13200148 advanced waste water treament
TRANSCRIPT
-
8/2/2019 13200148 Advanced Waste Water Treament
1/31
Advanced wastewater treatment
Gyeongsang National UniversityDepartment of Biological and chemical EngineeringEnvironmental Engineering Lab
Ngoc Thuan Le
-
8/2/2019 13200148 Advanced Waste Water Treament
2/31
2
Need for advanced wastewater treatment
1. Remove organic matter and TSS to meet more stringent discharge andreuse requirements.
2. Remove TSS for more effective disinfection.
3. Remove nutrients contained to limit eutrophication of sensitive waterbodies.
4. Remove specific inorganic (e.g., heavy metals) and organic constituents(e.g., MTBE) to meet more stringent discharge and reuse requirementsboth surface water and land-based effluent dispersal and for indirectpotable reuse application.
5. Remove specific inorganic and inorganic constituents for industrial reuse(e.g., cooling water, process water).
-
8/2/2019 13200148 Advanced Waste Water Treament
3/31
3
Technologies used for advanced treatment
1. Removal of organic and inorganic colloidal and suspended solids(suspended solids, organic matters), using filtration
Depth filtration Surface filtration Membrane filtratration
-
8/2/2019 13200148 Advanced Waste Water Treament
4/31
4
Depth filtration Surface filtration
-
8/2/2019 13200148 Advanced Waste Water Treament
5/31
5
2. Removal of dissolved organic constituents (total organic carbon,refractory organic, volatile organic compounds)
Carbon adsorption Reverse osmosis Chemical precipitation Chemical oxidation Advanced chemical oxidation Electrodialysis Distillation
3. Removal of dissolved inorganic constituents (ammonia, nitrate, nitrite,phosphorus, total dissolved solids)
Chemical precipitation Ion exchange Ultrafiltration Reverse osmosis Electrodialysis Distillation
-
8/2/2019 13200148 Advanced Waste Water Treament
6/31
6
4. Removal of biological constituents (bacteria, protozoan cysts andoocysts, viruses)
Depth filtration Micro and ultrafiltration Reverse osmosis Electrodialysis
Distillation
Because the effectiveness of the unit operations and processes listed isvariable, disinfection of the treated effluent is required for most
application
-
8/2/2019 13200148 Advanced Waste Water Treament
7/317
Introduction to depth filtration
a. Flow during filtration cycleb. Flow during backwash cycle
Grain size is the principal filter mediumcharacteristic that affects the filtrationoperation
-
8/2/2019 13200148 Advanced Waste Water Treament
8/318
Particle removal mechanisms
a. By strainingb. By sedimentation or inertial impactionc. By interception
d. By adhesione. By flocculation
Other phenomena: chemical/physical adsorption or biological growth
-
8/2/2019 13200148 Advanced Waste Water Treament
9/319
Selection and design considerations for depth filters
1. Selection and design filter technologies must be based on: Knowledge of the types of filters that are available A general understanding of their performance characteristics An appreciation of the process variables controlling depth filtration
2. Design for effluent filtration systems include: Influent wastewater characteristics Design and operation of the biological treatment process Type of filtration technology to be used Available flow-control options Type of filter backwashing system Filter control systems and intrumentation
-
8/2/2019 13200148 Advanced Waste Water Treament
10/3110
Available filtration technologies
a. Conventional mono-mediumdownflow filter b. Conventional dual-mediumdownflow filter c. Conventional mono-mediumdeep-bed downflow filter
d. Continuous backwash deep-bedupflow filter
e. Pulse-bed filter f. Traveling-bridge filter
-
8/2/2019 13200148 Advanced Waste Water Treament
11/3111
Synthetic-medium filter High pressure filter
Slow sand filter
-
8/2/2019 13200148 Advanced Waste Water Treament
12/31
12
Two-stage filtration
A large size sand diameter is used in the first filter to increase the contact time and to minimizecloggingA smaller sand size is used in the second filter to remove residual particles from the first stage filter
-
8/2/2019 13200148 Advanced Waste Water Treament
13/31
13
Effluent filtration with chemical addition
To achieve specific treatment objectives including removal of specificcontaminants
Phosphorus Metal ions
Humic substances
Chemicals commonly used in effluent filtration Organic polymers (cationic, anionic, or nonionic (no charge) Alum and ferric compounds (chloride)
-
8/2/2019 13200148 Advanced Waste Water Treament
14/31
14
Surface filtration
Materials: woven metal fabrics, cloth fabrics of different weaves, and variety of synthetic materialsSurface filters have openings in size range from 10 to 30m. In membrane filters the pore size can varyfrom 0.0001 to 1.0m
-
8/2/2019 13200148 Advanced Waste Water Treament
15/31
15
Membrane filtration
Materials: different organic or inorganic materials: polypropylene, cellulose acetate, aromatic polyamides,and thin film composite (TFC).
