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HomeMy WebLinkAboutTask Order No. 0805a with CH2M Hill, Inc. for Sidestream Nitrogen Removal Pilot TestTASK ORDER N0.0805a UNDER THE MASTER AGREEMENT FOR PROFESSIONAL SERVICES BETWEEN CITY OF MERIDIAN AND CH2M HILL, INC. This Task order is ernered into by and between City of MERIDIAN (OWNER} and CH2M HII.L, Inc. (ENGINEER), according to the terms and conditions of the Master Agreemern (AGREEMENT) for Professional Services, dated January 1, 2007. See Attachments A and B for the Scope and Fee for Task OSOSa. All other terms and conditions of the original agreement will remain in full force and effect. IN WITNESS WHEREOF, the parties execute below: For CH2M HILL, Inc. dated this ~ day of , 2009. By: - Y Name Title For City of Mericlia~n ,,~~~ p ~~j~ `~'~~,, dated this ~_ day of 2l3a9~~ ~ ~ rho '~ ~~, t $E~.. ,, By: ~ Tammy eerd, Mayor ~; -~'~~ :,~ Attest: cTQ~ . . 1 Jaycee Holz~in, City Clerk d ~/~~d P 'ng Date ,; ~~ ...~ A fir:. , tt c $~, /n9 Public Works Date Task Order 0805a Attachment A Sidestream Nitrogen Removal Pilot Test Project Understanding In anticipation of possible future NPDES effluent limits for nitrogen and current reuse permit limits, the City of Meridian (City) wants to evaluate several technologies to address its nitrogen rich recycle flow, principally from the centrate flow stream. Post aerobic stabilization of anaerobically digested solids is the chosen technology to remove nitrogen in the centrate flow stream. This process is new and innovative and CHZM HILL recommends pilot testing to demonstrate improved total nitrogen removal using aerobic post- stabilization of anaerobically digested solids. Also, the pilot test will demonstrate to stakeholders such as DEQ that bioaugmentation with biomass from thepost-aerobic digester will allow stable nitrification to occur at an SRT that would typically be too low to achieve stable ammonia removal. This scope defines the protocol of the pilot test and the estimated costs. Pilot Study Overview Two pilot scale process trains for nutrient removal will be compared, one test train and one control train. The process trains will be built to mimic the configuration of the full scale secondary nutrient removal process at the Meridian Wastewater Treatment Plant. Both process trains will be operated at an SRT too low to achieve complete nitrification for the duration of the pilot study without bioaugmentation. A pilot scale post-aerobic digester will also be built and operated to achieve simultaneousnitrification/denitrification. Qne nutrient removal process will be bioaugmented with nitrifiers from the post-aerobic digestion unit and the other will not. Goals 1. Demonstrate thatpost-aerobic digestion will reduce the dewatering centrate soluble total nitrogen concentration by at least 50°1° through operation to achieve simultaneous nitrification and denitrification without supplemental cazbon source addition. 2. (a) The bioaugmented process train will achieve lower effluent ammonia concentrations at an SRT near the nitrifier washout condition as compared to the control train, thus demonstrating the ability to run the main plant at the lower SRT while still meeting its nutrient removal goals. (b) Biomass from the bioaugmented process train will have a higher nitrification rate (mg/VSS/hr) than the control further demonstrating bioaugmentation. Scope of Work CH2M HILL will perform tasks as outlined below. Task 1 Post Aerobic Digester Setup and Start-Up CH2M HILL personnel will be responsible for the set up of the pilot post-aerobic digester and for the start-up of the system. The pilot test will be set up in unused space in an existing building near the active digesters. CH2M HILL will provide the materials far the set up of the pilot test. Two process trains will be built, one test treatment train and one control treatment train. Both process trains will be constructed to mimic the full scale secondary process at the Meridian wastewater treatment plant. The post-aerobic digester will be started first with fully aerobic conditions to achieve nitrification. The proposed initial biomass seed is mixed liquor from the secondary process. The high ammonia concentrations of the anaerobically digested solids are expected to cause toxicity problems with the un-acclimated secondary process biomass. Therefore, the loading rate of digested solids to the post-aerobic digester will slowly be increased until the full desired loading rate is achieved. Complete nitrification will be achieved at every loading rate before increase to allow gradual acclimation of the nitrifying organisms to high ammonia conditions. Alkalinity addition will likely be required to maintain stable, complete nitrification during this period. Once stable operation of the fully aerobic digester is established, the dissolved oxygen concentration will be decreased until the law DO concentrations reduce the nitrates and nitrites to the desired target level, while still maintaining nitrification. The primary goal of operation at low 1X? concentrations is the achievement of simultaneous nitrification/denitrification in the post-aerobic digester for total nitrogen removal. However, nitrite oxidizers are more sensitive to low DO conditions than ammonia oxidizers (i.e., the oxygen affinity constant for nitrite oxidizing bacteria is greater than that for ammonia oxidizing bacteria). Therefore, with the appropriate reactor conditions, nitrite oxidizers could be washed out of the system resulting in total nitrogen removal via nitrite. This latter item is an operational goal since the oxidation to nitrite and subsequent denitritiation of nitrite to nitrogen gas is both more energy efficient and requires less carbon. Task 2Post-Aerobic Digester Operation CH2M HILL will be responsible