VTechWorks Repository :: Browsing by Author "Sherrard, Joseph H."

Browsing by Author "Sherrard, Joseph H."

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The 1986 amendments to the Safe Drinking Water Act : impacts on Virginia's water supply industry
Cox, William E.; Sherrard, Joseph H.; Gaw, Christopher D. (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1991-10)
Comparative phosphorus removals using modified activated sludge processes
Elliott, William Richard (Virginia Tech, 1977-10-05)
The operation of three continuous flow units as modified activated sludge models using mean cell residence time as a principal operational parameter has led to the following conclusions: 1. Lower mean cell residence times result in higher phosphorus removal efficiencies in biological reactors. 2. Higher mean solids residence times result in higher phosphorus removal efficiencies in strictly chemical reactors. 3. Calcium-phosphate precipitation can occur in continuous flow reactors in a normal activated sludge pH range (7.5-8.5) given sufficient Ca++ concentrations. 4. Calcium-phosphate precipitation can occur in the activated sludge process without hindering COO removal efficiency. 5. The phosphorus sludge content only exceeded the one to two percent range in the biochemical and chemical units, where phosphorus precipitation was the predominate phosphorus removal mechanism. 6. The anaerobiosis and acid stripping procedure, as used in this investigation, is not effective in enhancing either a biological or chemical unit's ability to remove phosphorus.
A comparison of oxygen utilization determination techniques for the activated sludge process
Stallard, Warren Michael (Virginia Tech, 1976-09-15)
Evaluation of the data from the series of batch experiments has led to the following conclusions: 1. Currently used methods of quantifying oxygen uptake rate, especially for batch reactors, yield values of oxygen utilization considerably lower than those predicted by mass balance considerations for these three wastes. In the face of Blok's published data indicating much better results with a short run reactor, it must be assumed that the length of run selected was at least partially responsible. 2. While quantitatively unsatisfactory, the methods for determining oxygen uptake used in these experiments seem to be of some use as monitors of biological systems. Changes in slope of the oxygen utilization curve were found to be more apparent at lower loadings.
Corona switching: an osmogene mitigation technique
Atkinson, R. Dwight (Virginia Polytechnic Institute and State University, 1988)
Odorous gases such as hydrogen sulfide have long been associated with wastewater treatment plants, especially those with long forced mains which allow septic conditions to develop. With the encroachment of urban and suburban populations, many wastewater treatment plants are no longer located far enough from residential areas to prevent odor problems. This has lead to renewed efforts to develop odor control techniques. The application of high energy coronas as a means to oxidize odorous gases has been limited by the relatively small size of the corona region around a given charged wire, approximately 1 centimeter at an applied voltage of 35 kilovolts. Attempts to enlarge the effective corona region by spacing wires such that their coronas would overlap have failed due to corona extinction, the destructive interference of the electric fields surrounding adjacent charged wires. This study demonstrates that corona extinction can be avoided in a system of closely spaced wires flanked by grounded plates if the wires are energized individually instead of' simultaneously. By employing a rapid load-switching technique an essentially continuous corona sheet can be produced. A bench-scale device utilizing the rapid switching principle was constructed and its ability to remove odorous gases, including hydrogen sulfide, was demonstrated. The influence of parameters such as flowrate, inlet concentration, switching frequency, temperature, and humidity on removal efficiency was evaluated.
Curbside collection of recyclable materials: fifteen cases studies in the United States
Waterman, Donna Ruth (Virginia Tech, 1988-03-01)
Fifteen curbside recycling programs in the United States, from communities representing a variety of economic, geographic and political situations, were reviewed in this study. Case studies were analyzed and discussed with respect to four areas of interest to program planners: administration, operations, promotion and evaluation. No objective rating of the programs was attempted, but approaches were reviewed with respect to their ability to satisfy the goals of the programs. Comparisons of participation rates, waste diversion rates, and costs were used cautiously because of the inconsistencies in how the data were developed from program to program. Administrative approaches found in the case studies included: (a) complete ownership of the collection and processing system by municipalities; (b) contracted service by private waste management firms; (c) contracted or subsidized service by non-profit organizations; and (d) combinations of municipal, private, and non-profit services. Operational systems were examined with respect to the effectiveness of the service in stimulating participation, given the practical, political, and budgetary constraints. Variables of operation are closely related and include: (a) which materials are collected; (b) the degree of materials separation required; (c) the type of collection vehicle(s) used; (d) collection frequency and coincidence with garbage collection; (e) the provision of in home containers; and (t) the extent of post-collection materials processing. Four categories of promotional techniques used in curbside recycling programs were discussed: (a) publicity and education; (b) personal contact; (c) economic incentives; and (d) ordinances mandating source-separation. The impacts of these techniques on participation in the case study programs were discussed. Techniques for evaluating the efficacy of curbside recycling programs were also discussed. Participation rates, waste diversion rates, and cost were reviewed with respect to current usage and recommendations were made for increasing their usefulness as indicators of the success of programs or program elements.
