Francis de los Reyes III (original) (raw)

Papers by Francis de los Reyes III

Research paper thumbnail of The Complicated Issue of Human Waste

After you've eaten your food, you generate waste. In modern wastewater treatment plants, waste is... more After you've eaten your food, you generate waste. In modern wastewater treatment plants, waste is converted to carbon dioxide and water is cleaned. Yet billions of people around the world, including 1.4 million in the U.S., don't have access to safe, sustainable sanitation and many (mostly children) die from related diseases and infections. UN Sustainable Development Goal 6 aims to achieve access to adequate sanitation for all. How must we think about this wicked problem? Francis L. de los Reyes III, Ph.D., discusses four key areas to target: government policies and regulations, technologies, business opportunities for sanitation companies, and social and behavioral change.

Research paper thumbnail of Factors Affecting the Formation of Fats, Oils, and Grease Deposits in Sewer Systems and Fate of FOG Deposit Forming Precursors in Sewer Systems

This Final Report combines the reports for the two WRRI projects, as they are related, and being ... more This Final Report combines the reports for the two WRRI projects, as they are related, and being conducted by the same research team (PIs, grad student and undergraduate assistants). The objective of the first project was to quantify the effects of kitchen wastewater characteristics on fat, oil, and grease (FOG) deposit formation mechanism and rate. The objective of the second project was to test the hypothesis that FOG formation in sewers is caused via a saponificationlike reaction involving major chemical precursors: free fatty acids, a metal cation, and surfactant. Thus, the overall goal of the combined projects was to determine the mechanism(s) of FOG deposit formation in sewer lines, and to elucidate the role of various factors in the deposit phenomenon, with the end-goal of understanding how to control sewer line blockages due to FOG formation. The projects used a variety of techniques and methods to achieve these goals. Initial experiments were aimed at exploring the interplay of various hypothesized factors, such as oil type, calcium, potassium, and attachment surface (e.g., concrete coupons), and were conducted in batch tests using a jar apparatus. In parallel, a pipe loop system simulating a sewer line was constructed. These experiments were designed to induce the formation of FOG deposits in lab-scale. After many attempts, FOG deposits were formed in a batch system using grease interceptor (GI) effluent from a restaurant. To our knowledge, this is the first time that FOG deposits have been formed under lab conditions. FTIR analysis showed that the FOG deposits were metallic salts of fatty acid as revealed by comparisons with FOG deposits collected from sewer lines and pure calcium soaps. Based on the data, we proposed that the formation of FOG deposits occurs from the aggregation of excess calcium compressing the double layer of free fatty acid micelles, and a saponification reaction between aggregated calcium and free fatty acids.

Research paper thumbnail of Using Detrending to Assess SARS-CoV-2 Wastewater Loads as a Leading Indicator of Fluctuations in COVID-19 Cases at Fine Temporal Scales: Correlations Across Twenty Sewersheds in North Carolina

Wastewater surveillance emerged during the COVID-19 pandemic as a novel strategy for tracking the... more Wastewater surveillance emerged during the COVID-19 pandemic as a novel strategy for tracking the burden of illness in communities. Previous work has shown that trends in wastewater SARS-CoV-2 viral loads correlate well with reported COVID-19 case trends over longer time periods (i.e., months). We used detrending time series to reveal shorter sub-trend patterns (i.e., weeks) to identify leads or lags in the temporal alignment of the wastewater/case relationship. Daily incident COVID-19 cases and twice-weekly wastewater SARS-CoV-2 viral loads measured at 20 North Carolina sewersheds in 2021 were detrended using smoothing ranges of ∞, 16, 8, 4 and 2 weeks, to produce detrended cases and wastewater viral loads at progressively finer time scales. For each sewershed and smoothing range, we calculated the Spearman correlation between the cases and the wastewater viral loads with offsets of -7 to +7 days. We identified a conclusive lead/lag relationship at 15 of 20 sewersheds, with detrend...

