The purpose of this investigation was to study the effects of activated sludge aerobic digestion on the subsequent performance of a centrifuge. Two runs, utilizing two, 55 gallon barrels as digesters per run, were conducted using detention periods of 15 and 14 days, for run #1 and #2, respectively. Besides centrifugation, various water quality parameters were monitored during the two digestion runs. Results of this investigation indicated that the aerobic digestion process is suitable for waste activated sludge stabilization. Significant total and volatile solids reductions in conjunction with consistent supernatant COD and BOD₅ reductions were noted. However, prolonged periods of aeration caused a decrease in both the filterability and the centrifugation performances. Both reached their optimum peaks within the first 5 days of aeration and then gradually declined. This seems to indicate that once a sludge reaches the endogenous respiration state that sludge handling becomes much more difficult. The improvement in centrifugation efficiency that occurred during the early stages of aerobic digestion was not enough to justify the expense of aerobic digestion prior to centrifugation. / Master of Science

The purpose of this research was to determine whether there were differences between male and female performance on the horizontal water level task. A sample of 18 boys and 17 girls who were in elementary school were selected. The Chi-square test of significance was used where variables and factors were statistically examined. Five factors were considered in relation to the horizontal water level task. They were (1) differences in performance on perception and prediction tasks, (2) sex differences in the ability to comprehend the horizontal water level principle, (3) sex differences in the stage of development as a result of instruction, (4) sex differences after instruction on the number of correct responses on horizontal tasks, and (5) changes within the stages after instruction. The findings indicated that there were significant differences between male and female performance on this task. Males did significantly better than females. The findings further indicated that there were differences between performance on prediction and performance on perception. Instruction made a significant difference in female performance as judged by change of stage on the prediction task. The results indicated that females could improve in their performance on this task when given instruction. / Master of Science

This thesis was written to be used as a textbook by undergraduates majoring in home economics. The chapters are organized in such a manner as to lead the student through a sequence that will provide an overview and yet in some areas a detailed observation of a television station. The early chapters are devoted to a description of and comments on the many facets of a television station. Special attention is given to acquainting the student with elements of the industry ranging from coverage maps and ratings to hand signals. The later chapters deal with specific areas. One is, "The Solo Demonstration and the Sewing Machine", another, "The Standup Demonstration" and a third is devoted to "The Interview". While in some areas the elements overlap, in each chapter the student is acquainted with certain problems and offered solutions relative to the various situations. The final chapter deals with "Television as a Teaching Tool". At the end of each chapter is a series of problems which will lead the student into some activity involving the immediate subject. Use of these exercises will give the student practical experience in the area under discussion. Following the problems is a feature that will aid the teacher in evaluating the student‘s performance. The appendix deals with additional visual elements of television. While this thesis is structured around the undergraduate student in home economics, it could be valuable reading for others who wish to use the medium of television. / Master of Arts

Using a singular solution for a part circular crack by F. W. Smith, a Taylor Series Correction Method (TSCM) was verified for extracting stress intensity factors from photoelastic data. Photoelastic experiments were then conducted on plates with part circular and flat bottomed cracks for flaw depth to thickness ratios of 0.25, 0.50 and 0.75 and for equivalent flaw depth to equivalent ellipse length values ranging from 0.066 to 0.319. Experimental results agreed well with the Smith theory but indicated that the use of the "equivalent" semi-elliptical flaw for correlating the part circular flaw results with semi-elliptical flaw results was not valid for a/2c<< 0.20. Best overall agreement for the moderate (a/t ≃ 0.5) to deep flaws (a/t ≃ 0.75) and a/2c > 0.15 was found with a semi-empirical theory due to J. C. Newman when compared on the basis of equivalent flaw depth and area. The Smith theory, when correlated on the basis of flaw depth and area, appears to yield reasonable estimates (within 10%) of the SIF for flat bottomed flaws for the geometries studied here. / Master of Science

The purpose of this investigation was to define and analyze some operational parameters of the FAS process. Specifically: the settleability of filamentous sludge produced by the treatment system, the yield coefficient of the biological population, and the carbon to phosphorus ratio which limits organic removal efficiency. Findings of this study indicate that the sludges produced by the FAS process have settling characteristics and settleability remarkably similar to the solids of conventional activated sludge. While being tested, the sludges displayed a single clearly defined sludge-supernatant interface, good compaction, and cohesion between particles. The effect of varied diameter cylinders revealed that the true settleability of the sludge could not be determined in cylinders with a diameter less than 10 cm because smaller diameter settling tubes accentuated the "wall effect." The SVI and suspended solids appeared to be directly related because as the solids concentration decreased the SVI increased. No significant relationship could be established between the suspended solids concentration and the interface settling velocity because factors other than solids concentration influenced the value of this parameter. The yield coefficient of 0.23 derived from this investigation is approximately one-half the value associated with activated sludge but comparable to some coefficients reported for the FAS process. Filamentous organisms are capable of utilizing twice as much carbon per unit of phosphorus as the organisms of conventional activated sludge. A carbon to phosphorus ratio of 307:1, based on C.O.D., was found to be the limiting ratio for efficient organic removal. The amount of carbon used by the system per mg/l of phosphorus uptake averaged 230 mg/l as C.O.D. both before and after breakpoint. The dominant organisms in the biological unit throughout this investigation were fungi. / Master of Science