The economic impacts of the 1986 Safe Drinking Water Act amendments
Gaw, Christopher D. (Virginia Tech, 1991-12-05)
During the early 1980s, concern over the poor quality of the nation's drinking water began to arise. Though the Safe Drinking Water Act (SDWA) had been passed almost a decade earlier, many problems still existed. These problems included the inability of the Environmental Protection Agency to promulgate new drinking water standards and to enforce new and existing standards. To address the shortcomings of the original act, Congress passed the 1986 SDWA Amendments. This document attempts to accomplish two main goals. The first is to summarize selectively the requirements of the 1986 Safe Drinking Water Act (SDWA) Amendments as reflected in proposed and finalized drinking water regulations. The areas of coverage include proposed regulations for eight inorganic and thirty synthetic organic chemical contaminants, the Surface Water Treatment Rule (SWTR), and the Total Coliform Rule (TCR). In order to facilitate an understanding of the SDWA and the 1986 Amendments, a sectional analysis was provided in an appendix. The second goal of this document is to assess the economic impact of this legislation upon Virginia water facilities. In this regard, the cost of water treatment technologies whose use will likely increase as a result of the legislation have been estimated, compiled, and documented. These technologies include granular activated carbon (GAC); reverse osmosis; ion exchange; and various aeration, filtration, and disinfection technologies. Several case studies that assess and highlight the direct impacts of the 1986 SDWA Amendments upon Virginia water facilities are presented.
The effects of nickel on the completely mixed activated sludge process
Sujarittanonta, Suthirak (Virginia Tech, 1979-04-05)
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.
Evaluation of alternative pretreatment methods for use in direct filtration water treatment
Eberly, Harold Thomas (Virginia Tech, 1977-08-15)
The purpose of this study was to evaluate the performance of alum alone, alum in conjunction with a polymeric coagulant aid, and a primary coagulant polymer in the coagulation-flocculation-sedimentation portion of a water treatment process and to study the implications of the results with respect to future use in direct filtration. The performance of the coagulant, coagulant aid, and primary coagulant polymer was evaluated by altering the flocculation and sedimentation retention times in the pretreatIDEnt process chain. Among the water quality parameters monitored were turbidity, pH, total alkalinity, total hardness, and total solids. A brief literature review for direct filtration and coagulation-flocculation theory was also conducted. The results of this investigation indicated that reduced retention times in the pretreatment process chain treated the selected raw waters sufficiently to enable consideration of direct filtration a viable treatment alternative. Analysis of data obtained indicated the use of polyelectrolyte as a primary coagulant or coagulant aid produced a pinpoint floc which is essential to successful utilization of direct filtration and that the floc formed settled more rapidly than floc from use of aluminum sulfate alone. The use of a polyelectrolyte as a primary coagulant or coagulant aid also reduced the chemical dosages required to provide appropriate turbidity removals.
An evaluation of carbon monoxide and methane as substrates for the denitrification of water
Gayle, Benjamin P. (Virginia Tech, 1990-03-05)
This study involved the use of soil and suspended growth microcosms to study the variation in groundwater denitrification rates using different substrates. Two gaseous substrates, carbon monoxide and methane, were studied and compared to a common liquid substrate, methanol. Denitrification with carbon monoxide as a substrate was achieved using an acclimated seed of mixed activated sludge and anaerobic digester sludge. Kinetic studies of denitrification using carbon monoxide suggested a strong substrate inhibition effect. The observed maximum denitrification velocity of 0.026 mg N/d-mg VSS occurred at a carbon monoxide partial pressure of 0.10 atmospheres (2.8 mg/ℓ). At higher carbon monoxide partial pressures, denitrification velocities decreased. The denitrification velocities at various carbon monoxide concentrations were described by a modified form of the Haldane substrate inhibition model. The biomass yield using carbon monoxide was 1.1 mg VSS/mg VSS, the maximum specific growth rate was 0.03 mg VSS/d-mg VSS, and the half velocity constant was 26 mg-N/ℓ. Denitrification rates using carbon monoxide as a substrate were much slower than those obtained using methanol, and the cost of carbon monoxide was much higher. Denitrification occurred readily, when methanol was provided as a substrate, in microcosms containing either a clay soil, a sandy soil, or activated sludge. Under the conditions of this study, denitrification was not achieved in clay soil or sandy soil microcosms using methane or carbon monoxide as substrates. Denitrification was not achieved using methane as a substrate with an activated sludge seed.
