Rauch-Williams, Tanja

Dr. Tanja Rauch-Williams serves as Carollo's Wastewater Process and Innovation Lead and Principal Technologist with more than 20 years of experience in wastewater treatment, water reuse and applied research. Her work has focuses on wastewater treatment, optimization, codigestion, resource recovery, energy optimization, and trace organic removal. Tanja is a member of LIFT's Steering Committee, a member of WEF's municipal resource recovery design committee, and Chair of the Rocky Mountain Innovative Water Technologies Committee.

Titles from this speaker

Description: Co-digestion of Source Separated Organic Food Waste: Status and Case Studies in the...

Co-digestion of Source Separated Organic Food Waste: Status and Case Studies in the US, Canada, and Europe

Abstract

This paper presents the findings from Phase 1 of the Water Research Foundation (WRF) project 4915 “Characterization and Contamination Testing of Source Separated Organic Feedstocks and Slurries for Co-Digestion at Resource Recovery Facilities”. This project aims to develop accurate and reproducible analytical methods for food waste characterization. Ultimately, the goal is to deliver practical guidance for the wastewater industry to create cost-effective and meaningful sampling strategies as well as acceptable minimum quality specifications for accepting SSO substrates for co-digestion. Phase 1 of the project consists of an international state-of-the-industry review of SSO co-digestion practices and experiences supported by a utility survey conducted among utilities in the U.S. and Canada. This paper summarizes the findings from the state-of-the-industry review which include current status of SSO feedstock codigestion, pretreatment practices, feedstock characteristics, quality standards, and data limitations. The paper also summarizes information from the utility survey including monitoring practices, and method limitations and needs. Finally, this paper presents a proposed tiered analytical strategy for SSO characterization for co-digesting utilities to streamline resources, and useful data that can be employed for operational decision making.

SpeakerRauch-Williams, Tanja

Presentation time

09:30:00

09:50:00

Session time

08:30:00

10:30:00

SessionOpportunities, Challenges, and Impacts of Co-digestion with Source Separated Organics

Session number519

Author(s)

C. TasserR. GuptaC. PoloC. PoloS. FevigC. SchaumT. Rauch-Williams

Author(s)C. Tasser1; R. Gupta1; C. Polo2; C. Polo2; S. Fevig3; C. Schaum4; T. Rauch-Williams5;

Author affiliation(s)Carollo Engineers, CA1; Carollo Engineers, Inc., CA2; The Water Research Foundation, CO3; Bundeswehr University Munich4; Carollo Engineers, CO5; University of Michigan Dept of Civil Eng Env, MI6; University of Michigan, MI7; Bundeswehr University Munich, Muenchen8

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2020

DOI10.2175/193864718825157475

Volume / Issue

Content sourceWEFTEC

Word count18

Combining Metabolic, Kinetic and Physical Selection to Achieve Full-Scale Continuous Flow Densified Activated Sludge and Nutrient Removal at Robert W. Hite Treatment Facility