Research paper thumbnail of Fat, oil, and grease (FOG) deposits yield higher methane than FOG in anaerobic co-digestion with waste activated sludge

Journal of Environmental Management

Research paper thumbnail of Systems and Methods for Studying Microbial Processes and Communities in Landfills

Advances in Environmental Microbiology

Research paper thumbnail of The role of emptying services in provision of safely managed sanitation: A classification and quantification of the needs of LMICs

Journal of Environmental Management

Research paper thumbnail of Comparison of

FEMS Microbiology Ecology

Refuse decomposition in landfills is a microbially mediated process that occurs primarily under a... more Refuse decomposition in landfills is a microbially mediated process that occurs primarily under anaerobic conditions. Because of limited moisture conditions, hydraulic transport as a means of cellular translocation within the landfill appears limited, especially during the initial stages of decomposition. Thus, microbial communities within the incoming refuse serve as a primary source of facultative and obligate anaerobic microorganisms that initiate refuse decomposition. Fresh residential refuse was collected five times over 26 months, and microbial communities in these samples were compared with those in individual refuse components and decomposed refuse. Bacterial and archaeal community structures were determined using T‐RFLP. The Bacterial microbial community richness was correlated (r 2 = 0.91) with seasonal differences in ambient air temperature. Analysis of the results shows that fresh refuse is most likely not the source of methanogens in landfills. Microbial communities in ...

Research paper thumbnail of Development of trash exclusion for mechanized pit latrine emptying

Environmental Science: Water Research & Technology

The trash-excluding attachment (Excluder) can be connected to a custom vacuum (such as the Flexcr... more The trash-excluding attachment (Excluder) can be connected to a custom vacuum (such as the Flexcrevator), a vacuum truck, or a sludge pump. The system allows the mechanized emptying of pit latrines with high levels of trash without manual “fishing”.

Research paper thumbnail of Kenaf addition has mixed effects on process performance of sequencing batch reactors treating municipal wastewater

Environmental Science: Water Research & Technology

The effects on wastewater treatment due to addition to the mixed liquor of a fine lignocellulosic... more The effects on wastewater treatment due to addition to the mixed liquor of a fine lignocellulosic powder made of dried kenaf were assessed using lab-scale sequencing batch reactors (SBRs) operated for over 200 days.

Research paper thumbnail of Dynamic Modeling of Microalgae Growth and Lipid Production under Transient Light and Nitrogen Conditions

Environmental Science & Technology

Research paper thumbnail of Microbial ecological succession during municipal solid waste decomposition

Applied microbiology and biotechnology, 2018

The decomposition of landfilled refuse proceeds through distinct phases, each defined by varying ... more The decomposition of landfilled refuse proceeds through distinct phases, each defined by varying environmental factors such as volatile fatty acid concentration, pH, and substrate quality. The succession of microbial communities in response to these changing conditions was monitored in a laboratory-scale simulated landfill to minimize measurement difficulties experienced at field scale. 16S rRNA gene sequences retrieved at separate stages of decomposition showed significant succession in both Bacteria and methanogenic Archaea. A majority of Bacteria sequences in landfilled refuse belong to members of the phylum Firmicutes, while Proteobacteria levels fluctuated and Bacteroidetes levels increased as decomposition proceeded. Roughly 44% of archaeal sequences retrieved under conditions of low pH and high acetate were strictly hydrogenotrophic (Methanomicrobiales, Methanobacteriales). Methanosarcina was present at all stages of decomposition. Correspondence analysis showed bacterial pop...

