SUMMER 2016 NORTH AMERICA’S LARGEST CANTON MBR … · The project cost per gallon of ... with influent coarse screens and pumping from the ... the membrane footprint and needed

solutionsS U M M E R 2 0 1 6

America’s Authority in Membrane Treatment

Improving America’s Waters Through Membrane Filtration and Desalting

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n NORTH AMERICA’S LARGEST...CANTON MBR WATER RECLAMATION FACILITY UNDER CONSTRUCTIONBy Terry M. Gellner, P.E., TnT Engineering, LLC, 5900 SOM Center Road, STE 12 -133, Willoughby, Ohio 44094, Phone 440-478-5445, Email [email protected]

Project BackgroundConstruction began in March 2014 and initiation of membrane bioreactor activated sludge (MBR) process train No. 1 is underway at this writing. Six - 6.5 million gallon per day (MGD) average day flow (ADF) MBR trains operating in parallel will be constructed when the plant is completed. The project cost per gallon of treated wastewater is under $2.25 and significantly lower than most MBR plants. The design ADF is 39 MGD and the peak day flow is 88 MGD. The ADF was three to four times greater than any MBR operating at the time design began.

Construction of this MBR improvement at the Canton WRF will satisfy new and more stringent permit limits for phosphorus and total nitrogen. In addition to treating the new effluent limits the average day capacity of secondary treatment will be increased from approximately 35 MGD to 39 MGD, and the peak flow through secondary treatment and processes thereafter will be increased from approximately 70 MGD to 88 MGD. Experienced pumped peak instantaneous flows up to 110 MGD will continue to be processed through a new advanced preliminary treatment process with longitudinal grit/grease removal and two stage fine screening. Flows in excess of 88 MGD passing through the advance preliminary treatment process will be equalized in either of two stages. Accordingly, plant flow conditions, influent pollutant loadings and effluent permit limits for the final design are as follows:

Design Flow Parameters

Average Daily Design Flow 39 MGD

Minimum Day Flow 16 MGD

Maximum Month Flow 42 MGD

Peak Day Flow 88 MGD

Peak Instantaneous Flow 110 MGD

Pollutant Characteristics Influent Effluent

CBOD 160 mg/l 10.0 mg/l

TSS 170 mg/l 12.0 mg/l

Phosphorus 5 mg/l < 1.0 mg/l

NH3-N; Ammonia Nitrogen 17 mg/l 1.85 mg/l

TKN 26 mg/l

Total Nitrogen <8.0 mg/l

Dissolved Oxygen 6.0 mg/l

Plant Improvement OverviewThe existing wet stream process configuration begins with influent coarse screens and pumping from the southwest corner of the site to the elevated southeast end of the site. From this point flow across the site is by gravity. The pumped flow discharges to existing

FigureAerial View of Canton, Ohio WWTP

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detritus, pre-aeration and primary settling tanks. These process units could convey and/or treat up to 110 MGD. The existing activated sludge process followed by secondary settling tanks, and tertiary filters is limited in biological treatment to approximately 35 MGD and to a peak flow capacity of approximately 70 MGD. Chemical disinfection follows with peak flow capacities above the 110 MGD.

The new construction consists of a simplifier wet stream configuration capable of treating the average day and peak day flows of 39 MGD and 88 MGD respectively. The existing influent coarse screens and pumping facility will remain. The existing preliminary treatment facility is being demolish and/or modified to include a new parshall flume, longitudinal grit/grease, and fine screens prior to the MBR process.

The MBR process is being installed in the existing six activated sludge tanks without use of the existing primary and secondary settling tanks. These sixteen settling tanks are being modified and used for equalization. The MBR technology provides for a complete upgrade of the secondary treatment process within the existing six basins and without new tanks and/or pumping structures. The primary settling tanks will be converted to Stage 1 equalization. The existing six conventional activated sludge basins achieving nitrification will be converted to six individual 6.5 MGD MBR trains utilizing biological nutrient removal. The permeate from the MBR trains will be conveyed through a modified plant effluent system to a new post aeration process located in the existing chlorine contact tank before being discharged to Nimishillen Creek, an upper reach of the Tuscarawas River which flows to the Ohio River. The secondary settling tanks will be converted to Stage 2 equalization and the tertiary filters will be demolished. The chemical disinfection system is being removed.

