Egg-shaped Digesters - DC Water
Egg-shaped Digesters - DC Water
Egg-shaped Digesters - DC Water
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Objectives? Discuss odor controlimprovements? <strong>Egg</strong>-<strong>shaped</strong> <strong>Digesters</strong> aspart of biosolidsmanagementimprovements5
Reducing odors from selectedtreatment processes? Grit and screeningfacilities? Primary treatment area? Biological treatmentarea? Sludge handling area6
Reducing odors? Grit andscreeningfacilities– New odor controlsystem in the Gritand ScreeningBuilding– Eliminate open airgrit piles7
Reducing odors? Primary treatment area– Improvements to scum andsludge collection andpumping systems– Ongoing processmodifications toreduce odorsfrom septicsludge8
Reducing odors? Biological treatment area– Evaluating opportunitiesfor odor reduction9
Reducing odors? Sludge handling area– New chemical feed system forgravity thickeners to controlodor10
<strong>Egg</strong>-<strong>shaped</strong> <strong>Digesters</strong>? Outdated undergrounddigesters have beentaken out of serviceOut of service digesters(below grade)? <strong>Egg</strong>-<strong>shaped</strong><strong>Digesters</strong> will replacethe old digestersand will treat 100%of solids producedat Blue PlainsProposed <strong>Egg</strong>-<strong>shaped</strong>Digester Facility11
Fundamentals of wastewater treatmentTrash anddebris areseparatedthroughbarscreensSuspendedsolids andorganicscontinuethrough thesettlingandfilteringprocessBiologicalreactorsconvertorganics tosolids, thensettling tanksremove solidsCleanwaterreturnsto riverPotomacRiverTrash fromscreening tolandfillSolidsSolidstreatmentanddigestion12
Digestion, defined? Digestion is a solidstreatment process where– Microbes that use sludge asfood are mixed in heatedtanks? Process destroys pathogens,reduces mass of solids, andproduces useful digester gas? Resulting in a less odorousmaterial (biosolids), suitablefor agricultural uses13
<strong>Egg</strong>-<strong>shaped</strong> <strong>Digesters</strong>reduce truck traffic and noise? Reduces numberof trucks from 70to 35 per day? Reduces trucknoise? Saves more than1.2 milliontruck milesyearly17
<strong>Egg</strong>-<strong>shaped</strong> <strong>Digesters</strong> reduceodor potential? Digestion reducesodor at offsite landapplicationsites18
Construction schedule and costDateItemDescriptionConstructionCost2 nd quarterof 2004Bid ConstructionContract No. 1Foundation andtanks$100 million1 st quarterof 2005Bid ConstructionContract No. 2Digestionprocess andsupport facilities$120 million19
<strong>Egg</strong>-<strong>shaped</strong> <strong>Digesters</strong> save millionsper year in operating costsCategoryCost SavingsLand Application $ 9.7MO&M $ 6.2MTotal Savings per year$15.9M20
<strong>Egg</strong>-<strong>shaped</strong><strong>Digesters</strong> in theUnited States.21
Back River Wastewater Treatment PlantBaltimore, Maryland22
Appleton, Wisconsin23
Oceanside, California24
Deer Island, Boston, Massachusetts25
Hillsboro, Oregon(Rock Creek, Portland)26
ByDay NightArchitect’s rendering of<strong>Egg</strong>-<strong>shaped</strong> <strong>Digesters</strong> at Blue Plains27
Preliminary site planAccessed by2 stairtowers atNorth andSouth endsof siteExterior<strong>Egg</strong>-<strong>shaped</strong>Digestercladding:aluminumor stainlesssteel, orother28
Potential future projects? Use digester gas to– generate electricity to heat<strong>Egg</strong>-<strong>shaped</strong> <strong>Digesters</strong> and/orother facilities– produce biosolidspellets29
Schedule? Planning Schedule– Public meetings March–June 2003– Notice of PUD Application May 2003? Design and Construction Schedule– Preliminary design June 2003– Final design January 2005– 100% digestion online Aug 200830
? Resolution insupport of PlannedUnit Development(PUD) application? Testimony insupport at the PUDhearing31
Questions and Answers32
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