Abstract

Introduction: Metro Water Recovery's (Metro) Robert W. Hite Treatment Facility (Hite) in Denver, CO is permitted for a maximum month (MM) flow of 220 mgd and has two parallel liquids treatment trains including the North Secondary (NSEC). The NSEC utilizes a modified Ludzack Ettinger (MLE) process with a sidestream anaerobic reactor (SAR) to achieve nutrient removal. In 2018, Metro's facility plan identified a need for increased aerobic solids retention time (aSRT) to meet future potential total nitrogen (TN) and total phosphorus (TP) regulations (Colorado Regulation 31). To avoid costly expansion, Metro commissioned a full-scale demonstration train (NAB2) to trial densified activated sludge (DAS). This work documents findings from the full-scale demonstration facility and discusses how Metro is translating DAS into a full-scale solution at the RWHTF. Specifically, this paper will discuss factors that have led to the development and long-term operation of DAS with biological and physical selection, as well as provide insights into how particle size distribution (PSD) may be impacted by operational parameters and influence nutrient removal. Materials and Methods: DAS facility: The DAS demonstration facility (denoted as NAB2) consisted of an isolated, paired aeration basin and secondary clarifier from NSEC. Description of the facility is provided elsewhere (Avila et al., 2021). Metro operated NAB2 to test multiple distinct metabolic and kinetic selector configurations, with two primary configurations, Fig 1. A 'control' train was also operated without physical and biological selection. Routine influent/eff concentrations of organics, solids and nutrient content were determined using Standard Methods for the Examination of Water and Wastewater. PSD of the MLSS, hydrocyclone UF, and hydrocyclone OF were routinely characterized. Settling Column Testing: Settling column testing of bulk DAS ML was conducted on multiple occasions to determine the Vesilind equation settling coefficients (V0 & k) as well as the PSD. Additionally, settling properties for particle size fractions: <200µm, 200-600µm, and >600µm were characterized across a concentration range of approximately 1,500 mg/L to 6,000 mg/L. Activity Testing: Batch scale activity testing of bulk mixed liquor and three particle size fractions was used to evaluate nutrient removal rates of activated sludge in 5-gallon reactors. Analytes (NH4, NO3, NO2, and PO4) were measured with HACH TNT kits. Hydrocyclone Nozzle Testing: Hydrocyclone UF nozzle sizes ranging from 15 to 25 mm were individually tested at a target pressure of 30 psi. Flow measurements from the hydrocyclone feed and OF were recorded via flow meter. Total suspended solids (TSS) and PSD samples were collected from the RAS, OF, and UF. Process and Capacity Modeling - Data from NAB2 testing were used to develop, calibrate, and validate AB2 specific and a whole plant process model in BioWinTM and computational fluid dynamics (CFD) models of the NSEC secondary clarifiers. These models establish system capacity of existing infrastructure and design criteria for full-scale implementation. Results and Discussion: Impact of biological selection on densification: PSD of NAB2 biomass during configuration 1 (SAR-MLE) mode) stabilized into a uni-modal distribution, with median size increasing from 100 to 200 um respectively (Fig 2A). The average SVI30 for the NAB2 versus control basins were 102 mL/g and 153 mL/g respectively. PSD of NAB2 biomass during configuration 2 (SAR-A2O) mode reflected a bi-model distribution (Fig 2B). The average SVI30 for the test versus control basins were 81 mL/g and 173 mL/g respectively. Cumulatively, results suggest that improved settleability is observed when the mass fraction of granules (particles >212 um) in the sludge exceeds 15%. This was observed on multiple occasions when NAB2 operated in SAR-A2O mode with anaerobic food to microorganism ratio (F/M) being sustained between 1.0 and 3.0 lb sCOD/lb MLVSS-day. Impacts on PSD on Settling Performance and Biomass Activity: Settling velocity and compressibility were observed to increase as the particle size fraction increased (Table 1). Biomass activity results indicated that larger particle size fractions had lower denitrification and nitrification rates versus smaller particle size fractions while Bio-P activity was highest in particles greater than 200 um. These results indicate that minimizing particles sizes greater than 600 um may allow Metro to exploit high nitrification/denitrification/Bio-P rates and with superior settling and compressibility (Quoc et al., 2021). Influence of Physical Selective Pressures on PSD in NAB2 (Fig 3): Results indicated that mass flow through the UF could be reduced when the nozzle size decreases (Fig 2). This phenomenon can potentially be exploited to craft a wasting strategy focused on developing and keeping a target PSD. DAS impacts on Capacity: Stress testing indicated that NAB2 could be loaded at surface overflow rates (SORs) >700 gpd/sf and solids loading rates (SLRs) >60 pounds per day per square foot (ppd/sf) while still maintaining reliable blanket control and stable effluent TSS (Fig 4). Whole plant process and CFD modeling indicated that the densified scenario could allow Metro to successfully treat 2040 flows without needing to invest in additional aeration basins or secondary clarifiers, allowing for savings of $50 million dollars.

To meet future nitrogen and phosphorus regulations without constructing new infrastructure, Metro Water Recovery conducted a full-scale demonstration of densified activated sludge (DAS) at its Robert W. Hite Treatment Facility. This study evaluated the DAS system, focusing on metabolic and kinetic selector configurations, particle size distribution, and nutrient removal efficiency. Results include impacts of configurations, particle size, and nozzle size and projected capital cost savings.

SpeakerMaltos, Rudy

Presentation time

09:00:00

09:30:00

Session time

08:30:00

10:00:00

SessionFull-scale Intensification Experience

Session number510

Session locationRoom 343

TopicFacility Operations and Maintenance, Intermediate Level, Municipal Wastewater Treatment Design, Nutrients, Research and Innovation

Author(s)

Maltos, Rudy, Rauch-Williams, Tanja, Freedman, Daniel, Cavanaugh, Liam, Scopp, Anna, Priest, Ryan, Griborio, Alonso, Mayer, Alyssa, Noteboom, Haley, Latimer, Ron, Sun, Yewei, Khunjar, Wendell

Author(s)R. Maltos1, T. Rauch-Williams1, D. Freedman1, L.M. Cavanaugh1, A. Scopp2, R. Priest2, A. Griborio3, A.J. Mayer4, H. Noteboom5, R.J. Latimer6, Y. Sun7, W. Khunjar8

Author affiliation(s)1Metro Water Recovery, CO, 2Hazen and Sawyer, CO, 3Hazen & Sawyer, FL, 4Hazen & Sawyer, OH, 5Hazen & Sawyer, NY, 6Hazen and Sawyer, GA, 7Hazen and Sawyer, VA, 8Hazen & Sawyer PC, VA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159645

Volume / Issue

Content sourceWEFTEC

Word count24

Description: Full-Scale Performance Comparison of Sidestream Nitrogen Removal Processes Prevalent...

Full-Scale Performance Comparison of Sidestream Nitrogen Removal Processes Prevalent in the United States

Abstract

Full-scale performance data is compared from the prevalent sidestream nitrogen removal technologies in the United States: ANITA™ Mox (Veolia), conventional nitrification/denitrification (NDN), DEMON® (World Water Works), AnammoPAQ™ (PAQUES), and DigestivorPAD™ (Ovivo). Empirical data was used to compare relevant metrics for daily ammonia removal, total inorganic nitrogen (TIN) removal, alkalinity usage, air usage, and energy usage. Feedback was requested from the staff that monitor and operate these facilities and compared for all processes. This data review and summary includes a discussion of real process differences related to critical design and operational findings. The aim is to provide municipalities operational familiarity and overall performance outcomes when selecting a SST technology for a site-specific application.

