on Charged Organic Compounds Anionic Surfactants, Soaps & Dispersants Do Not Act on Most Dissolved SOLIDS Salts, Acids, Nonionic Surfactants, Ammonia or Soluble Organic Compounds such as Sugar, Alcohols, etc.

2 SUSPENSION CHEMISTRY. THE KEY TO EFFECTIVE. LIQUID / SOLIDS SEPARATION . SUSPENDED SOLIDS VARIABLES. Surface Charge MOST. Charge Density Particle Size IMPORTANCE. Composition Particle Density Particle Shape LEAST. MICROSCOPIC FORCES. ELECTROSTATIC. BROWNIAN. VAN DER WAALS. GRAVITY. Colloidal Particle in Water + +. +. + + + +. + + + Almost all Particles + + + + of Industrial Interest Have a Negative + + + Surface Charge. + + + +. The Particle is + + + + Surrounded by an + Equal Number of + + + Positive Counterions. + + +. + + + +. + +. PARTICLES IN WATER REPEL EACH OTHER. +. + + ++ + + + + +. + + + + +. + + + + + +. + + + + +. + + +. + + + +. + +. + + +. ++ +. + + + + +. +. +. + + + + +. +. + + + + +. + + + + + + + + + +. + + + + +. Colloidal Particle in Water + +. + + + + OF EXCESS. RATIO. +. + + +. CATIONS. + + + +. + +. +. + +. + + EQUAL. + + + + NUMBER. OF POSITIVE. AND NEGATIVE. + + + CHARGES.

3 +. + + +. + + + +. + + DISTANCE FROM PARTICLE. ADSORPTION OF CATIONIC POLYMER. NEUTRALIZES CHARGES AND COLLAPSES FIELDS. Van der Waals Force of Attraction Now Stronger Than The Electrical Force of Repulsion NEUTRALIZED PARTICLES COAGULATE. STOKE'S LAW: = 2Gr2 ( . ) / 9 . = SETTLING RATE. G= GRAVITATIONAL CONSTANT. r= RADIUS OF PARTICLE. = DENSITY OF PARTICLE. o = DENSITY OF LIQUID . = VISCOSITY OF LIQUID . BIGGER SETTLES FASTER. Effect of Decreasing Particle Size MATERIAL DIAMETER SETTLING TIME. (in mm) PER METER. Gravel 10 1 second Course sand 1 10 seconds Fine sand 2 minutes Silt 90 minutes Bacteria 1 week Colloidal particles 2 years Colloidal particles 20 years Colloidal particles 200 years EFFECT OF COAGULATION AND. FLOCCULATION. MANY FEWER. SMALL LARGE. OPTIMUM MIXING FOR. CLARIFICATION APPLICATIONS. COAGULANT FLOCCULANT. NO MIXING. EFFLUENT. STATIC. MIXER. LIQUID . INFLUENT FAST SLOW. SLUDGE. CHARGE BRIDGING SETTLING.

4 NEUTRALIZATION + OF FLOCS. + FLOC. INTER-PARTICLE GROWTH. COLLISIONS. COAGULATION PROCESS. Adsorption of Cationic Coagulant Neutralizes Negative Surface Charges Reduces Electrical Barrier Allows Van der Waals Forces to Predominate Interparticle Collisions Brownian Motion Mixing Energy Primary Particles Stick Together FLOCCULATION. + =. SOLIDS FLOCCULANT FLOC. COAGULATION AND FLOCCULATION. Coagulation Charge Neutralization Rapid Mixing (High Shear). Promotes Interparticle Collisions Flocculation Bridging of Microflocs Slow Mixing (Low Shear). Builds Floc Size TYPICAL CLARIFICATION PROGRAM. Add Cationic Coagulant to Neutralize Anionic Charges on Particles Add Anionic Flocculant to Bridge Neutralized Particles NOTES: (1) Coagulants should be be pre-diluted in water for best results (2) Flocculants MUST be pre-diluted in water for any results (3) Add cationic coagulant as far back in the line as possible (4) Do not add anionic flocculant too close to cationic coagulant Primary / Secondary WASTEWATER TREATMENT System FINAL OR.

