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Water & Resource Recovery Center Odor Abatement Efforts UpdateCity of Dubuque City Council Meeting Action Items # 02. Copyrighted December 18, 2023 ITEM TITLE: Water & Resource Recovery Center Odor Abatement Efforts Update SUMMARY: City Manager providing an update on odor abatement efforts at the Water & Resource Recovery Center. SUGGESTED Receive and File; PresentationSuggested Disposition: DISPOSITION: ATTACHMENTS: Description MVM Memo Type City Manager Memo Staff memo, Water & Resource Recovery Center Odor Staff Memo Abatement Efforts Update Public Input Presentation —Uploaded 12.18.23 Supporting Documentation Supporting Documentation THE C Dubuque DUjIBQTE WAWca 914 Masterpiece on the Mississippi YP pp aoo�•o 13 z0i7*20*�oi9 TO: The Honorable Mayor and City Council Members FROM: Michael C. Van Milligen, City Manager SUBJECT: Water & Resource Recovery Center Odor Abatement Efforts Update DATE: December 14, 2023 Water & Resource Recovery Center Director Deron Muehring is providing an update on odor abatement efforts at the Water & Resource Recovery Center. v Mic ael C. Van Milligen MCVM:sv Attachment CC' Crenna Brumwell, City Attorney Cori Burbach, Assistant City Manager Deron Muehring, Water & Resource Recovery Center Director Dubuque THE C DUUB--*--TE M[Amldea EiV Masterpiece on the Mississippi � pp z°°'.° 13 zoi7*20*zoi9 TO: Michael C. Van Milligen, City Manager FROM: Deron Muehring, Water & Resource Recovery Center Director SUBJECT: Water & Resource Recovery Center Odor Abatement Efforts Update DATE: December 14, 2023 INTRODUCTION The purpose of this memo is to provide an update on odor abatement efforts at the Water & Resource Recovery Center. BACKGROUND The Water & Resource Recovery Center (WRRC) uses physical, biological, and chemical processes to remove up to 98% of incoming organic pollutants. This process does result in the creation of gases and compounds that can create unpleasant odors. The nature of the odors is a function of the chemical characteristics of the influent wastewater received at the WRRC. The wastewater generated in Dubuque has higher concentrations of pollutants than typical domestic waste. Therefore, it has a higher propensity to produce odors. As wastewater with high organic content undergoes decomposition, it releases gases such as hydrogen sulfide (1­12S) and mercaptans. 1­12S is also called "sewer" gas known for its pungent "rotten egg" odor even at low concentrations. Mercaptans are known for their pungent "smelly sock" odor. These gases can be produced and released at multiple locations within the treatment system. In fact, these gases can be present to some degree in the wastewater when it first reaches the WRRC. The most likely sources for the odors at the WRRC, listed from highest contributor to lowest, are the primary clarification process, raw influent from forcemain/pressurized sewers, blended sludge storage, waste activated sludge storage, and anaerobic digestion. Even though odor producing compounds will always be present at the WRRC, there are steps that can be taken to minimize the release of the gases and odors into the atmosphere. In June of 2023, the City hired US Peroxide, LLC (USP) to assist WRRC staff with performing an odor control evaluation at the WRRC. USP is a leading provider of peroxygen-based technologies and full -service chemical treatment programs for municipal and industrial water and wastewater treatment applications. They have extensive experience in liquid phase treatment for odor control. USP provides temporary chemical feeds equipment to dose the system and monitoring equipment to measure the effectiveness of the chemical dosing. The odor control evaluation began with discussing treatment objectives, suspected locations of odor release, treatment facility design and wastewater characteristics. The initial consultation was followed by bench testing of wastewater from several process locations to determine the extent of possible sulfide removal at varying reaction times and dose rates. Bench testing was conducted, with multiple chemicals, to identify which chemicals would likely provide the most efficient and cost-effective odor reduction. In August of 2023, the WRRC began dosing hydrogen peroxide between where the wastewater reaches the WRRC (the headworks) and the primary clarifiers where the highest levels of hydrogen sulfide (H2S) can be expected. DISCUSSION While progress is being made to identify the location/source, and reduce the presence of, odor producing gases and compounds at the WRRC, those improvements are now masked by odors created because of temporary operational changes — changes necessary to continue to receive and treat the city's wastewater in accordance with the federal Clean Water Act. The operational changes were necessary due to an unfortunate error by a private contractor hired to assist with the