Research was undertaken in order to simulate and optimize an Aquatair Model P-3 package sewage treatment plant for which operating data from the National Sanitation Foundation was available. The treatment plant consists essentially of a plastic medium trickling filter mounted overtop of a complete-mix activated sludge (CMAS) tank; the unit also has a primary sludge holding tank and a secondary clarifier. From consideration of reaction kinetics, reactor type, and geometry, a mechanistic model was developed to explain the phenomena of substrate removal in the Aquatair Model P-3. The two-factor SIMPLEX optimization procedure was used to determine the best set of biological reaction constants K1 and K2 which would characterize the substrate removal behavior of the Aquatair biological oxidation tower and recirculation chamber, respectively, based on actual plant data. Once the behavior of the plant was accurately simulated, cost functions were developed in order to relate the various design variables to cost. An n-factor PERPLEX optimization routine was then used to optimize the various plant variables for a given flow, organic load, and efficiency. PERPLEX, a modification of the Box COMPLEX method, was shown to be a useful tool for evaluating the factor space defined by a set of mathematical assumptions. The cost benefit of aerobic digestion occurring in the Aquatair bio-oxidation tower was predicted by the model and confirmed by nitrification data and sludge production calculations. / Master of Science

no abstract provided by author / Master of Science

Previous research relating to alum sludge land application has primarily been restricted to laboratory studies of short-term environmental effects. In general, most research has concluded that the environmental effects of alum sludge constituents can be easily controlled. This study investigated the fate of land-applied alum sludge constituents nearly three years after incorporation into a Slagle soil. An existing field site was used. The site had been used for a pilot study examining the land application of alum sludge from the Harwood's Mill Water Treatment Plant in Newport News, Virginia. Alum sludge and lime were applied to the site in November, 1989. Soil, soilwater, groundwater and pine needle tissue media were sampled during the summer of 1992. It was determined that the alum sludge posed no observable long-term threat to groundwater quality or vegetative productivity. Migration of alum sludge constituents through the soil profile could not be confirmed in this research. However, acid precipitation may have destroyed the alkalinity added to the soil. Thus, long-term management of alum sludge land application to acid soils may require additional increments of alkalinity. / Master of Science

The current Environmental Protection Agency (EPA) method utilized for analysis of trace organic chemicals and heavy metals leached from solid waste is the Extraction Procedure (EP) Toxicity Test. Because of various operational problems and limitations of the EP, the EPA has developed and plans to implement the Toxicity Characteristic Leaching Procedure (TCLP), which is an expanded version of the EP capable of analyzing more organic components, in particular volatile organic chemicals. The purpose of this research was to investigate and compare the ability of the EP and TCLP test procedures to quantitatively recover added surrogate standards (1,2-dibromoethane, bromoform, 1â chlorooctane, fusarex, heptachlor, and DDT) and also qualitatively identify and evaluate unknown trace organic chemicals in domestic wastewater sludges. In order to meet the research objectives established, three small (approximately 1 MGD or less) municipal wastewater treatment plants that land applied their sludges were analyzed. / Master of Science

Master of Science

The objectives of this study were to investigate the effects of the crystal seeding technique on certain handling characteristics of nickel hydroxide sludge and to investigate the changes in sludge particle properties that mediated any changes in those characteristics. A continuous-flow nickel hydroxide precipitation reactor was operated with and without solids recycle to produce sludge for analysis. The concentration of solids produced in the reactor clarifier was monitored and the specific resistance of the sludge was measured. Batch settling tests were also conducted on the sludge samples. The particle size distribution of the sludge produced was measured by an electronic particle counter and the density of the sludge flocs were measured. After the initiation of solids recycle in experiment I, the concentration of sludge solids increased from a range of 9,510-13,720 mg/l to 27,500-76,000 mg/l. Specific resistance values decreased an order of magnitude from an average of 4.01 x 10¹² m/kg before recycle to an average of 2.73 x 10¹¹m/kg during recycle in experiment I. Also, batch settling tests indicated an improvement in solids settling velocity. Similar results were obtained in the second experimental run. The improvement in these sludge handling parameters was attributed to an increase in particle size and particle density. Mean sludge particle diameter increased from an average of 2.9 microns before solids recycle to an average of 3.9 microns during recycle. Sludge particle density also increased during the recycling of sludge. These changes in sludge particle size and density were produced by an alteration of the crystal growth process. / Master of Science

An investigation has been made to determine the effect of geometry on the performance of six collection troughs that served to collect and store grit captured by a model grit chamber. The grit employed was a 0.1mm sand fraction obtained by sieving and the width of the channel of the model grit chamber was 0.5 ft. Over a hundred experiments were performed which spanned a range of velocities of from 0.31 to 1.1 ft/sec and a range of depths of from 0.1 to 0.36 ft. The performance of the grit chamber - collection trough units was evaluated in terms of percentage grit capture under comparable flow conditions and observation of grit travel patterns. The results indicated that the performance of the troughs was influenced by the volume, the depth to length ratio and the slope of the upstream and downstream walls. High performance appeared to be induced by large volumes, moderate depth to length ratio, vertical upstream wall slope, and a downstream slope of 2 vertical to 1 horizontal. / M.S.