5 2' EFFLUENT. 1' EFF AERATION SECONDARY. WASTE PRIMARY BASIN CLARIFIER. CLARIFIER MIXED LIQUOR. WATER. RETURN ACTIVATED. SLUDGE (RAS). WASTE ACTIVATED. SLUDGE (WAS). PRIMARY SLUDGE SLUDGE. DIGESTER or HOLDING TANK. LIQUID PHASE. SLUDGE. SLUDGE CAKE. FILTRATE, CENTRATE, PRESSATE DEWATERING. POLYMER CHEMISTRY. VERSATILITY IS A MUST. COAGULANTS. EPI / DMA POLYMER. AKA EPICHLOROHYDRIN - DIMETHYLAMINE. OH CH3. [ CH3 Cl- ]. -------- CH2 - CH - CH2 - N+ ---------------- n CAS NUMBER: 42751-79-1. POLY [DADMAC] POLYMER. AKA POLY DIALLYLDIMETHYL AMMONIUM CHLORIDE. AKA POLY [DMDAAC]. [ H2C CH2. ]. -------- CH2 - CH ---- CH - CH2 --------- n N+ .. Cl- H3C CH3. CAS NUMBER: 26062-79-3. INORGANIC COAGULANTS. Aluminum Sulfate: Al2(SO4)3. Aluminum Chloride: AlCl3. Polyaluminum Chloride (PAC). Aluminum Chlorohydrate (ACH). Ferric Chloride: FeCl3. Ferric Sulfate: Fe2(SO4)3. Ferrous Sulfate: FeSO4. Sodium Aluminate: Na2Al2O4.

6 HYDROLYSIS OF ALUMINUM (III). 1,1. 1,0 1,4. Log Soluble [Al]. 1,2. 1,3. 2 3 4 5 6 7 8 9 10 11. System pH. HYDROLYSIS OF IRON (III). 1,0. Log Soluble [Al]. 1,1. 1,2 1,4. 1,3. 2 3 4 5 6 7 8 9 10 11. System pH. DEPRESSION OF SYSTEM pH. WITH ALUMINUM or FERRIC SALTS. DOSAGE OF CALCULATED. 28% ACTIVE FINAL pH. 1 ppm 10 ppm 100 ppm 1000 ppm ASSUMES UNBUFFERED WATER STARTING AT pH = ORGANIC COAGULANTS. ADVANTAGES OVER INORGANICS. Sludge Volume Reduction Larger, More Stable Floc Less Pinfloc and Carryover Lower Flocculant Requirements Work Over Wide pH Range (2- (2-12). Do Not Change System pH. Lower Caustic Requirements INORGANIC COAGULANTS. ADVANTAGES OVER ORGANICS. Inorganics Can Produce Very Low Turbidity Waters Because the Metal Hydroxides Can Sweep Fine Particles from Suspension Low Price per Pound Looks Very Attractive to Purchasing Agents FLOCCULANTS. NONIONIC MONOMER. ACRYLAMIDE. O. CH2 = CH - C - NH2.)

7 AM. ANIONIC MONOMER. ACRYLIC ACID. O. _. +. CH2 = CH - C O H. AA. CATIONIC MONOMERS. AETAC. Q-9. +. POLYACRYLAMIDE. CH2 - CH - CH2 - CH - CH2 - CH. C=O C=O C=O. NH2 NH2 NH2. POLYMER SHORTHAND. POLYACRYLAMIDE. H. CH2 C. C=O. NH2. n n is about 282,000 @ 20 million Molecular Weight HOMOPOLYMERIZATION. YELLOW = ACRYLAMIDE. FLOCCULANTS ARE TYPICALLY 200,000+ MONOMERS. ANIONIC. POLYACRYLAMIDE. COPOLYMER. aka AM/SA. ANIONIC POLYACRYLAMIDE. H H. CH2 C CH2 - C. C=O C=O. NH2 O. m Na+. n RANDOM COPOLYMER. m+n=1. COPOLYMERIZATION. YELLOW = ACRYLAMIDE; RED = ACRYLATE. 25% ANIONIC CHARGE. COPOLYMERIZATION. YELLOW = ACRYLAMIDE; RED = ACRYLATE. 50% ANIONIC CHARGE. CATIONIC. POLYACRYLAMIDE. COPOLYMER. aka AM/Q9. CATIONIC POLYACRYLAMIDE. H R'. CH2 C CH2 - C. C=O C=O. NH2 O. m (CH2)2. +. RANDOM COPOLYMER H3C N CH3. m+n=1. n CH3 Cl COPOLYMERIZATION. YELLOW = ACRYLAMIDE; BLUE = CAT. 10% CATIONIC CHARGE. COPOLYMERIZATION.

