Sturm, Belinda

Presented at WEFTEC 2023.

Titles from this speaker

Advancing Low-Energy Biological Nutrient Removal through Low Dissolved Oxygen Operation: Is Biological Selection the Key?

Abstract

Introduction In the activated sludge process (ASP), dissolved oxygen (DO) is an important factor for aeration cost, nitrification efficiency, nutrient removal, and N2O emission. Even though, the term 'low DO' has been used in a somewhat subjective manner and can vary depending on the context and specific requirements, the overall objective of this study is to pave the way for full-scale implementation of low DO BNR through scientific investigation to systematically answer questions on the impact of DO concentrations on nitrification, denitrification, BPR, microbial ecology, and greenhouse gas emissions. This abstract presents results developed as part of the WRF No. 5083 titled 'Advancing Low-Energy Biological Nitrogen and Phosphorus Removal.' Methodology To quantify the impact and benefits of low DO operation in the capacity and performance of existing ASP, several participating facilities that were operating at low DO and high DO conditions were studied as part of this project. Long-term operational data from the facilities was assessed and compared with the baseline information collected during the literature review. Mixed liquor samples from the participating utilities were collected and assessed through lab-scale studies. Low dissolved oxygen control and batch test procedures were developed as part of the project and used to investigate the impact of low DO on biokinetic rates. This information provided a unique comparison and tabulation of important biokinetic parameters to better understand the implications of low DO BNR on plant capacity and performance. In addition, this provides guidelines for the selection of proper important biokinetic coefficients for process modeling. Results and Discussion Bench-scale, and full-scale experiments were conducted to investigate the impact of DO concentrations on nitrification, denitrification, BPR, microbial ecology, and N2O emissions with the goal to advance low DO BNR. The following biokinetic insights were collected as part of this study. Nitrification: Specific nitrification rates for ASP operating with long-term exposure to low DO conditions were approximately 60-80% of the nitrification rates at high DO as presented in Figure 1. This study concluded that long-term low DO operation results in a shift in the nitrifier community structure, with comammox, and in some case ammonia oxidizing archaea, being selected over ammonia oxidizing bacteria. Experimental results confirm that these communities selected under stable low DO operation have a higher oxygen affinity than AOB and Nitrobacter-related NOB. TIN Removal: The maximum TIN removal rates were found at DO concentrations ranging from 0.2 to 0.5 mg/L. At this DO range, the nitrification rate equals the denitrification rate, which would therefore lead to complete SND in non-carbon limiting conditions as depicted in Figure 2. At DO concentrations of less than 0.2 mg/L, the TINRR is inhibited by nitrification and at DO concentrations higher than 0.5 mg/L, TINRR is limited by denitrification. This observation may change from plant to plant since there are multiple parameters that could affect the results including floc size and porosity, mixing intensity, and microbial population. Biological Phosphorus Removal: Biological phosphorus removal is not impacted by low DO operation. Based on the experimental results from 12 full-scale plants, the low DO phosphorus uptake rates measured in this study were higher compared to the P uptake rates for high DO/ conventional systems. Phosphorus uptake rates slows down significantly when the DO is 0.1 mg/L suggesting that the KDO for PAO is lower around 0.1 mg/L. N2O Emissions: In this work, pilot and bench-scale testing demonstrated that long-term exposure of biomass to low DO does not result in an increase in total N2O emissions (Fig. 3a). Even though this study did not investigate the specific N2O production mechanisms and pathways associated with low DO BNR, the work suggests that the N2O emissions are lower than conventional high DO systems since the relative abundance of AOB and Nitrobacter-related NOB are relatively low (Fig. 3b) limiting the N2O produced via NH2OH oxidation pathway and nitrifier denitrification by AOB. In the low DO BNR systems, Nitrospira-related NOB and comammox were dominant nitrifiers suggesting they do not have the same reduction pathways of NO2 and NO to N2O and therefore produce less N2O comparable to AOB. Conclusion DO is an important parameter influencing aeration cost, nitrification efficiency, nitrogen and phosphorus removal efficiency, treatment plant capacity and N2O emission. As presented in this study, there are several WRRF that utilize low DO operation in the ASP achieving effluent water quality with respect to N and P and require less energy than conventional ASP. The DO setpoints in such plants vary depending on loading conditions, aeration controls, and operator's preferences. Therefore, selecting a single DO setpoint to represent low DO BNR is difficult. Based on the experimental results obtained during this study, low DO can be defined as the bulk liquid DO concentration or range in the aerobic zones where simultaneous N and P removal reactions occur, often ranging from 0.2 mg/L to 0.5 mg/L. Results from this study demonstrate that long-term exposure to biomass at these DO concentrations allow for biological selection of microorganisms with very high oxygen affinities.

