The Future of Activated Sludge - Central States Water Environment ...

Some Thoughts ht On The FutureOf Wastewater Treatment15 th Annual Education SeminarCentral States Water Environment AssociationMadison, WIApril 5, 2011George TchobanoglousProfessor Emeritus of Civil and Environmental EngineeringDepartment of Civil and Environmental EngineeringUniversity of California, Davis

Basis for PresentationWASTEWATER AND FOODWASTES ARE RENEWABLERECOVERABLESOURCES OF ENERGY,RESOURCES, AND WATER

A Question and Answer AboutWastewater Treatment in the FutureQUESTIONHow can we enhance wastewatertreatment, reduce energy usage, andrecover additional energy and resources?ANSWERTo accomplish these objectives it will benecessary to modify the characteristicsof the waste to be treated

Overview of Presentation• What to do with Food Waste• Wastewater Constituents and Characteristics• Energy Content of Wastewater Versus EnergyNeeded For Treatment• Modification of Wastewater Characteristics –Near-Term Interventions• Modification of Wastewater Characteristics –Long-Term Interventions• A Final Thought and Sustainability Challenge

Food Waste Management Options

Wastewater CharacteristicsConventional• Organic constituents• Inorganic constituentsAdditional• Heat energy• Chemical energy

Constituents t in WastewatertConstituent Unit Value (typical)Solids, total (TS) mg/L 390 -1230 (720)Dissolved, total (TDS) mgIL 270 – 860 (500)Suspended solids, total (TSS) mg/L 120 – 400 (210)Biochemical oxygen demand(BOD) 5-d, 20°Cmg/L 110 – 350 (190)Ttl Total organic carbon (TOC) mg/L 80 – 260 (140)Chemical oxygen demand(COD)mg/L 250 – 800 (430)Oil and grease mg/L 30 – 90 (60)Flowrate gal/capita•d 200 – 60 (120)

Energy Content of WastewaterHeat energySpecific heat of water = 4.1816 J/g •°C at 20°CChemical oxygen demand (COD)C 5 H 7 NO 2 + 5O 2 = 5CO 2 + NH 3 + 2H 2 O(113) 5(32)Chemical energy (Channiwala,1992), )HHV (MJ/kg) = 34.91 C + 117.83 H - 10.34 O- 1.51 N + 10.05 S - 2.11A

Energy Content of WastewaterConstituent Unit ValueWastewater, heat basis MJ/10°C•10 3 m 3 41,900Wastewater, COD basis MJ/kg COD 12 - 15Pi Primary sludge, dry MJ/kg TSS 15 - 15.9Secondary biosolids, dry MJ/kg TSS 12.4 - 13.5

Required and Available Energy forWastewater t Treatment, t Exclusive of Heat Energy• Energy required for secondary wastewatertreatmentt t1,200 to 2,400 MJ/1000 m 3• Energy available in wastewater for treatment,using previous dataQ = [430 kg COD/1000 m 3 ) (1000 m 3 ) (13 MJ/ kg COD)5,590 MJ/1000 m 3• Energy available in wastewater is 2 to 4 timesthe amount required for treatment

What is the Key Question – How toRecover and Use Energy ?• Anaerobic digestion and power generation• Ambient temperature anaerobic treatment andpower generation• Complete treatment without biological processingwith heat drying and power generation• Upstream recovery of heat and chemical energy

Heat Recovery from WastewaterSOURCE : City of Vancouver, Sustainability website retrieved fromhttp://vancouver.ca/sustainability/neuTechnology.htmFALSE CREEK ENERGY CENTER

Modification of WastewaterCharacteristics – Near-Term Interventions1. Reduce energy usage through reducedorganic loading2. Modify particle size to enhancetreatment3. Additional energy recovery throughanaerobic digestion4. Separate treatment for return flows5 Conversion of food waste and fats oils5. Conversion of food waste and fats, oils,and grease

