ABSTRACT Continuous flow column studies were conducted to characterize suspended sol ids and heavy metal reduct ions through sedimentation with varying overflow rates. The heavy metals tested were cadmium, zinc, copper, iron, lead, nickel and chromium. Stormwater derived samples spiked with street sweepings categorized into particle size ranges less than 500 microns in diameter were utilized in the research. Overflow rates investigated ranged from 28 to 3600 gallons per day per square foot. Theoretical predictions of suspended solids reductions with the application of Stoke's Law exceeded observed reductions for the continuous flow system. Performance curves for all reductions over the observed range of overflow rates are described by a parabolic relationship with the general equation as follows: Reduced fraction= a+ b(Overflow Rate - c) 2 where a, b and c are constants specific to each parameter. Similarities in performance curves for all metals indicate a dependence on suspended solids for reductions. Cadmium and chromium reductions were a function of overflow rate, but did not show a statistically significant dependence on initial total suspended solids concentration. Lead, copper, zinc and iron reductions were a function of initial total suspended solids concentration as well as overflow rate. Iron and nickel exhibited dependence on initial concentration of the specific metal for reductions, as well as dependence on overflow rate and initial total suspended solids concentration. The steady-state models selected from the results of this research for total suspended sol ids and each of the heavy metals are limited to the mixture, specific experimental conditions, and range of overflow rates observed in this research. Observed reductions of total suspended solids and heavy metals are considered to be 1 imited to physical sedimentation processes, in that processes that may effect reductions of these elements in a natural system are not factors in the results of this research.

The effects of effluent type, effluent loading rate, dosing interval, and temperature on denitrification in low pressure distribution, on-site wastewater treatment and disposal systems (OSWTDS) were evaluated in this study. The treatments were surface and subsurface soil horizons; nitrified and non-nitrified wastewaters; 0.5, 1.0, and 1.5 times the Virginia Department of Health (VDH 1989) recommended wastewater loading rate; 24 and 48 hour dosing intervals; and summer and winter temperatures. Surface and subsurface soil cores were collected from a Groseclose silt loam soil (clayey, mixed, mesic Typic Hapludult) and subjected to the various treatments. The effects of the treatments on denitrification were evaluated based on analyses of leachate from the cores, soil chemical analyses, and microcosm studies to estimate actual denitrification activity. A model was developed from the study that estimated the mean N₂O production for each combination of experimental treatments. The results of the study and the model indicate that denitrification can be enhanced in OSWTDS by the application of non-nitrified wastewater at one-half the VDH recommended loading rate, or 1.25 cm/day, for surface soil horizons (30 min inch⁻¹ percolation rate) using a 48 hour dosing interval. A field study was conducted on a Lowell silt loam soil (fine, mixed, mesic Typic Hapludalf). Denitrification was measured at this site using acetylene blocking and the results compared to those predicted by the denitrification model developed from the laboratory data. The field measurements of denitrification based on N₂O concentration in the soil atmosphere were three orders of magnitude higher than that predicted by the model. It was concluded that the laboratory techniques can be used to determine optimum method of operation for denitrification in a low pressure distribution system, but it cannot be used to determine the field design loading rates. / Ph. D.

The purpose of this investigation was to conduct batch and continuous flow laboratory experiments with bench scale activated sludge units to determine the effects of nickel on the completely mixed activated sludge process. The model units were located in a constant temperature room maintained at 20±2°C. The batch reactors were operated under acclimated and shock loaded condition with various nickel concentration to determine its effects on the rate of COD removal. The continuous flow units were operated until steady state conditions were obtained at each mean cell residence time studied and then data were recorded for an approximate 7 days period and averaged to obtain one steady state data point. Nickel was added to the waste water at various concentration to determine its effects on COD removal efficiency, degree of nitrification and on the biokinetic constants Ymax and kd. / Ph. D.

