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Authors: Klotzsche, A.; Advisor: -; Participants: Lärm, L.; Vanderborght, J.; Cai, G.; Morandage, S.; Zörner, M.; Vereecken, H.; van der Kruk, J. (2019) - The SWC data were analyzed for four growing seasons between 2014 and 2017, two soil types (gravelly and clayey–silty), two crops (wheat [Triticum aestivum L.] and maize [Zea mays L.]), and three different water treatments. We acquired more than 150 time‐lapse GPR datasets along 6‐m‐long horizontal crossholes at six depths. The GPR SWC distributions are distinct both horizontally and vertically for both soil types. A clear change in SWC can be observed at both sites between the surface layer (>0.3 m) and subsoil. Alternating patches of higher and lower SWC, probably caused by the soil heterogeneity, were observed along the horizontal SWC profiles. To investigate the changes in SWC with time, GPR and time‐domain reflectometry (TDR) data were averaged for each depth and compared with c...
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Authors: Rehman, H.U.; Advisor: -; Participants: Knadel, M.; Kayabali, K.; Arthur, E. (2019) - Our objective was to develop visible–near‐infrared spectroscopy (Vis‐NIRS, from 400–2500 nm) based reliable models to estimate the Atterberg limits. Two conventional methods for each Atterberg limit were used to generate the reference data: paraffin wax and Hg methods for SL; rolling and motorized devices for PL; and Casagrande cup and drop‐cone penetrometer methods for LL. Calibration models were built on 80% of the data using partial least squares regression and validated with the remaining 20% of the dataset. The Vis‐NIRS independent validation of LL showed very good estimation with standardized RMSE (SRMSE = RMSE/Range) of 0.16 and 0.15, respectively, for LLdrop‐cone and LLCasagrande methods. Similarly for PL, the Vis‐NIRS estimation accuracy was quite good with SRMSE values of ...
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Authors: Mohammed, O.; Advisor: -; Participants: Mumford, K.G.; Sleep, B.E. (2019) - The presence of trapped gas in otherwise water‐saturated porous media has a substantial effect on water flow, which is important to a wide variety of subsurface applications including groundwater remediation, CO2 sequestration, and the release of greenhouse gases associated with oil and gas development. Trapped gases can be created by external drainage and imbibition, where fluids invade from system boundaries, or by internal drainage (exsolution), where gas is produced at nucleation sites within a porous medium. A series of laboratory experiments were conducted in thin flow cells, in which H2 gas was produced by the reaction of sodium borohydride and water to produce a range of trapped gas saturations. Aqueous relative permeability was measured following H2 exsolution and during di...
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Authors: Williams, M.R.; Advisor: -; Participants: McAfee, S,J.; Kent, B,E. (2019) - The lysimeters were air dried for 150 d, after which two sealed and two unsealed lysimeters were resaturated. All lysimeters were then subjected to a 1‐h rainfall simulation (3.3 cm h−1), with dye added to the rainfall. Rewetting both sealed and unsealed lysimeters resulted in less horizontal dye coverage compared with the dry treatments due to reduced matrix–macropore interaction. Dye staining patterns for unsealed lysimeters showed that edge flow was the predominant flow pathway through the soil regardless of soil moisture status. While sealing lysimeters with petroleum jelly largely limited flow between the soil and the casing, shrinkage cracks formed during drying that coincided with the extent of petroleum jelly infiltration into the soil. This new hydrophobic edge served as a ...
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Authors: Wyer, M.D.; Advisor: -; Participants: Kay, D.; Morgan, H.; Naylor, S.; Clark, S.; Watkins, J.; Davies, C.M.; Francis, C.; Osborn, H.; Bennett, S. (2018) - This study built a detailed record of water quality change through 60 days at a UK coastal bathing water in 2011 using half-hourly samples each subjected to triplicate filtration designed to enhance enumeration precision. On average, the mean daily variation in FIO concentrations exceeded 1 log10 order, with the largest daily variations exceeding 2 log10 orders. Significant diurnality was observed at this bathing water, which would determine its EU Directive compliance category if the regulatory samples were collected at the same time each day. A sampling programme of this intensity has not been reported elsewhere to date and, if this pattern is proven to be characteristic of other bathing waters world-wide, it has significance for: (a) the design of regulatory sampling programmes; ...
