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Presenter: Walid Al-Ani, P.Eng, P.E., BCEE, LEED® AP Project Manager for Stantec Consulting Michigan Inc.

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Presentation on theme: "Presenter: Walid Al-Ani, P.Eng, P.E., BCEE, LEED® AP Project Manager for Stantec Consulting Michigan Inc."— Presentation transcript:

1 Presenter: Walid Al-Ani, P.Eng, P.E., BCEE, LEED® AP Project Manager for Stantec Consulting Michigan Inc.

2 Overview of the Cadillac WWTP Background Information Filtration Technologies Evaluation & Selection Design Highlights Construction Highlights Post-Construction Performance Questions and Answers 2

3 Plant Rated for 3.2 MGD Average Daily Flow and 4.5 MGD Maximum Daily Flow Influent Pump Station – Screw Pumps Equalization Basin Preliminary Treatment Primary Treatment Secondary Treatment – Activated Sludge/Chemical Addition for Phosphorous Removal Rotating Biological Contactors Tertiary Filters UV Disinfection Anaerobic Digestion Biosolids Land Application 3

4 4

5 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 life Replacement of the sampling pumps Replacement of the samplers Design completed in the summer of 2007 Construction completed in the early spring of 2008 Overall construction cost approximately $3,800,000 Construction cost for Tertiary Treatment Improvements approximately $1,000,000 Construction cost for the installed filters approximately $620,000 5

6 Three sand filters (Hydroclear) commissioned in 1977 Some rehabilitation work performed over the years including replacement of filter media, valves, and control system Deteriorating performance and extensive backwashing necessary 6

7 Traveling Bridge Filters Traveling Hood Filters Disc Cloth Media Filters Synthetic Media Filters Deep Sand Filters Membrane Biological Reactors (MBRs) 7

8 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. 8

9 9 Source Aqua-Aerobics Systems, Inc.

10 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. 10

11 11 Source Water Online

12 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. 12

13 13 Source Aqua-Aerobic Systems, Inc.

14 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 Schreibers Fuzzy Filter. 14

15 15 Source SchreiberSource: Schreiber

16 16 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 Parksons DynaSand Filter.

17 17 Source DynaSand Source: DynaSand

18 18 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.

19 19 Source: Memcor

20 Required performance based on NPDES effluent limitations for the summer months listed in the Cadillac WWTP permit: 30-Day Average BOD 5 7 mg/L 30-Day Average TSS 20 mg/L 30-Day Average Ammonia Nitrogen (N) 0.9 mg/L 30-Day Average Phosphorous 0.5 mg/L Evaluation of all technologies indicated that the effluent limitation for TSS could be met. 20

21 Filter TypeBudgetary Price * Traveling Bridge Sand Filter$200,000 Traveling Hood Sand Filter$300,000 Disc Cloth Media Filter$500,000 Synthetic Media Filter$700,000 Deep Bed Sand Filter$800,000 Membrane Biological Reactor$2,400, * 2006 Prices – Based on equipment cost from manufacturers

22 Filter TypeRemarks Traveling 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 FilterFits into the existing filter footprint but requires removal of the mud well. Deep Bed Sand FilterDoes not fit into the existing building. Membrane Biological ReactorDoes not fit into the existing filter footprint but may fit into existing building with structural modifications. 22

23 Filter TypeRemarksWarrants Further Consideration Traveling Bridge Sand Filter Does not fit into existing building No Traveling Hood Sand Filter Does fit into existing filters footprint No Disc Cloth Media FilterFits into existing filters footprint Yes Synthetic Media FilterFits into existing filters footprint Yes Deep Bed Sand FilterDoes not fit into existing building No Membrane Biological Reactor Does not fit into existing building and is too costly No 23

24 Filter TypeInstallations in MI and other Surrounding States as of early 2007 RemarksWarrants Further Consideration Disc Cloth Filter Media (Aqua – Aerobic) Several nationwide including MI Will not require pilot testing due to sufficient experience in MI Site visit to Sutton Bay WWTP, MI Conference call with Superintendent of Champagne Sanitary District WWTP Yes Disc Cloth Filter Media (Kruger) One in MI one in Ravenna, OH May require pilot testing due to limited experience in MI Site visit to Ravenna WWTP, OH Yes Synthetic Media Filter (Schreiber) One in MI Likely to require pilot testing due to limited experience in MI and high loading rates due to small footprint No 24

25 Item of Comparison Cloth Media Disc Filter (Aqua-Aerobic) Cloth Media Disc Filter (Kruger) Equipment Cost$547,000$500,000 Structural Modifications Demolition of Mud Well Columns and beams remain Partial demolition of mud well Columns and beams remain Significant concrete work required to accommodate open channel flows Access Into Existing Building Requires demolition of building exterior wall Experience in Michigan Several Installations Pilot testing not required One installation only as of early 2007 Pilot testing likely required Experience at Similar Installations Sutton Bay WWTP In Operation since 2006 No Mechanical Problems Good Workmanship Urbana-Champagne Sanitary District WWTP In Operation since 2005 Good responsiveness during construction, start-up, and post construction Decision to install same type of filters at the larger Districts WWTP Peak flows of 17 MGD were handled with no reported problems Ravenna WWTP Difficulty meeting the 2 MGD peak flow with one filter out of service Belt supporting the discs has failed Major rigging required for belt replacement 25

26 Decision was to adopt the cloth media filter technology (Aqua-Aerobic) based on the following: Established experience nationwide including Michigan Ease of Maintenance Demonstrated ability to handle peak flows Ability to meet the projects strict milestones since no pilot testing would be required 26

27 Limitations on when construction could occur had to be established, due to the NPDES Limitations Higher 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 27

28 Structural integrity had to be confirmed to allow partial demolition of the walls and slab Existing piping arrangement had to be confirmed to allow bypass of the filters to the disinfection process Demolition of existing exterior walls had to be addressed to verify access issues 28

29 Hydraulic calculations had to be performed to ensure new filters would not be a bottleneck Filters, piping, platforms, and controls had to be fitted into the existing space 29

30 Entire work (demolition, installation, start-up, on-line) had to be completed in three months 30

31 Access limited through existing building wall 31

32 Filters demolished and removed 32

33 All piping in gallery removed 33

34 Mud Well slab demolished 34

35 New Floor 35

36 Filter concrete support pads 36

37 New filter piping 37

38 Filters installed on concrete pads 38

39 New piping in gallery 39

40 Filters in operation 40

41 Filter Control Panels 41

42 Backwash and Sludge Valves 42

43 Back Wash Cycle Back Wash Initiation: Water level exceeds specified level Time interval elapses Manual back wash cycle High level float switch activates Back Wash Set Points: Back Wash interval, time between automatic backwash cycles Back Wash duration, wash time for each collection manifold Back Wash level, water level that triggers a back wash cycle 43 Sludge Cycle Sludge Removal Initiation: Time interval elapses Back wash counts elapse Manual sludge cycle Sludge Cycle Set Points: Sludge interval, time between automatic sludge cycles Backwash count, number of back washes between automatic sludge cycles Sludge duration, duration of the sludge cycle

44 Filters are operating successfully and meeting the NPDES requirements 44

45 45

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