Goel, Ramesh

Ramesh Goel is a professor of Environmental Engineering at the University of Utah. He researches at the interface of environmental process engineering and microbiology.

Titles from this speaker

Description: Anoxic Granular Activated Sludge Process For Simultaneous Denitrification and...

Anoxic Granular Activated Sludge Process For Simultaneous Denitrification and Perchlorate Reduction: Process Performance and Anoxic Granulation Strategy

Abstract

Introduction
Granular sludge (GS) is an emerging biological wastewater treatment technology that is gaining world-wide attention due to its high rates of removal of both nutrients and recalcitrant organic matter from wastewater [1]. Of the various types of GS, anoxic GS (AxGS) is the least studied when compared to aerobic GS (AGS) and anaerobic GS (AnGS), where thus the formation mechanisms of AxGS are even more ambiguous. Anoxic granules comprising microbial communities mediating anaerobic ammonium oxidation (anammox) represent the bulk of previous literature on AxGS. However, AxGS bioreactors exclusively operated for denitrification have received less academic inquiry. Multiple studies have reported GS formation under denitrifying conditions [2]â€“[5], however, the complete characterization of the anoxic granulation process was not reported in these studies and thus the formation mechanisms of denitrifying AxGS still remain unclear and subject to debate. Therefore, this study seeks to characterize the anoxic granulation process under denitrifying conditions with perchlorate present as a competing electron acceptor to infer possible formation mechanisms and assess the temporal variation in biomass characteristics as the loose flocs compact into dense microbial aggregates. Microbial ecology was also assessed to determine the temporal distribution in phylotypes as anoxic granulation ensued.
Objectives
The main objectives of this study include:
(1) bioprocess optimization for concurrent denitrification and perchlorate reduction;
(2) characterizing the anoxic granulation process; and
3) to study the microorganisms comprising the AxGS biomass.
Significance
Findings from this study will contribute to the advancement of AxGS process bioreactors by demonstrating at the lab-scale the application this biotechnology.
Status
An AxGS process bioreactor has been operational for over 350-d, where dense anoxic granules have been cultivated. Bioprocess optimization has been executed, resulting in the consistent removal of >99% of the influent perchlorate and nitrate, while concurrently oxidizing >90% of the influent COD.
Methodology
A Plexiglass bubble-column bioreactor (2.625' diameter, 27' height) was fabricated to cultivate anoxic granules. The reactor was seeded with a mixture of hypersaline lake sediments, river sediments, anaerobic digester sludge solids, and aerobic activated sludge solids, previously enriched for denitrifying and perchlorate reducing organisms. Enrichment of perchlorate-reducing and denitrifying organisms was performed by providing perchlorate and nitrate as electron acceptors along with acetate as the electron donor in a basal medium described by Song et al. (2019). The anoxic granulation process was characterized through a combination of sludge settling analyses, solids concentrations, extracellular polymeric substance (EPS) extraction and analyses, microscopy, and microbial methods. Complete cycle analyses were conducted so that specific rates could be expressed. Microbial ecology of the AxGS biomass was characterized by high-throughput 16S rDNA amplicon sequencing as described by Stein et al. (2021). All anions were quantified using a Compact 930 IC Flex ion chromatograph (IC; Metrohm, USA). COD was quantified according to standard methods [8] and dissolved