In the ASP, DO is an important factor for cost, nitrification efficiency, and N2O emission. The objective of this study was to investigate the impact of DO concentrations on nitrification, denitrification, BPR, microbial ecology, and N2O emissions. Based on the experimental, low DO can be defined as the DO concentration or range in the aerobic zones where SND reactions occur, often ranging from 0.2 to 0.5 mg/L allowing for biological selection of microorganisms with very high oxygen affinities.

SpeakerJimenez, Jose

Presentation time

13:40:00

13:50:00

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)

Jimenez, Jose, Miller, Mark, Bauhs, Kayla, Sturm, Belinda, Wittman, Megan, Dold, Peter, Fevig, Stephanie

Author(s)J.A. Jimenez1, M. Miller2, K. Bauhs3, B. Sturm4, M. Wittman4, P. Dold5, S.M. Fevig6

Author affiliation(s)1Brown and Caldwell, FL, 2Brown and Caldwell, NC, 3Brown and Caldwell, TN, 4University of Kansas, KS, 4, 5Envirosim Associates Ltd., ON, 6South Platte Renew, CO

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159576

Volume / Issue

Content sourceWEFTEC

Word count16

Evaluating Nitrogen Oxides Transformations at Low Dissolved Oxygen Concentrations

Abstract

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

This study evaluates nitrogen oxides transformations at low-DO concentrations. Microbial community data coupled with biokinetics, and detailed process modeling facilitated an analysis of the fundamental mechanisms associated with SND and its interaction between biomass and intermediate nitrogen oxide species and readily biodegradable COD.

SpeakerJimenez, Jose

Presentation time

08:30:00

08:50:00

Session time

08:30:00

10:00:00

SessionLow Carbon BNR Fundamentals and Controls

Session locationRoom S502 - Level 5

TopicAdvanced Level, Facility Operations and Maintenance, Municipal Wastewater Treatment Design, Nutrients

Author(s)

Jimenez, Jose

Author(s)J. Jimenez 1; J. Boltz 2 ; M. Miller 3; K. Bauhs 5; B. Sturm 6; B. Rittmann 7; J. Jimenez 1;

Author affiliation(s)Brown and Caldwell 1; Woodard and Curran 2 ; Brown and Caldwell 3; Brown and Caldwell 5; University of Kansas 6; Arizona State University 7; Brown and Caldwell 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159062

Volume / Issue

Content sourceWEFTEC

Word count10

Description: Evidence of Antibiotic Resistant Genes Sorbed to Microplastics in Biosolids and...

Evidence of Antibiotic Resistant Genes Sorbed to Microplastics in Biosolids and Mobilized to Runoff

Abstract

Microplastics (MPs) with accumulated Antibiotic Resistant Genes (ARGs) can be captured in biosolids and contaminate the terrestrial environment through biosolids land application. A field experiment with land-applied biosolids combined with rainfall simulations was conducted to control the biosolids loading, biosolids application methods, and rainfall events. The attached ARGs on MPs were analyzed from soil and runoff samples. Through biosolids application, some ARGs were significantly increased; tetW on MPs in soil increased 5-10 times. In runoff from biosolids-amended plots, the relative abundance of ARGs on MPs increased by 159% and 34%, as compared to the abundance in soil for spreading and incorporating plots, respectively. The biosolids application method affected the mobility of MPs and their associated ARGs to runoff, with surface spreading having the greatest mobility.

Antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) have potential risk to human health but cannot be efficiently removed by wastewater treatment and may even be proliferated. Microplastics (MPs) with accumulated ARGs can be captured in biosolids and contaminate the terrestrial environment through biosolids land application. This is one of the first field studies to investigate the transport of ARGs on MPs from biosolids to land and runoff.

SpeakerSturm, Belinda

Presentation time

10:30:00

11:00:00

Session time

10:30:00

12:00:00

SessionMicroplastics Interaction with Pathogens and Other Microconstituents

Session locationRoom S502 - Level 5

TopicDisinfection and Public Health, Intermediate Level, Microconstituents and Contaminants of Emerging Concern (Non-PFAS), Research and Innovation

Author(s)

Sturm, Belinda

Author(s)B. Sturm 1; Z. Li 1 ; Y. Hiripitiyage 2; B. Sturm 1;

Author affiliation(s)University of Kansas 1; University of Kansas 1 ; University of Kansas 2;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159183

Volume / Issue

Content sourceWEFTEC

Word count15

Five Years after Start-up of Sidestream Fermenter at the Wakarusa River WWTP: The Bad and The Good.

Abstract

Introduction At WEFTEC 2019, data from one year of operation of a newly built sidestream fermenter for a biological phosphorus removal (BPR) system was presented. This paper covers the first 5 years of operation of the Wakarusa River wastewater treatment plant (WWTP) at Lawrence, Kansas. New processes are always scrutinized by the industry. Was the pilot operation a fluke? Can its performance be repeated? Is the system lightly loaded? Is the process resilient and reliable? Data from the last 5 years shows that sidestream fermentation is reliable, but there were periods of degraded performance. The Wakarusa River WWTP was designed to treat 2.5 mgd (9 500 m3 /d) annual average flow of domestic sewage. The Wakarusa facility is essentially a new train located at another site for the Kansas River WWTP. Flow to Wakarusa has averaged about 2 mgd over the 5-year period (80 percent of the design capacity). The Wakarusa Facility is a 3-stage Bardenpho process with a flow-through anaerobic zone, an anoxic zone, and an oxidation ditch for aerobic treatment plus a sidestream fermenter for enhanced biological phosphorus removal (EBPR). The raw influent to Wakarusa is fairly 'fresh' with a little VFA (12 mg/L) and a low rbCOD to TP ratio (50% of the time less than 13.5). Not enough rbCOD was available for good BPR performance. The Bad: Impact of Return Flows on EBPR Performance Figure 1 shows the effluent orthophosphate (OP) concentrations from an online analyzer, and effluent total phosphorus (TP) concentrations from operator collected data and 24-hour composites for 2019. This graph contains over 150,000 data points from the on-line analyzer. Figure 2 shows the 30,000 points spanning from Nov 2019 to Sept 2020 and it is much easier to see the periods of good effluent from the not so good effluent quality. The permit limit is 1 mg/L TP on a 365-day rolling average. The Figure 1 graph show periods, highlighted by the pink transparent boxes, of high effluent P coinciding with periods when biosolids land application was delayed by excessively wet fields. This pattern repeats each year. Solids