Presentation on theme: "Evaluation of Filtration Technologies and Upgrade of the Filtration System at the Cadillac Wastewater Treatment Plant Presenter: Walid Al-Ani, P.Eng,"— Presentation transcript:
1 Evaluation of Filtration Technologies and Upgrade of the Filtration System at the Cadillac Wastewater Treatment PlantPresenter: Walid Al-Ani, P.Eng, P.E., BCEE, LEED® AP Project Manager for Stantec Consulting Michigan Inc.
2 Presentation Overview Overview of the Cadillac WWTPBackground InformationFiltration Technologies Evaluation & SelectionDesign HighlightsConstruction HighlightsPost-Construction PerformanceQuestions and Answers
3 Overview of the Cadillac WWTP Plant Rated for 3.2 MGD Average Daily Flow and 4.5 MGD Maximum Daily FlowInfluent Pump Station – Screw PumpsEqualization BasinPreliminary TreatmentPrimary TreatmentSecondary Treatment – Activated Sludge/Chemical Addition for Phosphorous RemovalRotating Biological ContactorsTertiary FiltersUV DisinfectionAnaerobic DigestionBiosolids Land Application
5 Background Information Project plan prepared in 2006 to address overall plant needs – Requirement for seeking State Revolving Funds (SRF)Tertiary Treatment major needs identified:Replacement of the sand filters that were nearing the end of their useful lifeReplacement of the sampling pumpsReplacement of the samplersDesign completed in the summer of 2007Construction completed in the early spring of 2008Overall construction cost approximately $3,800,000Construction cost for Tertiary Treatment Improvements approximately $1,000,000Construction cost for the installed filters approximately $620,000
6 Filtration System Before Implementing Improvements Three sand filters (Hydroclear) commissioned in 1977Some rehabilitation work performed over the years including replacement of filter media, valves, and control systemDeteriorating performance and extensive backwashing necessary
7 Filtration Technologies Preliminary Options Traveling Bridge FiltersTraveling Hood FiltersDisc Cloth Media FiltersSynthetic Media FiltersDeep Sand FiltersMembrane Biological Reactors (MBRs)
8 Traveling Bridge Sand Filters Continuous downflows, automatic backwash, low head, granular medium depth filter.Filter bed is divided into independent filter cells.Treated wastewater flows through the medium by gravity and exits to the clearwell plenum via a porous-plate, polyethylene underdrain.Each filter cell is backwashed individually by an overhead traveling – bridge assembly, while the other cells remain in service.During the backwash cycle, wastewater is filtered continuously through the cells that are not being backwashed.Example is the US Filter Davco Products – Gravisand.
9 Traveling Bridge Sand Filters Source Aqua-Aerobics Systems, Inc.
10 Traveling Hood Sand Filters Similar to the Traveling Bridge Sand Filter.Uses a pneumatically driven self – propelled hood instead of a conventional rail-mounted traveling bridge.Simpler, more compact installation, lower equipment cost compared to the Traveling Bridge Sand Filter.Example is EIMCO Water Technologies.
11 Traveling Hood Sand Filters Source Water Online
12 Disc Cloth Media Filters Filter tank contains a series of circular disk elements covered with a specialized cloth media.The cloth media traps particulates within its interior as well as forming a particulate layer upon its outer surface.Backwash cycle begins at a predetermined water level.During the backwash cycle, the center tube rotates while a centrifugal pump draws filtered water through a suction header from the clean side of the filter cloth.Examples are the Aqua-Aerobic Aqua Disks and the Kruger Hydrotech Disc Filter.
13 Disc Cloth Media Filters Source Aqua-Aerobic Systems, Inc.
14 Synthetic Medium Filters Filters use highly porous synthetic medium.Porosity modified by compressing the filter medium.Wastewater flows through medium; not around filtering medium as in conventional sand and anthracite filters.Wastewater introduced in bottom of filter and flows upward through filter medium, which is retained by two porous plates.Upper porous plate raised mechanically in backwash. Flow to filter continues and air introduced below lower porous plate causing medium to move in a rolling motion.Example is Schreiber’s Fuzzy Filter.
15 Synthetic Medium Filters Source: SchreiberSource Schreiber
16 Deep Bed Upflow Continuous Backwash Sand Filters Wastewater introduced into bottom of filter where it flows upward through a series of riser tubes.Wastewater then flows upward through downward moving sand and exits filter.Sand particles and trapped solids are drawn downward into the suction of an airlift pipe. A small volume of compressed air draws sand, solids, and water upward.At the top of the airlift, the dirty slurry spills over into a central reject compartment. Sand settles and is cleaned further as it moves down through a washer.Example is Parkson’s DynaSand Filter.
17 Deep Bed Upflow Continuous Backwash Sand Filters Source: DynaSandSource DynaSand
18 Membrane Biological Reactors (MBRs) MBRs combine secondary & tertiary treatment into one process.Integrated bioreactor uses membranes immersed in bioreactor; re-circulated MBR in which mixed liquid circulates through a membrane module located outside the bioreactor.In the integrated bioreactor wastewater is drawn through the membranes using vacuum. Compressed air is used to scour the membrane surfaces.In the re-circulated MBR wastewater is pumped into the membranes where solids are retained inside the membranes and wastewater passes through to the outside. The membranes are backwashed systematically to remove solids.Examples are MBRs manufactured by Zenon, US Filter Memcor, and Envirogroup.
20 Evaluation of Filtration Technologies - Performance Required performance based on NPDES effluent limitations for the summer months listed in the Cadillac WWTP permit:30-Day Average BOD mg/L30-Day Average TSS mg/L30-Day Average Ammonia Nitrogen (N) 0.9 mg/L30-Day Average Phosphorous mg/LEvaluation of all technologies indicated that the effluent limitation for TSS could be met.
