Lagoon Design and PerformancePresented by:Dwight HOUWELING, Ph.D.EnviroSim Associates, Flamborough, ON4-hour Seminar presented September 22nd, 2008at Environment Canada, Burlington, Ontario

*

*OutlineLagoon PerformanceBiologyLagoon DesignOperation and Sampling

*

*Protecting Receiving WatersRaw SewageTreated EffluentBiomassLAGOON PERFORMANCE

*Protect Receiving Waters from pollution associated with Raw SewageWhats wrong with raw sewage? Effect of BOD on receiving waters, pathogens and toxicity of NH3 Use 2 main mechanisms: sedimentation and biology Remove settleable solids through sedimentation and biodegradable material through contact with biomass Criteria for treatability will be particulate vs. soluble and biodegradable vs. non-biodegradable Treated Effluent benefits from the removal of particulates through sedimentation and solubles and colloidals through biodegradation.

Sedimentation and biodegradation are the basis for treatment in lagoons.

*Solids SeparationTrucked or piped in wastewater enters the lagoonLAGOON PERFORMANCE

*

*Solids SeparationWastewater components separate through sedimentation. Settleable solids sink to the bottom layer. Soluble and fine solids remain in the top layer.LAGOON PERFORMANCE

*

*Solids SeparationSettling removes only removes a portion of the pollutionParticulatesSolubles and Fine ParticulatesLAGOON PERFORMANCE

*

*Biological ActivityBacteria consume soluble matter and fine particulates and then settle to bottom, which clears up water top layerParticulatesBacteria ConsumeSolubles and Fine ParticulatesBacteria Grow and SettleLAGOON PERFORMANCE

*

*Treatment PerformanceGood settling depends on:quiescent conditions (still waters), not too much wind;Minimum depth of water above sediment layerGood biological activity depends on:Temperature, dissolved oxygen, other factors

LAGOON PERFORMANCE

*

*Treatment PerformanceThe biggest variable in operating lagoons in Canada is temperature change between winter and summer

Cold temperatures and ice cover will affect biology but not so much settling

LAGOON PERFORMANCE

*

*Winter PerformanceiceSettling is good in winter but biological activity slows downLittleBiological ActivityLAGOON PERFORMANCE

*

*Summer PerformanceSignificantBiological ActivityWarm temperatures and sunlight allow good treatment in summerLAGOON PERFORMANCE

*

*Summer PerformanceAlgaeGrowth of Algae is beneficial but can sometimes be excessiveLAGOON PERFORMANCE

*

*Summer PerformanceWaterways choked with algae while they are alive they provide beneficial oxygen but when they die they consume oxygen, which can lead to anaerobic conditions (no oxygen)LAGOON PERFORMANCE

*

*Biological ActivityBiological activity is critical to the treatment performance of lagoon processesRate of activity is temperature dependantBacteria do most of the workType of biological activity depends on whether oxygen is present (aerobic) or not (anaerobic)Aerobic activity is the most energy efficient for life and leads to better pond performance

LAGOON BIOLOGY

*

*Lagoon is an ecosystemMetcalf and Eddy, 1991LAGOON BIOLOGY

*

*Components of interestSuspended Solids (TSS)TSS includes human waste, pathogens, nutrients, algae and other bacteria etc.Biochemical Oxygen Demand (BOD)Organic Matter that depletes oxygenNutrients - EutrophicationToxicityPathogens

LAGOON BIOLOGY

*

*Treatment in LagoonsWhat is the fate of each of the following: TSS, BOD, Ammonia, P, Pathogens?LAGOON BIOLOGY

*

*BacteriaBacteria consume organic matter and nutrientsAlgae are photosynthetic bacteria that produce oxygenBacteria work fastest with oxygen but can work without which can lead to foul odoursLAGOON BIOLOGY

*Make this one dynamic

*GrazersRotiferProtozoa filter the water and consume bacteriaLAGOON BIOLOGY

*Make this one dynamic

*Biological Activity: Big and SmallBacteria 0.001 mmProtozoa, Rotifers0.1 mmDaphnia1 mmGeese 1 mLAGOON BIOLOGY