annual inspection of equipment that helps ensure that the WRRC effectively treats the wastewater generated in the Dubuque community. As the manufacturer of the equipment, they were hired because they would possess unparalleled insight into the intricacies of the equipment. Utilizing the manufacturer for servicing minimizes the learning curve often associated with third -party service providers. Their familiarity with the WRRC system should translate to streamlined processes and quicker responses when issues arise. By choosing them, the City was entrusting the equipment to a contractor with years of experience in designing, manufacturing, and servicing similar equipment. Their expertise should have ensured that the WRRC equipment would be kept in peak operational condition. Unfortunately, that was not the reality. Inspection of the equipment required the contractor to remove the electrical service and controls to allow access to the interior of the equipment. Following inspection, the contractor re -wired the unit to put it back into service. After finishing up unrelated maintenance of the unit, they went to start the equipment and it failed to function correctly. The contractor returned to try and help troubleshoot the equipment but left without having resolved the issue, believing that it wasn't related to the equipment but had something to do with the WRRC computer system that controls the equipment. That left WRRC staff and a second contractor, a computer program logic controller (PLC) contractor, to try and troubleshoot the issue. They tried a variety of things to rule out various elements of the controller system. Finally, a week later the WRRC team, along with the PLC contractor discovered that the service contractor had re -wired the equipment incorrectly. Once corrected, the unit started up. The WRRC employs an anaerobic digestor system to break down organic material in system solids. This process involves microorganisms that thrive in anaerobic (oxygen -free) conditions. The breakdown of volatile organic material in an anaerobic digester occurs through a series of microbial activities, primarily carried out by bacteria and other microorganisms. The equipment that was inoperable for a week helps to maintain the delicate balance and relative population of the microorganisms in the anerobic digesters. As a result of the inoperable equipment, two of the four digester units became dormant. They could no longer accept and treat the waste stream. The other two remained active. However, to ensure they would remain so, to ensure that the discharge from the WRRC remains within permit discharge limitations, WRRC staff had to limit the waste stream sent to the two functional digesters. To accommodate this, waste is being temporarily stored in tanks where they normally are not. As a result, the odor producing gases can readily escape into the atmosphere. And this has resulted in what might be unprecedented odors coming from the WRRC. WRRC staff have been doing what they can to bring the dormant systems back to life. That has 2 included collecting digester seed sludge from Iowa City's wastewater treatment facility and introducing it into the dormant digester units to try and jump start the regrowth of the microorganism ecosystem. The effectiveness of the steps taken to date will be assessed during the week of December 18. If the system shows clear signs of recovery, then more of the solids waste stream will be sent to the digesters for treatment. This will be done gradually to ensure that the system can handle the waste. If the system reacts well to the additional waste, the WRRC might be able to return to normal operations by early January. Unfortunately, that will not eliminate the odors as it will take some time to reintroduce the waste that is being temporarily stored in the tanks exposed to the air. Again, that material will have to be slowly reintroduced, metered back into the treatment process. But if the system comes back as described, the temporary tanks would be emptied and cleaned in February. Recognizing the failure of the contractor and the City's costs that have resulted, not to mention the intangible effect the odors have on citizens in the community, discussions are underway with the Legal Department to explore possible legal remedies due to the contractor's error. As stated previously, progress has been made to identify the location/source and reduce the presence of odor producing gases and compounds at the WRRC as measured by the reduction in hydrogen sulfide. It has been determined that a 50% reduction in H2S can be achieved if between 50 and 60 gallons of peroxide per day is added into the waste stream between the headworks and the primary clarifiers. That would cost between $130,000 and $150,000 per year based on current chemical pricing. Based on these results, an improvement package will be included as part of the Fiscal Year 