Arney, Danielle

Danielle Arney works at Evoqua Water Technologies as a Chemical Product Manager. Her primary focus is research and development within wastewater collection systems with emphasis on odor and corrosion control solutions. She specializes in product quality analyses and process development. Danielle received her chemistry degree from Appalachian State University and spent the years before Evoqua in a pharmaceutical lab developing assay methods and degradation studies of APIs. Her time outside of work involves many water-related activities including scuba diving, fishing, and whitewater rafting.

Titles from this speaker

Description: Bypass Pumping and the Sulfide Challenge - Solutions for Remedying the Unique...

Bypass Pumping and the Sulfide Challenge - Solutions for Remedying the Unique Safety, Odor and Corrosion Challenges Faced in Temporary Bypass Pumping Projects Due to Hydrogen Sulfide

Abstract

Our linear infrastructure requires regular maintenance, refurbishment, upgrades, and sometimes. replacement, for it to continue to effectively serve our communities. In order to properly care for this aging infrastructure, sewage bypass projects are frequently a critical component of many of these linear infrastructure projects. Temporary bypass systems is the typical solution to transfer water and sewage flow and maintain uninterrupted service during the necessary bypass of the existing infrastructure. The unfortunate side effect of this type of bypass project is frequently an increased release of hydrogen sulfide and other sewer gasses. These gases can cause a nuisance for the surrounding community via increased odor release. Also important, these gases can cause corrosion to concrete, metals and electrical components not intended to be exposed to sewer gases, potentially shortening the useful life of critical infrastructure. Most critically, however, Hydrogen Sulfide and other sewer gases are frequently found at concentrations toxic to human health, frequently reaching fatal concentrations in sewer systems. Open access points in sewer network, plus additional turbulence at the downstream discharge point all contribute to increased exposure to the environment of the gases that would otherwise be contained within the sewer system. Sulfide control at bypass pumping has traditionally involved a fan and undersized activated carbon canister that requires frequent replacement. There are a range of better suited solutions that can be implemented to effectively manage the sewer gas releases challenge. This paper will discuss the challenges of designing and implementing a sewage bypass pumping service and the merits of implementing effective sulfide control measures for any bypass operation including the use of liquid phase chemical treatment and foul air scrubbing technologies. The available technologies will be reviewed, and examples of best practice application will be discussed. There is no single perfect solution for sewer bypass sulfide control, and the appropriate technology combination is often project specific. The vapor phase technologies suitable for bypass pumping most commonly include appropriately sized activated carbon systems and packaged biofiltration technologies. Other vapor phase technologies such as chemical scrubbing may not be suitable due to the complexity of operation and project site requirements but may suit some specific bypass pumping sulfide challenges. In addition, either instead of or supplemental to the vapor phase technologies, a range of liquid phase technologies can be utilized to reduce the release of the sulfides into the gas phase, thereby improving the work environment for those involved in the upgrade project and making the management of sulfide gas release less challenging. These liquid phase technologies include sulfide capture, alternative biological oxygen sources, fast acting oxidants and pH adjustment technologies. The reader will learn that a comprehensive sulfide control strategy allows for the effective mitigation of hazardous, odorous and corrosive sewer gasses, minimizing the impact to our communities during maintenance or capital improvement activities both at the project site and at downstream discharge points.

This paper was presented at the WEF Collection Systems and Stormwater Conference, April 9-12, 2024.

SpeakerHorst, Calvin

Presentation time

14:30:00

15:00:00

Session time

13:30:00

15:00:00

SessionPumping Operations

Session number06

Session locationConnecticut Convention Center, Hartford, Connecticut

TopicAsset Management, Bypass pumping, Collection Systems, Combined Sewer Overflow, Deep Sewer Tunnel, Flow control, Hydrogen Sulfide, Odor and Corrosion Control, Operations And Maintenance, Pump station, forcemain

Author(s)

Trainor, Sean

Author(s)S. Trainor1, 2, C. Horst1, D. Arney2

Author affiliation(s)Xylem / Evoqua Water Technologies 1; Xylem 1; Evoqua Water Technologies 2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Apr 2024

DOI10.2175/193864718825159411

Volume / Issue

Content sourceCollection Systems and Stormwater Conference

Word count28

Description: Sustainability Within Collection Systems: Methane Mitigation as a Result of Odor and...