Membranceprocess
Membranedriving force
Typicalseparationmechanism
Operatingstructure(pore size)
Typicaloperatingrange, m
Permeatedescription
Typical constituentsremoved
Microfiltration Hydrostaticpressure difference sieve Macropores (>50nm) 0.08-2.0 Water+dissolvedsolutes TSS, turbidity, protozoan,some bacteria and viruses
Ultrafiltration Hydrostaticpressure difference
sieve Mesopores(2-50nm)
0.005-0.2 Water+smallmolecules
Macromolecules, colloids,most bacteria, someviruses, protein
Nanofiltration Hydrostaticpressure difference
sieve+solution/diffusion+exclusion
Micropores(
-
8/2/2019 13200148 Advanced Waste Water Treament
16/31
16
Reverse osmosis (RO)
When two solutions having different solute concentrations are separated by a semipermeable membrane, a difference in chemical potential will exist across themembrane
RO is used for the removal of dissolved constituents from the wastewater remainingafter advanced treatment with depth filtration of microfiltration.
a. Osmotic flowb. Osmotic equilibrium
c. Reverse osmosis
-
8/2/2019 13200148 Advanced Waste Water Treament
17/31
17
Electrodialysis (ED) In the electrodialysis process, ionic components of a solution are separated through the use of
semipereable ion-selective membrane The current required for electrodialysis can be estimated by Faradays Laws of electrolysis
Where:I = current, ampF = Faradays constant
= 96,485amp.s/gram equivalent = 96,485A.s/eq
n = number of cell in the stackEc = current efficiency expressed as a
fraction
nEc
FQN I
-
8/2/2019 13200148 Advanced Waste Water Treament
18/31
18
Adsorption
Adsorptionis the process of accumulation substances that are in solution on a suitable interface
Types of adsorbents: activated carbon, synthetic polymeric, and silica-based adsorbents Activated carbon: (1)powdered activated carbon (PAC), a diameter of less than 0.074mm (200
sieve), and (2)granular activated carbon (GAC), a diameter greater than 0.1mm (140 sieve)
Parameter Unit Type of activated carbon
GAC PAC
Total surface area m2 /g 700-1300 800-1800
Bulk density kg/m3 400-500 360-740
Particle density, wetted in water kg/l 1.0-1.5 1.3-1.4
Particle size range mm (m) 0.1-2.36 (5-50)
Effective size mm 0.6-0.9 na
Uniformity coefficient UC 1.9 na
Mean pore radius 16-30 20-40
Iodine number 600-1100 800-1200
Abrasion number minimum 75-85 70-80
Ash % 8 6
Moisture as packed % 2-8 3-10
-
8/2/2019 13200148 Advanced Waste Water Treament
19/31
19
Fundamentals of adsorption Absorbent phase concentration data
Where:q e = absorbent (solids) phase concentration
after equilibrium, mg adsorbate/gadsorbent
C o = initial concentration of adsorbate, mg/LC e = final equilibrium concentration of
adsorbate after absorption hasoccurred, mg/L
V = volume of liquid in the reactor, Lm = mass of absorbent, g
m
V C C q ee
)( 0
-
8/2/2019 13200148 Advanced Waste Water Treament
20/31
20
Types of activated carbon contactors
-
8/2/2019 13200148 Advanced Waste Water Treament
21/31
21
Gas stripping
Gas strippinginvolves the mass transfer of a gas from the liquid phase to the gas phase.