organic carbon (DOC) was quantified using a Shimadzu, TOC-V Total Organic Carbon (TOC) Analyzer (Shimadzu, USA). Findings Reactor Performance The overall performance of the AxGS bioreactor in terms of perchlorate, nitrate, and COD removal efficiencies, as well as chloride accumulations in the effluent, is summarized in Figure 1. The AxGS biomass efficiently reduced both the influent perchlorate and nitrate, while simultaneously oxidizing the influent COD. Average perchlorate, nitrate, and COD removal efficiencies have been 97.3Â±7.2%, >99.9%, and 90.1Â±3.07%, respectively. Average chloride accumulation in the effluent has been 153Â±23.7 mg/L, which is representative of an 80.3% (mol/mol) molecular conversion of the influent perchlorate to chloride. The initial mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) concentrations in the bioreactor were 1.09 g/L and 0.93 g/L, respectively. The biomass concentrations in the reactor steadily increased until reaching an average steady-state MLSS and MLVSS concentration of 3.11Â±1.15 g/L and 2.76Â±1.01 g/L, respectively, while maintaining a solids retention time (SRT) of 20-d. The 5-min sludge volume index (SVI5) of the AxGS biomass rapidly decreased in the first 150-d of reactor operation as the loose flocs gradually transformed into dense microbial aggregates. The SVI5 stabilized at a steady-state value of 24.9Â±11.7 mL/g. Both the specific protein and carbohydrate content of the EPS comprising the AxGS biomass steadily increased as the floccular biomass transformed into compact aggregates. Additionally, the protein fraction of the EPS became >90% as the anoxic granules matured and reached steady-state. Figure 1 also displays the results of a complete cycle analysis conducted over a standard reactor operational cycle under steady-state conditions. Nitrate was reduced to below detection 6-h into the cycle, where specific reduction rates of 6.12Â±1.68 mg NO3-N/g VSSâ€¢h were recorded. DOC became limiting 6-h into the cycle, where specific oxidation rates of 8.60Â±2.66 mg DOC/g VSSâ€¢h were recorded. Perchlorate was reduced to below detection before the effluent was withdrawn from the reactor, where specific reduction rates of 8.62Â±2.36 mg ClO4-/g VSSâ€¢h were recorded. Specific chloride production rates of 2.18Â±0.60 mg Cl-/g VSSâ€¢h were also recorded. Microscopy Figure 2 displays micrographs of the AxGS biomass captured throughout reactor operation. Initially, the biomass was comprised of loose flocs consisting of a dispersed web of EPS. The loose flocs then gradually underwent compaction until irregularly-shaped, distinguishable anoxic granules were observed on reactor operational day 97, where the EPS matrix became compact and smooth. The anoxic granules then became much larger and more compact, while also taking on a more symmetrical, spherical shape starting on reactor operation day 146. The EPS matrix of the granules became slightly rougher starting on reactor operational day 146 and remained that way. Microbial Ecology Figure 3 displays the taxonomic classification at the phylum (panel 'a') and genus (panel 'b') level for the microbial community comprising the AxGS biomass throughout reactor operation. At the Phylum level, Proteobacteria (94.1-98.2%) were dominant at all sampling events. Minor phyla identified were Acidobacteriota (0.2â€“1.54%) and Bacteroidota (0.43â€“4.74%). At the genus level, Dechloromonas (49.5â€“90.6%) and Azospira (3.16-40.8%) were the clear dominant genera throughout reactor operation, both of whom have members known to be perchlorate reducing and denitrifying organisms [9]â€“[11]. Minor genera identified were Holophagaceae (0.01-1.33%), Lentimicrobium (0.25-4.16%), Dechlorosoma (0.36-9.17%), Denitratisoma (0-5.46%), and Thauera (0.35-6.44%).