Sustainability Within Collection Systems: Methane Mitigation as a Result of Odor and Corrosion Prevention Programs Utilizing Calcium Nitrate

Abstract

Introduction Greenhouse gases (GHGs) such as methane and carbon dioxide are common byproducts of chemical reactions within collection systems but are less commonly considered by municipalities during sustainability analyses. Understanding the scope of the impact of these GHGs requires an understanding of their relative effects on global warming. The Intergovernmental Panel on Climate Change (IPCC) created the Global Warming Potential (GWP) metric to compare different GHGs via an equivalency to carbon dioxide (CO2e), the reference gas. Methane has a GWP of 28, meaning that it has 28 times the impact on global warming as compared to carbon dioxide. After outlining and studying the theoretical reactions of sulfide generation in wastewater collection systems and calcium nitrate dosing for sulfide prevention, we hypothesize that dosing calcium nitrate for odor and corrosion control significantly reduces the overall impact of GHGs emitted by wastewater within collection systems. Objective In the proposed paper, we will set the groundwork to understand the theoretical mitigation of methane generation resulting from calcium nitrate dosing in US wastewater collection systems, as well as test the theoretical mitigation with a use case in Manatee County, FL. Theoretical Methodology In an untreated collection system, an anaerobic BOD reduction occurs in the wastewater as follows (all reactions assume methanol as carbon source for simplicity and consistency in comparison): SO4= + 4CH3OH â†’ S= + 4H2O + 2CH4 + 2CO2 In a collection system being dosed with calcium nitrate for sulfide prevention, the intent is to drive an anoxic BOD reduction in the wastewater instead of anaerobic, which occurs as follows: 6NO3- + 5CH3OH â†’ 5CO2 + 3N2 + 7H2O + 6OH- While more CO2 is generated in this reaction versus the anaerobic reaction, no methane is produced. Based on the comparison of these reactions and the GWP of methane, for every 1 lb of sulfide prevented, 25.25 lbs of net CO2e is prevented. Assuming that all GHGs are fully released from the wastewater into the atmosphere, we calculate that a maximum of 11.83 lbs CO2e can be prevented per gallon of 3.5 lb NO3-O/gal solution dosed into collection systems as part of an odor prevention program. In fiscal year 2021, theoretically a maximum of 71,887 metric tons of CO2e could be prevented as a result of all the chemical shipped to customers in the US by Evoqua for use in odor prevention. While it is recognized that a municipality choosing an odor prevention program will be incurring additional GHG emissions via transportation, manufacturing, provision of service, etc, the analysis of the use case study will focus explicitly on changes in GHG emissions specifically related to the theoretical reactions described above in relation to calcium nitrate dosing into the collection system. Application Manatee County Utilities (MCU) operates an expansive collection system involving over 800 lift stations (LS) with many long retention time force mains. The collection system conveys over 22 million gallons per day (MGD) of flow across three service areas to a corresponding wastewater reclamation facility for each service area. To significantly reduce corrosive conditions, MCU set a target atmospheric hydrogen sulfide (H2S) control objective of 20 ppm average and 50 ppm peak. MCU utilizes multiple solutions within their program, including calcium nitrate and pH shift technologies, to achieve these goals. For additional knowledge and to establish a baseline, we decided to also test the methane mitigation from dosing other chemicals by testing sites treated with magnesium hydroxide and calcium hydroxide. Four portions of the collection system were selected for sample testing. Two portions, N4B force main to N1B LS and Greenbrook 2 force main to Lakewood Ranch Riverwalk LS, are treated with calcium nitrate. Another section, Pope Road Master LS, receives flow treated with magnesium hydroxide. The final section, Tara 20 LS, receives flow treated with calcium hydroxide. A portable H2S gas monitor was deployed at each injection point and each control point to log continuous sulfide measurements. Grab samples were taken for dissolved