Considerable attention: remove ammonia, odorous gases and volatile organic compounds (VOCs)
Countercurrent flow Current flowCross flow
Typical water and airflow patterns for gas stripping towers
-
8/2/2019 13200148 Advanced Waste Water Treament
22/31
22
Typical stripping towers for the removal of volatile gases from water
-
8/2/2019 13200148 Advanced Waste Water Treament
23/31
23
ION EXCHANGE
Ion exchangeis a unit process in which ions of a given species are displaced from aninsoluble exchange material by ions of a different species in solution. Domestic water softening: where sodium ions from a cationic-exchange resin replace
the calcium and magnesium ions in the treated water. Ion exchange has been used in wastewater application for removal of nitrogen, heavy
metals, and total dissolved solids
Ion-exchange materials: Naturally, zeolites (complex of aluminosilicates with sodium) Synthetic ion-exchange material: resins or phenolic polymers
1. Strong-acid cation2. Weak-acid cation3. Strong-base anion4. Weak-base anion5. Heavy-metal selective chelating resins
-
8/2/2019 13200148 Advanced Waste Water Treament
24/31
24
Typical ion-exchange reaction For natural zeolite (Z)
Ca2+ Ca2+ZNa+ + Mg2+ Z Mg2+ + 2Na+
Fe2+ Fe2+
For synthetic resin (R)
Strong acid cation exchange:RSO3H + Na+ RSO3Na + H+2RSO3Na + Ca+2 (RSO3)2Ca + 2Na+
Weak acid cation exchange:
RCOOH + Na+ RCOONa + H+
2RCOONa + Ca+2 (RCOO)2Ca + 2Na+Strong-base anion exchange:
RR3NOH + Cl- RR3NCl + OH-Weak-base anion exchange:
RNH3OH + Cl- RNH3Cl + OH-2RNH3Cl + SO42- (RNH3)2SO4 + 2Cl-
-
8/2/2019 13200148 Advanced Waste Water Treament
25/31
25
Application of ion-exchange
Typical flow diagram for the removal of ammonia by zeolite exchange
-
8/2/2019 13200148 Advanced Waste Water Treament
26/31
26
Application of ion-exchange
Typical flow diagram for the removal of hardness and for the completedemineralization of water
-
8/2/2019 13200148 Advanced Waste Water Treament
27/31
27
Oxidizing agents:
ozone (O3),
hydrogen peroxide (H 2O2),
permanganate (MnO 4),
chloride dioxide (ClO 2),
chlorine (Cl 2) or (HClO) andoxygen (O 2)
For reduction of:
BOD,
COD,ammonia,
nonbiodegradable organic compounds.
Chemical oxidation
-
8/2/2019 13200148 Advanced Waste Water Treament
28/31
28
Phosphate precipitation with aluminum and iron
Al 3+ + H nPO 43-n AlPO 4 + nH
Fe3+ + H nPO 43-n FePO 4 + nH
There are many competing reactions because of the effects of alkalinity, pH,trace elements, and ligands in wastewater
Dosages are established of bench scale test and occasionally by full scale tests.
-
8/2/2019 13200148 Advanced Waste Water Treament
29/31
29
Ozone/Hydrogen peroxide
H2O2 + 2O3 HO* + HO* +3O2
-
8/2/2019 13200148 Advanced Waste Water Treament
30/31
30
DISTILLATION
Distillationis a unit operation in which the components of a liquid solution are separated byvaporization and condensation.
-
8/2/2019 13200148 Advanced Waste Water Treament
31/31
Thank you for your attention!