1. CHEE 370 Waste Treatment Processes
Lecture #5-Wastewater Treatment Process

2. Review: WW Characterization
Solids content
TS, TSS, TDS, VS (organic), FS (inorganic)
Organic content
BOD, COD, TOC, ThOD
Micro-organisms
Total coliform, fecal coliform
Toxicity
Acute toxicity (LC50), Chronic toxicity
Nutrients
TKN, NH3, TP, ortho-phosphate
Flowrates
Hydraulic flowrates (peak and min), Loadings

3. Municipal WW Effluent (MWWE) Guidelines and Regulations

5. Management of MWWE More than 3500 WWTP in Canada No real “standard”
Treatment strategies range from no treatment to state of the art
In many systems, during wet weather the combined sewer outflow (CSO) of the sewer system and storm water system often exceeds total hydraulic capacity of the plant
Kingston has this particular problem!!!
Problems with aging infrastructure

9. Data for 1999

10. Legislation Municipalities are responsible for WW management
Provincial governments are responsible for regulating the operation of WWTP
There is currently no federal legislation on municipal WW effluent
Fisheries Act
Canadian Environmental Protection Act, 1999

11. Proposed Canada-wide Strategy for the Management of MWWE
Drafted Oct. 2007

12. Facility Size Categories
Flow (Q) [m3/d]
Very Small
Q ≤ 500
Small
500 < Q ≤ 2500
Medium
2500 < Q ≤ 17500
Large
17500 < Q ≤ 50000
Very Large
Q > 50000

13. National Performance Standards
Effluent from all treatment plants must satisfy:
CBOD5 ≤ 25 mg/L
TSS ≤ 25 mg/L
Total Residual Chlorine (TRC) ≤ 0.02 mg/L
Ammonia: Based on acute and chronic toxicity
TSS and CBOD5 values can be averaged:
Very Small - Medium WWTP: Quarterly
Large or Very Large WWTP: Monthly
Consider changes in TSS and BOD5 as a function of time of day and season!

14. Review: Toxicity Testing - Bioassays
LC50:
Median lethal concentration for 50% of the organisms
The diluted concentration of the wastewater that will kill 50% of the test population in a fixed time period
NOEC:
No Observed Effect Concentration
The highest concentration of diluted wastewater that has no observable effect on the test organisms
ACUTE TOXICITY
CHRONIC TOXICITY

15. Acute Testing Requirement
Rainbow Trout Test
Swim-up fry or fingerling ( g)
96-h single concentration test (100% and control)
10 fish/test
Three replicates=> To accommodate death arising from natural causes!
Daphnia Magna Test
“Water flea” - small freshwater crustacean
48-h single concentration test (100% and control)
30 daphnids/test
Three replicates

16. Daphnid

17. Acute Toxicity Testing
Failure = when the effluent at 100% concentration kills more than 50% of the test organisms in the specified time period
LC50 = 100%

18. Acute Toxicity Testing
What happens if a test fails?
“Toxicity Reduction Evaluation” (TRE)
Try to identify the source of the toxicity
Calculate the LC50 using a dilution series of the effluent within 5 days of a failed test
Minimum 5 test concentrations plus a control
Typical range: 100x (full strength) down to 1x (dilute) of the effluent

19. Acute Toxicity Units (TUA)
TUA = 100/LC50
“Effluent Discharge Objectives” (EDO)
EDO = 1 TUA
Measured “At the end of the pipe”
LC50 = 100%

20. Chronic Toxicity Testing considers the local environment
Requirements are influenced by site-specific factors
Type of waterway (river, stream, lake, etc.)
Spawning location, recreational facilities etc.
Effects on growth, reproduction, and swimming
Fathead minnow larvae and Ceriodaphnia dubia
7-day test is typical

21. EDO = 1TUC for diluted sample
Chronic Toxicity
NOEC = 100%
for diluted sample
TUC = 100/NOEC
EDO = 1TUC for diluted sample
Measured at “the end of the mixing zone”
Not at wastewater discharge point from plant!
Dilution factor based on the type of receiving waterway
Rivers and streams - Max 1:100 Dilution
Lakes, reservoirs, enclosed bays - Max 1:10 Dilution

22. Monitoring Frequencies
Facility Size
CBOD5, TSS, Coliform, TKN, TP, NH3
TRC
Acute Toxicity
Chronic Toxicity
Very Small
Monthly
Daily
n/a
Small
Quarterly
Medium
Every 2 weeks
Large
Weekly
2x / day
Very Large
Daily (5-7 days/week)
3x / day
Flowrates also monitored throughout the day

23. Guidelines and Regulations: Other Contaminants

24. Federal Discharge Guidelines
Fecal Coliforms: 100 colonies per 100 mL
Total Coliforms: 1000 colonies per 100 mL
TP: 1.0 mg-P/L
Ammonia: 1 mg/L
Nitrate: 10 mg/L
pH: 6 to 9
Temperature - not to alter the ambient water temperature by more than 1 ºC

25. Federal Discharge Guidelines
Cadmium: mg/mL
Copper: 0.2 mg/mL
Lead: 0 mg/mL (detection limit)
Mercury: 0 mg/mL (detection limit)
Nickel: 0.3 mg/mL
Zinc: 0.5 mg/mL
PCBs and dioxins: 0 mg/mL (detection limit)
PCBs are serious carcinogens!

28. Overview of Unit Operations in WW Treatment

29. Typical Municipal WW TSS: 220 mg/L VSS: 165 mg/L BOD5: 220 mg/L
COD: 500 mg/L
TKN: 40 mg-N/L
Ammonia: 25 mg-N/L
TP: 8 mg-P/L
Ortho-phosphate: 5 mg-P/L

31. Types of Reactors Used in WW Treatment
Batch
Continuously stirred tank reactor (CSTR)
CSTR with recycle
Plug flow
Plug flow with recycle
CSTR in series
Fluidized-bed
Packed-bed