Sidestream treatment (SST) processes in water resource recovery facilities (WRRFs) are becoming increasingly necessary and prevalent in the United States. A review was conducted of twelve, full-scale SST processes to identify long-term trends including process performance, alkalinity usage, energy usage, and reliability, as well as receive operator feedback. This study demonstrated that there are several viable treatment technologies on the market that achieve effective nitrogen removal.

SpeakerDapcic, Anton

Presentation time

08:30:00

08:50:00

Session time

08:30:00

10:00:00

SessionSidestream Nitrogen Removal: From Established to NextGen

Session locationRoom S501a - Level 5

TopicFacility Operations and Maintenance, Intermediate Level, Microconstituents and Contaminants of Emerging Concern (Non-PFAS), Municipal Wastewater Treatment Design, Research and Innovation

Author(s)

Dapcic, Anton

Author(s)A. Dapcic 1; T. Rauch-Williams 2 ; G. Kontos 3; A. Dapcic 1;

Author affiliation(s)Carollo Engineers 1; Carollo Engineers 2 ; Carollo Engineers 3; Carollo Engineers 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159066

Volume / Issue

Content sourceWEFTEC

Word count14

Killing More Than Just PFAS with One Stone

Abstract

WEFTEC, the largest water event of its kind in North America, offers water quality professionals the best in water quality education and training. With almost 200 technical sessions, workshops, mobile sessions, local facility tours and 1,000+ exhibitors, it is the premier water conference! The WEFTEC technical program is selected through a rigorous, peer-review process, ensuring that attendees experience the highest-quality education. WEFTEC speakers are experts and innovators, leading the way in water quality. The following paper was presented at WEFTEC 2020.

SpeakerRauch-Williams, Tanja

Presentation time

15:30:00

15:50:00

Session time

15:30:00

16:10:00

SessionManaging Aqueous Phase PFAS

Session number403

TopicDisinfection and Public Health, Microconstituents, Research and Innovation

Author(s)

T. Rauch-Williams

Author(s)T. Rauch-Williams1;

Author affiliation(s)Carollo Engineers, CO1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2020

DOI10.2175/193864718825157444

Volume / Issue

Content sourceWEFTEC

Word count9

Microbial Adaptation to Low DO Biological Nutrient Removal

Abstract

Introduction Biological nutrient removal (BNR) in wastewater treatment (WWT) requires aeration for biological processes, such as nitrification and phosphorus (P) removal. Low dissolved oxygen (DO) BNR is a means of maintaining effective WWT and operational capacity while reducing the amount of aeration (and other resources) required as the operating DO is decreased. It is also a critical enabler for more advanced shortcut nitrogen (N) removal technologies and for improving the reliability of biological P removal. However, this field of study lacks a fundamental understanding of microbial metabolic kinetics under low DO conditions. To address this knowledge gap, pilot work was performed to investigate microbial kinetic adaptation to low DO while also monitoring key operational parameters including N removal efficiency, simultaneous nitrification-denitrification (SND), enhanced biological P removal (EBPR), settling, and filamentous bacteria growth. Methods At Hampton Roads Sanitation District's Virginia Initiative Plant (Norfolk, VA), primary effluent was fed to a continuous-flow BNR pilot consisting of an anaerobic selector followed by 5 aerobic tanks-in-series at a rate of 5.5 m3/d. Throughout the study, the DO concentration in the aerobic zone was incrementally decreased from 2 mg/L to 0.2 mg/L. Both aerobic solids retention time (SRT) and temperature were maintained consistently at 8.5 days and 20oC, respectively. Twenty-four-hour composite samples from the primary and secondary effluent were analyzed daily for COD, NHx, NO2, NO3, TKN, OP, TP, VFA, TSS, VSS, SVI, and total alkalinity. Nutrient profiles across the BNR reactors were completed twice a week and filamentous bacteria count was obtained via microscopic examination once a week. Sensors within the BNR configuration included: DO, pH, TSS, and ammonia ion selective electrode. Declining DO (DDO) and SND-P uptake (SND/P) batch tests were used to investigate changes in microbial kinetics. The DDO test provides a measure of the respiration rate of nitrifiers as DO in the batch declines to zero. The DDO test yields an oxygen half-saturation coefficient (Ko) and maximum growth rate (µmax) for ammonia oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB), and endogenous respiration. The SND/P test measures substrate (N and P) uptake rates at various DO set points to obtain nitrifier Ko and µmax, denitrifier oxygen half-saturation inhibition coefficient (Kio), polyphosphate accumulating organism (PAO) Ko, and maximum P uptake rate. Results The pilot achieved stable nitrification at each DO set point which resulted in an average ammonia removal of 99 +/- 2%, additionally 92 +/- 9% of P was removed on average (Figure 1). Nitrifier adaptation to low DO was observed in both in-situ measurements and batch tests. Nearly 100% ammonia removal was achieved at each DO set point and the rate of ammonia uptake observed in-situ did not decrease meaningfully. The DDO test results indicate that the AOB Ko decreased as the pilot DO set point was reduced (Figure 2). The SNDP test also showed a decrease in the average estimated AOB Ko but the decrease was not significant (Figure 3). This demonstrates that nitrifiers were capable of achieving a higher affinity for oxygen throughout the adaptation period while the maximum ammonia removal rates remained relatively constant. OHOs also adapted to low DO conditions, with a bit of an unexpected result. A decrease in the Kio for denitrification was observed as the pilot transitioned to low DO (Figure 4). SND was expected to improve under low DO conditions, however, due to the apparent adaptation of heterotrophs, minimal additional SND was observed. The SND/P test revealed that, at all pilot operating DO set points, PAOs have an extremely low Ko. Repeatedly, at the lowest batch test DO set point of 0.1 mg/L, the P-uptake rate observed was at a maximum; thus the Ko of PAOs is expected to be less than 0.1 mg/L (Figure 5). Filamentous bacteria counts remained low and SVI30 was consistently ≤ 100 g/L throughout the transition to low DO (Figure 6). The results of the SVI30 and filament count measurements demonstrate that settleability can be maintained under low DO conditions, even in an A/O process with some degradable COD making its way to the aerobic zone. Conclusion The low DO BNR pilot successfully transitioned to low DO conditions while maintaining settleability, complete ammonia removal, and excellent EBPR. Throughout the adaptation period, four impactful observations have been made: 1. AOB Ko decreased, and in-situ ammonia removal rates remained consistent as operating DO was decreased from 2 mg/L to 0.3 mg/L, indicating nitrifier adaptation to low DO conditions. 2. OHOs similarly adapted to low DO conditions, showing a reduced Kio for denitrification as operating DO was decreased. Because of the decrease in Kio, no increase in SND was observed as the operating DO was decreased. 3. EBPR performed well across the range of operating DOs tested. Kinetic experiments show PAOs have an extremely low Ko for aerobic P uptake. 4. Settleability did not deteriorate as operating DO was decreased; SVI remained stable within an acceptable range and filament counts were relatively unchanged