A completely sealed, bubble-column, sequencing batch bioreactor was initiated in this study at the laboratory-scale for the cultivation of granular activated sludge under anoxic conditions with perchlorate and nitrate present as competing electron acceptors. A short settling time (2-min) in concert with a feast-famine feeding regime led to the rapid cultivation of anoxic granular activated sludge (AxGS). Perchlorate and nitrate removal efficiencies >99.9% on average were recorded for over 500-d

SpeakerGoel, Ramesh

Presentation time

08:30:00

08:55:00

Session time

08:30:00

09:30:00

TopicIntermediate Level, Industrial Issues and Treatment Technologies, Microconstituents and Contaminants of Emerging Concern (Non-PFAS), Research and Innovation

Author(s)

Goel, Ramesh

Author(s)Nathaniel Stein1; Aditi Podder 2; Ramesh Goel1

Author affiliation(s)Department of Civil and Environmental Engineering, University of Utah, Salt Lake City, UT1; Brown and Caldwell, Houston, TX2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158487

Volume / Issue

Content sourceWEFTEC

Word count18

Description: Combination of EBPR, Endogenous Denitrification, Partial...

Combination of EBPR, Endogenous Denitrification, Partial Nitrification/Denitrification and Anammox to Achieve Cost-effective Nutrient Removal

Abstract

To address the problem of eutrophication in the marine environment caused by excessive nutrient release and meet stringent nutrient discharge limits (e.g., TIN < 3 mg/L), a costeffective BNR (biological nutrient removal) technology is needed for equipping coastal wastewater treatment plants (WWTPs) with nutrient removal capacity. This pilot work was aimed to demonstrate how a conventional “A2O + tertiary MBBR” process can be easily modified to collectively achieve EBPR, endogenous denitrification, and Partial nitrification/ denitrification and anammox (PANDA) in one combination under novel system automation control. Nutrient discharge limits (average TIN < 3 mg/L) were met. Large amount of carbon and oxygen can be saved throughout the secondary and tertiary treatment innovation. The volume of aeration tank can be reduced.

Enhanced biological phosphorus removal (EBPR), endogenous denitrification, and Partial nitrification/ denitrification and anammox (PANDA) can be incorporated in an 'A2O + tertiary MBBR' process to achieve cost-effective nutrient removal under system automation control. Nutrient discharge limits (average TIN < 3 mg/L) were met. Large amount of carbon and oxygen can be saved throughout the secondary and tertiary treatment innovation. The volume of aeration tank can be reduced.

SpeakerWANG, JIEFU

Presentation time

09:30:00

10:00:00

Session time

08:30:00

10:00:00

SessionPdNA Whole Plant Considerations

Session locationRoom S504a - Level 5

TopicIntermediate Level, Nutrients

Author(s)

Wang, Jiefu

Author(s)J. Wang 1; Y. Sun 2 ; W. Khunjar 3; Z Wang 1; M. Winkler 4; R.K. Goel 5;

Author affiliation(s)Department of Biological Systems Engineering, Virginia Tech 1; Hazen and Sawyer 2 ; Hazen and Sawyer 3; Department of Biological Systems Engineering, Virginia Tech, Blacksburg, VA, USA 1; Department of Civil and Environmental Engineering, University of Washington 4; Department of Civil and Environmental Engineering, University of Utah 5;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159157

Volume / Issue

Content sourceWEFTEC

Word count15

Description: Process Densification and Emerging Contaminant, PFAS and EE2, Management in...

Process Densification and Emerging Contaminant, PFAS and EE2, Management in Wastewater Treatment using Reactive Migrating Carriers

Abstract

Abstract
In addressing stringent environmental regulations, aging wastewater treatment infrastructure, and heightened sustainability goals, advanced biological nutrient removal (BNR) systems have emerged as essential components for modern water reclamation facilities (WRFs). This abstract delves into the innovative application of reactive migrating biocarriers for process intensification to combat increased flows. The objective of this study was to utilize granular activated carbon as migrating carrier to simultaneous achieve nitrogen management and micropollutants removal. The model micropollutants used were short and long chain PFAS compounds, and one synthetic estrogen EE2. The findings outline operational strategy, key findings, challenges, and valuable lessons derived from this effort.