An evaluation of the relative importance of technical and non- technical factors which affect water and sanitation projects in developing countries
Billings, Richard (Virginia Tech, 1989-07-15)
Technical factors, such as engineering and medical approaches, and non-technical factors, such as education and community participation, were evaluated with regard to how they affect water and sanitation programs. Benefits and limitations of each factor were assessed to determine which limitations significantly impact the effectiveness of programs. With this appreciation of technical and nontechnical factors, case studies of control methods of different diseases were evaluated. This led to recommendations of appropriate mixes of technical and non-technical services for disease control. This evaluation was utilized to develop a planning approach to effectively integrate interagency efforts for the control of multiple diseases.
Federal, state, and local government interactions in the administration of wetland protection measures in Virginia
Cunningham, Laura Lynn (Virginia Tech, 1988-02-05)
The objective of this thesis is to determine the effectiveness of Federal, state and local government interactions in administration of tidal wetland protection measures in Virginia. Federal protection for wetlands is authorized by the Clean Water Act [33 U.S.C.A. 1251 et seq. (1986), as amended (Supp. 1987)] and the Rivers and Harbors Act [33 U.S.C.A. 401 et seq. (1986), as amended (Supp. 1987)]. State and local authority is provided by the Virginia Wetlands Act [Va.Code Ann., sec. 62.1-13.1 et seq. (1987)]. Because of overlapping jurisdictions of the statutes, Federal, state, and local governments must interact while implementing wetland protection programs. Effective interactions between the various levels of government are important for the preservation and protection of tidal wetlands. If the three levels of government are able to efficiently administer a program that provides adequate protection of wetlands, similar programs may be applied in other areas such as non-point source pollution control. A history of the development of the wetlands protection program is presented along with a description of applicable statutes, regulations, and permitting requirements. Included is an analysis of the implementation of the wetland statutes by case studies of program operations, a comparison of decisions on applications made by the three different government agencies, and identification of impacts and future trends of the wetland protection programs.
Floc density measurement and the effects of microproperty variations on sludge dewatering characteristics
Dishman, C. Michael (Virginia Tech, 1988-12-05)
The dewatering characteristics of sludges produced by water and wastewater treatment plants bear heavily on the methods chosen to treat and dispose of the sludge, as well as on the costs associated with handling the large volumes of sludge produced at these facilities. This study investigated why different sludges dewater to different dry solids concentrations, how sludge structure affects dewatering, and how sludge structure changes during gravity thickening and during different types of mechanical dewatering. It is generally thought that sludge can be described as having a three-tiered structure: (1) primary particles, (2) floc particles, and (3) aggregate particles. To investigate sludge structure in relation to sludge dewatering, this study has defined sludge structure using several sludge particle micro properties. A laboratory technique incorporating isopycnic centrifugation in gradients of Percoll^R media was developed to measure one micro property known as floc particle density. Six field and laboratory sludges were subjected to a series of dewatering tests: gravity thickening, centrifugation, and vacuum filtration. Each sludge was analyzed for macro- and micro properties through each stage of dewatering. It was concluded that improvements in thickening and dewatering characteristics were heavily dependent upon increases in sludge floc density and decreases in aggregate water content.