Research paper thumbnail of Fluid Shear Variation Potentially Plays a Role in Aerobic Granular Sludge Formation

Proceedings of the Water Environment Federation

Research paper thumbnail of Quantification of the Denitrification Gene nosZ in a Full Scale Wastewater Treatment Plant Using qPCR

Proceedings of the Water Environment Federation

FOGLE, KARA NICOLE KOPF. Quantification of the Denitrification Gene nosZ in a Full-Scale Wastewat... more FOGLE, KARA NICOLE KOPF. Quantification of the Denitrification Gene nosZ in a Full-Scale Wastewater Treatment Plant Using qPCR. (Under the direction of Dr. Francis L. de los Reyes III.) Excessive levels of nitrogen in wastewater effluent can result in DO depletion, toxicity, eutrophication, global warming, acid rain, and other undesired effects. Understanding the denitrification process that occurs in wastewater treatment plants is important to allow engineers and plant operators to achieve more efficient nitrogen removal from wastewater. Due to the wide variety of physiological and phylogenetic groups to which denitrifiers belong, quantifying them using ribosomal RNA is not feasible. However, specific denitrification genes can be targeted instead. nosZ is the gene that encodes for the enzyme nitrous oxide reductase, the enzyme that catalyzes the Quantification of the Denitrification Gene nosZ in a Full-Scale Wastewater Treatment Plant Using qPCR

Research paper thumbnail of Steam Application to Destroy Foam-Forming Bacteria in Activated Sludge Systems

Journal of Environmental Engineering

Research paper thumbnail of Physico-chemical Characterization of Grease Interceptors with and without Biological Product Addition

Water Environment Research, Mar 1, 2012

Hardened and insoluble fat, oil, and grease (FOG) deposits are the primary cause of sewer line bl... more Hardened and insoluble fat, oil, and grease (FOG) deposits are the primary cause of sewer line blockages leading to sanitary sewer overflows (SSOs). However, there have been very few long-term assessments of the physico-chemical characteristics of full-scale grease interceptors (GIs), the first "line of defense" against FOG buildup in sewer lines. In this study, we assessed the physico-chemical characteristics of two full-scale GIs (at a restaurant and a retirement community kitchen) over a one-year period. Statistically significant differences between bioaugmented and untreated cycles were detected for several chemical and physical properties. The treated cycles had lower BOD and COD at the grease interceptor outlet. While the combined data for all treated cycles did not show lower FOG concentrations in the GI outlet compared to the combined data for all untreated cycles, comparison of specific individual treated and untreated cycles show a positive effect due to the addition of product.

Research paper thumbnail of Microbial community structures in foaming and nonfoaming full-scale wastewater treatment plants

Water Environment Research, Sep 1, 2002

A survey of full-scale activated-sludge plants in Illinois revealed that filamentous foaming is a... more A survey of full-scale activated-sludge plants in Illinois revealed that filamentous foaming is a widespread problem in the state, and that the causes and consequences of foaming control strategies are not fully understood. To link microbial community structure to foam occurrence, microbial populations in eight foaming and nine nonfoaming full-scale activated-sludge systems were quantified using oligonucleotide hybridization probes targeting the ribosomal RNA (rRNA) of the mycolata; Gordonia spp.; Gordonia amarae; "Candidatus Microthrix parvicella"; the alpha-, beta-, and gamma-subclasses of the Proteobacteria, and members of the Cytophaga-Flavobacteria. Parallel measurements of microbial population abundance using hybridization of extracted RNA and fluorescence in situ hybridization (FISH) showed that the levels of mycolata, particularly Gordonia spp., were higher in most foaming systems compared with nonfoaming systems. Fluorescence in situ hybridization and microscopy suggested the involvement of "Candidatus Microthrix parvicella" and Skermania piniformis in foam formation in other plants. Finally, high numbers of "Candidatus Microthrix parvicella" were detected by FISH in foam and mixed liquor samples of one plant, whereas the corresponding levels of rRNA were low. This finding implies that inactive "Candidatus Microthrix parvicella" cells (i.e., cells with low rRNA levels) can cause foaming.

