Experiments were performed on alum, anaerobically digested and aerobically digested sludges to determine the optimum polymer conditioning for a belt filter press The optimum polymer dosages for all three zones of a belt filter press were compared with each other to determine the best overall conditioning. The requirements of all three zones of a belt filter press were the same. However, the gravity rate of drainage seems to under predict the dosages for optimum belt filter press performance. In addition the total mixing energy, G (the shear) and t (the mixing time), that represents the laboratory belt filter press was found to be approximately 45,000. Using a mixing energy input of 45,000 and a standard Buchner funnel apparatus the correct polymer dose for the belt filter press can be predicted. / Master of Science

The capability of the activated sludge process to operate with sea water included in the influent substrate. Sea water was added at various percentages from 5-40. The study concluded that from a biological standpoint the activated sludge process could operate successfully. However, rapid settling problems because of a build up of total solids became the limiting factor. / 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

Treatment of municipal and industrial wastewaters results in the production of wastes in the form of sludge. Since the quantity and characteristics of sludge depend upon the degree of treatment, the upgrading of treatment facilities has had the effect of increasing sludge production. Since the quantity of sludge is a function of the type of treatment provided, any attempt to minimize sludge handling should begin at the source. The hydrolytic assist activated sludge process provides positive control of the mixed liquor solids and is effective in the disposal of organic sludge created in the wastewater treatment process. In theory, this modification involves the hydrolysis of waste activated sludge by acid addition to a pH of 1.0 or with base addition to a pH of 13.0. Hydrolysis is followed by autoclaving at 15 psi and 121°c for a period of five hours. This treatment will solubilize most of the cellular material which can then be reintroduced to the aeration tank after pH neutralization. No sludge is wasted; it is all recycled as hydrolyzed sludge. The main objective of this research was to operate laboratory activated sludge units over a range of Qc values to determine effects and differences in process performance and operation for the hydrolytic assist mode. Results obtained during this study indicate that COD removal efficiency for the hydrolytic assist is compatible with the conventional process. In addition, the hydrolytic assist process proved to be an effective disposal method for sludge produced in the activated sludge process. / M.S.

Handling and disposal of residual solids from wastewater treatment plants is an expensive and difficult task. The acid hydrolytic assist activated sludge process is one method of minimizing sludge production from a biological wastewater treatment process. Acid hydrolysis of waste sludge involves pH adjustment to 1.0 or less followed by heat treatment. The hydrolyzed sludge can then be adjusted to a neutral pH and recycled to the treatment process as soluble organic material. In effect, hydrolysis promotes cellular autodigestion by artificially inducing the normally difficult metabolic steps. The use of hydrolysis in the extended aeration process allows periodic sludge wasting for control purposes but avoids the problem of ultimate sludge disposal. Previous research was limited to the use of hydrolysis in the extended aeration process. The effect of mean cell residence time, Θ_c, on an activated sludge process utilizing hydrolysis had not been evaluated. Also, only limited information is currently available regarding the kinetics of wastewater treatment with the hydrolytic assist activated sludge process. The purpose of this research was to gain additional insight into the hydrolytic assist activated sludge process with regard to mean cell residence time and the kinetics of wastewater treatment. Determination of the relative effect of hydrolysis on nitrification in the activated sludge process was a secondary objective of this study. Mathematical and stoichiometric equations were used to predict process performance characteristics. A laboratory investigation was then conducted to obtain actual operational results for comparison. A description of the investigative procedures and results is included along with a review of the literature. / Master of Science

The sludge blinding coefficient, β, was evaluated in this experimental study, to determine if β could be used as a useful characterization parameter for sludge filterability. Fresh activated sludge, activated sludge aged at room temperature, primary sludge, alum sludge, and a calcium carbonate slurry were filtered using a Buchner funnel apparatus and varying size filter media at various pressure differentials. Particle size measurements were also performed on the above mentioned sludges using an automated particle size analyzer to examine the impact of particle size and size distribution on β. Effects of conditioning, elutriation, supernatant removal, and replacement on β were also studied. In general, β correlated well with the average specific resistance, indicating that it could be useful in predicting a sludge filtration pattern. β was found to increase as the mean particle size of a sludge decreased, or the particle size distribution of a sludge widened. Conditioning, elutriation, supernatant removal, and replacement were found to reduce β by improving the mean particle size of a sludge and narrowing a sludge particle size distribution. In addition, β was found to increase by the applied pressure differential and filter media pore sizes for a few sludges. / Master of Science