*Make this one dynamic

*Biological activity : OxygenBacteria biodegrade organic aerobically (with O2) or anaerobically (no O2)Aerobic biodegradation is faster and produces no smellsAnaerobic biodegradation is slower and can produce foul smellsBacteria can be strictly aerobic, strictly anaerobic or facultative (active in both conditions)

LAGOON BIOLOGY

*Highlight the importance of O2 as electron acceptor

*Biological Activity : TemperatureBacteria are active at low temperatures (5oCGrowth slows with decreasing temperatureNet loss of bacteria when growth rate is lower than rate of (decay + predation + washout)

LAGOON BIOLOGY

*Show a shivering bacteria

*Biological Activity : Other FactorspH Measure of Acidity/AlkalinityToxicity Cyanide, Heavy metals (Copper, Chromium etc.) can inhibit growth of bacteriaContact between bacteria, pollutants and O2 if all the bacteria are in the bottom sediments and the O2 and pollutants are in the overlying water column then no biodegradation

LAGOON BIOLOGY

*Show

*Treatment Steps : Dilution

Sewage will be diluted in lagoon and undergo sedimentation

LAGOON BIOLOGY

*

*Treatment Steps : SettlingSolubles + Some SolidsSolidsFate sewage components will depend on settleability

Interested in knowing what fractions of influent waste are soluble and particulate (solid) components

LAGOON BIOLOGY

*

*Treatment Steps : BiodegradabilityAEROBIC REACTIONSANAEROBIC REACTIONSFate will depend on biodegradability

Most human waste will biodegrade eventually, but is it readily, slowly, very-slowly or impossibly slowly biodegradable?

Examples:ProteinsCarbohydratesToilet PaperWoodPlasticLAGOON BIOLOGY

*

*Treatment Steps : Gas TransferAmmonia can be removed by volatilization but it depends on pH

Useful to know what pH is

NH3NH+4+ H+LAGOON BIOLOGY

*

*

Total Influent CODBiodegradable CODUnbiodegradable CODSoluble Readily BiodegradableParticulate Slowly BiodegradableSoluble UnbiodegradableParticulate UnbiodegradableInfluent FractionsCOD (Chemical Oxygen Demand) is a measure of all the organic matter in a sampleLAGOON SAMPLING

**

*Suspended Solids (TSS)Suspended solids cause turbidityRemoving suspended solids means removal of BOD, pathogens, metals, and other componentsTurbidity used as criteria for safe drinking waterSuspended solids can clog receiving waters, block light penetration, muddy stream bottoms

LAGOON SAMPLING

*

*Suspended Solids (TSS)Suspended solids block light penetrationChanging the environment of receiving waters

LAGOON SAMPLING

*

*Biochemical Oxygen Demand (BOD5)BOD is a measurement of the amount of biodegradable organic matterTypically a 5-day test (BOD5)Units are mg O2/L because we are interested in knowing the amount of oxygen depleted after biodegradation of the organic matterBOD discharge can be associated with a depletion in dissolved oxygen (DO) concentrations in receiving watersWithout DO, fish die + bad smells

LAGOON SAMPLING

*

*Biochemical Oxygen Demand (BOD5)Case study shows DO sag due to BOD dischargehttp://www.oxscisoft.com/hermes/casestudies.htm

*

*Nutrients: N and PNitrogen (N) and especially phosphorus (P) are limiting elements for growth of algae in most Canadian lakes and riversHuman waste contain N and PDetergents contain PLead to eutrophication of receiving waters

LAGOON SAMPLING

*

*Nutrients: N and PChinese Lake choked with Algae

*

*Toxicity: AmmoniaSewage can contain toxic componentsIn domestic wastewater the principle source of toxicity is ammoniaIndustrial effluents and landfill leachates can contain toxic elements including metalsA government study found that ammonia was the principle source of toxicity in the Saint-Lawrence river (SLV 2000)

LAGOON SAMPLING

*

*Toxicity: AmmoniaToxicity of ammonia to fish is dependant on pHAmmonia can interfere with disinfection of drinking water

LAGOON SAMPLING

*

*Toxicity: AmmoniaFish Kills

*

*Acute toxicity of AmmoniaEnvironment Canada, 2004(Total Ammonia Nitrogen)LAGOON SAMPLING

*

*Seasonal FactorsTemperatureBiologyTurnover Ice CoverSunlightPhotosynthesis affects pH and DOpH has an important effect on effluent toxicity!!!