2025 budget to increase the WRRC operating budget to fund this odor reduction effort. The odor reduction evaluation doesn't end there. The next step for the odor reduction evaluation to start in early January is to evaluate the odor reduction benefits of adding a combination of peroxide and ferric salts (iron salts) to the waste stream at other strategic locations. In addition to binding up sulfur and reducing the production of H2S, iron salts can minimize the production of struvite within the system. Struvite is a mineral composed of magnesium, ammonium, and phosphate. It often forms as a crystalline precipitate in anaerobic digesters and pipes causing scaling and clogging of pipes. Therefore, dosing the waste stream before the it enters the anerobic digesters will be evaluated. It may take anywhere from eight to fourteen weeks to determine the optimum dosing rates, but odor reduction benefits could be realized right away. The evaluation will also include determining the effective dosing rate and combination of adding peroxide and iron salts in the waste stream before it enters the centrifuge. Determining the effective dosing rate at this location should only take about four weeks once dosing is initiated. Periodic updates on the progress towards addressing both the short-term odor issue and the comprehensive odor reduction evaluation will be posted on the City of Dubuque website at www.cityofdubugue.org/odorcontrol. ACTION REQUIRED This memorandum is intended for informational purposes. Cc: Crenna Brumwell, City Attorney William O'Brien, W&RRC Manager 3 Bradley and Becky Plummer 12/15/23 1041 Shady Oaks Drive Dubuque, IA 52003 Dear Mayor, Council Members and City Manager: I am writing to you regarding the odor issues emanating from the Dubuque Water & Resource Recovery Center. I appeared before the City Council earlier this year to plead my personal dissatisfaction with the odor problems created by the Recovery Center and its impact on our family and the ability to enjoy our household. Now I am appealing to you on behalf of a much larger contingent of residents of the South End of Dubuque and multiple business leaders to express our complete disgust with the lack of progress to rectify the situation. The past several weeks have realized pollution of a magnitude not realized in the 13 years of my residence on the South end of town. This is a pollution situation. Previously the odor issues were largely contained to Summertime with high humidity, however since the arrival of additional commercial waste contributors the problem has worsened severely. One week prior to this letter, the odor was the most offensive in recollection and beyond adjectives to describe in writing. For purposes of expedience, we should all stipulate that the problem is real and acknowledged as exhibited by your own agenda and previous minutes. However, it is evident that the actions taken to date are insufficient to rectify the situation and we seem to be moving from excuse to excuse. We understand there was a system failure related to ongoing maintenance performed by a third party, and that the City is contemplating recourse due to the same. It is known STREET ADDRESS, CITY, ST ZIP CODE T (123) 456-7890 U WINAN.COMPANY.COM that roughly 10 years ago, a significant capital expenditure was completed to enhance the Recovery Center. It is more than evident that in the time since then the composition of the waste intake has intensified due to external processing contracts and the facility has failed to keep pace with the volume and intensity of the incoming waste. Recognizing that there is no such thing as a quick, immediate fix we are proposing that the following issues be contemplated immediately. Long -Term: The City should allocate appropriate funds for an expert consulting firm to assess the entirety of the situation and solve for long-term accommodation of our collective needs. In the upcoming budget cycle, we demand allocation for such expert opinions and preparation of funds for necessary capital expenditure to resolve the situation. Currently we are simply putting patches on the problem and kicking the can down the field. There are literally thousands of cities that do not have this problem. Dubuque wants to be seen as an example, but I purport not in this light that would be easy to shine. Immediate: Understanding that the issues are not immediately reparable, we implore that the City explore all avenues to mitigate the impact immediately. We understand that we are under contracts with private entities and various political subdivisions for waste intake, and this is magnifying our problem. Those contracts aside, we argue that the City's contract with its tax -paying citizens and businesses supersedes any external contractual obligations, and we should cease taking in waste from outside of our community despite the impact to City revenues and the effects to its current