sulfides, pH, temperature using gas detector tubes and a calibrated Hach portable pH probe. Gas samples were collected from the headspace of the wet wells using tedlar bags and CO2/CH4 concentrations analyzed via GC/MS by a certified third-party lab. Samples were collected at periodic intervals based on route efficiency and record keeping. Results and Discussion From six sample sets taken from the N4B force main to N1B LS, five showed a decrease in methane concentration from the injection point to the calcium nitrate-treated control point, with an average decrease in methane concentration of 38%. Half the samples showed an increase in CO2 emissions at the control point. Similarly, five of the six sample sets collected at the Greenbrook 2 force main to Lakewood Ranch Riverwalk LS saw a decrease in methane concentration with an average decrease of 13%. CO2 results from Greenbrook 2 mostly decreased in concentration, but only by small fractions. More data is needed to draw conclusions regarding CO2 results. Overall, methane was broadly reduced with nitrate treatment, with an average of 24% reduction in methane emissions during nitrate dosing. The CH4 concentrations at Pope Road Master LS treated with magnesium hydroxide were similar to that of the control points treated with calcium nitrate but showed lower CO2 values. The CH4 and CO2 concentrations at Tara 20 LS treated with calcium hydroxide were similar to the results obtained from the control points of N4B force main to N1B LS and Greenbrook 2 force main to Lakewood Ranch Riverwalk LS. This paper will go further into the analysis of the results, discussing outliers, testing challenges, and comparing test results to theoretical assumptions. We will also discuss the immediate and future steps to support the project, such as utilizing a continuous method of data collection for more robust data to decrease standard deviation. Another municipality has expressed interest in continuing the research within their collection system, which will provide more information on methane mitigation regarding different collection system designs, climates, and wastewater characteristics. We will also discuss the long-term sustainability target of evaluating GHG emission impacts from the full life cycle of calcium nitrate dosing for odor control, including manufacturing and transportation impacts. Benefits The theoretical mitigation calculation method would allow any municipality to calculate the methane mitigation they are achieving as a result of their odor control program utilizing calcium nitrate, making it easier to quantify the sustainability benefit of the program and communicate it with their community. As sustainability metrics become more important, including GHG metrics, these calculations can play a critical role in quantifying the overall GHG impact of the wastewater treatment and collection system and providing an additional method of GHG reduction. In the case of Manatee County (the County), the benefits are less theoretical. The County conducted a GHG Audit that was completed in June 2020, and while it took into consideration the wastewater treatment plants and overall utility operations, it did not examine GHG emissions from the collection system. This audit recommended a reduction of nearly 3,000 metric tons of CO2e a year to reach net zero by 2040. Understanding GHG emissions and particularly methane mitigation of the odor prevention program could allow MCU to demonstrate a more robust view of the wastewater contributors towards GHGs for the County as well as provide potential solutions towards the recommended reduction goal through a method that neither party may have considered beforehand. Whether or not wastewater authorities or utilities have their own GHG goals, they can provide benefit to their municipalities that are more likely to have them, as well as build public support through communicating the sustainability impacts of their operations.

This paper was presented at the WEF Odors and Air Pollutants Conference, May 16-19, 2023.

SpeakerArney, Danielle

Presentation time

11:15:00

11:45:00

Session time

10:45:00

11:45:00

SessionMeasuring and Mitigating Greenhouse Gas Emissions from Wastewater Treatment

Session number1

Session locationCharlotte Convention Center, Charlotte, North Carolina, USA

TopicSustainability and Greenhouse Gases