LAGOON SAMPLING

*

*Seasonal FactorsAverages of 3-years of measurements effluent of 1st lagoon at Drummondville (2000-2003)Snowmelt DilutionBiological Activity(nitrification)LAGOON SAMPLING

*

*COD testChemical Oxygen Demand

LAGOON SAMPLING

*

*BOD5 testBiochemical Oxygen Demand

LAGOON SAMPLING

*

*TSS testTotal Suspended SolidsLAGOON SAMPLING

*

*NH3 testColorimetric analysisLAGOON SAMPLING

*

*PO4 testColorimetric analysisLAGOON SAMPLING

*

*E. coliCFU/100 mL

Important to know because of effect on human health but not a large contributor to oxygen demandLAGOON SAMPLING

*

*Case Study: Role of AlgaeWeekly Sewage LoadLAGOON SAMPLING

*

*Case Study: Role of AlgaeSewage is added to lagoon and bacteria use the oxygen to degrade organic matter (COD)Oxygen is replenished by algae at the surface of the lagoon using energy from the sunOxygen is initially depleted because bacteria use oxygen faster than algae can produce it

LAGOON SAMPLING

*What happens in spring?-Not just temperature-Light has to be able to penetrate for photosynthesis

*Case Study: Role of AlgaeOxygen is depleted faster at night when algae cannot produced oxygenIf lagoon is loaded heavily so that bacteria use oxygen faster than algae can replenish it, oxygen will drop to zero and anaerobic conditions will exist, leading to odours

LAGOON SAMPLING

*What happens in spring?-Not just temperature-Light has to be able to penetrate for photosynthesis

*Case Study: Role of AlgaeAlgae tend to increase the pH in the lagoon which favours volatile form of ammonia

NH4+ NH3 + H+Ammonia exists in equilibrium between non-volatile (NH4+) and volatile (NH3) forms. At neutral pH, the non-volatile form is dominantLAGOON SAMPLING

*What happens in spring?-Not just temperature-Light has to be able to penetrate for photosynthesis

*Types of LagoonsFacultativeOxygen input from algae and wind is significantOdours generated in bottom layer are eliminated in overlying aerobic layer

LAGOON DESIGNO2O2O2O2O2ANAEROBIC

*

*Types of LagoonsAnaerobicOxygen input is relatively insignificant (organic load is too high)

LAGOON DESIGN

ANAEROBICOdours

*

*Facultative Lagoon Process OperationAerobic and Anaerobic Zones allow for varied biologyWater Column is aerobicSediments are anaerobicExchanges between Sediments and Water Column can be significantRelease of soluble organic matter and nutrients from sediments (Benthic Load)

LAGOON DESIGN

*

*Facultative Lagoon Design CriteriaLow Organic LoadHydraulic Detention Time : several daysDepth (shallow to maximize A:V)L:W ratio (Plug flow vs. Complete Mix)FreeboardInlet and outlet size, placement, depth (distribution boxes to avoid a jet)Clay or geomembrane lining to limit seepage

LAGOON DESIGN

*

*Anaerobic Lagoon Process OperationDeep to minimize the effect of oxygen transfer across the lagoon surfaceBoth Water Column and Sediments are anaerobicSignificant gas production leads to odour problemsShould be upstream of an aerobic process

LAGOON DESIGN

*

*Anaerobic Lagoon Design CriteriaHigh Organic LoadHydraulic Detention TimeDepth (deep)L:W ratioFreeboardInlet and outlet size, placement, depth (distribution boxes to avoid a jet)Clay or geomembrane lining to limit seepage