build up in the plant MLSS (or system increased SRT) and the basin MLSS concentration rises significantly which interferes with sidestream fermentation efficiency. A process model was developed in SUMO (Dynamita) to simulate the plant performance at increasing SRT conditions. Model simulations indicated that the VFA production in the fermenter decreased as the SRT in the activated sludge basin increased while maintaining a constant flow to the fermenter. Model simulations are continued to further explore this phenomenon to determine if operational conditions can improve fermenter performance. In 2022 there was an upset between Sept and Nov in system performance. The centrifuges had been in operation for 4 years and erosion/ wear of internals resulted in poor solids capture. The net result was poor BPR performance in Sept through Nov of 2022, highlighted on Figure 1. Poor solids capture resulted in the recycling of high concentrations of BOD, TSS and TP to the plant influent (Figure 3). Once the centrifuges were repaired and solids capture was under control, the effluent OP and TP returned to very low concentrations. After 5 years of operation, no ferric chloride has been added nor has there been any supplemental addition of a carbon source. After the high inventory of MLSS was reduced, the fermenter bounced back and produced a very low effluent OP concentration. The Good: Impact of Low DO Operation on TN and TP Removal Performance and Microbial Ecology Figure 4 shows the nitrogen profile in the system during the summer of 2022. The abrupt decline in the effluent nitrate concentration was intentional. The facility has two online DO probes located in the outer curve and the inner curve of the ditch system. The DO setpoints were initially set at 0.8 mg/L and 0.5 mg/L during start-up and during the summer of 2022 plant staff lowered the DO setpoints to around 0.2-0.3 mg/L. Effluent nitrate concentrations dropped to below 1 mg N/L. The effluent phosphorus concentration remained very low (Figure 1). During the July — August 2022 timeframe, the effluent OP and TP concentrations remained very low. Near the end of this trial period, centrifuge performance began to deteriorate and excessive solids in the system interfered with good BPR. These results indicate that low DO operation did not have a negative impact on phosphorus uptake as well as nitrification. As the DO setpoints were lowered, the AOB (ammonia oxidizing bacteria) population declined and the population of Commamox increased. Recent studies demonstrated the prevalence of Comammox Nitrospira can be dominant ammonia oxidizers in a mainstream low DO nitrification reactor. The Good: Impact of Fermenter SRT on VFA Species and PAO/GAO Population A study performed by University of Kansas on fermenter SRT and operating parameters showed the impact of SRT on the quantity of VFA formed and the diversity of VFA species (Figure 5). Acetic acid is still the predominant VFA present in the fermenter effluent. Figure 6 shows the PAO versus GAO as a fraction of the overall microbial population in the anaerobic zone. Very few GAOs were present in the system. Summary The sidestream fermentation process has been reliable and consistent in producing a low effluent OP concentration while at plant loading of 80% of design capacity