The study of nitrate utilization as the final electron acceptor in biological phosphorus removal systems was investigated. The objectives of the study were (1) to determine whether polyphosphate (polyP) microorganisms can use nitrate as the final electron acceptor, and (2) to evaluate and compare polyP accumulation in the biomass of the system using nitrate as the terminal electron acceptor to the system using oxygen as the terminal electron acceptor. Two lab-scale biological phosphorus removal systems were operated as the A/O Process under the same conditions except for the terminal electron acceptor involved. The first system, System I, was operated as an Anaerobic/Anoxic process and the other, System II, was operated as an Anaerobic/Anoxic process. Both systems were operated at a 5-day sludge age and the same nominal hydraulic retention time of 9.1 hours (2.9 hours anaerobic, 6.2 hours anoxic or aerobic). The sludge recycle flow rate was equal to the influent flow rate. The two systems were fed with the same domestic wastewater spiked with sodium acetate and potassium phosphate to give the wastewater a COD concentration of 300-400 mg/L and a phosphorus concentration of 13-14 mg/L as P. Nitrate was fed to the second reactor of System I, while the second reactor of System II was aerated. The results showed that polyP microorganisms can use nitrate as the final electron acceptor. In this research, the Anaerobic/Anoxic system removed more phosphorus (74 mg P/day) from solution than the Anaerobic/Aerobic system (64 mg P/day). The phosphorus content of the sludge in the Anaerobic/Anoxic system was greater than that of the Anaerobic/Aerobic system, i.e. 6.5% as compared to 5.6%. The above evidence strongly confirms that polyP microorganisms can use nitrate as the final electron acceptor and that excess biological phosphorus uptake occurs under anoxic condition. The implication is that COD stored in the anaerobic reactor can be used to simultaneously remove nitrogen and phosphorus, which can substantially reduce the amount of COD required for combined nutrient removal. / Master of Science

The effect that mean cell residence time (MCRT) had on the dewaterability of biological sludges was examined in this study. Aeration basin sludge and waste activated sludge from a full scale domestic wastewater treatment facility, in addition to sludges produced from two laboratory scale reactors fed with a synthetic substrate and a primary effluent-dog food mixture, respectively, were used to perform dewatering tests. The sludges were evaluated at various MCRT values for optimal dewatering resistances, optimal conditioning requirements, and optimal compressibility conditions. Specific resistance determinations were made using a 3uchner funnel apparatus to evaluate all of the above mentioned parameters. Also particle size analyses were performed on all sludges to investigate how particle size affected dewatering resistance and conditioner requirements, and also to investigate how MCRT affected particle size. All particle size determinations were made using a HIAC PC-320, twelve channel particle size analyzer. Results from the study revealed that plants can operate under extended aeration and still maintain good sludge dewatering characteristics. Likewise, by varying MCRT shifts in particle size distribution and corresponding changes in dewatering resistance were noted in the laboratory reactors. However, no optimum MCRT with respect to dewatering could be founded. Particle size proved to be the most important parameter affecting dewatering, and it was affected by conditioning, periods of anaerobiosis, and MCRT in the laboratory reactors. / Master of Science

This report is the result of investigation of the feasibility of increasing the use of autamatic controls at the Florida Technological University Wastewater Treatment Plant. This investigation was to include a literature search and visits to wastewater treatment plants. During the writers course of study, he was privileged to make a series of tests of a residual chlorine analyzer which was made in the school shop. Since this work was closely related to automatic controls the data are included in this report.

A high strength industrial wastewater was treated in a bench-scale activated sludge reactor modified by the addition of biomass support media to the aeration tank. Two experimental biomass support systems (BSS) and one conventional activated sludge system were operated at different mean cell retention times (mixed liquor MCRTs). Three separate media were tested, NOR-PAC and Linpor used as free-floating supports, and BIONET used as a fixed-bed support. The effect of the media on substrate and oxygen utilization, and solid-liquid separation was investigated. Substantial attached growth did not occur on the NORPAC and BIONET media. The attached biomass concentration in the Linpor systems increased with increased media concentration. The ratio of attached volatile solids to total volatile solids (attached volatile solids + MLVSS) decreased with increased mixed liquor MCRT. The advantages of the BSS would occur at low mixed liquor MCRTs. Both the BSS and control systems achieved greater than 94% COD removal and substrate utilization rates (mg/h) did not significantly change during the experiments. Therefore, both systems were substrate limited. The substrate limitations caused decreased oxygen uptake rates of the attached biomass with increased mixed liquor MCRT. The sludge settling of the Linpor systems was a function of mixed liquor MCRT, filamentous upsets, and the presence of the media. Enhanced settling was observed in the Linpor system only at the 3 day mixed liquor MCRT experiment. / Master of Science

