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Civil, Geological and Environmental

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https://hdl.handle.net/10388/12463

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Now showing 1 - 5 of 5
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    A universal empirical equation to estimate the abundance of carbapenem-resistant genes during aerobic digestion of wastewater sludge
    (Water Practice & Technology, 2024-11) Poorasgari, Eskandar; Örmeci, Banu
    Carbapenem-resistant genes (CRGs) exist in wastewater and accumulate in wastewater sludge. Due to the potential threat posed by the CRGs, it is important to quantify CRGs and predict their removal and discharge concentrations during aerobic sludge digestion. Nonetheless, gene quantification is tedious, error-prone and expensive. This study aims to develop multiple regression models to estimate CRGs from sludge parameters that are routinely measured for the monitoring and design of aerobic sludge digesters. Batch reactors were operated at mesophilic and thermophilic temperatures for 20-35 days. Sludge samples were periodically taken during aerobic digestion. Three CRGs (blaGES, blaOXA-48 and blaIMP-27) together with 16S rRNA and integron class 1 genes were quantified. Aerobic digestion reduced the abundance of all target genes. Multiple regression modelling was conducted in linear (LM) and non-linear (NLM) modes. Sums of squared errors of the LM models were 0-0.048, whereas those of the NLM models were 0–0.003. Adjusted R2 ranges of the LM and NLM models were 0.774–0.931 and 0.986–1, respectively. Overall, the NLM models predicted the abundance of target genes more accurately than the LM models. NLM models may be used to modify the design and operational parameters of aerobic sludge digesters.
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    Assessment of Rapid and Conventional RT-qPCR-Based Systems for Wastewater Surveillance
    (ACS Publications, 2024-09-05) Asadi, Mohsen; Hamilton, Daniel; Shomachuk, Corwyn; Oloye, Femi F.; De Lange, Chantel; Liang, Jiaqi; Xia, Pu; Osunla, Charles A.; Cantin, Jenna; Mejia, Edgard M.; Gregorchuk, Branden S. J.; Becker, Michael G.; Mangat, Chand; Brinkmann, Markus; Jones, Paul D.; Giesy, John P.; McPhedran, Kerry M.
    Conventional wastewater surveillance (WS) relies on highly trained personnel, advanced instrumentation, and significant resources, making the development and use of simple, rapid, and sensitive alternative technologies valuable for reducing costs, time, and labor intensity. For the first time, this study investigated the use of two well-developed rapid systems, including the GeneXpert and LuminUltra, in parallel with a conventional WS reference methodology for the assessment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in three cities: Saskatoon, Prince Albert, and North Battleford, Saskatchewan, Canada. RNA extractions from wastewater samples were carried out for the conventional reference and LuminUltra methods, while GeneXpert was used for both raw and concentrated wastewater samples. Bland–Altman plots showed a combination of systematic bias and random error between these real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR)-based systems. Additionally, results indicated the reasonable performance of GeneXpert in viral detection with a sensitivity rate of >98%, as compared to the conventional reference methodology of 100% and LuminUltra with >65%. A Spearman correlation test showed meaningful relationships between the GeneXpert and conventional reference methodology viral level results across all cities, indicating GeneXpert’s reliability for accurate viral detection and disease prevalence determination, specifically in limited-resource communities, with a shorter processing time and cost-effectiveness in analysis.
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    Developing a universal equation to estimate the mass of dewatered wastewater sludge during biological digestion at mesophilic and thermophilic temperatures
    (Water Science & Technology, 2024-11) Poorasgari, Eskandar; Örmeci, Banu
    A series of dewaterability tests were conducted on various types of sludges to establish a wholistic relationship between sludge water fractions. Sludge samples were obtained from batch and continuous sludge digesters, which were operated anaerobically and aerobically under mesophilic and thermophilic conditions. Dewaterability of the sludge samples and the distribution of water fractions were studied using centrifugation and thermal drying. Thickened waste activated sludge (T-WAS) contained 10-11 g bound water (BW)/g of total solids (TS), and it was more hydrophilic than primary and digested sludges. During anaerobic digestion, BW content fluctuated between 3.2 and 4.2 g BW/g TS. However, aerobic digestion at 55°C reduced the BW content of the mixed T-WAS + primary sludges from 3.7 to 2.1 g BW/g TS. A linear function was developed to correlate supernatant and BW mass fractions (R2 = 0.995). An equation was derived from the linear function to estimate the mass of dewatered sludge based on the TS concentration of the initial wet sludge. The developed expression is applicable to different kinds of wastewater sludges. Such an expression would be helpful for the designers and operators of sludge thickening and dewatering systems that use centrifugal separation.
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    Hydraulic Structures
    (Saskatoon: Smith, 1995) Smith, C.D.
    This book presents general information on the form and function of many types of hydraulic structures and to give detailed theory and design procedures on some of the more common ones. The application of principles is intended to be sufficiently rigorous that a student of the subject will gain a working knowledge of the basic procedures used in hydraulic design. While, of necessity, certain design procedures are empirical, this book is not concerned with the "how" aspect of hydraulic design alone. Equal emphasis is placed on the "why" aspect, since it is only through this approach that the engineer can properly assess the merits of a proposed design for a specific application.
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    Sustainable enhancement of biogas production from a cold-region municipal wastewater anaerobic digestion process using optimized sludge-derived and commercial biochar additives
    (Elsevier, 2024-10-11) Zeynali, Rahman; Asadi, Mohsen; Ankley, Phillip; Esser, Milena; Brinkmann, Markus; Soltan, Jafar; McPhedran, Kerry M.
    Anaerobic digestion (AD) of municipal wastewater sludges produces valuable solid digestate and biogas. Biogas is a source of clean energy and enhancement of its production has been of recent interest for increased electricity generation, among other products. The objective of this study was the development of a novel municipal sludge-derived biochar and its application in a municipal wastewater AD system to increase the biogas production rate. Thickened waste-activated sludge (TWAS) samples were collected from the cold-region municipal wastewater treatment plant and used to synthesize biochar applied in the simulation of AD processes using laboratory-scale reactors. The TWAS-derived biochar was synthesized using the commonly used furnace pyrolysis (sludge-based biochar, SBC), and more novel microwave pyrolysis including phosphoric acid as a microwave activator (activated sludge-based biochar, ASBC). The microwave pyrolysis conditions were optimized using a computational fluid dynamics (CFD) technique. In addition, various commercially available carbon-based additives were assessed for their impacts on the AD process including activated carbon, wood-derived biochar, and forest residue-derived biochar. Results showed that the ASBC increased the cumulative methane production by 50% (333 mL/g VS) versus the control sample (221 mL/g VS) after 30 d. The ASBC showed higher surface area, electrical conductivity, and metal contents versus the other biochars which boosted the AD microbial community growth leading to higher organic matter conversion into biogas. In the ASBC-amended digesters, the bacterial phylum Bacteroidota, which contains a major genus of the dgA-11-gut-group, exhibited a synergy between organic substrate fermentation and volatile fatty acid production, resulting in enhanced biogas production. The TWAS biochar demonstrated promising performance in enhancing the AD process fostering energy and resource self-sufficiency at municipal wastewater treatment plants. This smart sludge management aligns well with sustainable waste management practices and clean energy production strategies, especially considering that the biochar was sourced from a readily available continuous waste-product stream.