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Authors: Rocard, J.M.; Advisor: -; Participants: Asadishad, B.; Samonte, P.R.V.; Ghoshal, S.; Tufenkji, N. (2018) - We investigated the influence of temperature fluctuations around the freezing point, known as freeze-thaw (FT), on the inactivation rates, growth, and biofilm formation of a manure-isolated strain of Salmonella typhimurium. Moreover, the effects of FT on the transport characteristics of S. typhimurium in quartz sand were monitored in model porewater solutions of two different ionic strengths (IS: 10 and 100 mM KCl) and two different humic acid (HA) concentrations (1 and 5 mg/L). Increasing numbers of FT cycles were found to decrease the deposition of S. typhimurium onto quartz sand and increase the percentage of detached cells in sand-packed column experiments. Based on the calculated bacterial attachment efficiencies, the predicted minimum setback distances between the location of ...
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Authors: Swain, L.E.; Advisor: -; Participants: Knocke, W.R.; FalkinhamIII, J.O.; Pruden, A. (2018) - The primary objective of this research was to assess the role of Mn-reducing microorganisms in the release of soluble Mn from MnOx(s)-coated filter media following interruption of pre-filtration chlorination. Bench-scale filter column studies were inoculated with Shewanella oneidensis MR-1 to investigate the impacts of a known Mn-reducing bacterium on release of soluble Mn from MnOx(s) coatings. In situ vial assays were developed to gain insight into the impacts of MnOx(s) age on bioavailability to Mn-reducing microorganisms and a quantitative polymerase chain reaction (qPCR) method was developed to quantify gene copies of the mtrB gene, which is involved in Mn-reduction. Results demonstrated that microbially-mediated Mn release was possible above a threshold equivalent of 2 × 102 S...
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Authors: Hollender, J.; Advisor: -; Participants: Rothardt, J.; Radny, D.; Loos, M.; Epting, J.; Huggenberger, P.; Borer, P.; Singer, H. (2018) - The remaining total concentrations of the MPs in the raw drinking water accounted to 0.6–1.6 μgL−1 with only a few compounds exceeding 0.1 μgL−1, an often used threshold value. The attenuation was most pronounced in the first meters of infiltration with a full elimination of 17 compounds at all three sites. However, a mixing with groundwater related to regional groundwater flow complicated the characterisation of natural attenuation potentials along the transects. Additional non-target screening at one site revealed similar trends for further non-target components. Overall, a risk assessment of the target and estimated non-target compound concentrations finally indicated during the sampling period no health risk of the drinking water according to current guidelines. Our results demo...
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Authors: Sanawar, H.; Advisor: -; Participants: Pinel, I.; Farhat, N.M.; Bucs, Sz.S.; Zlopasa, J.; Kruithof, J.C.; Witkamp, G.J.; van Loosdrecht M.C.M.; Vrouwenvelder, J.S. (2018) - Results indicated that two-stage CO(NH2)2/HCl cleaning was as effective as cleaning with NaOH/HCl in terms of restoring the feed channel pressure drop (>70% pressure drop decrease). One-stage cleaning with urea only was not as effective indicating the importance of the second-stage low pH acid cleaning in weakening the biofilm matrix. All three chemical cleaning protocols were equally effective in reducing the concentration of predominant EPS components protein and carbohydrate (>50% reduction in concentrations). However, urea-based cleaning strategies were more effective in solubilizing protein-like matter and tyrosine-containing proteins. Furthermore, ATP measurements showed that biomass inactivation was up to two-fold greater after treatment with urea-based chemical cleanings com...
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Authors: Venkiteshwaran, K.; Advisor: -; Participants: Pokhrel, N.; Hussein, F.; Antony, E.; Mayer, B.K. (2018) - The resultant PBP beads were saturated with Pi and exposed to varying pH (pH 4.7 to 12.5) and temperatures (25–45 °C) to induce Pi release. Increase in temperature from 25 to 45 °C and pH conditions between 4.7 and 8.5 released less than 20% of adsorbed Pi. However, 62% and 86% of the adsorbed Pi was released at pH 11.4 and 12.5, respectively. Kinetic experiments showed that Pi desorption occurred nearly instantaneously (<5 min), regardless of pH conditions, which is advantageous for Pi recovery. Additionally, no loss in Pi adsorption or desorption capacity was observed when the PBP beads were exposed to 10 repeated cycles of adsorption/desorption using neutral and high pH (≥12.5) washes, respectively. The highest average Pi adsorption using the PBP beads was 83 ± 5%, with 89 ± 4.1%...
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