Many soils are marginally suited for installation of on-site wastewater disposal systems. With soil limitations, additional wastewater treatment prior to soil application may allow for a reduction in soil depth. Undisturbed 20-cm-diameter soil columns (fine loamy, mixed, mesic Typic Hapludult), in a factorial arrangement between depth of soil (15, 30, and 45 cm) and type of effluent (septic tank, constructed wetlands, and recirculating sand filter), were used in this study. Effluent (670 cm³/d) was applied 6 times daily. Additional treatment of septic tank effluent by a constructed wetland and a recirculating sand filter resulted in 30 and 70% higher average soil infiltration rates, 92 and 96% reduction in fecal coliforms, 34 and 44% reduction in total nitrogen, and a 60 and 94% reduction in BOD₅, respectively. Fecal coliforms were present only in soil leachate from the 15 and 30 cm soil depths receiving septic tank effluent and the 15 cm depth that received constructed wetland effluent. Average soil leachate NO₃⁻-N concentrations were 19, 10 and 14 mg/L from soil columns receiving septic tank, constructed wetland, and recirculating sand filter effluents, respectively. Soil leachate contained <5 mg/L TKN and 1.8 mg/L NH4⁺-N. Total nitrogen losses were 55, 73, and 66 for the septic tank, constructed wetland, and recirculating sand filter treatments, respectively. BOD₅ averaged less than 4 mg/L in the soil column leachate, despite a 10 fold difference among influent types. In comparing the 1993 and 1994 growing seasons, average plant tissue dry weight, percent nitrogen, and percent phosphorus were greater during the 1994 growing season. The results from this study indicate that additional treatment of septic tank effluent can be substituted for soil depth. / Master of Science

Equilibrium powdered activated carbon (PAC) concentrations of 20, 160, and 280 mg/L in activated sludge reactors treating cellulose acetate manufacturing wastewater were found to enhance substrate removal. The improved substrate removal as measured by COD averaged 20 percent. The apparent mechanism of improved removal was the stimulation of greater biomass growth. PAC addition increased the oxygen uptake rate (OUR), the observed cell yield coefficient (Ybbs) and the first order substrate removal coefficient (Kb) of the activated sludge system, which were operated at a temperature of 18°C and a biological solids retention times of fourteen days. The addition of PAC also improved the sludge settleability but this resulted in higher effluent suspended solids concentration because zone settling Velocity was the primary factor affecting effluent suspended solids. A type of activated sludge bulking, known as jelly formation, plagued the biological reactors but nitrogen addition appeared to solve the problem / Master of Science / incomplete_metadata

The decolorization of reactive dye-containing waste streams using oxidizing chemicals and the determination of the effect of the oxidizing agents on the subsequent biotreatment of the streams was investigated. Three oxidizing schemes were chosen for study: molecular ozone, base-promoted ozonation, and Fenton’s reagent (Fe²⁺ and H₂O₂). The ADMI color value of the solutions was used as the primary parameter for color comparison and dissolved organic carbon (DOC) removal was the measure of the effect of biodegradation. Three different waste streams from a textile dyeing facility were chosen: a Navy slack washer effluent from a pad-dyeing operation, a Navy dyebath effluent from a dyejet, and a Brilliant Blue dyejet effluent. Pure dye solutions were oxidized as well to determine the effect of interfering species in the waste streams. The results demonstrated that base-promoted ozonation was more effective than molecular ozone for the decolorization of the Navy slack washer effluent. In both cases the ADMI color value could be decreased by 82% but almost half as much ozone was necessary for the high pH trials. The high pH ozonation proved more effective for the Navy jet-dye effluent, as well, achieving a much lower color value with less ozone. Greater decolorization (96%) of the Navy jet-dye effluent was achieved by Fenton’s reagent than for either of the ozonation schemes. Ozonation of the Brilliant Blue jet-dye bath showed no dependence on pH and the color value of the solution was reduced could be 63%. The results indicate that the dyes were selectively oxidized by ozonation and the amount of ozone required for decolorization depended mainly the initial color of the dye waste stream. The amount of hydrogen peroxide required for Fenton’s reagent oxidation depended on the initial DOC of the dye waste stream. Oxidation of the wastewater streams proved to neither enhance nor hinder the operation of the biological reactors. The color removals by biological activity were minimal for both control and experimental reactors. Dissolved carbon removal was not enhanced by oxidative pretreatment. / Master of Science / incomplete_metadata