Research paper thumbnail of Characterization of Restaurant Gravity Grease Interceptors and the Impact of Bioaugmentation on Performance

Gravity grease interceptors (GGIs) from four restaurants surrounding a shopping mall were treated... more Gravity grease interceptors (GGIs) from four restaurants surrounding a shopping mall were treated with a bioaugmentation product containing bacterial spores and surfactants and monitored for changes in effluent quality compared to untreated control periods. The study consisted of four cycles lasting between 62 and 82 days each, depending on the normal pumping frequency. In each cycle, two GGIs were treated and two were untreated. Regular analyses included oil and grease, total chemical oxygen demand, soluble chemical oxygen demand, total suspended solids, pH, temperature, biochemical oxygen demand, grease cap thickness, and bottom solids accumulation. A commercial jar sampler modified with an air vent was effectively used to sample from the effluent tee within the interceptor. In most cases there was a positive correlation between oil and grease in the effluent and time after pumping. Bioaugmentation in three of four restaurants resulted in lower oil and grease concentrations compared to untreated cycles by 20%, 35% and 41%. Oil and grease in the remaining restaurant was similar in the treated and untreated cycles. This restaurant, however, had the lowest effluent concentrations of oil and grease and suggests that bioaugmentation may be more effective in GGIs where higher amounts of oil and grease are present. Grease caps and bottom solids accumulation typically increased in volume over time. There were no indications that bioaugmentation led to a deterioration of effluent quality or released additional amounts of FOG to the collection system.

Research paper thumbnail of Aerosolization of a Human Norovirus Surrogate, Bacteriophage MS2, during Simulated Vomiting

PLOS ONE, 2015

Human noroviruses (NoV) are the leading cause of acute gastroenteritis worldwide. Epidemiological... more Human noroviruses (NoV) are the leading cause of acute gastroenteritis worldwide. Epidemiological studies of outbreaks have suggested that vomiting facilitates transmission of human NoV, but there have been no laboratory-based studies characterizing the degree of NoV release during a vomiting event. The purpose of this work was to demonstrate that virus aerosolization occurs in a simulated vomiting event, and to estimate the amount of virus that is released in those aerosols. A simulated vomiting device was constructed at one-quarter scale of the human body following similitude principles. Simulated vomitus matrices at low (6.24 mPa*s) and high (177.5 mPa*s) viscosities were inoculated with low (10 8 PFU/mL) and high (10 10 PFU/mL) concentrations of bacteriophage MS2 and placed in the artificial "stomach" of the device, which was then subjected to scaled physiologically relevant pressures associated with vomiting. Bio aerosols were captured using an SKC Biosampler. In low viscosity artificial vomitus, there were notable differences between recovered aerosolized MS2 as a function of pressure (i.e., greater aerosolization with increased pressure), although this was not always statistically significant. This relationship disappeared when using high viscosity simulated vomitus. The amount of MS2 aerosolized as a percent of total virus "vomited" ranged from 7.2 x 10-5 to 2.67 x 10-2 (which corresponded to a range of 36 to 13,350 PFU total). To our knowledge, this is the first study to document and measure aerosolization of a NoV surrogate in a similitude-based physical model. This has implications for better understanding the transmission dynamics of human NoV and for risk modeling purposes, both of which can help in designing effective infection control measures.

Research paper thumbnail of Combining CFD, FLOC Dynamics, and Biological Reaction Kinetics to Model Carbon and Nitrogen Removal in an Activated Sludge System

Proceedings of the Water Environment Federation, 2011

ABSTRACT

Research paper thumbnail of Optimization of activated sludge designs using genetic algorithms

Water science and technology : a journal of the International Association on Water Pollution Research, 2002

We describe a framework in which a genetic algorithm (GA) and a static activated sludge (AS) trea... more We describe a framework in which a genetic algorithm (GA) and a static activated sludge (AS) treatment plant design model (WRC AS model) are used to identify low cost activated sludge designs that meet specified effluent limits (e.g. for BOD, N, and P). Once the user has chosen a particular process (Bardenpho, Biodenipho, UCT or SBR), this approach allows the parameterizations for each AS unit process to be optimized systematically and simultaneously. The approach is demonstrated for a wastewater treatment plant design problem and the GA-based performance is compared to that of a classical nonlinear optimization approach. The use of GAs for multiobjective problems such as AS design is demonstrated and their application for reliability-based design and alternative generation is discussed.

