Engineering Commons^™

A Method For Computing Infiltration And Redistribution In A Discretized Moisture Content Domain, Fred L. Ogden

Fred L. Ogden

A new one-dimensional infiltration and redistribution method is proposed as an alternative to the Richards equation (RE) for coupled surface and subsurface models. The proposed method discretizes soil water content into hypothetical hydraulically interacting bins. The entry and propagation of displacement fronts in each bin are simulated by means of explicit infiltration and drainage approximations based on capillary and gravitational driving forces. Wetting front advances within bins create water deficits that are satisfied by capillary-driven interbin flow. The method inherently provides numerical stability by precluding the need to directly estimate nonlinear gradients through numerical schemes. Comparisons of the performance of …

Nebraska Water Map

Literature from The Nebraska Water Center

Nebraska Water is a full-color, 24"x36" poster, that is appropriate for educational use. The information presented on the maps is the best available as of July 2008. The content and level of detail of each map is based on available space and map scale.

Aquatic Bacteria Removal Using Carbon Nanotubes, Suvish Melanta

Biological and Agricultural Engineering Undergraduate Honors Theses

The purpose of this project is to explore the functionality of carbon nanotubes as a bacterial removal method, specifically towards water-borne bacterial pathogens in wastewater by utilizing its unique magnetic and bacteria-binding properties. The general protocol set for this research follows five steps: 1) Preparation of wastewater media, 2) preparation of CNT culture, 3) preparation of reaction mixture with CNTs for bacterial binding, 4) magnetic separation of bacteria-bound-CNT clusters and, 5) assessment of supernatant. The CNTs effectively removed bacterial contaminants in the wastewater (10%, v/v) after the sand filtration process from the Paul R. Noland Wastewater Facility at Fayetteville, Arkansas. …

Sustainable Portland: Implementation Series 1, New England Environmental Finance Center

Climate Change

When the Sustainable Portland Task Force Report was released in November 2007, under the leadership of Mayor Jim Cohen, Portland Councilor Kevin Donoghue had the idea that students at the Muskie School of Public Service might be able to help implement recommendations from the report. It may have helped that Kevin was himself a graduate of the Community Planning and Development Master’s program at the Muskie School, but it was a good idea nevertheless. He approached Professor Sam Merrill in the CPD program, who spoke with the new Mayor Ed Suslovic about a possible partnership between the City and the …

Bench-Scale Disinfection Of Bacteria And Viruses With Pulsed Arc Electrohydraulic Discharge, L H. Lee, A J. Arnold, C A. Santillan, M B. Emelko, Sarah E. Dickson, J. -S Chang

Sarah E Dickson

Pulsed arc electrohydraulic discharge (PAED) offers concurrent treatment of chemical and microbial target compounds in water by several mechanisms. Here, Escherichia coli, Bacillus subtilis spore, and MS2 bacteriophage inactivation by PAED were investigated using two bench-scale reactors (0.7 and 3 L). A plasma channel was created between a pair of iron electrodes set 0.5 mm apart in these reactors. Pulsed applied voltage was supplied at approximately 0.3 kJ/pulse (~100 ìsec). In the 0.7-L reactor, median E. coli, B. subtilis, and MS2 reductions of 2.4-, 4.6-, and 3.7-log, respectively, were observed after approximately 80 seconds of treatment in water with a …

Expansion Of The Discontinuous Gas Phase And Its Effect On Mass Flux From A Non-Aqueous Phase Liquid (Napl) Pool, Kevin G. Mumford, James E. Smith, Sarah E. Dickson

Sarah E Dickson

The partitioning of non-aqueous phase liquid (NAPL) compounds to a discontinuous gas phase results in the repeated spontaneous expansion, snap-off, and vertical mobilization of the gas phase. This mechanism has the potential to significantly affect the mass transfer processes that control the dissolution of NAPL pools by increasing the vertical transport of NAPL mass and increasing the total mass transfer rate from the surface of the pool. The extent to which this mechanism affects mass transfer from a NAPL pool depends on the rate of expansion and the mass of NAPL compound in the gas phase. This study used well-controlled …

On The Appropriate “Equivalent Aperture” For The Description Of Solute Transport In Single Fractures: Laboratory-Scale Experiments, Qinghuai Zheng, Sarah E. Dickson, Yiping Guo

Sarah E Dickson

Three distinct definitions of ‘‘equivalent aperture’’ have been used in the literature to describe variable-aperture fractures; however, significant inconsistencies exist in the literature as to which ‘‘equivalent aperture’’ is appropriate for simulating solute transport. In this work, a systematic series of hydraulic and tracer tests was conducted on three laboratory-scale fracture replicas, and the cubic law, mass balance, and frictional loss apertures were calculated. The analytical solution of the one-dimensional advectiondispersion equation was fit to the experimental breakthrough curves. Additionally, one of the experimental aperture fields was measured directly using a light transmission technique. The results clearly demonstrate that the …

Slow Gas Expansion In Saturated Natural Porous Media By Gas Injection And Partitioning With Non-Aqueous Phase Liquids, Kevin G. Mumford, Sarah E. Dickson, James E. Smith

Sarah E Dickson

The partitioning of volatile non-aqueous phase liquid (NAPL) compounds to a discontinuous gas phase can result in the expansion of that gas phase, and the resulting gas flow can significantly affect the mass transfer from NAPL source zones. This recently reported gas flow generated by the spontaneous expansion of a discontinuous gas phase has not been extensively characterized in the literature. This study measured the expansion rate of a single gas cluster in a 1.1 mm sand above a pool of trans-1,2-dichloroethene (tDCE) in small-scale flow cell experiments. To characterize the gas flow, gas injection experiments in three sizes of …

Spontaneous Expansion And Mobilization Of Gas Above Dnapl, Kevin G. Mumford

Sarah E Dickson

No abstract provided.

Attachment Of Bacterial Indicators To Particulates In Runoff From Various Soils, Michelle L. Soupir, Saied Mostaghimi

Michelle L. Soupir

A field study was conducted to examine the fate of E. coli and enterococci transport from three bare soil types receiving cowpat treatments and develop relationships between bacterial partitioning and phosphorous and carbon transport. Particles sizes to which cells preferentially associated were also identified.

The History Of The Unl Water Center From 1964, Water Center, School Of Natural Resources

Literature from The Nebraska Water Center

Water is an integral part of Nebraska’s economy and well being in a state that depends on an adequate supply for all uses, including agricultural, municipal, industrial, recreational and wildlife habitat.

Nebraska is fortunate with regard to its water supply, having tremendous groundwater reserves which are estimated to be in excess of two billion acrefeet (an acre-foot being enough water to cover one acre of land with a foot of water, or approximately 325,000 gallons), combined with an estimated annual precipitation of 86 million acre-feet and annual average surface water inflows of 1.7 million acre-feet, give the state adequate supplies …