8 YELLOW = ACRYLAMIDE; BLUE = CAT. 25% CATIONIC CHARGE. COPOLYMERIZATION. YELLOW = ACRYLAMIDE; BLUE = CAT. 50% CATIONIC CHARGE. NUMBER OF MOLECULES TYPICAL MOL-WT DISTRIBUTION. RESIDUAL THIS PRODUCT WOULD. HAVE AN AVG MOL-WT. MONOMER OF ~7 MILLION. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15. MOLECULAR WEIGHT IN MILLIONS. TYPICAL MOL-WT DISTRIBUTIONS. CATIONICS ANIONICS. NUMBER OF MOLECULES. 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30. MOLECULAR WEIGHT IN MILLIONS. LINEAR POLYMER STRUCTURE. LIGHTLY BRANCHED. POLYMER STRUCTURE. HIGHLY BRANCHED. POLYMER STRUCTURE. CROSS- CROSS-LINKED POLYMER STRUCTURE. ASHLAND WATER TECHNOLOGIES. EMULSION POLYMER PRODUCT LINE. 20. 18. RELATIVE MOLECULAR WEIGHT. 16. 14. 12. 10. 8. 6. 4. -40 -30 -20 -10 0 +10 +20 +30 +40 +50 +60 +70 +80. RELATIVE POLYMER CHARGE. GENERAL INDUSTRIAL COAGULANT AIDS. 20. 18. RELATIVE MOLECULAR WEIGHT. 16. 14. 12. 10. 8. 6. 4. -40 -30 -20 -10 0 +10 +20 +30 +40 +50 +60 +70 +80.

9 RELATIVE POLYMER CHARGE. MINING FLOCCULANTS. 20. 18. RELATIVE MOLECULAR WEIGHT. 16. 14. 12. 10. 8. 6. 4. -40 -30 -20 -10 0 +10 +20 +30 +40 +50 +60 +70 +80. RELATIVE POLYMER CHARGE. LOW pH SYSTEM FLOCCULANTS. 20. 18. RELATIVE MOLECULAR WEIGHT. 16. 14. 12. 10. 8. 6. 4. -40 -30 -20 -10 0 +10 +20 +30 +40 +50 +60 +70 +80. RELATIVE POLYMER CHARGE. BIOSOLIDS DEWATERING FLOCCULANTS. 20. 18. RELATIVE MOLECULAR WEIGHT. 16. 14. 12. 10. 8. 6. 4. -40 -30 -20 -10 0 +10 +20 +30 +40 +50 +60 +70 +80. RELATIVE POLYMER CHARGE. DEWATERING VERY YOUNG. HIGH F/M PURE BIOSLUDGES. 20. 18. RELATIVE MOLECULAR WEIGHT. 16. 14. 12. 10. 8. 6. 4. -40 -30 -20 -10 0 +10 +20 +30 +40 +50 +60 +70 +80. RELATIVE POLYMER CHARGE. MIXED PRIMARY/SECONDARY. DEWATERING FLOCCULANTS. 20. 18. RELATIVE MOLECULAR WEIGHT. 16. 14. 12. 10. 8. 6. 4. -40 -30 -20 -10 0 +10 +20 +30 +40 +50 +60 +70 +80. RELATIVE POLYMER CHARGE. PAPER MILL SLUDGE. DEWATERING FLOCCULANTS.

10 20. 18. RELATIVE MOLECULAR WEIGHT. 16. 14. 12. 10. 8. 6. 4. -40 -30 -20 -10 0 +10 +20 +30 +40 +50 +60 +70 +80. RELATIVE POLYMER CHARGE. PAPER MILL PRIMARY TREATMENT . 20. 18. RELATIVE MOLECULAR WEIGHT. 16. 14. 12. 10. 8. 6. 4. -40 -30 -20 -10 0 +10 +20 +30 +40 +50 +60 +70 +80. RELATIVE POLYMER CHARGE. WATER & WASTEWATER . TREATMENT LAB TESTS. PREPARING SOLUTIONS. Organic, Inorganic & Blended Coagulants Recommended Concentration: 1 - 10%. Use Correction Due to High Density Emulsion Flocculants Recommended Concentration: - Density Correction Unnecessary Dry Flocculants Recommended Concentration: - Requires Accurate Balance ( +/- +/- g Minimum). PROCEDURE FOR 1%. COAGULANT SOLUTIONS. Fill a 4 oz Bottle with 99 mls of Water Determine Volume of Coagulant = gram VOL = 1 / ; Where = Specific Gravity Specific Gravity; = D / ; Where D = lbs/gal Add Coagulant to the Water and Cap Bottle Shake Well Until Dissolved (~30 sec).