Research paper thumbnail of The Complicated Issue of Human Waste

After you've eaten your food, you generate waste. In modern wastewater treatment plants, waste is... more After you've eaten your food, you generate waste. In modern wastewater treatment plants, waste is converted to carbon dioxide and water is cleaned. Yet billions of people around the world, including 1.4 million in the U.S., don't have access to safe, sustainable sanitation and many (mostly children) die from related diseases and infections. UN Sustainable Development Goal 6 aims to achieve access to adequate sanitation for all. How must we think about this wicked problem? Francis L. de los Reyes III, Ph.D., discusses four key areas to target: government policies and regulations, technologies, business opportunities for sanitation companies, and social and behavioral change.

Research paper thumbnail of Factors Affecting the Formation of Fats, Oils, and Grease Deposits in Sewer Systems and Fate of FOG Deposit Forming Precursors in Sewer Systems

This Final Report combines the reports for the two WRRI projects, as they are related, and being ... more This Final Report combines the reports for the two WRRI projects, as they are related, and being conducted by the same research team (PIs, grad student and undergraduate assistants). The objective of the first project was to quantify the effects of kitchen wastewater characteristics on fat, oil, and grease (FOG) deposit formation mechanism and rate. The objective of the second project was to test the hypothesis that FOG formation in sewers is caused via a saponificationlike reaction involving major chemical precursors: free fatty acids, a metal cation, and surfactant. Thus, the overall goal of the combined projects was to determine the mechanism(s) of FOG deposit formation in sewer lines, and to elucidate the role of various factors in the deposit phenomenon, with the end-goal of understanding how to control sewer line blockages due to FOG formation. The projects used a variety of techniques and methods to achieve these goals. Initial experiments were aimed at exploring the interplay of various hypothesized factors, such as oil type, calcium, potassium, and attachment surface (e.g., concrete coupons), and were conducted in batch tests using a jar apparatus. In parallel, a pipe loop system simulating a sewer line was constructed. These experiments were designed to induce the formation of FOG deposits in lab-scale. After many attempts, FOG deposits were formed in a batch system using grease interceptor (GI) effluent from a restaurant. To our knowledge, this is the first time that FOG deposits have been formed under lab conditions. FTIR analysis showed that the FOG deposits were metallic salts of fatty acid as revealed by comparisons with FOG deposits collected from sewer lines and pure calcium soaps. Based on the data, we proposed that the formation of FOG deposits occurs from the aggregation of excess calcium compressing the double layer of free fatty acid micelles, and a saponification reaction between aggregated calcium and free fatty acids.

Research paper thumbnail of Using Detrending to Assess SARS-CoV-2 Wastewater Loads as a Leading Indicator of Fluctuations in COVID-19 Cases at Fine Temporal Scales: Correlations Across Twenty Sewersheds in North Carolina

Wastewater surveillance emerged during the COVID-19 pandemic as a novel strategy for tracking the... more Wastewater surveillance emerged during the COVID-19 pandemic as a novel strategy for tracking the burden of illness in communities. Previous work has shown that trends in wastewater SARS-CoV-2 viral loads correlate well with reported COVID-19 case trends over longer time periods (i.e., months). We used detrending time series to reveal shorter sub-trend patterns (i.e., weeks) to identify leads or lags in the temporal alignment of the wastewater/case relationship. Daily incident COVID-19 cases and twice-weekly wastewater SARS-CoV-2 viral loads measured at 20 North Carolina sewersheds in 2021 were detrended using smoothing ranges of ∞, 16, 8, 4 and 2 weeks, to produce detrended cases and wastewater viral loads at progressively finer time scales. For each sewershed and smoothing range, we calculated the Spearman correlation between the cases and the wastewater viral loads with offsets of -7 to +7 days. We identified a conclusive lead/lag relationship at 15 of 20 sewersheds, with detrend...