Background
There is an urgent need to increase the capacity of existing WWTPs and achieve process intensification through densification and efficient nitrogen management. Much of the infrastructure associated with WWTPs was built between the 1940s and 1970s. Most Wastewater Treatment Plants (WWTPs) in the U.S. need significant upgrades in terms of the treatment of wastewater to accommodate population growth (e.g., increased flows), industrialization, and more stringent effluent regulations for nitrogen management. There is an increase in concern for managing micropollutants, especially for treatment plants discharging into sensitive waterbodies. Expanding existing WWTPs through new construction is often not feasible due to space and budget limitations related to high infrastructure costs. We use granular activated carbon (GAC) as migrating reactive carriers to accomplish densification-intensification. The reactive or absorptive media such as cellulosic plant-based such as hemp or kenaf and granular activated carbon add to the removal mechanisms and are less expensive, and environmentally friendly compared to the use of plastic carriers. The use of migrating carrier allowed for SRT decoupling between slow (such as nitrifiers) and fast-growing organisms (thus enabling shorter floc-based SRT), as well as enabled the sorption of micropollutants to increase their localized concentrations.

Approach
Two identical lab-scale plexiglass SBRs (2H/D ratio, 3L working volume) were operated at room temperature (22±1oC) in Dr. Goel's lab. 2 g/L of GAC was added in RAC. Both RAC and RC were operated in an anaerobic-anoxic-oxic (A2O) process. Each cycle was comprised of 6-h, involving 9-min of anaerobic synthetic wastewater feeding, 51-min of anaerobic, 50-min anoxic (by dosing nitrate to mimic internal recycling), 229-min of aerobic, 20-min of settling, and 1-min of effluent discharge. The DO levels were maintained in the 0.4 to 0.6 mg/L range in oxic phase to achieve simultaneous nitrification and denitrification (SND) with P removal. The targeted feed concentrations of EE2 and each PFAS were 5 µg/L and 50 ng/L, respectively. The hydraulic retention time (HRT) was 10-h, and the solids retention time (SRT) was maintained at 10-d by wasting sludge through a 500 µm sieve.

Important findings and discussion
The migrating reactive carrier concept is fundamentally different from moving bed biofilm reactors (MBBR). Unlike inert plastic carriers, the reactive migrating carrier concept is a novel concept. In reactive migrating carriers, the media supporting biofilm is reactive (i.e., adsorptive). Reactive or absorptive carriers can interact with various dissolved contaminants, especially micropollutants.
- Both RC and RAC showed nearly similar removal efficiencies for organic carbon (represented by COD), ammonium, ortho-P, and total inorganic nitrogen (TIN). TIN and ortho-P removals signify the presence of active denitrification and enhanced bio-P removal (EBPR) activities in both reactors. A typical complete cycle analysis for both reactors in terms of nutrients, organic carbon and EE2 is shown in figure 1. GAC supplemented migrating carrier reactor had much higher granulation >500µm (nearly 87 % as compared to 52 % in the control based on volatile suspended solids) than in the conventional reactor.
- The short-chain PFAS compounds passed through both reactors without showing any removal (figure 2). However, nearly 40 to 50 % removal of long-chain PFAS compounds was recorded consistently in both reactors, with the GAC-supplemented reactor (red dots) showing consistently higher removal than the other reactor (blue dots) over more than 100 days of feeding. Similar observation for EE2. The primary removal mechanism of both types of micropollutants from the bulk liquid was adsorption on GAC and granules followed by potential biodegradation revealed by batch tests. The long-chain PFOA and PFOS concentrations in the biomass (including GAC biofilm) were 413.58±12.3 and 474.39±11.7 ng/g TSS in the RAC- and 31.2±8.8 and 36.3±3.9 ng/g TSS in the RC control SBR respectively. We also conducted a mass balance on long-chain PFAS in RAC based on concentrations in the influent, effluent and measured concentrations of both long-chain PFAS in the biomass. Based on this estimate, we concluded that although the immediate mechanism of removal is sorption to the biomass/biofilm, other processes, such as biodegradation, are also contributing to the disappearance of PFAS parent compounds.