21 Evaluation of Filtration Technologies Cost Filter TypeBudgetary Price *Traveling Bridge Sand Filter$200,000Traveling Hood Sand Filter$300,000Disc Cloth Media Filter$500,000Synthetic Media Filter$700,000Deep Bed Sand Filter$800,000Membrane Biological Reactor$2,400,000* 2006 Prices – Based on equipment cost from manufacturers
22 Evaluation of Filtration Technologies Footprint and Required Modifications to Existing Facilities Filter TypeRemarksTraveling Bridge Sand FilterDoes not fit into the existing building.Traveling Hood Sand FilterDoes not fit into the existing filter footprint but may fit into existing building with structural modifications.Disc Cloth Media FilterFits into the existing filter footprint but requires removal of the mud well.Synthetic Media FilterDeep Bed Sand FilterMembrane Biological Reactor
23 Evaluation of Filtration Technologies - Summary Filter TypeRemarksWarrants Further ConsiderationTraveling Bridge Sand FilterDoes not fit into existing buildingNoTraveling Hood Sand FilterDoes fit into existing filters footprintDisc Cloth Media FilterFits into existing filters footprintYesSynthetic Media FilterDeep Bed Sand FilterMembrane Biological ReactorDoes not fit into existing building and is too costly
24 Evaluation of Filtration Technologies Filter TypeInstallations in MI and other Surrounding States as of early 2007RemarksWarrants Further ConsiderationDisc Cloth Filter Media (Aqua – Aerobic)Several nationwide including MIWill not require pilot testing due to sufficient experience in MISite visit to Sutton Bay WWTP, MIConference call with Superintendent of Champagne Sanitary District WWTPYesDisc Cloth Filter Media (Kruger)One in MI one in Ravenna, OHMay require pilot testing due to limited experience in MISite visit to Ravenna WWTP, OHSynthetic Media Filter (Schreiber)One in MILikely to require pilot testing due to limited experience in MI and high loading rates due to small footprintNo
25 Evaluation of Filtration Technologies Item of ComparisonCloth Media Disc Filter(Aqua-Aerobic)Cloth Media Disc Filter (Kruger)Equipment Cost$547,000$500,000Structural ModificationsDemolition of Mud WellColumns and beams remainPartial demolition of mud wellSignificant concrete work required to accommodate open channel flowsAccess Into Existing BuildingRequires demolition of building exterior wallExperience in MichiganSeveral InstallationsPilot testing not requiredOne installation only as of early 2007Pilot testing likely requiredExperience at Similar InstallationsSutton Bay WWTPIn Operation since 2006No Mechanical ProblemsGood WorkmanshipUrbana-Champagne Sanitary District WWTPIn Operation since 2005Good responsiveness during construction, start-up, and post constructionDecision to install same type of filters at the larger District’s WWTPPeak flows of 17 MGD were handled with no reported problemsRavenna WWTPDifficulty meeting the 2 MGD peak flow with one filter out of serviceBelt supporting the discs has failedMajor rigging required for belt replacement
26 Final Selection of Filtration Technology Decision was to adopt the cloth media filter technology (Aqua-Aerobic) based on the following:Established experience nationwide including MichiganEase of MaintenanceDemonstrated ability to handle peak flowsAbility to meet the project’s strict milestones since no pilot testing would be required
27 Design Highlights Limitations Limitations on when construction could occur had to be established, due to the NPDES LimitationsHigher SS discharge limits allowed December 1 through April 30 (30 lbs/day on a monthly basis compared to 20 lbs/day for rest of the year)Therefore, taking the existing filters off-line and completing installation of the new filters was allowed for December 1 through April 1
28 Design Highlights Demolition Work Structural integrity had to be confirmed to allow partial demolition of the walls and slabExisting piping arrangement had to be confirmed to allow bypass of the filters to the disinfection processDemolition of existing exterior walls had to be addressed to verify access issues
29 Design Highlights New Work Hydraulic calculations had to be performed to ensure new filters would not be a bottleneckFilters, piping, platforms, and controls had to be fitted into the existing space
30 Construction Highlights Challenges Entire work (demolition, installation, start-up, on-line) had to be completed in three months
31 Construction Highlights Challenges Access limited through existing building wall
32 Construction Highlights Demolition Work Filters demolished and removed
33 Construction Highlights Demolition Work All piping in gallery removed
34 Construction Highlights Demolition Work “Mud Well” slab demolished
36 Construction Highlights New Work Filter concrete support pads
37 Construction Highlights New Work New filter piping
38 Construction Highlights New Work Filters installed on concrete pads
39 Construction Highlights New Work New piping in gallery
40 Operation and Controls Highlights Filters in operation
41 Operation and Controls Highlights Filter Control Panels
42 Operation and Controls Highlights Backwash and Sludge Valves
43 Operation and Controls Highlights Back Wash CycleBack Wash Initiation:Water level exceeds specified levelTime interval elapsesManual back wash cycleHigh level float switch activatesBack Wash Set Points:Back Wash interval, time between automatic backwash cyclesBack Wash duration, wash time for each collection manifoldBack Wash level, water level that triggers a back wash cycleSludge CycleSludge Removal Initiation:Time interval elapsesBack wash counts elapseManual sludge cycleSludge Cycle Set Points:Sludge interval, time between automatic sludge cyclesBackwash count, number of back washes between automatic sludge cyclesSludge duration, duration of the sludge cycle
44 Operation and Controls Highlights Filters are operating successfully and meeting the NPDES requirements