The existing solids stream process accepted primary and waste activated sludge into four gravity thickeners. The thickened sludge was then pumped to a dewatering process feed well and pumped again to the dewatering units. Cake sludge was discharged to a conveyor system that transported the sludge cake to two incinerators. Ash from the incinerators was discharged to trailers and hauled to a landfill for ultimate disposal. The new construction will modify the sludge handling process. The incinerator process was removed from service prior to December 31, 2014, rather than upgrading the facility to meet new regulations. The incinerators are being demolished as part of the work. Primary sludge will no longer be generated and only waste activated sludge will be processed. The gravity thickeners are being converted to aerated holding. The thickened sludge pumps are being replaced and will discharge directly to the dewatering unit. The dewatering units feed well and associate pumps/piping are being eliminated. The dewatering units were to remain, however, a current sludge study is proposing that they be replaced. The existing conveyor system transporting sludge to the incinerators has been removed and a new screw conveyor system has been installed which conveys dewatered sludge cake to a new sludge loadout building located adjacent and north of the dewatering building. The new sludge loadout facility and conveyor system was put

into operation prior to the end of December 31, 2014 to replace the incinerator process. Raw sludge cake is loaded into trailers and then hauled to either of three local landfills for ultimate disposal.

MBR Supplier Pre-SelectMBR was the selected treatment process and the evaluation is discussed in the paper previously published. Only two membrane suppliers had significant large plant experience. The largest operating plant was 25 to 40 percent of the proposed ADF plant capacity for the Canton WRF.

These two membrane suppliers were notified by letter in mid-August, 2010 and invited to submit proposals based on a “best value pre-select process”. The pre-select process allowed each supplier to submit their best process application for the site specific conditions. Prior to submitting the proposal, both suppliers were invited to visit the project site, make presentations of their membrane system to the Owner and guide the Owner on visits at two (2) plants using their membrane technology.

The request for membrane systems included the plant influent criteria, effluent criteria and specific parameters of the secondary treatment process based on the site conditions. Each supplier was to determine the process configuration, basin sizes, the membrane footprint and needed systems to support their MBR process. They were to submit proposals based on their best system for the application using their design standards for their technology. Each was to supplement the submittal with pertinent information such as performance history, process calculations, technical support, warranty documents, equipment scope of supply, capital cost, power usage, chemical usage and other pertinent information for consideration.

The intention was to configure the MBR process in the existing six activated sludge tanks. Influent and effluent criteria was as stated previously. Membranes are hydraulically limiting so the following criteria was to be satisfied by the membrane system and included in the proposed configuration.

Existing Average Day Flow 29.5 MGD

Design Average Day Flow 39.0 MGD

Design Max. Monthly Flow 48.0 MGD

Design Sustained Peak Flow (24 hour) 96.0 MGD

Design Peak Instantaneous Flow (8 hour sustained)

108.0 MGD

Design Temperature 11 Degree C

Any need for additional tanks beyond the existing six tanks would require new tank construction or use of the existing primary and secondary settling tanks. At the time of the request, it was felt that the MBR process could be configured in the existing six activated sludge tanks. The existing settling tanks would be reviewed after for equalization and optimization of the overall process design.


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The pre-selection process utilized the “best value” selection approach which considers life cycle cost in lieu of only capital cost. It also incorporates other considerations such as historical performance, technical support, warranties, scope of supply, system operation and maintenance, etc., determined critical to the Owner. This approach provides one of the best methods to competitively secure membrane systems and their associated pricing early in the design process.

Ovivo was the selected membrane system supplier and they became part of the design team at the 30 percent design level. Extending the pre-select process to multiple membrane suppliers and engaging the selected supplier in the document preparation for the final design gave the City a comprehensive, cost effective project for implementation. At the completion of the pre-select process, the selected MBR system capital cost was just under $30,000,000.