Hydrocyclone density-driven particle separation may offer up improved settling performance for wastewater treatment facilities experiencing poor settleability. Hydrocyclones are fed mixed liquor through the feed inlet and experience a centrifugal motion that separates solids based on density. The variation in hydrocyclone nozzle sizes will report different calculated hydraulic and mass split percentages for the overflow and underflow. Previous research conducted with hydrocyclones have at multiple full-scale facilities used a 10 m3/hr hydrocyclone to promote better settleability as well as aid the formation of aerobic granular sludge (AGS). There has been a multitude of settling improvement experiments and initiatives for full scale wastewater treatment. However, little research has been produced utilizing larger hydrocyclones (20 m3/hr) at a full-scale wastewater treatment facility during continuous operation. Two Hampton Roads Sanitation District (HRSD) plants served as sites for this research: James River (JR) Wastewater Treatment Plant located in Newport News, VA and Urbanna (UB) Wastewater Treatment Plant located in Urbanna, VA. Both treatment facilities have utilized the hydrocyclone for more than two years, to fulfill wasting requirements. The JR plant operates the hydrocyclone continuously for wasting purposes, while UB only uses the hydrocyclone for approximately 30-45 minutes per day. In order to evaluate the effectiveness of the hydrocyclone and its overall impact on settleability at the JR plant, eight hydrocyclones were installed. JR samples were taken from the underflow sample port (representing a mixture of underflow samples representing the number of hydrocyclones operational at the sample time) and overflow samples were taken from the outfall point of a single hydrocyclone. The UB plant only operated one 5 m3/hr hydrocyclone on Treatment Train 1 during wasting operations, while Treatment Train 2 served as the control train for the duration of this research. Hydrocyclone performance at JR was assessed through direct measurement of hydraulic and mass split of the underflow and overflow components, initial settling velocity (ISV), sludge volume index (SVI), and SVI5/SVI30 ratio. UB hydrocyclone and settling performance was measured by ISV, SVI5, SVI30, and SVI5/SVI30 ratios during different comparison experiments: hydrocyclone vs. no hydrocyclone, hydrocyclone vs. polymer addition, and hydrocyclone with polymer addition to Train 1 vs. polymer-only addition to Train 2. Nutrient concentrations from both treatment trains were collected and analyzed to determine any significant changes based on hydrocyclone use. T-test statistical analysis, and a dose response analysis included direct measurements of the ISV, SVI5, SVI30, mass split percentages, along with the effect of polymer with and without the use of a mechanical selector. Hydrocyclone settleability measurements at JR over time revealed a statistically significant positive correlation with the ISV, SVI5, and SVI30 measurements of the aeration effluent. Therefore, the hydrocyclone statistically had a strong impact on three settling parameters that are instrumental in determining overall settling efficiency. Statistically, no strong correlation was determined between the hydrocyclone operation and the total phosphorus (TP) concentration in the secondary effluent, or the ferric addition to the secondary clarifiers. The dose response based on the underflow ISV rate provided understanding of the nozzle comparison and the effect it provided to the underflow sample. Hydrocyclone performance at UB was hindered by the re-seed of Train 1 (inDENSE™) due to over wasting, and most of the data were not representative. Before the re-seed, hydrocyclone performance was improving the overall settleability of the mixed liquor in comparison to Train 2 (Control). All settling parameters measured were in favor of the hydrocyclone operation. After the re-seed the plant mixed liquor changed microbial populations for a brief time and was not representative of the overall treatment efficacy. The hydrocyclone did provide a quicker settling velocity than the polymer addition when the polymer addition was steady, and through both polymeric spikes. Polymeric addition to both trains, while inDENSE™ train still employing the hydrocyclone did not provide any conclusive data as to whether polymer addition with the use of a hydrocyclone was more effective than polymer-only addition. Nutrient profiles from UB did not provide any change in NH4-N, NO3-N, NO2-N, or PO4-P, with the hydrocyclone being operational or not on the secondary clarifier effluent. / Master of Science / Wastewater treatment facilities rely on settling tests to be indicators for plant settling performance. A way to improve plant settling is to separate the sludge on a density basis and retain the dense sludge in the system for better performance downstream, while the less dense sludge is taken out of the system. By implementing a mechanical device that can ensure the separation of dense material and be retained in the system can aide in improved plant settling performance by improving settling parameter measurements. With the ability of using a mechanical device (a hydrocyclone) to physically separate sludge on a density-basis, it will improve settling measurements of the plants taken by operators on a daily basis.