waste customers. The City's obligation should be first to its environment, citizens and businesses that have supported it far before the external contracts existed. Myself, and the many constituents I represent in this letter hope for an immediate, focused effort to fix this issue. This is not the first time this has been aired in public forum, but now it is much more severe. We are all positive supporters of the City of Dubuque, however it is irrefutable that our environment, citizens and businesses have suffered physical, emotional and real economic loss due to the City's inability to resolve this problem. We will collectively consider taking additional steps to rectify this if our current representation cannot resolve it. On behalf of multiple citizens and businesses: Respectfully, Bradley J. Plummer �Y• '.{�"yam - r ` THE CITY OF DUB E Masterpiece on the Mississippi ' M;;n;;ging nrinr IrqHPq at thp Water :. --r AM :M; Resource RecoveryCemer = Odor Reducti �t�. •, '+"icy. k ~ • � -, _ ti r i yr a i �+• 4L r on Analysis Update December 18, 2023 I F THE CITY OF DUB E Masterpiece an the Mississippi Odor Reduction Analysis Update 1. Background 2. Recent extraordinary odor issues I Odor reduction strategy a. Where we are in the process b. What's next in the process December 18, 2023 Lys. Background THE CITY OF DUB E Masterpiece an the Mississippi The top priority of the Water & Resource Recovery Center (WRRC) is to serve the city by treating wastewater generated in the community in accordance with the federal Clean Water Act. Odor Reduction Analysis Update December 18, 2023 Background ■ The WRRC uses physical, biological, and chemical processes to remove up to 98% of incoming organic pollutants. ■ Odors are generated from every phase of wastewater management including collection, treatment, and disposal. Just as the character of the wastewater changes as it progresses through the treatment process, so do the odors released from that wastewater. ■ The nature of the odors at the WRRC are a function of the chemical characteristics of the influent wastewater received at the WRRC. ■ Because the wastewater generated in Dubuque has higher concentrations of organic pollutants than typical domestic waste, it has a higher propensity to produce odors. FA THE CITY OF DUB E Masterpiece on the Mississippi Odor Reduction Analysis Update December 18, 2023 PP- . -..: r Background THE CITY OF DUB E Masterpiece on the Mississippi ■ All odor emissions from wastewater are considered objectionable, but some treatment processes release larger odor volumes and more objectionable odors than others. ■ Generally, three conditions are required to create an odorous emission: 1. Odorous compounds in the source wastewater 2. Exposed surface area, from which compounds can be emitted; and 3. A driving force that causes the compound to pass from the facility to the surroundings. Odor Reduction Analysis Update December 18, 2023 Extraordinary Odors Cause THE CITY OF DUB E Masterpiece an the Mississippi ■ Routine maintenance ■ Contractor error ■ Impact to anaerobic digesters ■ Modified operations to continue to treat wastewater in compliance with the federal Clean Water Act ■ Storing wastewater in tanks open to the atmosphere. Odor Reduction Analysis Update December 18, 2023 1 t' Extraordinary Odors Cause THE CITY OF DUB E Masterpiece an the Mississippi ■ Routine maintenance ■ Contractor error ■ Impact to anaerobic digesters ■ Modified operations to continue to treat wastewater in compliance with the federal Clean Water Act ■ Storing wastewater in tanks open to the atmosphere. ■ Generally, three conditions are required to create an odorous emission: 1. Odorous compounds in the source wastewater 2. Exposed surface area, from which compounds can be emitted; and 3. A driving force that causes the compound to pass from the facility to the surroundings. Odor Reduction Analysis Update December 18, 2023 Extraordinary Odors Actions THE CITY OF DiUB E Masterpiece on the Mississippi ■ Reviving anaerobic digesters • Temporary storage of waste, reducing load to digesters • Introducing sludge from healthy digester into dormant digester • Transporting seed sludge from Iowa City anaerobic digester and pumping it into dormant digesters • Adjusting alkalinity in dormant digesters ■ Exploring legal remedies related to the maintenance contractor ■ Examining steps to take to prevent this situation from occurring again (maintenance schedule/timing and stocking spare parts). Odor Reduction Analysis Update December 18, 2023 Extraordinary Odors Milestones THE CITY OF DUB E Masterpiece on the Mississippi ■ Digesters are healthy enough to start resuming normal treatment operations. • Health of biological ecosystem will be evaluated this week. Additional seed sludge may be hauled from Iowa City. • If healthy enough, increase waste load to the digesters (possibly the week of December 25). • Monitoring the