Wet Stream Final Project and OptimizationsInfluent coarse screening and pumping will remain. The peak day design capacity is 88 MGD and a peak instantaneous capacity is 110 MGD with all equipment operational. Improvements included rehabilitation of the 40-year-old steel pump discharge piping and minor modifications to the existing SCADA system.

Preliminary Treatment: The preliminary treatment facility prior to a MBR process often times defines the performance success of the MBR operation. A new preliminary treatment facility has been constructed in the existing detritus and pre-aeration tanks. A schematic of the new process footprint illustrates the configuration and flow pattern. The parshall flume measures all flows from the nightly low through an instantaneous peak flow of 110 MGD. The flow measurement is needed to confirm the influent flow and is used to control MBR operation.

Two longitudinal grit/grease removal trains (55 MGD each) and three fine screening trains (40 MGD) each were constructed within the existing pre-aeration basins. The process units are divided into flow trains to better manage normal daily and peak instantaneous flow variations. The capacity of each grit/grease and screening train is such that one train of each needs to operate during normal daily flows and below maximum monthly flows. This approach allows plant personnel to address normal maintenance when the units are in standby mode and prolongs the service life of the equipment while easing the demand for operator attention while in operation. Operators can focus their efforts on operations rather than balancing maintenance and operations.

Two stage, in lieu of single stage, fine screening was selected for a small increase in capital cost. The two stage system will reduce stress on the 2 mm screens and increase overall reliability/longevity of the process.

A new preliminary treatment solids building was constructed for dewatering, consolidating and/or washing of the grit, grease, and screenings removed from the wet stream process.

Figure Fine Screens

Solids are washed and compacted to reduce odors, return organics for treatment, reduce handling and improve the consistency of the solid being disposed at the landfill.

Equalization and MBR Flow Optimization: Once the MBR supplier was selected and the existing basin use confirmed, the equalization process and peak flow rate was optimized. Ten years of historical flow records were reviewed. The peak flow occurrences and volumes associated with those in excess of 70 MGD, 80 MGD, 90 MGD and 100 MGD were calculated. The design was optimized by identifying the expected frequency and needed equalization for flow rates in excess of those listed based on the previous experience of flows at the plant. It was determined that flows in excess of 70 MGD seldom occurred and that the available tanks for equalization should be able to retain all of the events the plant had experienced since 2000. Also, the membrane peak instantaneous flow capacity of 108 MGD and the 24 hour peak sustained flow of 96 MGD were reduced to the final design peak day flow rate of 88 MGD.

The peak flow analysis calculated that nearly 5 million gallons (MG) of equalization (EQ) would be sufficient to retain any of the experienced flows above 88 MGD. EQ was therefore divided into two stages. The existing primary settling tanks would be converted to Stage 1 EQ having a capacity of approximately 5 MG and the system would include dewatering and recirculation pumps. The existing secondary settling tanks would be converted to Stage 2 EQ and also have a volume of approximately 5 MG, however the existing plant drain system would be used to dewater the Stage 2 EQ system. Historical flow data and calculated volumes for flows in excess of 88 MGD indicate Stage 2 EQ should never be used.

This EQ division into two stages gives the operator flexibility as associated with the use of EQ and with operation of the MBR process. The use of multiple tanks within each stage and the concept of two stages allows operator flexibility to control peak flow occurrences, diurnal flows if desired, and limits the use to as few tanks as possible. It also minimized the amount of support equipment associated with EQ. The operator can maintain the EQ process so maintenance and operator attention can be limited.


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A flow control chamber after preliminary treatment is used to control diurnal and/or peak flow to the MBR process. Diurnal flow peak shaving and/or peak flows in excess of 88 MGD are redirected and conveyed to Stage 1 or Stage 2 EQ via this flow control system.

The MBR Process Design: The existing six activated sludge tanks would be used for the MBR process. Other existing secondary process facilities considered for reuse included the influent rate of flow control valves to each of the six activated sludge tanks, the five centrifugal blowers (4-800 hp; 1-500 hp), a centralized return activated sludge (RAS), sludge well and screw pumps lifting the RAS to gravity flow back to the activated sludge process through rate of control valves, a combined waste sludge pump system and combined influent/effluent flow channels.