This paper was presented at the WEFTEC 2024 conference in New Orleans, LA October 5-9.

SpeakerMcIntosh, Lilian

Presentation time

13:50:00

14:00:00

Session time

13:30:00

15:00:00

SessionMicrobial Ecology Selection Under Low DO Concentration

Session number409

Session locationRoom 253

TopicAdvanced Level, Energy Production, Conservation, and Management, Municipal Wastewater Treatment Design, Nutrients, Research and Innovation

Author(s)

McIntosh, Lilian, Morgan, Haley, McCullough, Kester, Gagnon, Alexandria, Klaus, Stephanie, Rauch-Williams, Tanja, Vanrolleghem, Peter, Bott, Charles

Author(s)L.A. McIntosh1, H.M. Morgan2, K.K. McCullough3, A. Gagnon3, S. Klaus3, T. Rauch-Williams4, P. Vanrolleghem5, C.B. Bott3

Author affiliation(s)1Virginia Tech / HRSD, VA, 2HRSD, VA, 3Hampton Roads Sanitation District (HRSD), VA, 4Metro Water Recovery, CO, 5Université Laval, QC

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159570

Volume / Issue

Content sourceWEFTEC

Word count9

Description: Optimizing Dissolved Organic Nutrient Management: Exploring Carbon-Based Advanced...

Optimizing Dissolved Organic Nutrient Management: Exploring Carbon-Based Advanced Treatment Strategies

