Program Fundamentals of Wastewater Treatment Fundamentals of Wastewater Treatment Wastewater Treatment Activated sludge processes Fixed film and suspended processes Aerobicanoxicanaerobic processes modifications ID: 426387
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Slide1
Chemical Security
Program
Fundamentals
of Wastewater TreatmentSlide2
Fundamentals of Wastewater TreatmentSlide3
Wastewater Treatment
Activated sludge processes
Fixed film and suspended processes
Aerobic/anoxic/anaerobic processes modifications.Nutrient removal nitrification / denitrification, phosphorous removalWater reuse and reclamation membrane bioreactorsDisinfectionSatellite and On-site Wastewater Treatment
3Slide4
4
Wastewater
Contaminants
Bacteriological,
Vibrio
Cholerae
, Campylobacter, Salmonella ,
Shigella
,
Viruses
Hepatitis A, Norovirus
Protozoan
Giardia, Cryptosporidium,
Entamoeba
Biological
oxygen demand
Organic matter causes algae to thrive and deplete dissolved oxygen
Nutrient
removal to prevent eutrophication
Nitrogen and phosphorus from waste, and agricultureSlide5
What
Does Wastewater Look Like
?
5
Measurement
Value
Units
Total Suspended Solids (TSS)
210
mg/L
BOD
190
mg/LTOC 430mg/LCOD 140mg/LOrganic Nitrogen15mg/LFree Ammonia25 mg/LNitrite/Nitrate0/0 mg/LPhosphorous7mg/LTotal coliform107-109 colonies/100mLFecal coliform104-106 colonies/100mLCryptospiridium oocysts0.1-10 no./100mLGiardia Lamblia0.1-100no./100mL
Source: Wastewater Engineering, Metcalf and Eddy- medium strength WWSlide6
Routine
Bacterial Testing Consists
of Measuring Indicator Organisms
6Testing for pathogens directly is expensive and hazardous
Indicators from the family
Enterobacteriacae
are used
(E. Coli,
Citrobacter,Enterobacter
,
Klebsiella
)Grow bacteria on a specified medai and count the number of colonies after incubationOther assays are used and are approved by the US EPA (Colilert shown)Slide7
Initial
Steps
in Satellite and
Centralized Wastewater Treatment7
Fixed film process
Primary settling
Screens
Sludge drying
Grit removal
DigesterSlide8
Fixed
Film Biological Processes
8
Treated Water
Waste Water
Facultative/Anaerobic
Bed Media
Aerobic
100µm
~
1 mm
BiofilmSlide9
Fixed
Film Biological Processes
9
Trickling filter
Uses biofilm to treat water to remove BODSlide10
Trickling
Filter Effectiveness
10
BOD
5
removal rates for trickling filters
Filter Type
Hydraulic loading m
3
/m
2
day
BOD5 Removal (%)Low Rate1-480 - 90Intermediate 4-1050 - 70High Rate10-4065 - 85Roughing Filter 40 - 65Source: Environmental Engineers Handbook, 1997.Slide11
Suspended
Growth Biological Processes
11
Anoxic – no dissolved oxygen
Waste Water
Aerobic
Treated Water
Activated Sludge
Anoxic
sludge
Return activated sludge
Coagulation
ClarifierSlide12
BOD and
Nutrient
(Nitrogen and
Phosphorous) Removal 12
Aerobic Conditions
Anoxic Conditions
BOD + O
2
CO
2
+ increased cell mass
NO
3 Organic NNH4NO2 NO3 N2 Aerobic ConditionsPincreased cell massAnaerobic/Aerobic ConditionsAlumorganic sludgeinorganic sludgeSlide13
Suspended
Growth Activated Sludge Processes Requires Energy
13
Use forced air suspension of biological sludge to reduce BOD
Largest expense for this process is the electrical energy requiredSlide14
14
Anoxic Basin
Sedimentation
Final Clarification
Aerobic Basin
Activated
Sludge Process StagesSlide15
Anaerobic
Sludge Digestion Reduces
Solids -
Makes Methane15
Anaerobic sludge digestors produce methane
(65% CH
4
- 35% CO
2
)
On-site electricity is produced with the methane 50% of plant power (2.2MW)Slide16
Liquid
Process Train
16
Aeration
Sedimentation
Sedimentation
Solids Handling
N
org
NH
3+NH3+ NO2NO2 N2MixingC6H14 Biomass + CO2Slide17
Exemplary
Process Stages
17
Modified Ludzack-Ettinger (MLE Process)
A
2
O
Bardenpho
RAS = Return Activated Sludge
WAS = Waste Activated SludgeSlide18
18
CH
4
+ CO
2
C
6
H
14
+ H
2
O
Anaerobic Fermentation (30 days)Aeration Blowers6.6 MWDisposal or Reuse (150 t/day)Diesel GeneratorsBiosolidsCentrifugesPNMSolids Handling Involves Anaerobic ConditionsSlide19
A Typical
Process :
19
NH
3
+
Settling & Aeration
Fermentation
River
Sewers
CO
2
N2CH4MicrobesCompostingCO2H2OH2O+C+N+SO2HumusHeatPowerH2SCO2HOCl-SO2(Biosolids)Slide20
Water
Reuse Often Uses Membrane Bioreactor
with Submerged Membranes
20
Uses submerged hollow fiber membranes
High Solids Retention Time membrane bioreactor
Conventional activated sludge plant
MBR membrane cassetteSlide21
21
Screens
Anoxic
Aerobic
Submerged Membrane
Membrane
Bioreactors Offer Small Size
,
High Rate
of
Reaction
for
Satellite
WWSlide22
Membrane
Separation Spectrum
22
Source: Zenon MembranesSlide23
Screen
Before Membrane Bio Reactor
23Slide24
Kubota MBR
Pilot Plant
24Slide25
25
Raw
Feed
and MBR P
roductSlide26
26
RO treated water is better than most surface water sources
Reverse
Osmosis After
MBR
Makes Water Suitable
for
Groundwater RechargeSlide27
Hyperion Wastewater Plant
Los Angeles 450
mgd
27
10% of discharge from this plant is sent to microfiltration plant to purify for groundwater injectionSlide28
West Basin Microfiltration Plant
(35
mgd from Hyperion)
28
Submerged microfiltration for treated wastewater effluentSlide29
The
Final Step
is Disinfection and
Discharge (No Residual Free Chlorine)29
Chlorination to kill the remaining pathogens
Cl
2
HOCl
Dechlorination
to remove chlorineSO2 + HOCl + H2O HCl + H2SO4SO2 + NH2Cl + 2H2O NH4Cl + H2SO4UV radiation reduces chemical needs and chlorinated productsSlide30
Effect of
Wastewater
on Disinfection
30
Chlorine
Ozone
UV
BOD,COD,TOC
Chlorine demand
Ozone demand
Little effect
Oil and grease
Chlorine demandOzone demandMay block lightNitriteForms NDMAOxidized No effectNitrateForms chloraminesReduce O3effectivenessNo effectIron and ManganeseOxidizedOxidizedMay block lightForms disinfection byproductsYesYes, but nonchlorinatedNoSource: Wastewater Engineering- Metcalf & EddySlide31
Satellite and
On-site Waste Disposal
Satellite facilities are mid scale sewage treatment plants that treat waste near the point of generation
LagoonsAeration ditchesTrickling filters
Membrane bioreactor
On-site
waste disposal is septic tank system with drain field
Provides low cost alternative
Can be very effective
Need little maintenance (but maintenance is important)
31