Yan, Yuan

Yuan got her Ph.D. degree at Tongji University and now works as a postdoc at Cornell University. Her research focuses on the biological removal of Nitrogen and phosphorus from wastewater. Through the utilization of biomolecular technologies, including 16S sequencing, single cell Raman spectrum analysis, and flow cytometry analysis, she aims to identify new microbial candidates that have the potential to efficiently remove N and P. Expanding the scope of her research, she plans to investigate microbial interation between microorganisms and plants.

Titles from this speaker

Evaluating the Potential of Recovering Vivianite for Phosphorus Removal and Improving Class A Biosolids Applications

Abstract

INTENDED OBJECTIVE: Biosolids from water resource recovery facilities (WRRFs ) are increasingly used for agricultural and recreational land purposes due to their sustainable means to replenish macronutrients. However, the relatively high phosphorous content of biosolids limits certain applications. This study aims to identify optimal locations for recovering vivianite and subsequently phosphorus, to allow class A biosolids reach ideal phosphorus levels. INTRODUCTION: Global consumption rates of synthetic fertilizers per unit of cropland have increased 3 to 8 times over the past half century (Lu et al. 2017). Class A biosolids are increasingly explored as an alternative to commercial fertilizers due to their effective means to replenish carbon and macronutrients (Gilmour et al. 2013). However, the N:P ratio of biosolids is typically lower than commercial fertilizers which can cause an accumulation of phosphorus when applied to soil, increasing risk for eutrophication (Penn et al. 2002). Therefore, it is critical to implement efficient phosphorus-removal technologies/techniques within the biosolids treatment train to improve the N:P ratio and limit the amount of phosphorus that result in the cake. Therefore, this study aims to analyze the P mass balance of the Blue Plains advanced wastewater treatment plant in Washington, DC as well as its vivianite characterization in full-scale. The process sampling, modelling and analysis led to identification of potential locations for vivianite recovery, and initial estimations on how much the P content in our class A biosolids might be reduced by recovering vivianite upfront. MATERIALS AND METHODS: Sampling campaign: Samples were collected in DC Water Blue Plains over a 3-month period (Mid-February to Mid-May 2022). Quantitative analysis: Phosphorus is measured by the EPA 365.1 method. Scanning Electron Microscopy with Energy Dispersive and Mossbauer Spectroscopy: Prepared by method in Prot et al. 2021. Modelling method: Visual Minteq version 3.3 with DOC SHM model RESULTS & DISCUSSION P mass balance at Blue Plains and P content in biosolids product Blue Plains advanced WWRF achieved a 98% incoming TP removal over its primary (enhanced-chemical phosphorus removal) and secondary systems through iron dosing. The removed P is diverted to the solids fraction and results in a Class A biosolids product (BLOOM) with 2.88% P (dry weight basis) and 28-32%TS (Fig.1A). The P:N ratio of our product is 1:1 and thus higher in P content than the target of 1:2 P:N for typical fertilizers. Decreasing P content in BLOOM by 50% or thus recovery 60% of vivianite would increase the value and applicability of BLOOM. Vivianite formation and formation potential along the Solids Treatment Train A total Fe/P molar ratio of 1.5 or greater allows for optimal vivianite precipitation (Cong et al. 2017) which is reflected in DC Water treatment flow diagram (Figu 1). Vivianite was detected in primary thickened sludge, blend of thickened primary (PS) and waste activated sludge (WAS), and digested sludge b ased on sequential extraction method in Wang et al. 2021. This was also further supported by the clear co-location of Fe and P in SEM images (Figure 2A and 2B). These locations are consistent with the vivianite scaling seen in primary sludge gravity thickening lines and centrifuge lines in the facility. Through quantitative analysis, the vivianite mass flow in thickened primary sludge, blended PS/WAS and digested solids accounted for 8%, 52%, and 49% of the incoming P to the plant (Fig. 1). These vivianite ranges are like those reported by iron-dosing plants in Prot et al. 2021 and Wilfert et al. 2016. Estimation of P recovery potential needed to impact Class A biosolids P content Based on the current vivianite-P levels in the three identified locations (Fig. 1), sludge after anaerobic digestion contained the highest level of vivianite-P. This is likely due to higher orthophosphorus levels after thermal hydrolysis treatment which allows for additional vivianite formation with Fe(II). This notion is supported by the low levels of Fe(II) concentrations after anaerobic digestion indicating that most of it is bound (Fig. 1). We estimated how much vivianite recovery efficiency we might need to decrease the P content in the BLOOM with an ideal target of ~0.014 kg P/kg TS and acceptable target of 0.022 kg P/kg TS. Given the highest vivianite levels in digested sludge, a recovery efficiency of at least 40% with ideally 70% is sufficient to meet our targets (Fig. 3). Utilizing vivianite recovery technologies such as magnetic separation (80% of vivianite recovery in digestates according to Wijdeveld et al. 2022), and other alternative options could provide the potential recovery target needed to improve BLOOM. CONCLUSIONS Based on current vivianite-removal technology efficiencies, removing vivianite will significantly impact the phosphorus levels in BLOOM. Results suggest that after anaerobic digestion is a preferred and feasible option to implement recovery technology due to its high vivianite content as well as the opportunity to recover vivianite in a fraction of the digestate to produce low P BLOOM rather than the whole biosolids treatment train. Future testing will explore recovery efficiencies of P and vivianite to confirm feasibility and setup a path towards pilot testing approaches.

Biosolids from water resource recovery facilities (WRRFs) are increasingly used for agricultural and recreational land purposes due to their sustainable means to replenish macronutrients. However, the relatively high phosphorous content of biosolids limits certain applications. This study aims to identify optimal locations for recovering vivianite to manage phosphorous levels in class A biosolids.

SpeakerGuo, Peibo

Presentation time

08:30:00

08:50:00

Session time

08:30:00

10:00:00

SessionEnhancing Digestion to Improve Operations and Resource Recovery: Capture of Control

Session number501

Session locationRoom 256

TopicBiosolids and Residuals, Energy Production, Conservation, and Management, Facility Operations and Maintenance, Intermediate Level

Author(s)

Guo, Peibo, Yan, Yuan, Ngo, Nam, Peot, Chris, Gu, April, Reid, Matthew, Bollmeyer, Melissa, De Clippeleir, Haydee

Author(s)P. Guo1, Y. Yan2, N.H. Ngo3, C.J. Peot4, A.A. Gu5, M. Reid2, M. Bollmeyer2, H. De Clippeleir6

Author affiliation(s)1Brown and Caldwell, VA, 2Cornell University, NY, 3, CA, 4DC Water & Sewer Authority, DC, 5, NY, 6DC Water & Sewer Authority, VA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159698

Volume / Issue

Content sourceWEFTEC

Word count16

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

Base text size -

Yan, Yuan

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