In an effort to provide wastewater treatment operators with the capability to be proactive in assessing and solving deflocculation events, this study has tested the components of a biosensor to predict deflocculation and investigated the mechanistic cause of deflocculation relating to chlorination of activated sludge cultures. In order to effectively manage upset events, it is necessary to know the source of an upset and the causative mechanism that the source initiates. The Glutathione-gated potassium efflux (GGKE)induced activated sludge deflocculation biosensor incorporates novel microtechnology with a whole cell biological element to predict deflocculation from electrophilic sources. This sensor utilizes microfluidic channels to conduct influent wastewater across a biofilm of Eschericia coli K 12 and monitors the bacterial response to the influent. The bacterial response, which is efflux of K+ ion from the cytoplasm, is monitored with a fluorescence-based sensor called an optode. The components of the system satisfy the project requirements, which include minimal expense (both operation and manufacture), on-line capability and minimal maintenance. The research conducted to date demonstrates the ability of the components of the biosensor to fulfill the design requirements. The optode K+ detector successfully measured an increase in soluble K+ following the exposure of E. coli K-12 to the electrophile N ethyl malemide. The manufacture of the microfluidic device has been completed and the device has demonstrated the ability to conduct influent under negative pressure across an established biofilm with the optode in place. The establishment of a biofilm under expected hydrodynamic conditions has also been completed. Future research efforts will include integrating the components of the biosensor into a working prototype that will be capable monitoring the reaction of bacteria to the presence of electrophilic compounds in wastewater. Sensors of this nature will provide operators with the early warning necessary to be proactive against toxic upsets rather than reactive. The knowledge needed to create a biosensor resides in the identification of bacterial response mechanisms that cause upset events in wastewater treatment facilities. The biosensor that has been developed relies on the discovery of the link between electrophile-induced GGKE and activated sludge deflocculation. Research has been concluded, which expands the role of GGKE and activated sludge deflocculation to include chlorine-induced GGKE. Through a series of laboratory-scale reactors, a relationship has been established between chlorine addition to control filamentous bulking, increased soluble K+ levels and an increase in effluent suspended solids . The results demonstrate that the addition of chlorine to control filamentous bulking may elicit the GGKE mechanism, initiating activated sludge deflocculation, similar to observations of chlorination at full-scale activated sludge wastewater treatment facilities. Establishing a mechanistic cause of deflocculation related to chlorination will permit operators to apply chlorine in a manner that may avoid deflocculation, rather than reacting to deflocculation after it has occurred. / Master of Science

The flow parameters involved in the transportation of sludge from the place of origin to the place of disposal has long been a problem to the sanitary engineer. To obtain the greatest efficiency in the design of pumps and pipelines the properties of sludge need to be thoroughly understood. This investigation examined the flow characteristic of raw and digested sludge from the Blacksburg Treatment Plant using a rheological approach. A Brookfield viscosimeter was used in the investigation and formulas developed by Krieger and Maron (1) were used to determine the shear stress and velocity gradient. A series of graphs involving shear stress vs velocity gradient were plotted. These graphs were compared to the Standard Newtonian and Non-Newtonian curves, in order to determine the flow behavior of the sludges. The results showed the method of analysis was satisfactory for determining the flow behavior of sewage sludges. The curves obtained showed that the raw and digested sludge examined was pseudoplastic in behavior and shear stress values for the domestic sludge showed it to be more viscous than the raw sludge. / M.S.

In this study, the effects of organics removal efficiency, oxidant dose, and alum dose on aluminum hydroxide sludge characteristics were assessed. In order to maintain control over operating parameters, a continuous-flow laboratory-scale plant was operated in the laboratory with daily monitoring of pH, as well as influent and effluent turbidity, total organic carbon, and color. Sludge thickening and dewatering characteristics were found to worsen when increasing amounts of organic matter were incorporated into the sludge floe matrix. Sludge properties improved with increases in oxidant dose and decreases in alum dose and alum/influent turbidity ratio. Changes in coagulation mechanism from sweep to charge neutralization were hypothesized to be partially responsible for changes in sludge properties caused by changing alum dose. Improvements in thickening and dewatering characteristics were found to be heavily dependent upon increases in sludge floe density, as well as decreases in aggregate water content. / M.S.