Bachmann, Megan, Bachmann

Megan Bachmann is a PhD student at Virginia Tech earning a degree in Environmental Engineering. She is completing her research at Hampton Roads...

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About Bachmann, Megan

Megan Bachmann is a PhD student at Virginia Tech earning a degree in Environmental Engineering. She is completing her research at Hampton Roads Sanitation District (HRSD) where she focuses on the optimization of anammox in mainstream wastewater treatment systems to short-cut traditional nitrogen removal processes.

Bachmann, Megan

Titles from this speaker

Full-scale Implementation of Partial Denitrification/Anammox (PdNA) IFAS

Abstract

Moving and fixed media have been installed in a full-scale partial denitrification with anammox process at HRSD’s James River Treatment Plant with the goal of improving treatment, saving carbon and aeration energy, and intensifying current processes. In the moving media configuration, anammox activity was observed after 93 days of carbon addition. Currently 0.46 ± 0.32 g/m2 /day of ammonia removal is observed across this zone. The fixed media, 62 days post carbon addition at the time of writing, is subject to an ongoing monitoring campaign for anammox.

Moving and fixed media have been implemented in HRSD's James River Treatment Plant, accompanied with a full-scale partial denitrification with anammox (PdNA) process to improve treatment, save both carbon and aeration energy, and achieve process intensification. 93 days after the addition of carbon, anammox activity was observed on the moving media.

SpeakerCornelius, Lawrence

Presentation time

13:30:00

14:00:00

Session time

13:30:00

15:00:00

SessionLessons Learned from Early PdNA Implementation

Session locationRoom S504a - Level 5

TopicIntermediate Level, Nutrients, Research and Innovation

Author(s)

Cornelius, Lawrence

Author(s)L. Cornelius 1; N. Wieczorek 2 ; L. Cornelius 1; N. Wieczorek 2; M. Bachmann 3; M. Parsons 1; S. Klaus 2; C. Bott 2;

Author affiliation(s)Hampton Roads Sanitation District 1; Hampton Roads Sanitation District 2 ; Hampton Roads Sanitation District 1; Hampton Roads Sanitation District 2; Hampton Roads Sanitation District 3; Hampton Roads Sanitation District 1; Hampton Roads Sanitation District 2; Hampton Roads Sanitation District 2;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159087

Volume / Issue

Content sourceWEFTEC

Word count8

Description: Model-based Investigation of the Fate and Transport of Internal and External Carbon...

Model-based Investigation of the Fate and Transport of Internal and External Carbon Sources to Drive Partial deNitrification (PdN)-based Nitrogen Removal Processes

Abstract

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

SpeakerAl-Omari, Ahmed

Presentation time

11:30:00

11:45:00

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)

Al-Omari, Ahmed

Author(s)A. Al-Omari 1; P. Regmi 2 ; T. Wadhawan 3; M.L. Bachmann 4; K. Bauhs 5; J.A. Jimenez 7; I. Takacs 8; CB Bott 4; A. Al-Omari 1;

Author affiliation(s)Brown and Caldwell 1; HRSD 2 ; Dynamita 3; HRSD 4; Dynamita 5; Dynamita 7; Dynamita 8; Dynamita 4; Brown and Caldwell 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159193

Volume / Issue

Content sourceWEFTEC

Word count22

Shedding Light on the Complex of Internal Carbon Driven Denitrifiers in Biofilm & Floc