Conclusion: The use of GAC intensify the process and micropollutant management is creative and presents the next generation of innovation in wastewater.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

08:30:00

08:45:00

Session time

08:30:00

10:00:00

SessionInnovative Approaches to Micropollutant Removal in Wastewater

Session locationMcCormick Place, Chicago, Illinois, USA

TopicResearch

Author(s)

Goel, Ramesh, Quereshi, Tayyab, Goswami, Anjan, Murthy, Sudhir, Giraldo, Eugenio

Author(s)R. Goel1, T. Quereshi1, A. Goswami4, S. Murthy2, E. Giraldo3

Author affiliation(s)University of Utah1, NEWhub Corp2, Carbon Materials LLC3, Bron and Coldwell4

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2025

DOI10.2175/193864718825159976

Volume / Issue

Content sourceWEFTEC

Word count17

Description: Successful Implementation of Biofilm Anammox in IFAS A2O Process for Simultaneous N...

Successful Implementation of Biofilm Anammox in IFAS A2O Process for Simultaneous N and P Removal in Main Stream Treatment Train

Abstract

This research studied integrated fixed film activated sludge (IFAS) technology to simultaneously remove N and P in real municipal wastewater by combining anammox biofilms with flocculent activated sludge for enhanced biological P removal (EBPR). The study was conducted in a sequencing batch reactor (SBR) operated as a conventional A2O (anaerobic-anoxic-oxic) process with an 8.8 h hydraulic retention time. After achieving steady-state operation, the reactor showed robust performance, with average removal efficiencies of 91.3±4.1% for total inorganic nitrogen (TIN) and 98.4±2.4% for phosphorus (P). Denitrifying polyphosphate accumulating organisms (DPAOs) were responsible for 15.9% of P uptake during the anoxic phase, while biofilms showed anammox activity in the aerobic step. The IFAS configuration with a low solid retention time (SRT) of 5 days prevented the washout of biofilm anammox bacteria and allowed selective washout of unwanted organisms. The results demonstrated the successful coexistence of anammox bacteria with other bacteria for efficient nutrient removal in real wastewater conditions.

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

SpeakerGoel, Ramesh

Presentation time

09:00:00

09:30:00

Session time

08:30:00

10:00:00

SessionPdNA Whole Plant Considerations

Session locationRoom S504a - Level 5

TopicIntermediate Level, Nutrients

Author(s)

Goel, Ramesh

Author(s)R. Goel 1; S. Hong 1 ; R. Goel 1;

Author affiliation(s)Department of Civil and Environmental Engineering, University of Utah 1; Department of Civil and Environmental Engineering, University of Utah 1 ;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159156

Volume / Issue

Content sourceWEFTEC

Word count21

Description: The Effect of Change in Temperature and Exposure of Sulfide and Heavy Metals in...

The Effect of Change in Temperature and Exposure of Sulfide and Heavy Metals in Anammox Process

Abstract

The effect of change in temperature, exposure of sulfide, lead, mercury, arsenite and cyanide on anammox activity was studied. Specific anammox activity (SAA) reduced from about 0.4 to 0.25 g N/g VSS d when the temperature dropped from 35 to 21°C and reduced to 0.05 g N/g VSS d at 13°C. Sulfide was also found to have a tremendous negative effect on SAA, where the anammox activity decreased with the increasing sulfide concentrations. Severe decrease in SAA for CN- concentration of 0.5 mg/L and Hg2+ concentration of 0.8 mg/L was observed. A slight decrease in SAA was seen at Pb2+ concentration of 0.8 mg/L. A multi-day inhibition test performed to study the recovery response. Partial recovery of SAA for maximum CN- concentration 0.15 mg/L and Hg2+ concentration of 5 mg/L was observed

SpeakerGoel, Ramesh

Presentation time

09:50:00

10:10:00

Session time

08:30:00

10:10:00

SessionInnovative Nitrogen Removal Approaches and Pathways

Session number511

TopicEnergy Production, Conservation, and Management, Facility Operations and Maintenance, Intelligent Water, Municipal Wastewater Treatment Design, Nutrients

Author(s)

R. GoelR. GoelB. BhattaraiB. BhattaraiS. Hong