health of the system will determine how soon, but if all goes well, a return to normal treatment operations could happen in early to mid -January. ■ Feed stored waste back into the system • Feeding of the stored waste into the system must be controlled and monitored to ensure it does not shock the system. • Depending on the recovery, the waste could be completely removed from the tanks sometime in February. " Clean tanks (February or March depending on weather) Odor Reduction Analysis Update December 18, 2023 H2s H /� IS� H I SO M�J 10 ML Hydrogen Sulfide Colorless gas; rotten -egg smell. Irritating to eyes/skin/respiratory tract. Poison! Inhalation causes headache. dizziness, nausea; high levels (>100❑ ppm) can be instantly fatal causing respiratory paralysis. Cardiac effects may occur. Highly flammable. CAS No fibs-C6-4 Odor Reduction Analysis Background THE CITY OF DUB E Masterpiece on the Mississippi ■ As wastewater with high organic content undergoes decomposition, it produces gases and compounds that have unpleasant odors. ■ Hydrogen sulfide (H2S), also called "sewer" gas known for its pungent "rotten egg" odor, is generally the most prevalent odor causing compound in wastewater and Is the design -driving contaminant for most odor control strategies. ■ All odor emissions from wastewater are considered objectionable, but some treatment processes release larger odor volumes and more objectionable odors than others. Odor Reduction Analysis Update December 18, 2023 r� n Odor Reduction Analysis Process THE CITY OF DUB E Masterpiece on the Mississippi ■ Identify where and at what levels 1-12S exists within the treatment process Evaluate the effectiveness of chemical dosing - ; sites and rates to reduce 1-12S levels in system Determine cost and provide options for permanent odor reduction measures Odor Reduction Analysis Update December 18, 2023 H202 is Safe Despite its power, H202 is a natural metabolite of many organisms, which decompose the H202 they produce into oxygen and water. And since H202 is totally mixable with water, the issue of safety is one of concentration. Industrial strength H202 is a strong oxidizer and does require handling precautions. H202 is Selective The reason why hydrogen peroxide can be used for such diverse applications is the different ways in which its power can be directed — termed selectivity. By simply adjusting the conditions of the reaction (e.g., pH, temperature, dose, reaction time, and/or catalyst addition), H202 can often be made to oxidize one pollutant over another, or even to favor different oxidation products from the same pollutant. Odor Reduction Analysis Steps to Date THE CITY OF DUB E Masterpiece on the Mississippi • Hired US Peroxide, LLC who helped identify the highest source of H2S in the treatment system. ■ Set up temporary systems to be able to dose the treatment train with hydrogen peroxide (H2O2) and be able to measure the corresponding H2S reduction. H2O2 1i< °.ir' x Odor Reduction Analysis Update December 18, 2023 THE CITY OF TEOdor DUB Masterpiece an the Mississippi Ste s to Date A Owe. ■ Determined that adding between 50 and 60 gallons of hydrogen peroxide (1-1202) per day - . -- - -. ■ to the waste stream before the primary clarifier achieved a 50% reduction in 1-12S. w PV %Z! • The cost to continue adding H2O2 would be between $130,000 and $150,000 per year. ■ An improvement package recommendation will be submitted for consideration with the proposed Fiscal Year 2025 budget. Odor Reduction Analysis Update December 18, 2023 �• ••A Y ? �,r - 'r.h�TiC "_ :or:- - --- Odor Reduction Analysis Next Steps THE CITY OF D B TE Masterpiece on the Mississippi ■ Evaluate dosing the system with a combination of peroxide and ferric salts (iron salts) and other compounds at other strategic locations in the waste stream. ■ Dosing the waste stream before it enters the centrifuge. Reduction in 1-12S (odor) will be realized right away (4 to 6 weeks to find optimum dosing concentrations). ■ Dosing the waste stream before the it enters the anerobic digesters. Reduction in odor will be realized right away (8 to 14 weeks to find optimum doing concentrations). ■ In addition to reducing 1-12S, compounds like iron salts and can minimize the production of struvite in the system. Odor Reduction Analysis Update December 18, 2023 H202 . i ot' CI C,I ,Fc.CI Mg HOB S0 H Odor Reduction Analysis Next Steps THE CITY OF DUB E Masterpiece on the Mississippi ■ Determine the optimum combination and dosing rates of the additives. ■ Determine cost and provide options for implementing additional, permanent odor reduction measures ■ Continually assess overall effectiveness of odor reduction measures Aln Odor Reduction Analysis Updates THE CITY OF DUB E Masterpiece on the Mississippi Periodic updates will be posted on the City of Dubuque website at: www.citvofdubuque-orq/odorcontro- Odor Reduction Analysis Update December 18, 2023