Abstract

Introduction Achieving energy-neutrality is an ongoing driver for new wastewater treatment approaches[1]. Since the successful application of anaerobic ammonia oxidation (anammox) in sidestream processes, concerted efforts have been devoted to integrating anammox into mainstream processes. Both partial nitritation (PN) and partial denitrification (PdN) produce the necessary electron donor, nitrite, for anammox bacteria to oxidize ammonia. Mainstream PN with anammox (PNA) requires the least amount of aeration energy and carbon addition, but stability of PN in mainstream treatment is still difficult to achieve. In contrast, the stability of PdN treating low carbon influent (C/N ~ 2-3) has been found to be robust and attracts increasing interest for implementing PdN with anammox (PdNA) in mainstream processes[2]. In 2020, pilot work at the Hampton Roads Sanitation District's (HRSD) James River Treatment Plant (JRTP) confirmed that stable PdN could be achieved in a second anoxic PdNA integrated fixed film activated sludge (IFAS) process[3]. Using feedback-controlled COD dosing to maintain an effluent nitrate residual, the ratio of consumed COD to removed total inorganic nitrogen was reduced to 1.08 to 2.183. In addition to PdN, these reductions in excess carbon could potentially be attributed to denitrification driven by bacterial intracellular stored carbon (here termed as Internal carbon-driven denitrification, ICD). However, the functional group (flocs vs. biofilm) that contributes to this phenomenon has not been identified. In addition, there is a knowledge gap for which conventional denitrifiers or other bacteria contribute to intracellular stored carbon to perform denitrification. To address this gap, this study employed flow activated cell sorting (FACS) and Single Cell Raman Spectrum (SCRS) techniques in combination with 16S sequencing to track the internal carbon accumulating organisms a second anoxic IFAS tank, with the aim to elucidate the carbon sources and organisms that may support ICD. Methods Sampling for this study was conducted at HRSD's JRTP, an A2O plant, where there were two parallel pilot PdNA IFAS reactors treating mixed liquor from JRTP's aerobic effluent. One IFAS reactor was acclimated to glycerol as an external carbon source, and the other was acclimated to methanol.[4] Specific denitrification rate (SDNR) tests were conducted on both IFAS reactors as well as just the suspended flocs using glycerol, methanol, or no external carbon during batch tests. The concentrations of nitrite, nitrate, and ammonia were measured throughout the test using HACH tubes. Floc samples were sampled directly while biofilm samples were collected by washing and shaking biofilm off vigorously in 0.1% NaCl solution. Sludge samples were fixed immediately and stored at 4 oC. After the batch test, fixed samples went for Fluorescence activated sludge sorting (FACS). SYBR Green and Nile Red were used in FACS process to bind with DNA and PHA (and similar lipid structures), respectively. Samples before and after sorting were sent out for 16S sequencing. SCRS detection was prepared according to Majed and Gu (2010).[5] Results 1. PdN and ICD were contributed by biofilm and flocs, separately. The SDNR rate in each IFAS reactor and the suspended sludge were measured separately. After subtracting the nitrogen removal contributed by flocs, the SDNR in the biofilm with glycerol and methanol were 0.36 and 0.49 g-N/gVSS/day, respectively. The SDNR in the flocs were 0.06 and 0.07 g-N/gVSS/day, respectively. The nitrite accumulation rates in the flocs were only 1-4% of that in the biofilm, indicating that the PdN in the IFAS system was mainly contributed to the biofilm. When no external carbon was provided, the biofilm SDNR would rapidly decrease to less than 10% of the original rate (Figure 1). In contrast, the SDNR in flocs without carbon addition decreased only 17%~29%. Additionally, flocs alone did not significantly consume external carbon. These results indicate that nitrite accumulation was mostly attributed to the biofilm through external carbon driven PdN, while organisms in flocs seemed to be more prone to internal carbon accumulation, and they performed additional ICD. 2. PHA-like internal carbon accumulators changed at the end of denitrification process. To further elucidate the potential internal carbon-driven denitrifiers, flocs samples were fixed before and after SDNR tests. It should be mentioned that Nile Red would stain not only PHA, but also lipids with a similar structure. Therefore, cells stained by SYPR Green and Nile Red were considered PHA-like internal carbon accumulators and sorted via FACS for microbial community analysis (Figure 2). Without sorting, the community was unchanged. However, the PHA-containing community changed significantly after 3h carbon-free denitrification (Figure 3). Genera labeled in red represent PHA accumulators that disappeared after SDNR tests, linking them to the observed ICD. To further analyze the intracellular carbon compounds, SCRS analysis showed ~20-30% of floc cells contained PHA, though no trends were evident (Figure 4). Undetectable GC-MS PHA corroborates that PHA is likely not the main carbon source in ICD.Though greater than PHA, the limited glycogen-containing cells (~10%) suggest glycogen may also not be the primary ICD substrate. Further research into identifying the specific carbon source(s) in post-denitrification is warranted.

This study investigates partial denitrification (PdN) and internal carbon-driven denitrification (ICD) mechanisms in an integrated fixed film activated sludge (IFAS) system treating low carbon-to-nitrogen ratio wastewater. This research provides new insights into the microbial communities and carbon sources supporting PdN and ICD in IFAS systems.

SpeakerYan, Yuan

Presentation time

09:00:00

09:30:00

Session time

08:30:00

10:00:00

SessionInternal Stored Carbon for Nutrient Removal

Session number309

Session locationRoom 243

TopicAdvanced Level, Nutrients, Research and Innovation

Author(s)

Yan, Yuan, Bachmann, Megan, Baldwin, Mathew, Klaus, Stephanie, Bott, Charles, Gu, April

Author(s)Y. Yan1, M.L. Bachmann2, M. Baldwin1, S. Klaus3, C.B. Bott3, A.A. Gu4

Author affiliation(s)1Cornell University, NY, 2Virginia Tech and Hampton Roads Sanitation District (HRSD), VA, 3Hampton Roads Sanitation District (HRSD), VA, 4, NY

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159491

Volume / Issue

Content sourceWEFTEC

Word count15

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Bachmann, Megan

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