Abstract

Introduction As population growth, urbanization, and climate change intensify pressures on water resources, utilities are faced with an increased urgency for advanced water treatment (AWT) solutions and a need to enhance resilience against evolving climatic conditions. Concurrently, wastewater resource recovery facilities (WRRFs) are faced with increasingly stringent nutrient discharge limits that surpass the capabilities of conventional treatment methods. Consequently, utilities are compelled to adopt innovative approaches to address the quality and quantity of water supplies while ensuring regulatory compliance and sustainability. In this work, we highlight case studies of two forward-thinking utilities, distinguished by geographical contexts and unique drivers, yet united by a commitment to advance climate change adaptation strategies, achieve ultra-low nutrient limits, and integrate holistic one water initiatives. Metro Water Recovery (Denver, CO): Upcoming Colorado water quality regulations are set to impose stringent stream standards, notably 2.01 mg/L for total nitrogen (TN) and 0.10 mg/L for total phosphorus (P) on WRRFs, including Metro Water Recovery's Robert W. Hite Treatment Facility (RHWTF) and Northern Treatment Plant (NTP). AWT technologies like carbon-based advanced treatment (CBAT) schemes (e.g., coagulation/flocculation/sedimentation (floc/sed), ozone (O3), biofiltration (BAF), and granular activated carbon (GAC)) may address stringent nutrient limits while also aligning with Direct Potable Reuse (DPR) requirements. A study was initiated to: 1) assess the treatability of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and soluble non-reactive phosphorus (sNRP) using CBAT technologies; and 2) discern the capabilities of CBAT in concurrently achieving nutrient limits and DPR compliance. Evaluation of nutrient removal through tertiary CBAT processes spanned full-scale applications (floc/sed at NTP and BAF/floc/sed at RHWTF's Denver Water Recycling Plant (DWRP)) and pilot-scale (O3 only, BAF only, and O3/BAF at RHWTF), supplemented by bench-scale floc/sed (jar testing) and GAC evaluations (rapid small-scale column tests). Parameters such as O3 dose and empty bed contact times aligned with potable reuse standards. While full-scale floc/sed/filtration at NTP (Figure 1; Figure 2) and DWRP (Figure 3, Figure 4) (~20 mg/L alum) effectively managed particulate P and sNRP removal, it did not meet DOC and DON targets for Direct Potable Reuse (DPR) applications. CBAT testing showed potential for control of DOC and DON, albeit with the need for multiple potentially costly unit processes. The GAC runtime (up to 3,500 Bed Volumes for DOC and DON targets) was notably extended through enhanced upstream treatment. While floc/sed processes achieved comparable DOC and DON removal rates (up to 40% each) at the expense of elevated coagulant doses (80 mg/L Ferric chloride), O3/BAF treatments realized a modest 26% reduction in DON. Future pilot efforts aim to assess the efficacy of a comprehensive CBAT treatment train, inclusive of tertiary denitrifying BAF, to fulfill TN requirements and optimize DPR suitability. AWT Utility (Midwest): A midwest AWT utility has seen significant population growth in recent years and is estimated to double by 2040. Rapid growth and a desire improve the health of the receiving water body have urged the utility to consider alternative water supplies. Subsequently, the utility commissioned a CBAT pilot consisting of O3, two-stage BAF, GAC, and UV advanced oxidation process (UVAOP). The objective of this study was to pilot CBAT technologies to demonstrate the ability of AWT process trains to produce high quality finished water that meets stringent water quality targets. This study utilized a multi-barrier scheme of O3/two-stage BAF (aerobic/anoxic) to meet low TN limits. Filters were operated in several phases (Table 1) until effluent quality targets were met (TOC < 3 mg/L, TN < 2 mg/L, contaminants of emerging concern (CECs)- meet MCLs) and steady-state was achieved. Select operational parameters were varied during each phase and the resulting water quality surrounding the first anoxic BAF (BAF 3) is shown in Figure 8. Table 2 shows the effluent DO, nitrate (NO3-N) concentrations and corresponding % NO3-N removal achieved across each anoxic BAF. Results indicate that when supplemental carbon and upstream feed DO levels were controlled, anoxic BAF 1 established and maintained anoxic conditions and achieved NO3-N removals up to 60% with anoxic BAF 2 acting as a polishing biofilter (%NO3-N removal ~30%). When supplemental carbon and upstream DO quenching chemical doses were reduced, anoxic BAF 1 turned into a sacrificial BAF, consuming excess DO and displaying poor nitrate removals (~15%), while anoxic BAF 2 became the dominant anoxic biofilter (> 60% NO3-N removal). Piloting efforts demonstrate how a modified CBAT train may simultaneously meet low TN targets (< 2 mg/L) and produce high quality product water. Conclusion Case studies at Metro Water Recovery and a midwest AWT utility demonstrate CBAT's potential for improving finished water quality for reuse and meeting ultra-low nutrient discharge requirements. Project findings provide first guidance on how WRRFs can adjust operational setpoints using CBAT process infrastructure to meet DPR or discharge water quality requirements in ecologically sensitive and drought-prone watersheds.

This study explores carbon-based advanced treatment (CBAT) as an alternative to reverse osmosis for removing dissolved organics and nutrients. Case studies at the Franklin Water Reclamation Facility in Tennessee and the Metro Water Recovery Robert W. Hite Treatment Facility in Colorado evaluated CBAT pilots. Using various configurations, the study measured the removal efficiency of dissolved organic carbon, dissolved organic nitrogen, dissolved organic phosphorus, and total inorganic nitrogen.

SpeakerHlad, jeffrey

Presentation time

11:00:00

11:30:00

Session time

10:30:00

12:00:00

SessionAdvancements in Non-RO Treatment for IPR/DPR: Exploring Cutting-Edge Solutions

Session number530

Session locationRoom 235

TopicIntermediate Level, Microconstituents and Contaminants of Emerging Concern (Non-PFAS), Sustainability and Climate Change, Water Reuse and Reclamation

Author(s)

Hlad, jeffrey, Freedman, Daniel, Ram Mohan, Gayathri, Khunjar, Wendell, Scopp, Anna, Peterson, Eric, Rauch-Williams, Tanja, Wang, Jiefu

Author(s)J. hlad1, D. Freedman1, G. Ram Mohan2, W. Khunjar3, A. Scopp4, E. Peterson4, T. Rauch-Williams1, J. Wang5

Author affiliation(s)1Metro Water Recovery, 2Hazen and Sawyer, 3Hazen and Sawyer, VA, 4Hazen and Sawyer, 5Virginia Tech, VA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159696

Volume / Issue

Content sourceWEFTEC

Word count11

Description: Process Roadmaps to Low DO Operations - Lessons Learned from a North American Survey...

Process Roadmaps to Low DO Operations - Lessons Learned from a North American Survey on Suboxic and Low DO Activated Sludge Facilities

Abstract

Facilities throughout the United States are successfully implementing low dissolved oxygen (DO) and suboxic nutrient removal (SBNR) operations using a variety of plant configurations and controls strategies to decrease energy consumption while achieve high effluent quality standards. As part of a Department of Energy project, several facilities participated in workshops to identify common operational strategies and challenges for low DO/SBNR operational. From the workshop, it was determined that successful low DO/SBNR systems can be achieved with a variety of aeration process configurations and controls strategies. Aeration demand and blower turndown were the largest obstacles in achieving low DO operations. Instrumentation is key: understanding which probes are appropriate and the importance of probe location can significantly influence process performance. In addition, Los Angeles County Sanitation Districts is implementing SBNR operations at the Pomona Water Reclamation Plant which will provide real-world guidance on SBNR execution and operations.