Attempts were made to control black root rot of apple with the fungicides, benomyl, captan, thiabendazole and triarimol, and to determine their fungitoxic effects on the causal pathogen Xylaria mali. The pathogen responded differently in various bioassay methods, but all fungicides were inhibitory to its vegetative growth. Disease control was evaluated by applying the fungicides as amendments or as drenches to the soil in which the roots were artificially inoculated. The best therapy was obtained with a captan drench (4,000 ppm), followed by captan (1,000 ppm) and benomyl (300 ppm) drenches, Root growth was suppressed at all higher concentrations except with captan; root development was directly correlated with chemotherapy. Fungitoxicants were recovered from leaves of seedlings treated with all fungicides except triarimol. Higher bioassay activity was observed in plants treated by the soil amendment method. Leaves from benomyl-treated plants exhibited the greatest bioassay activity. / Master of Science

Three strains of channel catfish, Ictalurus punctatus (Rafinesque), from the southeastern United States were cultured in cages to select a strain that would attain a marketable size during the relatively short Virginia growing season. The strains were compared in terms of yield, survival, mean weight, food conversion, coefficient of condition, and percent marketable fish. Statistical analysis indicated that the Kansas strain was significantly different from both the Arkansas and North Carolina strains, but the latter two were not significantly different with respect to yield, mean weight, food conversion, and percent marketable fish. A financial analysis, conducted to evaluate the feasibility of culturing channel catfish in cages moored in small farm ponds, showed that the fish would have to be sold for more than $.610 per kg ($.277/lb.) to make the operation profitable. Cage culture of channel catfish is possible in Virginia, but is not generally recommended for small still-water farm ponds. / Master of Science

The purpose of the present study was to investigate the effects of a rest period on kindergartners’ performance in a simple reaction time situation. Effects of sex, class, time of measurement and practice on simple reaction time were also factors investigated in the present study. The sample consisted of 32 children ranging in chronological age from 62 months to 74 months. The children were enrolled in kindergarten at Pembroke Elementary School, Giles County, Virginia. Data were collected over 20 days with seven additional days for make-up. An overall analysis of variance was performed to determine any significant differences in reaction time. Males were significantly faster than female subjects in one class but not in the other. The subjects reacted slower in both classes as the day progressed. The subjects in Class One reacted slower between the morning and pre-rest periods. For both classes, subjects reacted slower after a rest than before a rest. Results were discussed in relation to the findings of the study. / Master of Science

The legal socialization of elementary school children from three demographically distinct Virginia localities was investigated. The attitudes of these children toward the law and police were measured by a questionnaire administered by the classroom teachers. The results obtained tended to reinforce the conclusions of previous socialization theorists with respect to the attitudes of young children toward the law and the police. The attitudes of the children were found to differ as a function of their area of residence. Although this area variable influenced the socialization process, another variable, called sophistication, also seemed significant. This variable, sophistication, seemed to be directly related to the relative socio-economic status of the child, as higher socio-economic children tended to demonstrate the variable to a greater extent. Children of greater sophistication differed from their less sophisticated peers in that they tended to demonstrate a more mature attitude toward the law and police. It was concluded that the children's attitudes toward the law and the police were influenced by their area of residence and their relative sophistication. / Master of Arts

The objective of this research was to analyze a pure oxygen activated sludge process and its claimed advantages. The major emphasis of both the claims and this research was the settleability of the sludge and the biological kinetics. An identical conventional air activated sludge unit was also operated as a direct comparison. Settling tests were run in three different cylinders with increasing diameters to collect data on the sidewall effects in addition to the settling rates. The settling velocities were also calculated and the average values for the oxygen and the air sludges were 95.0 ml/min and 104.0 ml/min, respectively. The results indicated there was no significant difference in the settling rates and the mixed liquor solids concentration did not affect these rates. The mass settling rate, a new parameter obtained by multiplying the settling velocity times the mixed liquor solids concentration, indicated the oxygen sludge settled more mass in a given time period than the air sludge and therefore compacted to a greater degree. The substrate utilization rate of the oxygen process was found to be 2.8 times greater than that of the conventional air process. This finding is comparable to other published reports. The oxygen utilization rate for the sludge from the air unit was slightly higher than that of the oxygen sludge. The coefficients of the kinetic formula did indicate that the oxygen system had a greater degree of endogenous stabilization occurring than did the air. The oxygen unit used in this study consistently had better BOD removal efficiencies than did the air. The oxygen unit averaged 94%, while the air unit averaged 85%. This investigation also indicates that an air unit will not operate at the identical parameters utilized in an oxygen process. This is due primarily to hydraulic difficulties encountered. / Master of Science