Various configurations for the MBR process were evaluated early in the design and the final configuration was chosen once the MBR supplier was selected. One approach considered was a combined influent system, combined effluent system, combined RAS, combined air systems, combined internal recycle systems and combined WAS system as associated with the six activated sludge tanks. This approach was similar to the existing plant configuration. The new equipment for this approach would be limited in quantity, large in size and heavy, requiring hoists, cranes and lifts to move. Each equipment component is expensive to replace, often non-standard and replacement parts are costly. The individual cost of each equipment item is well above the authorized purchase capability of the Canton WRF staff. It would likely be necessary to maintain a large inventory of spare equipment and/or parts or nearly every purchase would require approval by City Council.

The associated piping or conveyance channels would be large requiring large spaces and massive structures. Re-splitting of these large combined flows when redirected to the individual activated sludge basins or other tributary tanks requires massive control structures, weirs and/or channels creating undesirable hydraulic conditions or control structures. It would require significant new construction, large elevated pipes and operational difficulties to control flows. The support systems for the pumps, structures and control system are also massive or of significant support members.

An alternative approach consisted of a combined influent flow which would be split to each of the six basins utilizing the existing influent control valves. Each basin would then be configured as a separated treatment train complete with all components. Accordingly, separate internal recycle, RAS, waste activated sludge (WAS) and effluent systems would be part of and within each train whereby each train operates as a separate independent treatment plant. This approach reduces the size and weight of equipment making it more manageable by the operator. Replacement equipment and part costs are now within the financial limitations of the Canton WRF staff abilities to purchase without Council action. The cost associated with parts inventory is reduced and the inventory is more readily available by the manufacturers since the components are more standard and common stock items.

Pipes and conveyance systems are of smaller diameter and can for the most part be piped rather than constructing massive concrete channels, wells and structures. The plant control is also broken down into smaller parallel components so an upset has less impact on the overall operation. Monitoring of multiple smaller process components provides a better view for the operator to follow trends, outliers and address problems on an incremental basis.

The selected configuration for this 39 MGD MBR plant is individual and contained 6.5 MGD ADF MBR processes, one within each of the six existing activated sludge basins. This approach simplified the overall secondary treatment design significantly and kept capital and lift cycle cost lower.

Currently, night time flows are near 16 MGD and daily average flows are near 30 MGD, well below the ADF of 39 MGD. Historical records indicated that once morning flows increase and reach their maximum during the day they maintain that rate throughout the day before tapering down to the night flow. The operating philosophy of the plant would be to rotate MBR trains in an intermittent operation during the night, and as flows increase during the day, MBR trains would be brought on line to normally operate between 4 MGD and 5 MGD. When higher than 30 MGD flows are experienced, flows through all six MBR trains would be increased uniformly to treat the high flow rates. Similarly, flows among the six MBR trains would be decreased uniformly as influent flows diminished and returned to normally experienced flows.

The biological selector process chosen for the Canton WRF is similar to the VIP or UCT process. These are similar to the A2/O process which consists of an anaerobic zone, anoxic zone and aeration zone in series. However, the traditional RAS of 4Q to 6Q is directed to the beginning of the anoxic zone and an internal recycle of mixed liquor (1Q) is taken from the end of the anoxic zone and returned to the anaerobic zone. This process has been designed for biological nutrient removal of phosphorus (P) and total nitrogen (TN). Bio-P removal is to approximately 1 mg/l. An iron salt chemical feed system is provided to supplement phosphorus removal below levels

FigureAeration Basin


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achieved by bio P. Total nitrogen is being removed through the selector process to a TN equal to or less than 8 mg/l.

The process configuration includes a “swing” aeration zone which is located between the anoxic and aeration zones. This “swing” zone can operate as an anoxic zone or aeration zone depending on the biological loadings and treatment performance required. The aeration zone consists of the pre-aeration and the membrane basins.

Flow from the primary control chamber is conveyed through the existing influent channel and the existing rate of flow control valves to the east end of the MBR process. Flow enters a combined anaerobic zone and then passes under baffles to a split process train, A and B sides, where each side contains the remaining selector basins. The anaerobic and anoxic zones utilize vertical shaft hyperbolic mixers for mixing and the swing zone and pre-aeration zones have fine bubble diffusers for oxygen transfer and mixing.

