The environment has been exposed to a number of hazardous chlorinated
organic compounds. These compounds may be anaerobically biotransformed by
sequential reductive dechlorination reactions in which the chlorine atoms are
replaced with hydrogen atoms. Because reductive dechlorination processes may
occur very slowly in the environment and chlorine position affects the...
This investigation deals with the chaotic rocking response and overturning
stability of offshore equipment subjected to base excitations due to wave-induced
motions of the supporting compliant offshore structural system. The equipment
compliant structural system is modelled as a free-standing rigid object subjected
to horizontal and vertical base accelerations. Three of...
The objective of this study was to develop a numerical model for the movement
and fate of chlorinated phenols in groundwater. In the first part, a numerical model for
several different equilibrium and nonequilibrium sorption processes under isothermal
conditions is developed for one-dimensional, steady-state water flow in soil columns.
The...
Daily evaporative flux and meteorological data from three sites were
collected and analyzed. Analysis included evaluation of several
reference evapotranspiration estimating methods which were theoretically
based on distinct physical laws. The estimating methods included pan
evaporation, energy-based Priestly-Taylor, and combination methods with
and without biological adjustments. The data set represented...
Chlorinated low molecular weight solvents have been discovered in a number of the nation's groundwater supplies. Remediation of these aquifers will require some form of treatment. Presently, the dominant treatment method is air stripping which results in transfer of the solvent from the aqueous phase into the atmosphere. Biodegradation is...
Knowledge of a compound's degradation pathway is crucial to the assessment of risk at contaminated sites. Pentachlorophenol and its metabolic products can serve as model compounds to study the fate and transport of halogenated aromatic compounds in the environment. Acclimation of anaerobic sewage sludge to pentachlorophenol produced a microbial consortium...
This dissertation describes the development of a mechanistic
overlay design procedure. The mechanistic analysis represents a new
trend in both new pavement and overlay design. The greatest advantage
of the mechanistic pavement analysis is that it considers the
fundamental characteristics of materials to be used, is capable of
considering changes...
Adsorptive bubble-separation processes are used to
remove adsorptive contaminants from wastewater. A
mathematical model was developed for the adsorptive bubble
separation processes in a countercurrent column. The model
included an assumption that linear adsorption of the solute
occurred on the gas bubbles. Predictions indicated that
aqueous column height has less...
This study involves the development of a biofilm
reactor that supports growth of a deep biofilm on a gas
permeable membrane. The reactor solution is not aerated,
and oxygen is supplied through the membrane. The reactor
is termed a substratum-aerated-biofilm reactor or SAB.
With adequate concentrations of electron-donors and
electron-acceptors,...
Studies are currently underway to determine the suitability of Yucca Mountain
in Nevada as the nation's first high-level nuclear waste repository. Values of net
infiltration are required to determine pre-waste emplacement groundwater travel times
and the performance of the repository as a waste containment system. The objective of
this study...
This report details the derivation of an analytical model for a flexible membrane
wave barrier. The wave barrier consists of a thin flexible membrane suspended in the
water column by a moored cylindrical buoy on the free surface and fixed to a hinge at
the seafloor.
The analytical model combines...
Chlorinated phenols are toxic compounds and often released into natural
environments from improper disposal or non-point sources. One important factor in
assessing the environmental fate and transport is the rates of microbial degradation in
soils and natural waters. In this study, eight chlorophenols (4-chlorophenol (4-CP),
2,4-dichlorophenol (2,4-DCP), 3,4-dichlorophenol (3,4-DCP), 3,5-dichlorophenol...
Maximum equilibrium scour depths, equilibrium scour volumes,
and induced equilibrium movements at isolated obstacles on river
beds were investigated in clear-water scour. The research was
achieved by a systematic flume study based on the results of
dimensional analysis of local scour.
The main tested obstacles for local scour were cubes....
Land application of industrial wastewater with high levels of nitrogen requires
adequate management practices to prevent groundwater pollution by nitrates. In this study
a predictive computerized model was developed for nitrate leachate concentrations
resulting from land application of wastewater onto crop systems including poplars. The
study included a literature review,...
Implementation of a small-scale irrigation project in southern Mauritania is analyzed in
this report. The main objective is to demonstrate that small-scale irrigation farming is
the best suited solution for Mauritania's agriculture. To reach this objective different
steps are taken in this study. The first step highlights the different aspects...
Groundwater resources have become seriously threatened
due to improper use by industrial, municipal, and even public
sectors. Widespread contamination of aquifer systems has
jeopardized human health and the environment and methods for
restoring these systems are needed. Biological and chemical
in situ remediation, where contaminants are degraded within
the natural...
Thermal cracking of asphalt concrete pavements is responsible for millions
of dollars in annual maintenance and rehabilitation costs in the United States and
Canada. Thermal cracking is typically associated with low temperatures in
northern climates and at high elevations. However, another form of thermal
cracking, known as thermal fatigue cracking,...
The response of lightweight equipment in structures supported on
resilient-friction-base isolators (R-FBI) subjected to harmonic ground motion and various
earthquake ground motions is examined. The equipment-structure base system is modeled
as a three degree-of-freedom discrete system (SDOF subsystems). An efficient
semi-analytical numerical solution procedure for the determination of equipment response...
A general analytical framework was established to investigate the scale-related variabilities in remote
sensing. The variabilities were studied first by investigating canopy structure, canopy interaction with
light, relation between spectral reflectance and plant phenological parameters. The variabilities
simulated by the plant model were compared with the actual spectral data acquired...