The Wakarusa River WWTP has used a novel biological phosphorus removal (BPR) process with a sidestream mixed liquor fermenter for the last 5 years. Influent to the plant is low in rbCOD for BPR, however, the effluent is below 0.15 mg P/L without supplemental chemicals. Modeling was performed to examine good and poor plant performance.

SpeakerKobylinski, Edmund

Presentation time

11:30:00

12:00:00

Session time

10:30:00

12:00:00

SessionUsing Side-Stream Enhanced Biological Phosphorus Removal to Improve EBPR Performance

Session number523

Session locationRoom 350

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

Author(s)

Kobylinski, Edmund, Lovett, Jay, Sturm, Belinda, Kasi, Sreerama Murthy, Harger, Melinda, Morris, Leah

Author(s)E.A. Kobylinski1, J. Lovett2, B. Sturm3, S. Kasi1, M. Harger4, L. Morris2

Author affiliation(s)1Olsson, KS, 2City of Lawrence, KS, KS, 3University of Kansas, KS, 4City of Lawrence, KS

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159623

Volume / Issue

Content sourceWEFTEC

Word count18

Improving Clarifier Models by Describing Extracellular Polymeric Substances

Abstract

Improved settleability in activated sludge processes is an essential feature of new innovations. To accelerate the adoption of such technologies, the ability to link operational conditions with settling characteristics is needed to support process design and prediction of improvements in settleability. The previous works indicated that the threshold of flocculation (TOF) (Mancell-Egala et al., 2017a), which describes the collision efficiency of particles, was successfully introduced as a simple experimental method to calculate the flocculent settling coefficient (rp) in 1-D clarifier models and to enhance the ability to predict clarifier effluent solids. TOF also showed to have a clear relationship with effluent quality making it a useful operational parameter to detect flocculation limitations. In addition, extracellular polymeric substances (EPS) quality, most often expressed as a protein over polysaccharides ratio has been linked to flocculation behavior, densification and granulation (McSwain et al., 2005). This knowledge was used to develop an empirical function between the composition of (EPS) expressed as EPS-TKN/COD and TOF. This relationship between EPS composition and TOF was introduced as a means of linking biological process models (i.e. Sumo2C model) and 1-D clarifier models (Ngo et al., 2021b). Essential for this approach is the prediction of EPS amounts and quality from process models as a function of feast-famine, and other operational conditions as this defines settling behavior. This paper discusses three approaches for EPS prediction from process models and will provide insights on 2 which type of EPS modeling might be needed for different purposes. While this abstract describes different datasets tested for the different models, the full paper will provide a full comparison of the three models on the full-scale dataset collected at Blue Plains

This paper discusses three approaches for EPS prediction from process models and will provide insights on which type of EPS modeling might be needed for different purposes. With optimized EPS quality prediction, it is possible to simulate settling improvements based on changes in operational conditions both based on a wide range of SRT as well as based on feast-famine driver. The latter will help to accelerate the adoption of intensification technologies.

SpeakerNgo, Nam

Presentation time

10:35:00

10:50:00

Session time

10:30:00

12:00:00

SessionPushing the Boundaries of Our Biological Models

Session locationRoom S404a - Level 4

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

Author(s)

Ngo, Khoa Nam

Author(s)N. Khoa Nam 1; T. Wadhawan 2 ; B. Sturm 3; J.P. Boltz 4; J. Hinojosa 5; A.N. Massoudieh 6; I. Takacs 7; J. Jimenez 8; H. De Clippeleir 9;

Author affiliation(s)District of Columbia Water and Sewer Authority 1; Dynamita SARL, France 2 ; University of Kansas 3; Woodard & Curran Arizona State University, USA 4; District of Columbia Water and Sewer Authority 5; Catholic University of America 6; Dynamita SARL, France 7; Brown and Caldwell, USA 8; District of Columbia Water and Sewer Authority, USA 9;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159190

Volume / Issue

Content sourceWEFTEC

Word count9

Sludge Densification and Low DO BNR: Anaerobic Selectors are the Key!

Abstract

Intensification of wastewater treatment aims to create higher treatment capacity while reducing energy demand. Low dissolved oxygen (DO) operation can reduce energy costs, but there are concerns about process performance, particularly sludge settleability. Three phases of experimentation were completed on two bench-scale treatment configurations to compare sludge settleability and microbial kinetic rates: 1. High DO, 2. Low DO and 3. Low DO, with an extended anaerobic HRT. Excellent sludge settleability was obtained in the A/O configuration (average SVI 83 ± 5 mL/g) at low DO concentrations of 0.3 – 0.6 mg/L. Whereas, an A2 /O configuration experienced filament growth and sludge bulking. When the HRT was increased to 1.5 hour anaerobic HRT and 0.5 hour anoxic HRT, the A2 /O train was able to achieve good sludge settleability (average SVI 101 ± 7 mL/g).

Low dissolved oxygen (DO) operation is an attractive approach compared to typical aeration levels of 1.5 - 2 mg/L. However, there are concerns for process performance, specifically sludge settleability and lower microbial kinetic rates. Two bench-scale treatment plant configurations (A2/O and A/O) were operated at high and low DO. An Excellent sludge settleability (SVI 101 ï‚± 7 mL/g) was achieved at low DO concentrations with a longer anerobic HRT of the selector zone.

SpeakerSturm, Belinda

Presentation time

14:30:00

14:45:00

Session time

13:30:00

15:00:00

SessionAdvancing Low-energy Biological Nitrogen and Phosphorus Removal Through Low DO Operation

Session locationRoom N426b - Level 4

TopicAdvanced Level, Municipal Wastewater Treatment Design, Nutrients

Author(s)

Sturm, Belinda