Treatment Process
40%of exam
Equipment + Maintenance
30%of exam
Lab + Math
15%of exam
SamplingBODTSSFormulasLab Picker
Safety + Compliance
15%of exam
Quick Facts
- Exam
- Wastewater Treatment
- Body
- WPI/state authority
- Questions
- 100 scored
- Pretest
- Up to 10
- Time
- 3 hours
- Pass
- 70%
- Math
- About 10-14%
- Credential
- State issued
- Classes
- I-IV
- Blueprint
- 2025 NTK
Process Flow
Screen, settle, aerate, clarify, disinfect.
ScreenSettleAerateClarifyDisinfect
Preliminary vs Primary
Preliminary
- Screens/grit
- Equipment protection
- No BOD focus
Primary
- Settling/scum
- BOD reduction
- Primary sludge
Protect vs settle
Process Problem Picker
- High effluent TSS→Check clarifier(Blanket/weirs)
- Low DO→Increase aeration(Verify blowers)
- High SVI→Check bulking(Settleability)
- Dark old sludge→Increase wasting(Lower MCRT)
- Pin floc→Reduce wasting(Raise MCRT)
- Ammonia breakthrough→Check DO/SRT(Nitrifiers)
- Rising sludge→Remove blanket(Denitrification)
- Brown foam→Check age(Old sludge)
Process Flow
- Headworks
- Protect equipment
- Screening
- Remove large debris
- Grit
- Remove abrasives
- Primary
- Settle solids
- Aeration
- Biological oxidation
- Final clarifier
- Settle biomass
- Disinfection
- Reduce pathogens
- Solids
- Treat sludge
Sludge Levers
Air, RAS, WAS, time, food.
AirRASWASMCRTF/M
RAS vs WAS
RAS
- Returns biomass
- Maintains MLSS
- Controls blanket
WAS
- Removes biomass
- Controls MCRT
- Solids handling
Return vs remove
Preliminary + Primary
- Bar screen
- Catch rags
- Comminutor
- Shreds solids
- Grit chamber
- Settles sand
- Equalization
- Dampens peaks
- Primary sludge
- Settled organics
- Scum baffle
- Keeps floatables
- Weirs
- Even flow
- Short-circuiting
- Poor detention
Chlorine Control
Dose, mix, contact, residual, dechlor.
DoseMixContactResidualDechlor
MCRT vs F/M
MCRT
- Sludge age
- Solids time
- Wasting driven
F/M
- Food ratio
- Loading signal
- MLSS driven
Age vs loading
Activated Sludge
- MLSS
- Mixed solids
- MLVSS
- Volatile biomass
- DO
- Dissolved oxygen
- F/M
- Food to bugs
- MCRT
- Sludge age
- RAS
- Returned biomass
- WAS
- Wasted biomass
- SVI
- Settling index
Chlorine vs UV
Chlorine
- Chemical residual
- Contact basin
- May dechlorinate
UV
- Light dose
- No residual
- Clean lamps
Chemical vs light
Process Troubleshooting
- Bulking
- Poor settling
- Foaming
- Surface solids
- Rising sludge
- Denitrification lift
- Pin floc
- Young sludge
- Toxic shock
- Biomass upset
- Low DO
- Oxygen deficit
- Nitrification
- Ammonia removal
- Denitrification
- Nitrate removal
Nitrification vs Denitrification
Nitrification
- Ammonia to nitrate
- Needs oxygen
- Slow growers
Denitrification
- Nitrate to gas
- Needs anoxic
- Can lift sludge
Oxygen vs anoxic
Nutrients + Disinfection
- Ammonia
- Nitrifier food
- Nitrate
- Denitrifier target
- Anoxic
- No free oxygen
- Anaerobic
- No nitrate/oxygen
- Phosphorus
- Nutrient limit
- Chlorine
- Chemical disinfection
- UV
- Light disinfection
- Dechlorination
- Remove residual
Solids Handling
- Primary sludge
- Raw settled solids
- WAS
- Excess biomass
- Thickening
- Raise percent solids
- Digestion
- Stabilize sludge
- Dewatering
- Remove water
- Belt press
- Mechanical dewatering
- Centrifuge
- Spin separation
- Biosolids
- Treated solids
Clarifiers
- Primary clarifier
- Settle raw solids
- Secondary clarifier
- Settle biomass
- Sludge blanket
- Settled solids layer
- Weir loading
- Flow over weirs
- Scum skimmer
- Removes floatables
- Rake
- Moves sludge
- Hydraulic overload
- Too much flow
- Solids washout
- Effluent TSS
Fixed Film + Ponds