Flow passes over a wall which separates the membrane basins from the upstream process zones. Each side has installed 5 rows with 7 SMU’s and 3 rows with 6 SMU’s for a total of 53 SMU’s per side and 106 SMU’s per train.

Permeate from each membrane basin is collected through a pipe system in a center gallery between the A and B sides. The permeate collection system is separate for each train side and includes an upper and lower header. These collection headers combine at the west end of the MBR train in an end gallery. This gallery provided access to the equipment and the center gallery and houses permeate system equipment. Permeate is intended to flow by gravity for a total plant flow between 60 MGD and 70 MGD. Flow conveyance above these rates will be assisted by permeate pumps. From the end gallery, permeate is conveyed through a new pipe system in the existing tunnel to the existing plant effluent system which extends to post treatment.

The following is a listing of pertinent plant design information for the Canton WRF MBR plant.

Overall Process Trains 6 each

Overall Dimensions 225 feet long x 68 feet wide x 17 feet wall height

Total Tank Volume 7.157 MG

Anaerobic Basins Total Volume 1.042 MG

Anoxic Basins Total Volume 2.30 MG

Swing Zone Total Volume 0.288 MG

Pre-Aeration Total Volume 1.019 MG

MBR Basins Total Volume 2.796 MG

MBR Basin Dimension 88.5 feet x 27.5 feet

Side Water Depth 12.5 feet

Surface area per SMU 4,305.6 sf

Flux Rate @ 39 MGD 14.2 gal/sf/day



MBR Scour Air 48,336 cf/min

Membrane Basin MLSS 12,000 mg/l to 13,000 mg/l

Normal TMP Range 0.25 psi to 1.5 psi

TMP peak 3.0 psi

Waste Sludge Max. 500,000 gallons

MBR System Pre Purchase and Project CostsHaving the membrane supplier identified through the pre-select process provided the City with the ability to pre-purchase the membrane system as opposed to assigning it to the General Construction Contractor (GC). Based on the authors experience, assigning the pre-selected system proposal to the GC is a common approach. However, at $75,000,000 to $80,000,000, the membrane system cost on this project was significantly higher than a typical project and may have precluded many of the local GCs from bidding. By pre-purchasing the membrane system, the City extended a reduced GC contract valued at under $50,000,000 and created a much more competitive GC bidding environment since more local GCs were now able to bond the improvement contract value and bid the project.

“The Canton WRF Phosphorus and Total Nitrogen Upgrade” project was bid in the last quarter of 2013. The MBR System pre-purchase agreement was secured prior to bidding for approximately $29,000,000. This combined with the successful construction bid of approximately $46,000,000 and other associated project costs such as engineering, etc.; established an after bid project costs of approximately $82,000,000 or approximately $2.10 per gallon (ADF) of wastewater treated.

It should be noted that the project cost includes sludge facility improvements and general site improvements including new pavement throughout the facillity.

FigureMBR Basin


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Building the PlantConstruction commenced in March 2014. Since construction began, the new sludge loadout building and the conveyor system to transition from sludge incineration to raw sludge dewatering and hauling was completed and made operational prior December 31, 2014 (Milestone 1).

Milestone 2, construction of the new preliminary treatment facility was necessary prior to completing and initiating MBR train operation. Construction of the new advanced preliminary treatment facility has occurred and operation was initiated in October 2015. This new facility was confirmed and deemed operational prior to the existing primary settling process being removed from service in January 2016.

Work on Milestone 3 ran concurrent to work on Milestone 2 under a completion schedule a few months’ later. Milestone 3 work addresses existing facilities being modified and new work necessary to be completed prior to the start-up of any MBR process operations. Milestone 3 work was staggered behind Milestone 2 work to permit the preliminary treatment facility some operational time before starting and operating a MBR train. This consists of facilities needed to support the MBR process including all the core equipment and extension of these systems to the extent for continued work as each MBR train is completed. Examples of these core systems include the electrical gear, power extensions and MCC’s; the instrumentation inner loop and core control systems to accept each MBR train; the influent flow control system; permeate piping; waste sludge piping; clean in place (CIP) chemical storage, pumping and piping; and the Stage 1 EQ. MBR Train No. 1 was also completed under Milestone 3. MBR Train No. 1 work was set in motion to complete the installation and place the train in service once the preliminary treatment facility was deemed operational.

