Theses and Dissertations from UMD

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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

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2011 - 20162

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Author: search.filters.author.Khorsha, GolnazSubject: search.filters.subject.Environmental engineering

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    Management of Ammoniacal Nitrogen in Stormwater Runoff
    (2016) Khorsha, Golnaz; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Nitrogen in stormwater runoff plays a dominant role in the eutrophication of receiving waters. The challenge in treating nitrogen lies in its diverse speciation and biological cycling. This work aimed to improve removal of influent and mineralized ammonium through the use of sorption media and nitrification in preparation for subsequent denitrification. Two media, clinoptilolite (ZT) and hydrous-aluminosilicate (CA), were characterized in a series of batch and sorption column experiments, which indicated superior performance of ZT because of its higher capacity (206 months life-expectancy) and faster kinetics (60 min). Competition with Ca2+ and K+ resulted in smaller and slower sorption for both media. Removed ammonium in ZT was highly extractable, signifying its potential bioavailability. Sorption columns exhibited high removal during influent NH4+ increases, desorption with influent concentration drops, and lower ammonium removal upon rewetting/saturateting. Nitrification in bio-active sorptive media enhanced removal efficiency, particularly for alternating wet/saturated-dry/unsaturated conditions, with smaller desorption occurring. ZT application in filtration-based stormwater control measures is recommended.
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    The Production and Fate of Fats, Oils, and Grease (FOG) from Small Dairy-Based Food Service Establishments
    (2011) Khorsha, Golnaz; Davis, Allen; Torrents, Alba; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Grease accumulation in sewers is the leading cause of sewer blockages resulting in Sanitary Sewer Overflows. Nationwide Fats, Oils, and Grease (FOG) control programs exist to address this problem, but the guidelines with respect to wastewater from dairy-based food service establishments (FSEs) are unclear, with no existing scientific investigation on potential separation of dairy products. The separation tendencies of wastewater originating from dairy-based FSEs were investigated, and significant separation of dairy constituents (Kjeldahl Nitrogen and fats) was observed under acidic conditions (pH 4-5.4), with maximum separation at the isoelectric point of casein proteins (pH = 4.6). Physical treatment at field-scale grease interceptors for dairy-based FSEs showed accumulation of dairy constituents, particularly fats, at pH 4.4-5 caused by dairy products souring. Separation induced by souring in neutralized pH persisted but to a lesser extent (10% vs. 2%). Based on research conducted, physical treatment of wastewaters originating from dairy-based FSEs is recommended.