Research paper thumbnail of Fat, oil, and grease (FOG) deposits yield higher methane than FOG in anaerobic co-digestion with waste activated sludge

Journal of Environmental Management

Research paper thumbnail of Systems and Methods for Studying Microbial Processes and Communities in Landfills

Advances in Environmental Microbiology

Research paper thumbnail of The role of emptying services in provision of safely managed sanitation: A classification and quantification of the needs of LMICs

Journal of Environmental Management

Research paper thumbnail of Comparison of

FEMS Microbiology Ecology

Refuse decomposition in landfills is a microbially mediated process that occurs primarily under a... more Refuse decomposition in landfills is a microbially mediated process that occurs primarily under anaerobic conditions. Because of limited moisture conditions, hydraulic transport as a means of cellular translocation within the landfill appears limited, especially during the initial stages of decomposition. Thus, microbial communities within the incoming refuse serve as a primary source of facultative and obligate anaerobic microorganisms that initiate refuse decomposition. Fresh residential refuse was collected five times over 26 months, and microbial communities in these samples were compared with those in individual refuse components and decomposed refuse. Bacterial and archaeal community structures were determined using T‐RFLP. The Bacterial microbial community richness was correlated (r 2 = 0.91) with seasonal differences in ambient air temperature. Analysis of the results shows that fresh refuse is most likely not the source of methanogens in landfills. Microbial communities in ...

Research paper thumbnail of Development of trash exclusion for mechanized pit latrine emptying

Environmental Science: Water Research & Technology

The trash-excluding attachment (Excluder) can be connected to a custom vacuum (such as the Flexcr... more The trash-excluding attachment (Excluder) can be connected to a custom vacuum (such as the Flexcrevator), a vacuum truck, or a sludge pump. The system allows the mechanized emptying of pit latrines with high levels of trash without manual “fishing”.

Research paper thumbnail of Kenaf addition has mixed effects on process performance of sequencing batch reactors treating municipal wastewater

Environmental Science: Water Research & Technology

The effects on wastewater treatment due to addition to the mixed liquor of a fine lignocellulosic... more The effects on wastewater treatment due to addition to the mixed liquor of a fine lignocellulosic powder made of dried kenaf were assessed using lab-scale sequencing batch reactors (SBRs) operated for over 200 days.

Research paper thumbnail of Dynamic Modeling of Microalgae Growth and Lipid Production under Transient Light and Nitrogen Conditions

Environmental Science & Technology

Research paper thumbnail of Microbial ecological succession during municipal solid waste decomposition

Applied microbiology and biotechnology, 2018

The decomposition of landfilled refuse proceeds through distinct phases, each defined by varying ... more The decomposition of landfilled refuse proceeds through distinct phases, each defined by varying environmental factors such as volatile fatty acid concentration, pH, and substrate quality. The succession of microbial communities in response to these changing conditions was monitored in a laboratory-scale simulated landfill to minimize measurement difficulties experienced at field scale. 16S rRNA gene sequences retrieved at separate stages of decomposition showed significant succession in both Bacteria and methanogenic Archaea. A majority of Bacteria sequences in landfilled refuse belong to members of the phylum Firmicutes, while Proteobacteria levels fluctuated and Bacteroidetes levels increased as decomposition proceeded. Roughly 44% of archaeal sequences retrieved under conditions of low pH and high acetate were strictly hydrogenotrophic (Methanomicrobiales, Methanobacteriales). Methanosarcina was present at all stages of decomposition. Correspondence analysis showed bacterial pop...