SMU’s were delivered to the project site for assembly and installation in early February 2016. The SMU installation was complete in approximately 2 weeks. The pre service testing and clean water testing was performed and completed by March 4, 2016 with seeding the week of March 7, 2016. Seed sludge was obtained from the existing conventional plant RAS wet well and pumped through a fine screen system before being discharged to MBR Train No. 1. Seeding and filling the MBR Train No. 1 process unit took nearly one week. The month of March was consumed with troubleshooting various items such as the possibility of debris in the existing influent channel, erratic operation of the existing influent rate of control valves, equipment malfunctions/corrections, process programming refinements and stabilizing the influent channel level control system. All these items interrupted flow to the process and impacted the initial operation of MBR Train No. 1. Uninterrupted service of MBR Train No. 1 began on March 31, 2016 and the MLSS concentration in the MBR train reached 8,000 mg/l by April 6, 2016. The MBR Train No. 1 sludge wasting system began operation by April 12, 2016. MLSS concentration was increased further to 11,500 mg/l by May 3, 2016. The target MLSS concentration is between 12,000 mg/l and 12,500 mg/l.

FigureCanton Construction Work

Weekly performance evaluations of flow performance, sludge filterability, MLSS and sludge condition through sCOD testing has been performed to monitor increased performance and maturation of the sludge. The sCOD testing has identified that the sludge condition is improving more slowly than anticipated. Intense flow testing during the week of May 31, 2016 identified the MBR Train No.1 performance is solid as related to processing flows upward of 8 MGD. Flow performance above 10 MGD has been limited to shorter than desired periods, however, the performance continues to improve toward the peak flow rate of 14.7 MGD as the sCOD concentration drops toward expected levels and as the operations are refined. During this time of sludge maturation, the Ovivo/Kubota team has reviewed the process operation, programming and equipment to continually refine performance. In late June 2016, sCOD concentrations began to approach expected levels as demonstrated in the pilot. Permeability and filterability has steadily improved. MBR Train No. 1 performance testing is expected to be completed in the near future which will complete the start up. Permeate quality has been very good. Phosphorus and total nitrogen are not at permit conditions yet, therefore emphasis to optimize nutrient performance will occur as construction progresses. Initial performance data follows:

CBOD < than 1.0 mg/l and often none detect

TSS < than 1.0 mg/l and often none detect

Turbidity < than 0.1

Ammonia < than 1.0 mg/l

P +/- 2.0 mg/l

TN no data

Milestone 4, began on April 19, 2016 when the second existing activated sludge basis was released to the Contractor for construction of MBR Train No. 2. Milestone 5 through 8 will continue one after another as each MBR train is completed and the next is constructed. The construction of MBR Train No. 1 has provided the Contractor, the Ovivo/Kubota team and


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the plant staff with sound experience through lessons learned which can be used to optimize the construction, start-up and demonstration of MBR TrainTrain Nos. 2 through 6. Currently it is anticipated that each MBR train will be constructed in sequence from the north basin to the south basin. The anticipated construction time for each MBR train is 4 months. The existing five blowers provide all the air to both the process air systems and the scour air systems. Upgrade and automation of the blowers is being done to substantiate the equipment reliability and longevity and to improve the operational interface with the MBR control system. Work to upgrade the scour air blowers began under Milestone No. 3 and continues one blower at a time. One blower was upgraded prior to start-up of MBR Train No. 1. However, a second blower upgraded and placed into operation malfunctioned. This blower was again removed from service, the work corrected and it has been returned and placed into operation. A third blower is expected to be removed for work in the next few weeks. Modifications to each blower takes 4 to 6 weeks. Two existing blowers remain in service and will be upgraded as the work progresses. The process air piping and blower system is new. The new blowers are being installed and the piping is being complete with each Milestone as appropriate. The new process air system operation will be initiated with the completion of MBR Train No. 3. Work pertinent to each MBR Train will be completed and interconnections to the core systems will occur as the MBR trains are completed. Likewise, existing facilities are removed from service as the MBR trains are completed and the existing facilities become obsolete, such as secondary clarifiers and RAS pipe systems to the existing activated sludge process tanks.Milestone 9 will be the demolition of existing facilities including the RAS pumps, existing waste pumping system and tertiary filter once the existing core systems are obsolete after all existing activated sludge tanks have been given to the Contractor for conversion to MBR trains. The new carbon source chemical system will be installed in the RAS wet well structure.