LAGOON DESIGN

*

*Methane Gas captureCalifornia Manure Lagoon

*Aerated process operationSupply of DO allows for biological activity in winterInfluent has heat input which may keep lagoon from freezing overIf rate of feed is low relative to volume, freeze over is likely

LAGOON DESIGN

*

*Aerated Design CriteriaSimilar to facultative lagoon except:Greater Depth is allowed because natural surface aeration is not important to treatmentEnergy for aeration can increase operation costs significantly

LAGOON DESIGN

*

*

Drummondville, QC WWTP60 000 m3/dV/Q = 11 days per lagoonAeration intensity = 0.5 1.2 W/m3

*This is a picture of the WWTP at Drummondville, Quebec. You can see that this is a rather large plant with 4 lagoons in series. The model Im going to present you is based on data from this plant.

*LAssomption, QC Qdesign = 7700 m3/d

*

*Seasonal DischargeIf lagoon freezes over and no aeration, minimal biological activity and poor treatmentSeasonal discharge is a good option in these cases to avoid discharging poor quality water in winter

LAGOON DESIGN

*

*Seasonal Discharge Design CriteriaHydraulic Detention Time : several monthsDepth : deep lagoons are good for storage in water but shallow lagoons favour aerobic activity in summerFreeboardInlet and outlet size, placement, depth are important for controlling dischargeClay or geomembrane lining to limit seepage

LAGOON DESIGN

*

*Seasonal FactorsTemperatureBiologyTurnover Ice CoverSunlightPhotosynthesis affects pH and DOpH affects volatility and toxicity of ammonia

LAGOON DESIGN

*

*Alberta Design CriteriaUnaerated sewage lagoons in Alberta have no effluent requirementsDesign must include 2 or 4 anaerobic cells with 2-day retention time in each cell 1 facultative cell with a 2 month retention time 1 storage cell with a 12 month retention time Lagoons are to be drained between late spring and fall and discharge period should not exceed 3 weeks. i.e. Discharged once per year

LAGOON DESIGN

*Alberta Design CriteriaAnaerobic cells are 3 m deep and designed for desludging. Facultative cell are a maximum depth of 1.5 m Storage cell are a maximum depth of 3 m and is intended to act as a facultative cell.Slope of cell walls is 3:1 Wastewater lagoons in Alberta must be lined to control seepage

LAGOON DESIGN

*Desludging

*Generally lagoon operators wait as long as possible before doing this

*Sludge Accumulation Slows downSolids accumulate in the lagoon sedimentsRate of accumulation gradually slows due to digestion

Drummondville, QC WWTPLAGOON DESIGN

*Calibration of sludge accumulation.

*Typical Wastewater Lagoon Design in AlbertaLAGOON DESIGN

*Quebec Design CriteriaFacultative lagoons are designed based on loading rates of 22 to 12 kg BOD5/ha/d in northern regions. In general, design is for only seasonal discharge: in spring and fall. Discharge should not be less than 3 weeks after the ice-melt. Systems generally comprise 2 cells in series or in parallel.Discharge should allow at least 0.3 m of liquid in the lagoon below which solids entrainment in the effluent can be significant.For systems with continuous discharge in summer, at least 3 cells are recommended which respect the loading rates recommended above.

LAGOON DESIGN

*Quebec Design CriteriaAs is the case for Alberta, operational requirements are specified rather than effluent requirements. MENV guide suggests design gives effluent BOD5 of 20-40 mg/L and TSS of 20-100 mg/L (depending on presence of algae)Data from installations in Quebec in 1990 had an average of 400 to 20 000 CFU/100 mLSampling at least once per month of continuous discharge, discharge must be made during allowed periods and beginning and end of discharge must be noted.