Research paper thumbnail of Fluid Shear Variation Potentially Plays a Role in Aerobic Granular Sludge Formation

Proceedings of the Water Environment Federation

Research paper thumbnail of Quantification of the Denitrification Gene nosZ in a Full Scale Wastewater Treatment Plant Using qPCR

Proceedings of the Water Environment Federation

FOGLE, KARA NICOLE KOPF. Quantification of the Denitrification Gene nosZ in a Full-Scale Wastewat... more FOGLE, KARA NICOLE KOPF. Quantification of the Denitrification Gene nosZ in a Full-Scale Wastewater Treatment Plant Using qPCR. (Under the direction of Dr. Francis L. de los Reyes III.) Excessive levels of nitrogen in wastewater effluent can result in DO depletion, toxicity, eutrophication, global warming, acid rain, and other undesired effects. Understanding the denitrification process that occurs in wastewater treatment plants is important to allow engineers and plant operators to achieve more efficient nitrogen removal from wastewater. Due to the wide variety of physiological and phylogenetic groups to which denitrifiers belong, quantifying them using ribosomal RNA is not feasible. However, specific denitrification genes can be targeted instead. nosZ is the gene that encodes for the enzyme nitrous oxide reductase, the enzyme that catalyzes the Quantification of the Denitrification Gene nosZ in a Full-Scale Wastewater Treatment Plant Using qPCR

Research paper thumbnail of Steam Application to Destroy Foam-Forming Bacteria in Activated Sludge Systems

Journal of Environmental Engineering

Research paper thumbnail of Physico-chemical Characterization of Grease Interceptors with and without Biological Product Addition

Water Environment Research, Mar 1, 2012

Hardened and insoluble fat, oil, and grease (FOG) deposits are the primary cause of sewer line bl... more Hardened and insoluble fat, oil, and grease (FOG) deposits are the primary cause of sewer line blockages leading to sanitary sewer overflows (SSOs). However, there have been very few long-term assessments of the physico-chemical characteristics of full-scale grease interceptors (GIs), the first "line of defense" against FOG buildup in sewer lines. In this study, we assessed the physico-chemical characteristics of two full-scale GIs (at a restaurant and a retirement community kitchen) over a one-year period. Statistically significant differences between bioaugmented and untreated cycles were detected for several chemical and physical properties. The treated cycles had lower BOD and COD at the grease interceptor outlet. While the combined data for all treated cycles did not show lower FOG concentrations in the GI outlet compared to the combined data for all untreated cycles, comparison of specific individual treated and untreated cycles show a positive effect due to the addition of product.

Research paper thumbnail of Microbial community structures in foaming and nonfoaming full-scale wastewater treatment plants

Water Environment Research, Sep 1, 2002

A survey of full-scale activated-sludge plants in Illinois revealed that filamentous foaming is a... more A survey of full-scale activated-sludge plants in Illinois revealed that filamentous foaming is a widespread problem in the state, and that the causes and consequences of foaming control strategies are not fully understood. To link microbial community structure to foam occurrence, microbial populations in eight foaming and nine nonfoaming full-scale activated-sludge systems were quantified using oligonucleotide hybridization probes targeting the ribosomal RNA (rRNA) of the mycolata; Gordonia spp.; Gordonia amarae; "Candidatus Microthrix parvicella"; the alpha-, beta-, and gamma-subclasses of the Proteobacteria, and members of the Cytophaga-Flavobacteria. Parallel measurements of microbial population abundance using hybridization of extracted RNA and fluorescence in situ hybridization (FISH) showed that the levels of mycolata, particularly Gordonia spp., were higher in most foaming systems compared with nonfoaming systems. Fluorescence in situ hybridization and microscopy suggested the involvement of "Candidatus Microthrix parvicella" and Skermania piniformis in foam formation in other plants. Finally, high numbers of "Candidatus Microthrix parvicella" were detected by FISH in foam and mixed liquor samples of one plant, whereas the corresponding levels of rRNA were low. This finding implies that inactive "Candidatus Microthrix parvicella" cells (i.e., cells with low rRNA levels) can cause foaming.