Bumps During ConstructionConstruction always brings about challenges that aren’t always expected during design. The Canton WRF is no exception. However, each bump in the road has been addressed positively by the Contractor, Ovivo/Kubota team and the City of Canton, providing a better outcome for the project overall. Some of the bumps continue and are simply a result of the transition from one technology to another.

Quality of Non Potable Water: The Canton WRF has a fairly large non-potable water system which is fed by the plant effluent. Plant effluent is pumped to an elevated tank and then distributed across the plant in a piping system. After construction began and some new facilities were being put into operation, the non-potable water quality was less than desired for “clean water” use during start-up of the new MBR trains. This was resolved by installing a temporary strainer system. Water quality is expected to improve as each MBR train is added to the process and will likely deem the strainer system unnecessary.

Sludge wasting volume: The elimination of both the existing primary settling tanks and the primary sludge has created a bit more sludge volume and stress on the dewatering systems. Previously, the primary sludge was combined with the waste

activated sludge resulting in a sludge concentration of about 5 percent before being pumped to the dewatering system. However, the primary tanks and sludge are no longer part of the Canton WRF process and the waste activated sludge volume is the largest at present with just one MBR train in operation. The current sludge production is near or over 1,000,000 gallons per day. The addition of each MBR train will reduce the sludge volume by nearly 125,000 gallons per day to a maximum final liquid sludge volume of 500,000 gallons per day.

RAS Rescreening: After construction was initiated, the membrane manufacturer (Kubota) encouraged the use of RAS rescreening on this project to enhance performance, possibly reduce maintenance and increase longevity of the membranes. This recommendation imposed a change in construction to include returning a portion of the RAS to the plant influent pump station for recirculation through the fine screening process before being conveyed to the MBR trains. Use of the permanent RAS rescreening system does not become an effective process operation until 4 of the 6 MBR trains are in service due to the plant configuration. Therefore, a temporary RAS rescreening system has been included in the construction for use through the construction of MBR Trains No. 1 through 4.

Transition from conventional activated sludge to MBR: Like any change in technology, the transition from the conventional treatment to the new technology creates challenges related to process operations and staff knowledge as the new system is installed and the old one is phased out. This project experienced many of those same challenges. The Contractor, Ovivo/Kubota team and Canton WRF staff have found that the best way to successfully address these changes is through good communication, frequent hands-on training, and a thoughtful consideration of the area of responsibility of others.Operational progress continues and the goal of constructing one MBR Train at a time to ensure uninterrupted plant treatment capabilities has benefitted the project by working through typical construction related issues. This experience is positively impacting the project construction and equipment start-ups. MBR train construction is expected to be completed in the last quarter of 2017 and the overall project completion is expected approximately 6 months thereafter. n

Mr. Gellner graduated from the University of Akron in 1979. His career focus has been in the water and wastewater industry planning, designing and monitoring construction of projects for communities of various sizes. His involvement with the MBR technology began in the early 2000’s when the technology began to be used in the United States. As senior engineer and project manager, he has planned for and designed MBR plants less than 250,000 gpd to currently one of the largest MBR plants in North America at 39 MGD ADF. His experience includes a research study involving the removal of bacteria and viruses by the MBR process, plant construction and operation. As a member of WEF he served on the Community of Practice, conference steering committee, presented papers and participated in workshops for the MBR technology.

Terry Gellner


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SUMMER 2016 NORTH AMERICA’S LARGEST CANTON MBR … · The project cost per gallon of ... with influent coarse screens and pumping from the ... the membrane footprint and needed