This paper was presented at WEFTEC 2023 in Chicago, IL.

SpeakerYoung, Michelle

Presentation time

13:30:00

15:00:00

Session time

13:30:00

15:00:00

SessionConversion of Conventional Activated Sludge to Suboxic (Low DO) Nutrient Removal

Session locationRoom S404c - Level 4

TopicEnergy Production, Conservation, and Management, Fundemental Level, Municipal Wastewater Treatment Design, Nutrients, Sustainability and Climate Change

Author(s)

Young, Michelle

Author(s)M Young 1; N. Beach 2 ; P. Ackman 3; T. Weiland 4; A. Ekster 5; S. Reifsnyder 6; T. Rauch-Williams 7;

Author affiliation(s)Carollo Engineers, Inc 1; Carollo Engineers, Inc 2 ; Los Angeles County Sanitation Districts 3; Los Angeles County Sanitation Districts 4; Ekster & Associates 5; Carollo Engineers, Inc 6; Carollo Engineers, Inc 7;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825158980

Volume / Issue

Content sourceWEFTEC

Word count23

Description: Source Separated Organic Food Waste Characteristics and Implication for Co-digestion...

Source Separated Organic Food Waste Characteristics and Implication for Co-digestion Performance, Operation, and Design

Abstract

Relevance Organic food waste is an underutilized energy and nutrient source in North America that is mostly disposed of in landfills. This common practice contributes to global warming and wastes precious carbon and nutrient resources. Some private and public entities have started to separate, collect, pretreat, distribute, and recover so-called 'source separate organics' (SSOs) at water resource recovery facilities (WRRFs). Many more WRRFs are interested in evaluating similar practices for their future operation. The substrate quality of SSOs added to anaerobic digesters requires focused evaluation: It varies between locations and might contain contaminants of potential concern to digester stability, operation, equipment, or final quality of biogas and biosolids. To date, we have a few but no standardized industry specifications to monitor and control the quality of SSO feedstock or pre-treated slurries accepted by WRRFs. To address these challenges, this project aims to develop accurate and reproducible analytical methods for food waste characterization. These methods are applied in this project to various engineered bioslurries produced from SSO food waste. This presentation will present the characterization results and implications for co-digestion performance, operation, and design. Results point to practical guidance for the wastewater industry to create cost-effective and meaningful sampling strategies as well as acceptable minimum quality specifications for accepting SSO substrates for co-digestion. Introduction The Water Research Foundation (WRF) Project #4915 called 'Characterization and Contamination Testing of Source Separated Organic Feedstocks and Slurries for Co-Digestion at Resource Recovery Facilities' aims to develop guidance for the characterization and assessment of SSO food waste quality for WRRFs who are planning or practicing co-digestion. The quality of accepted SSO foodwaste may impact the stability of digester operation, biogas production, quality of the final end products (such as biogas and biosolids) and even longevity of infrastructure used for receiving, pre-treating, storing, conveying, and digesting this material. SSO food waste may comprise of heterogeneous material from private households, restaurants, grocery stores, food producers and industry, and displays variability in quality characteristics depending geography, season, collection practices and pretreatment processes. Current laboratory methods applied by commercial producers of engineered bioslurries and by WRRFs have limitations and are not tailored to this type of material. For these reasons this project has the following objectives: 1. Identify, evaluate, and develop techniques for characterizing SSO feedstocks and slurries. Develop an Industry Guidance Document for a systematic, tiered, and comprehensive approach to characterizing feedstocks and slurries. Assess current and emerging concerns for potential SSO feedstock contamination. Define analytical methods for relevant feedstock characteristics needed for process modeling. 2. Standardize sampling protocols for rapid and comprehensive monitoring of feedstocks. Develop simple and robust methods for representative sample collection, preparation, and analysis. Recommend a timely and cost-effective quick-test strategy for WRRFs to assess relevant SSO feedstock characteristics. 3. Develop guidelines for minimum feedstock quality standards for various product goals. Provide guidance on potential contamination of SSO wastes and slurries, depending on their sources and pre-treatment process. Develop guidance on typical quality parameter ranges. Recommend limits for aesthetic, operational, and health-related parameters of concern, as well as final products and objectives. 