5 Management of MWWE More than 3500 WWTP in Canada No real “standard” Treatment strategies range from no treatment to state of the artIn 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 plantKingston has this particular problem!!!Problems with aging infrastructure
10 Legislation Municipalities are responsible for WW management Provincial governments are responsible for regulating the operation of WWTPThere is currently no federal legislation on municipal WW effluentFisheries ActCanadian Environmental Protection Act, 1999
11 Proposed Canada-wide Strategy for the Management of MWWE Drafted Oct. 2007
13 National Performance Standards Effluent from all treatment plants must satisfy:CBOD5 ≤ 25 mg/LTSS ≤ 25 mg/LTotal Residual Chlorine (TRC) ≤ 0.02 mg/LAmmonia: Based on acute and chronic toxicityTSS and CBOD5 values can be averaged:Very Small - Medium WWTP: QuarterlyLarge or Very Large WWTP: MonthlyConsider 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 organismsThe diluted concentration of the wastewater that will kill 50% of the test population in a fixed time periodNOEC:No Observed Effect ConcentrationThe highest concentration of diluted wastewater that has no observable effect on the test organismsACUTE TOXICITYCHRONIC TOXICITY
15 Acute Testing Requirement Rainbow Trout TestSwim-up fry or fingerling ( g)96-h single concentration test (100% and control)10 fish/testThree replicates=> To accommodate death arising from natural causes!Daphnia Magna Test“Water flea” - small freshwater crustacean48-h single concentration test (100% and control)30 daphnids/testThree replicates
17 Acute Toxicity Testing Failure = when the effluent at 100% concentration kills more than 50% of the test organisms in the specified time periodLC50 = 100%
18 Acute Toxicity Testing What happens if a test fails?“Toxicity Reduction Evaluation” (TRE)Try to identify the source of the toxicityCalculate the LC50 using a dilution series of the effluent within 5 days of a failed testMinimum 5 test concentrations plus a controlTypical 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 TUAMeasured “At the end of the pipe”LC50 = 100%
20 Chronic Toxicity Testing considers the local environment Requirements are influenced by site-specific factorsType of waterway (river, stream, lake, etc.)Spawning location, recreational facilities etc.Effects on growth, reproduction, and swimmingFathead minnow larvae and Ceriodaphnia dubia7-day test is typical
21 EDO = 1TUC for diluted sample Chronic ToxicityNOEC = 100%for diluted sampleTUC = 100/NOECEDO = 1TUC for diluted sampleMeasured at “the end of the mixing zone”Not at wastewater discharge point from plant!Dilution factor based on the type of receiving waterwayRivers and streams - Max 1:100 DilutionLakes, reservoirs, enclosed bays - Max 1:10 Dilution
22 Monitoring Frequencies Facility SizeCBOD5, TSS, Coliform, TKN, TP, NH3TRCAcute ToxicityChronic ToxicityVery SmallMonthlyDailyn/aSmallQuarterlyMediumEvery 2 weeksLargeWeekly2x / dayVery LargeDaily (5-7 days/week)3x / dayFlowrates also monitored throughout the day
24 Federal Discharge Guidelines Fecal Coliforms: 100 colonies per 100 mLTotal Coliforms: 1000 colonies per 100 mLTP: 1.0 mg-P/LAmmonia: 1 mg/LNitrate: 10 mg/LpH: 6 to 9Temperature - not to alter the ambient water temperature by more than 1 ºC
25 Federal Discharge Guidelines Cadmium: mg/mLCopper: 0.2 mg/mLLead: 0 mg/mL (detection limit)Mercury: 0 mg/mL (detection limit)Nickel: 0.3 mg/mLZinc: 0.5 mg/mLPCBs and dioxins: 0 mg/mL (detection limit)PCBs are serious carcinogens!