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...
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 ...
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”.
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.
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...
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.
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.
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.
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...
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 ...
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”.
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.
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...
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.
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.
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.
Uploads