LAGOON DESIGN

*Quebec Design CriteriaDischarge must be conducted in such a way as to limit solids entrainment and to limit erosion from the lagoon

Sludge must be removed before it reaches the bottom of the effluent weir

Geotechnical stability of the lagoon berm should be inspected visually (fissures, sloughing)

Need for lining to control seepage depends on conditions of site and potential impacts to drinking water supplies

LAGOON DESIGN

*Lagoon DesignPoor design can lead to problems:Poor effluent qualityFoul OdoursExcessive sludge accumulationUncontrolled dischargeUncontrolled seepage

LAGOON DESIGN

*Exfiltration LagoonsSeepage through berm adds a third treatment mechanism:

SettlingBiodegradationFilteringRate of seepage from lagoon will impact treatment performance significantly

LAGOON DESIGN

*Exfiltration LagoonsMost of the communities have a dumping lagoon that exfiltrates through the sand and gravel of a berm down a wetland slope anywhere from a few hundred metres to several kilometres long. The wetlands are lush and green with vegetation that thrives on the wastewater while helping to treat it. What were finding is that in smaller communities, such as Chesterfield Inlet or Whale Cove, it works very well. The water that reaches the ocean is of very high quality.

-Brent Wootton, senior scientist with the Centre for Alternative Wastewater Treatment at Fleming College Daily Commercial News and Construction Record, May 9, 2008, Reed Construction Data, Markham, ONLAGOON DESIGN

*Sewage Lagoon at Whale Cove, NUwetlandDownstream wetland provides further treatment beyond the lagoonLAGOON DESIGN

*Sewage Lagoon at Whale Cove, NULagoon effluent follows topography to oceanLAGOON DESIGN

*Exfiltration Lagoon PerformanceWhy wetlands do or do not work is a current topic of study. Important factors include:Loading (kg BOD5/m2)TemperatureRate of Seepage over YearExfiltration or uncontrolled runoffRetention time in downstream wetlands

LAGOON DESIGN

*ExfiltrationLAGOON DESIGN

*Operation and SamplingWhat do we sample for?

What do the tests tell us?

Sampling plan to characterizeLagoon BehaviourImpact on receiving waters.

LAGOON SAMPLING

*

*

Mass BalancesPropose a sampling campaign to characterize the removal of COD, N, and P for the following lagoon system.

*Flow In = Flow Out + Accumulation

*

*Sludge ProductionAfter 5 years, the seasonal discharge lagoon at Exampleville is 60% full of sludge. The seasonal discharge lagoon at Pleasanthamlet 100 km away is only 25% full after 10 years. How can this be?What information would you need to investigate your assumptions?Plan a sampling campaign to investigate your claims

After 10 yearsAfter only 5 yearsLow TSSHigh TSS

*

*

Ammonia dischargeLocal residents notice a fish kill in the river two years in a row in early June. The munipalitys lagoon discharges continuously into a wetland 500 meters from the river. Could effluent from the lagoon be responsible for the fish kill?Can you offer an explanation for the fish kill?What information would you need to investigate your assumptions?Plan a sampling campaign to investigate your claims

*

*Exfiltration into surrounding Wetlands

*

*

*

*Protect Receiving Waters from pollution associated with Raw SewageWhats wrong with raw sewage? Effect of BOD on receiving waters, pathogens and toxicity of NH3 Use 2 main mechanisms: sedimentation and biology Remove settleable solids through sedimentation and biodegradable material through contact with biomass Criteria for treatability will be particulate vs. soluble and biodegradable vs. non-biodegradable Treated Effluent benefits from the removal of particulates through sedimentation and solubles and colloidals through biodegradation.

Sedimentation and biodegradation are the basis for treatment in lagoons.

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*Make this one dynamic*Make this one dynamic*Make this one dynamic*Highlight the importance of O2 as electron acceptor*Show a shivering bacteria*Show*

*

*

*

**

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*What happens in spring?-Not just temperature-Light has to be able to penetrate for photosynthesis*What happens in spring?-Not just temperature-Light has to be able to penetrate for photosynthesis*What happens in spring?-Not just temperature-Light has to be able to penetrate for photosynthesis*

*

*

*

*

*

*

*

*This is a picture of the WWTP at Drummondville, Quebec. You can see that this is a rather large plant with 4 lagoons in series. The model Im going to present you is based on data from this plant.*

*

*

*

*Generally lagoon operators wait as long as possible before doing this*Calibration of sludge accumulation.*

*

*

*

*