Research paper thumbnail of Characterization of Restaurant Gravity Grease Interceptors and the Impact of Bioaugmentation on Performance

Gravity grease interceptors (GGIs) from four restaurants surrounding a shopping mall were treated... more Gravity grease interceptors (GGIs) from four restaurants surrounding a shopping mall were treated with a bioaugmentation product containing bacterial spores and surfactants and monitored for changes in effluent quality compared to untreated control periods. The study consisted of four cycles lasting between 62 and 82 days each, depending on the normal pumping frequency. In each cycle, two GGIs were treated and two were untreated. Regular analyses included oil and grease, total chemical oxygen demand, soluble chemical oxygen demand, total suspended solids, pH, temperature, biochemical oxygen demand, grease cap thickness, and bottom solids accumulation. A commercial jar sampler modified with an air vent was effectively used to sample from the effluent tee within the interceptor. In most cases there was a positive correlation between oil and grease in the effluent and time after pumping. Bioaugmentation in three of four restaurants resulted in lower oil and grease concentrations compared to untreated cycles by 20%, 35% and 41%. Oil and grease in the remaining restaurant was similar in the treated and untreated cycles. This restaurant, however, had the lowest effluent concentrations of oil and grease and suggests that bioaugmentation may be more effective in GGIs where higher amounts of oil and grease are present. Grease caps and bottom solids accumulation typically increased in volume over time. There were no indications that bioaugmentation led to a deterioration of effluent quality or released additional amounts of FOG to the collection system.

Research paper thumbnail of Aerosolization of a Human Norovirus Surrogate, Bacteriophage MS2, during Simulated Vomiting

PLOS ONE, 2015

Human noroviruses (NoV) are the leading cause of acute gastroenteritis worldwide. Epidemiological... more Human noroviruses (NoV) are the leading cause of acute gastroenteritis worldwide. Epidemiological studies of outbreaks have suggested that vomiting facilitates transmission of human NoV, but there have been no laboratory-based studies characterizing the degree of NoV release during a vomiting event. The purpose of this work was to demonstrate that virus aerosolization occurs in a simulated vomiting event, and to estimate the amount of virus that is released in those aerosols. A simulated vomiting device was constructed at one-quarter scale of the human body following similitude principles. Simulated vomitus matrices at low (6.24 mPa*s) and high (177.5 mPa*s) viscosities were inoculated with low (10 8 PFU/mL) and high (10 10 PFU/mL) concentrations of bacteriophage MS2 and placed in the artificial "stomach" of the device, which was then subjected to scaled physiologically relevant pressures associated with vomiting. Bio aerosols were captured using an SKC Biosampler. In low viscosity artificial vomitus, there were notable differences between recovered aerosolized MS2 as a function of pressure (i.e., greater aerosolization with increased pressure), although this was not always statistically significant. This relationship disappeared when using high viscosity simulated vomitus. The amount of MS2 aerosolized as a percent of total virus "vomited" ranged from 7.2 x 10-5 to 2.67 x 10-2 (which corresponded to a range of 36 to 13,350 PFU total). To our knowledge, this is the first study to document and measure aerosolization of a NoV surrogate in a similitude-based physical model. This has implications for better understanding the transmission dynamics of human NoV and for risk modeling purposes, both of which can help in designing effective infection control measures.

Research paper thumbnail of Combining CFD, FLOC Dynamics, and Biological Reaction Kinetics to Model Carbon and Nitrogen Removal in an Activated Sludge System

Proceedings of the Water Environment Federation, 2011

ABSTRACT

Research paper thumbnail of Optimization of activated sludge designs using genetic algorithms

Water science and technology : a journal of the International Association on Water Pollution Research, 2002

We describe a framework in which a genetic algorithm (GA) and a static activated sludge (AS) trea... more We describe a framework in which a genetic algorithm (GA) and a static activated sludge (AS) treatment plant design model (WRC AS model) are used to identify low cost activated sludge designs that meet specified effluent limits (e.g. for BOD, N, and P). Once the user has chosen a particular process (Bardenpho, Biodenipho, UCT or SBR), this approach allows the parameterizations for each AS unit process to be optimized systematically and simultaneously. The approach is demonstrated for a wastewater treatment plant design problem and the GA-based performance is compared to that of a classical nonlinear optimization approach. The use of GAs for multiobjective problems such as AS design is demonstrated and their application for reliability-based design and alternative generation is discussed.