4. Link characteristics to final product quality. Summarize cause-effect relationships for practitioners on how SSO feedback quality affects final effluent quality, process performance and stability, digester loading capacity, biogas/energy production, biosolids and biogas quality, and downstream treatment processes. The results for goal 1 have been previously presented. This presentation will focus on the results related to goals 2, 3, and 4. Methods Parameter Selection A broad literature review was conducted in the first part of the study from which our team identified relevant SSO food waste parameters for the operation, design and stability of co-digestion food waste systems. These parameters were then grouped into five tiers representing logical analytical parameter groups that can help utilities answer specific operational questions. 1. Tier 1: Immediate inspection. Parameters based on operators' fast inspection upon arrival of SSO to WRRFs. SSO delivery might be rejected or accepted based on this inspection. 2. Tier 2: Frequent routine monitoring screens. Parameters that are relevant for daily anaerobic digester operation and SSO feed control to the digesters. 3. Tier 3: Monitoring for final product quality. Parameters that are relevant for biogas, effluents, emissions or biosolids for land application. These parameters might be tested quarterly or when accepting material from new sources as they are more expensive and time consuming. 4. Tier 4: Comprehensive assessments. Parameters that are of interest for process modelling or research. These might need to be analyzed by commercial labs since they require specialized equipment. Table 1 lists the suggested parameters under each of the four tiers. Analytical Methods Analytical methods for SSO feed stock analysis were compiled from established standard methods currently employed by practitioners for the analysis for SSO feedstock bioslurries. A utility survey was conducted that solicited feedback on which protocols were challenging to conduct or resulted in poor analytical reproducibility or accuracy. The analytical protocols were established at the University of Michigan lab and were tested and refined on an exemplary sample received from a commercial producer of Engineered Bioslurry. Methods that resulted in poor reproducibility were refined until reproducible results were achieved. The written protocols were compiled and documented in a draft deliverable for publication by WRF upon completion of this project. Bioslurry Sample Sites and Monitoring Plan Four U.S. sampling locations were selected for sample collection and SSO feedstock characterization applying the analytical methods selected earlier in this project. The sample locations are in general terms listed in Table 2 and provide a diverse representation of bioslurries in the U.S. that reflect A geographical variety (within the U.S. and Canada); Pre-consumer and post-consumer SSO feedstock; A variety of pre-processing slurry technologies o onsite pretreatment process o commercial small scale pre-treatment o Commercial large-scale pre-treatment using various different technology approaches Good coverage of established slurry manufacturers Names and locations of the sample locations are kept anonymous by request while results can be published and shared. Samples are collected by the participant facilities on a monthly basis until early 2021. The samples are shipped to University of Michigan for analysis. and split samples are shipped to Eurofins for certain specialized tests. QA/QC procedures for sample preservation are followed prior to analysis. Split samples are shipped to Eurofins for certain specialized tests. Guidelines for Minimum Feedstock Quality Standards Monitoring data from the SSO bioslurry characterization is evaluated along with available full-scale data from the co-digestion facilities to assess cause effect relationships between the SSO food waste quality and co-digestion stability, operation, and quality of the final end products biogas, biosolids, and dewatering recycle streams. Table 3 summarizes relevant effects for WRRFs that could result from different SSO food waste characteristics. Conclusions Co-digestion of SSO food waste at WRRFs is quickly becoming industry practice in densely populated areas in the US where landfill space is limited and the sensitivity surrounding negative impacts of GHG emissions through climate change is rising. Co-digestion is an attractive option for WRRFs to increases energy recovery through enhanced biogas production and can generate economic benefits from tipping fees and reduced energy costs. This project fills an important need of the wastewater industry by developing robust analytical methods for the characterization of SSO food waste and helping WRRFs to understand cause-effect relationships between food waste quality and digester stability, operation, and design recommendations.