Wastewater Treatment Process Flow DiagramsWith Conventional and New Technologies

Particle Size ModificationWith Primary Effluent Filtration10Volum e distributio on,/cm3V/log d p(10 7 m 3 )8642Plant 1 - 3.4 m (11 ft) side water depthPlant 2 - 5.55 m (18 ft) side water depth12-15 m0-0.5 0 0.5 1.0 1.5 2.0Log of particle diameter, d p, m

Primary Effluent Filtration with Fuzzy Filter

Primary Effluent Filtration with WesTech Disk Filter

Impact of Recycle Flows onNitrogen RemovalReturnflowscontainnitrogen

Wastewater Treatment Process Flow DiagramsWith Conventional and New Technologies

Fine Screen for Solids RemovalAdelanto, CA200 micron cloth screenFontana, CADewatered solids

Stainless Steel Cloth Filter (10 m) forStainless Steel Cloth Filter (10 m) forFiltration of Secondary Effluent

Modification of WastewaterCharacteristics – Long-Term Interventions1. Separation of waste constituents at thesource into urine and black water2. Reduce phosphate h content t ofconsumer products3. Alternative treatment processes andconfigurations4. Recover wastewater solids upstream insatellite stations

Use of Existing Collection System ForUse of Existing Collection System ForSource Separated Resource Streams

Nutrients and Trace Organics in DomesticWastewater: A Case for Urine SeparationGreywater10080FecesGreywaterFecesGreywaterFecesComp position, %6040UrineUrineUrineGreywaterRelativedistributionunknown,preliminaryi> 70%in urineFecesandurine200Nitrogen Phosphorus Potassium Volume Trace organicsWastewater constituentSource: Jönsson et al.(2000) Recycling Source Separated Human Urine.

Examples of Urine Separation Fixtures

Urine Utilization in Indoor Wetland System

ConstituentPotential Impacts of Urine SeparationBased on 190 L/capita-d (50 gal/capita-d)Typical, Typical, With US, With US,g/capita-d mg/L g/capita-d mg/LBOD 5 85 450 85 ~450COD 200 1050 200 ~1050TSS 95 500 95 ~500NH 4 -N 78 7.8 42 06 0.6 3Organic N 5.5 30 2.4 13TKN 13.33 72 30 3.0 16P (biogenic) 1.4 7.4 0.6 3.3P (other) 10 1.0 5 05 0.5 26 2.6

Potential Impacts of Urine SeparationOn Biological Wastewater TreatmentConstituentWith US, After primary, Cell yield,mg/L mg/L mg/LBOD 5 ~450 292 190COD ~1050 525 -TSS ~500 150 -NH 4 -N 3 ~3Organic N 13 ~9TKN 16 ~12Req. N forcell growth23.5P (biogenic) 3.3 2.3 Req. PP( (other) 26 2.6 18 1.8 47 4.7

Future Wastewater Management

New Concept for the Treatment andRecovery of Energy from Wastewater• Replace primary and secondarysedimentation tanks with cloth screens• Use “plant adsorbent (e.g., Kenaf)” toadsorb organics and ammonia• Recover heat energy for drying solids• Generate energy from dried solids

Wastewater Treatment Process Flow DiagramWastewater Treatment Process Flow DiagramWithout Biological Treatment

Membrane Filtration of Screened Effluent

Integrated Wastewater Management WithDecentralized, Satellite, Centralized Facilities

SatelliteSystems forReclamationand Reuse

Recovery of Constituents fromRecovery of Constituents fromWastewater Collection System

Nutrient Separation, Storage, and RecoveryNutrient Separation, Storage, and RecoveryFrom Individual Residence

Take Away MessageIn closing, we must all continue to seeknew concepts and technologies tochange the status-quo with respect tohow the energy and resources inwastewater and food waste arerecovered to develop a more sustainablefuture – a challenge worthy of theattendees at this Education Seminar

THANK YOUFOR LISTENING