- Trickling filter
- Biofilm media
- RBC
- Rotating biofilm
- Biofilm
- Attached biomass
- Recirculation
- Improves wetting
- Pond
- Long detention
- Facultative
- Aerobic/anaerobic zones
- Lagoon
- Pond treatment
- Algae
- Oxygen source
Operator Controls
- Increase air
- Raise DO
- Decrease air
- Save oxygen
- Increase WAS
- Lower MCRT
- Decrease WAS
- Raise MCRT
- Increase RAS
- Lower blanket
- Check influent
- Find shock
- Verify lab
- Confirm data
- Trend data
- Avoid overreaction
Equipment Picker
- Screen headloss→Clean screen
- Pump cavitates→Check suction
- Blower trips→Check motor
- Diffusers clogged→Clean system
- Clarifier torque→Inspect drive
- Meter drift→Calibrate
- Valve stuck→Exercise valve
- SCADA alarm→Field verify
Equipment + Maintenance
- Pumps
- Move flow
- Blowers
- Supply air
- Diffusers
- Transfer oxygen
- Clarifier drive
- Moves scrapers
- Return lines
- Carry RAS
- Valves
- Control flow
- SCADA
- Monitor/control
- Calibration
- Verify instruments
Loading Factor
MGD times mg/L times 8.34.
MGDmg/L8.34lb/day
BOD vs TSS
BOD
- Oxygen demand
- Organic strength
- Biological load
TSS
- Suspended solids
- Clarifier performance
- Filter load
Demand vs particles
Lab Math Picker
- Need organic load→BOD loading
- Need solids load→TSS loading
- Need removal→Percent removal
- Need basin time→Detention time
- Need dose→Chemical dose
- Need sludge age→MCRT
- Need settling→SVI
- Need food ratio→F/M
Lab + Sampling
- Grab
- One-time sample
- Composite
- Time/flow blend
- BOD
- Oxygen demand
- CBOD
- Carbonaceous demand
- TSS
- Suspended solids
- pH
- Acidity intensity
- DO
- Available oxygen
- Residual
- Chlorine remaining
Grab vs Composite
Grab
- Single moment
- Fast changes
- pH/residual
Composite
- Blended sample
- Average loading
- Time/flow based
Moment vs average
Math Formulas
- Loading
- MGD x mg/L x 8.34
- Removal
- In-out / in
- Detention
- Volume / flow
- Dose
- Feed / flow
- F/M
- Food / MLSS
- SVI
- Settle volume / MLSS
- MCRT
- Solids in / solids out
- MGD
- Million gal/day
Confined Space
Test, ventilate, permit, monitor, rescue.
TestVentilatePermitMonitorRescue
NPDES vs SOP
NPDES
- Permit limits
- Discharge rules
- DMR reporting
SOP
- Plant procedure
- Operator steps
- Local method
Permit vs procedure
Compliance Picker
- Enter tank→Permit space
- Service pump→LOTO
- Chlorine leak→Evacuate/isolate
- Low O2→Ventilate/no entry
- Permit exceedance→Notify/report
- Sample transfer→Chain custody
- Chemical splash→Eyewash
- Power outage→Emergency plan
Safety + Compliance
- Confined space
- Permit entry
- LOTO
- Zero energy
- HazCom
- Chemical hazards
- H2S
- Toxic gas
- LEL
- Explosion limit
- NPDES
- Discharge permit
- DMR
- Monitoring report
- SOP
- Standard procedure
Common Traps
Pass vs certification
State certifies ≠ Exam alone does not
Air vs mixing
Air adds oxygen ≠ Mixing suspends solids
RAS vs WAS
RAS returns biomass ≠ WAS removes biomass
Dose vs residual
Dose is applied ≠ Residual remains after
Old vs young sludge
Old: dark foam ≠ Young: pin floc
Grab vs composite
Grab is moment ≠ Composite blends time
Permit vs process
NPDES sets limits ≠ Operations meet limits
pH vs alkalinity
pH is intensity ≠ Alkalinity buffers change
Last Minute
- 1.Follow flow sequence
- 2.Protect headworks equipment
- 3.Control DO and solids
- 4.RAS returns biomass
- 5.WAS controls sludge age
- 6.SVI shows settleability
- 7.Check lab QA/QC
- 8.Use 8.34 loading factor
- 9.Dechlorinate before discharge
- 10.LOTO before maintenance
- 11.Permit confined spaces
- 12.NPDES drives reporting
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