The following conference paper was presented at Residuals and Biosolids 2021: A Virtual Event, May 11-13, 2021.

SpeakerRauch-Williams, Tanja

Presentation time

11:15:00

11:30:00

Session time

11:00:00

12:15:00

SessionOptimizing Digestion and Co-Digestion

Session number3

Session locationSimu-Live

TopicBiogas, Co-Digestion With Other Organic Sources, food waste

Author(s)

T. Rauch-WilliamsP. PuenteL. RaskinR. GuptaC. TasserL. SchwinghammerC. Schaum

Author(s)T. Rauch-Williams1; P. Puente2; L. Raskin3; R. Gupta4; C. Tasser5; L. Schwinghammer6; C. Schaum7

Author affiliation(s)University of Michigan 1; University of Michigan 2; University of Michigan Dept of Civil Eng Env 3; Carollo Engineers 4; Carollo Engineers 5; Bundeswehr University Munich 6; Bundeswehr University Munich 7;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2021

DOI10.2175/193864718825157963

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count15

Description: Wastewater Thermal Heat Recovery: How Public Utilities Can Prepare and Take...

Wastewater Thermal Heat Recovery: How Public Utilities Can Prepare and Take Advantage Of This Upcoming Resource Recovery Opportunity

Abstract

BACKGROUND
Thermal heat recovery from wastewater is an underutilized technology market in North America but this is anticipated to change quickly. Sewer or wastewater heat recovery is using the latent heat of wastewater as an energy source, most commonly for hot water supply or for heating and air conditioning. Increasing efficiencies of heat exchangers and heat pumps make this a viable and cost-effective possibility. Systems are in operation utilizing in-building heat pumps, heat exchangers installed within the sewer piping itself, pumped bypasses from the sewer, or installations 'within the fence' at water resource recovery facilities (WRRFs). See Figure 1 for a typical system illustration and Figure 2 for common technology solutions on the North American market. Since about two decades, several central European cities have started to systematically evaluate and implement project opportunities for using the year-round moderate temperatures of wastewater for heating or cooling of buildings, hot water generation, or the heating of anaerobic digesters. North American municipalities can now benefit from the planning and technical approaches that have proved successful overseas (Velsen & Benz 2013, Brunk & Seybold 2014, Eccuro, 2020; Berlin Wasser, 2019). First pioneering utilities have implemented projects in the US and Canada defining the kind of project applications and technology solutions proven successful to make project payback periods attractive (Kohl 2019, personal interviews with various US and Canadian utilities and districts). Several ongoing developments make it timely for utilities to become aware of wastewater heat recovery opportunities for building heating and cooling and consider encouraging and supporting such projects within their service areas.
RELEVANCE
Key developments making wastewater thermal heat recovery timely in the US and Canada include:
1) Effluent Temperature Limits. Several US states have started to implement temperature standards for cold water surface water bodies that will require some water resource recovery facilities (WRRF) to cool effluents during parts of the year prior to discharge in coming years. The authors of this abstract alone have been involved in preparing effluent cooling cost studies for more than five utilities in three US states (Colorado, California, Oregon) over the past two years. The default technology for cooling compliance are cooling towers which come with significant capital expenditures, operational challenges, additional O&M costs, and increased energy consumption. Thermal energy is starting to be recognized as a wastewater pollutant and source mitigation through energy recovery is one viable, and much more sustainable compliance strategy. However, implementation of projects takes time and needs to be planned for early and broadly to be impactful in effectively supporting compliance strategies.
2) GHG reduction goals. A growing number of US cities and states have committed to clearly defined GHG reduction targets and timelines. As such, first cities have taken the implementation steps to develop renewable heating and cooling plans for buildings (e.g., City and County of Denver, June 2021) or preparing legislation to ban natural gas from new buildings to advance electrification codes (see Figure 3). The commonly considered renewable energy alternatives to natural gas are solar, wind, and geothermal energy. All of these technologies have limitations when it comes to the implementation for larger residential, commercial, or public buildings due to large space requirements. Heat recovery from wastewater, however, is a feasible renewable alternative specifically for larger construction projects due access to wastewater locally produced or located in adjacent large sewer interceptors. Return of investments of wastewater heat recovery systems can be more attractive compared to traditional renewable energy sources currently considered by planners and developers.
STATE OF THE INDUSTRY
To date, a variety of heat recovery systems are in operation in the US and Canada. Figure 4 highlights a few different types of systems across the US that will give WEFTEC participants an overview of possible technology scales and applications. King County (Seattle, WA) and Metro Water Recovery (Denver, CO) are implementing utility-wide systematic administrative approaches for regional heat recovery. These utilities are driven primarily by regional sustainability mandates. Metro Water Recovery in Colorado is also driven by future regulatory concerns related to temperature discharge. Their collaboration with the National Western Center Complex in Denver is to date the largest sewer heat recovery project in the US, with a 4 megawatt heat recovery system estimated to offset 2,600 tons of CO2 per year. Smaller developer or facility led sewer heat initiatives are also operational. For example, in Washington, DC, the American Geophysical Union renovated its campus in 2015, to utilize pumped sewer heat recovery for heating, cooling, and hot water for a 7-story office building. Avon, Colorado, has an older heat exchanger system that uses wastewater effluent heat recovery for heating of the community swimming pool. Madison MSD, WI, uses effluent heat in a similar fashion to heat their administrative building. The Boulder Commons net-zero project in Boulder, Colorado, is a more recent developer-led mixed use project utilizing sewer heat recovery for all hot water supply needs.
HEAT RECOVERY PROGRAM IMPLEMENTATION CHALLENGES
This paper will discuss common challenges utilities face when establishing heat recovery programs within their service districts and helpful resources available. This summary draws upon the experience of other utilities leading such efforts over past years in the US, Canada, and Europe that the authors collaborated with over past years, and from two ongoing wastewater heat recovery projects Carollo is currently conducting for the City of Boulder, Colorado, and Metro Water Recovery, Colorado, respectively, that aim to define the potential for heat recovery and help establish successful community-wide wastewater heat recovery programs. Briefly, key challenges that utilities should be prepared for include the following.
1. Data and information gaps. a. This includes temperature data in sewer lines.
2. Lack of interdepartmental coordination and private partnerships a. Identification and successful implementation of projects often requires the close collaboration of various departments and private owners, developers, or funding partners.
3. Understanding to how use applicable environmental attributes a. I.e., thermal renewable energy credits, the legal basis, broker process, and market values
4. Lack of awareness and incentives a. Lack of integration with local ordinances, building codes, etc. b. Public communication, marketing (Figure 5)
5. Establishing the necessary administrative process a. Support staff b. Legal contracts c. Engineering workflows d. Financial agreements
IMPORTANCE
This paper raises awareness of the potential, benefits, and successful examples of wastewater thermal heat recovery installations and programs in North America. Because it is anticipated that significant capital investments will made in effluent cooling infrastructure and alternative energy sources for private and public buildings in the US starting in coming years, it is important that utilities are aware of environmentally and fiscally responsible alternatives, technology options and resources that can help establish successful heat recovery programs.

Thermal heat recovery from wastewater is a growing market in North America. Effluent temperature limits, greenhouse gas reduction goals, and the need for renewable energy sources in densely populated areas drive the implement of wastewater thermal energy use projects for building space heating and cooling and water heating. This paper summarizes tangible steps that utilities can take to evaluate and proactively help develop opportunities within their service areas.

SpeakerRauch-Williams, Tanja

Presentation time

16:30:00

16:55:00

Session time

15:30:00

17:00:00

TopicIntermediate Level, Energy Production, Conservation, and Management, Facility Operations and Maintenance, Sustainability and Climate Change

Author(s)

Rauch-Williams, Tanja

Author(s)Tanja Rauch-Williams1; Jeff S. Berlin1

Author affiliation(s)Carollo Engineers, Broomfield, CO1