Nearly 700,000 Virginians depend on septic tanks and other wastewater treatment systems for treatment of household wastes. The Joint Subcommittee Report HJR 7 1987 reported that sixty percent of Virginia's residential septic “systems and drainfields are operating improperly. With the demand for rural and suburban development increasing, a viable alternative to septic systems and drainfields is needed. One proposed alternative is single family package treatment systems. One vital concern is that a majority of these systems discharge directly into surface waters. Thus, the objective of this study was to evaluate the performance of aerated package treatment systems (APTS). Five APTS located in southwest Virginia were chosen. Each site was visited three times during 1990 and 1991, and various parameters were monitored from the primary settling chamber, aeration chamber, and effluent. Systems were sampled in the morning, afternoon, and night. Also, two dye studies were conducted to evaluate hydraulic displacement. The results indicated that overall field performance was poor due to unreliable maintenance by homeowners, an ineffective chlorinator/dechlorinator system, inadequate biological treatment, and mechanical malfunctions. Eighty-one percent and 62% of the effluent samples were found to have five day Biochemical Oxygen Demand (BOD,) and total suspended solid (SS) concentrations exceeding 30 mg/L, respectively. Effluent dissolved oxygen values were less than 5 mg/L, the state's standard for small package treatment systems. Sixty-four percent of the effluent samples were found to contain more than 200 fecal coliforms/100 mL. In five instances where disinfection was evident, chlorine residuals were detected in the effluent, which also violates state standards. / Master of Science

Very few sewage and industrial waste treatment effluents are free from microorganisms and proteins. Such discharges require further treatment by the receiving stream and consequently lower stream quality. The object of this investigation was to evaluate chlorinated solvent processes for the removal of microorganisms, proteins, and other substances from sewage and other wastes. Six different chlorinated solvents were added to different waste samples in the ratio (by volume) of five percent solvent and 95 percent waste, mixed and allowed to settle for a specified period of time. The efficiency of the solvent extraction process was evaluated in terms of reduction of suspended solids, biochemical oxygen demand, and by increased weight of residue separable by sedimentation. The results showed that the process produced the following effects on settled sewage. Suspended solids were reduced by 85 percent, the weight of residue separable by sedimentation was increased 33 percent, and the biochemical oxygen demand was reduced 49 percent. The process was less effective for the treatment of raw sewage, trickling filter effluent, sewage lagoon effluent, or for separation of activated sludge. The variables investigated were temperature, pH and the solvent waste system. Temperature and pH appeared to have negligible effects on the extraction efficiency. The solvents employed were; chloroform, ethylene dichloride, chlorobenzene, carbon tetrachloride, trichloroethane, and dichloroisopropyl ether. Solvents with low vapor pressures and wastes with low concentrations of suspended solids appeared to be the most efficient system. The addition of 20 percent of butanol (by weight) to trichloroethane appeared to increase the extraction efficiency of trichloroethane. Bacterial counts made indicated that the solvent extraction process was affecting better than 90 percent removal of microorganisms from the waste samples. More research will be needed to completely evaluate chlorinated solvent processes for the removal of microorganisms, proteins, and other substances from sewage and other wastes. / Master of Science

The development of southwest Virginia’s coal mining areas is severely hampered by a lack of building sites and waste disposal facilities. New technologies to reclaim mined lands have the capacity to produce large level expanses of land suitable for building sites by using the minespoil to reshape the land contours. Because these areas are generally too remote for centralized sewer to be economically feasible, the problem of waste disposal remains. Also, the current Virginia Department of Health regulations forbid placement of on-site waste water treatment and dispsoal systems (OSWTDS) in any fill material, including minespoil. The objective of this research is to examine alternative OSWTDS technologies for their applicability to treating wastewater in fill materials with respect to both removal of biological and chemical contaminants and hydraulic performance. In the fall of 1989, topsoil and minespoil materials were transported from southwest Virginia to Blacksburg, Virginia. The soil material was screened, air-dried, and packed into large plastic cylinders. Septic tank effluent and sand filter effluent was applied to the soil columns daily at three different loading rates for a period of 5 months. Wastewater samples were collected after passing through the soil columns and analyzed for several chemical parameters as well as fecal coliforms. Antibiotic-resistant Escherichia Coli and bacteriophage T-1 (virus) were introduced into the columns and analyzed in the filtrate. The soil material in the columns was also characterized for selected physical parameters. The results indicate that the concentration of total inorganic N was reduced 15 to 60% after the effluent was passed through the soil columns. However, the NO₃ - N concentrations were still above the 10 mg/L drinking water standard indicating that housing density should be considered when fill material is used for OSWTDS. The quantity of P emerging from the columns was higher than anticipated in minespoil column effluent which is probably related to the indigenous P present in the minespoil. The P concentration in topsoil column effluent increased with influent application and this relationship could be described by quadratic functions. The numbers of fecal coliforms were reduced (93 to 99%) by passing effluent through the soil columns. The concentration of indicator organisms indicated a gradual decline in viable bacterial cells and viral particles over time, with the indicator virus assays being completely negative by day 11. The tracer organism study also indicates that the survival time of these organisms can be effectively controlled in topsoil by reducing the influent loading rates, and in minespoil by reducing the influent loading rates and using some type of pretreatment, such as a sand filter. This study indicates that OSWTDS can be placed in selected topsoil areas in reclaimed minelands. It further indicates that at least 60 cm of unsaturated topsoil should be available for wastewater renovation. Minespoils were also effective at renovating wastewater, but may require pretreatment before application, a lower loading rate, a deeper unsaturated zone, or perhaps a combination of these factors. / Master of Science