for implementing the proposed process changes. Treatment plant staff will be responsible for operation of both process trains after start up and between process changes. Treatment plant staff will be responsible for the operation of the post-aerobic digester after startup. The post-aerobic digester will be designed as a single flow through tank. Once the post-aerobic digester achieves stable operation, the reactor will be fed constantly at the target loading rate for the duration of the pilot study. No significant operator attention should be required. Before bioaugmentation of the test nutrient removal process train begins, the effluent of the aerobic digester will be wasted to a drain. Once bioaugmentatian begins, apre-determined fraction of the effluent of the digester will be fed into the anoxic zone of the test process train. Phase 1: Both trains will be seeded with biomass from the secondary process mixed liquor. The trains will then be fed continuously with primary effluent. Both process trains will be operated without bioaugmentation at a low SRT (assumed to be 7 days). The process trains will be operated for 3 SRTs (21 days} without bioaugmentation. Phase 2 The biomass from each process train will be mixed and redistnbuted, and bioaugmentatian of the test process train will begin. Both process trains will be operated for an additional 3 SRTs: the test process train will be augmented with biomass from the aerobic digester while the control process train will not. Batch experiments, descnbed below, to determine the nitrification rate of each process train before and after bioaugmentation will be performed to further demonstrate enhanced nitrification capacity using bioaugmentation. Parameters Measured During times when CH2M HILL is respons~le for pilot operation, CH2M HILL will also be responsible for taking samples for analysis. Similarly, during times when treatment plant staffs are responsible for pilot operation, treatment plant staff will also be responsible for taking samples for analysis. All necessary lab work will be performed by treatment plant staff or their designated lab, which will provide CH2M HILL with the results of analysis. In addition to the parameters listed below, a sludge sample from the post aerobic digester should be sent to the manufacturer of the treatment plant's existing centrifuge to evaluate how centrifuge operation might change with the change in solids properties. TABLE 1 Measured ameters Parameter Locations} Frequency Dissolved oxygen Each process train reactor 5 times per week ORP Aerobtc digester 5 times per wreak pH Each reactor, and aerobic digester 5 times per week 'fempereture Each reactor, and aerobic digester 5 times per week Alkalinity Aerobic digester influent Daily during startup of digester Prods train influent Othenarise week Ammonia Process train influent Daily during start up and after Process train effluent {test and control) process changes Aerobic digester influent 3 times per week Aerobic d er effluent Nitrate and nitrite Process train effluent (test and control) 3 times per week Aerobic digester influent Aerobic d ester effluent Soluble COD Process train influent 3 times per wreak Procress train effluent (test and control) Aerobic digester influent Aerobic di ester effluent TItBI.E 1 Measured ameters Parameter L.a~adon(s) Frequency Soluble Phosphorus Process train effluent 3 times per week Aerobic digester Influent Aerobic di ester effluent MLSS and MLVSS Secondary biomass (test and control) Weekly with additlonal samples Aerobk: digester influent during start up Aerobic d ester biomass Nitrification rate Secondary biomass (test and control) Duplicate measurements at the end of Phase I Duplicate measurements at the end of Phase II Task 3 Report Preparation and Final Workshop CH2M HILL will prepare a draft report on the information developed in the first two tasks of the project. A review meeting will be conducted to discuss comments on the report. Comments will be incorporated and a final report will be issued. Task 4 Project Management Project management will consist of: • Supervising project staff, • holding consultant staff coordination meetings as required, • documenting meeting decisions and action items, • assigning activities to team members, • monitoring project progress, including work completed, work remaining, budget expended, schedule, estimated cost of work remaining, and estimated cost at completion, • monitoring project activities for potential changes, anticipate changes when possible, and with Owner approval, modify project tasks, budgets, and approach, • preparing and submitting a monthly billing with backup documentation, • performing project quality control reviews of deliverables on this project. Attachment B Compensation level of Effort The task level of effort estimates are summarized in the following table. CH2M HILL has developed this level of effort estimate based on the work plan presented herein and assumptions stated previously. The fees will be billed as time and material, and will not exceed the total amount below without prior approval by the City. Level of Effort Task Description Total Task 1 PNot System Setup and Startup $21,872 2 Pilot System Operation $13,034 3 Report Preparation $11,414 4 Project Management $4,x-/3 Summary - ~-II Tasks $51,093 All costs will be billed as time and materials basis not to exceed the value above. All work will be completed and costs will be billed in accordance with the Master Service Agreement dated January 1, 2007. Schedule We recommend piloting to start in the fall so that the pilaf study can observe the biological treatment in cooler weather. Pilot System Setup and Startup Pilot Test Operation Completed 4 weeks after NTP 8 weeks after startup Report Delivered 4 weeks after completion of test