A laboratory study of solidification/stabilization technology for contaminated dredged material
Betteker, James Michael (Virginia Tech, 1986-03-05)
Safe disposal of contaminated dredged material has become a significant issue especially as public environmental awareness and concerns increase. Solidification/ stabilization technology potentially may provide for a safer, more effective and more economical means of disposal. This research investigated the technical feasibility of applying solidification/stabilization technology to contaminated sediment from Indiana Harbor Canal, Indiana. Specifically, physical strength and reduction of chemical leachability resulting from solidification/stabilization A with various cement based, pozzolanic, and proprietary additives were analyzed. Also investigated was the immobilization capability of a proprietary polymer for selected organic contaminants when used in conjunction with solidification/stabilization processes. Physical strength is an important parameter in determining the ultimate bearing capacity, stability of embankments and pressure against retaining walls. Physical stabilization of contaminated dredged material is a viable treatment option. Application of cement-based and pozzolanic—based processes uses the sediment moisture to form hydration products, therefore dewaterimg is not required. All process formulations produced a solidified sediment.
Long-term effectiveness and maintenance of vegetative filter strips
Dillaha, Theo A. III; Sherrard, Joseph H.; Lee, Dowon (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1986)
Vegetative filter strips (VFS) on 33 Virginia farms were visited and observed over a 13-month period to evaluate their long-term effectiveness for water quality improvement. Operational problems observed during the site visits were documented and design or maintenance procedures to alleviate the problems were evaluated. Of the VFS observed, 36% were judged to be totally ineffective, were no longer in existence, or were simply extensions of pastures - although all were, or had been, part of the state cost-share program. Most of the sites visited had topographic limitations which severely limited VFS performance. Accumulation of surface runoff in natural drainageways within fields before it reached the VFS was the most common and critical problem. Runoff from the drainageways crossed the VFS in a few narrow areas, totally inundating the filters and rendering them ineffective for sediment and nutrient reduction. This situation is difficult to control and VFS are probably not appropriate for fields with extensive internal drainageways unless the VFS extend up into the fields and parallel the drainageways forming wide grassed waterways. Vegetative filter strips were judged to be beneficial even when they could not filter sediment and nutrients from runoff because they provided localized erosion protection in critical areas along streambanks. They did not act as filters, however, and should therefore be referred to as vegetative buffer strips or critical area plantings.
Petroleum refining and air quality management
Abdullah, Abdul Hamid (Virginia Tech, 1985-08-15)
Management of the air quality surrounding Petroleum Refineries deserves attention because the industry contributes almost five percent of the total emissions from all anthropogenic sources. A document containing a complete set of guidelines for use in the refining industry which satisfies the current and anticipated air quality legislations and regulations in the U.S. is necessary. In the past, several documents have been prepared, but have not included a complete coverage of the air quality management as currently needed. Furthermore, due to the continuing revisions of the Clean Air Act, a document with current, updated regulations and air quality management principles is necessary. This study dealt with a broad range of topics including characteristics of emissions, control technology applied, regulations and legislative issues, monitoring and modeling practices, and issues of the 1980s together with future projections and implications. Air quality regulations and standards are periodically revised and are becoming more stringent with time. Issues like acid rain may lead to even more stringent emission standards if investigations carried out currently reveal that the refineries are significant contributors. Great measures are taken to control emissions from the refineries either by using good control equipment or using other alternative control strategies. Small operating refineries are closing down due to changing conditions. An agglomeration and or expansion of the existing refining capacity is occuring. The air quality trends associated with this transition in the industry are discussed.
Phosphorus readsorption on Occoquan sediments
Shugart, Steven Lee (Virginia Tech, 1976-03-05)
The purpose of this investigation was to determine the extent of phosphorus readsorption on Occoquan sediments and the amount of subsequent removal because of settling of the particles with time. Occoquan sediments were placed in six polyurethane cylinders and submerged. In two separate experiments, the cylinders were driven anaerobic, which allowed phosphorus, previously bound in the sediments, to release. The sedimentâ water system was then reaerated and mixed with a porous air diffuser. Analyses were conducted before and after the mixing period. From the results obtained, the following conclusions were drawn: phosphate readsorption occurred upon mixing the system, and as the turbidity decreased, the phosphate concentration decreased; phosphate readsorption occurred in a two-step process; each suspension tended toward equilibrium after mixing; interstitial waters contributed significant amounts of phosphorus upon mixing of the sediment-water systems; Occoquan sediments released variable amounts of phosphorus even within samples from similar sites; sediments from the Occoquan Creek arm contained less phosphorus than Bull Run sediments; and sediments low in phosphorus concentrations removed greater amounts of phosphorus in a shorter period of time.
Precombustion desulfurization of coal by photochemical methods and pyrite depression in froth flotation
Stallard, Michael L. (Virginia Tech, 1990)
The precombustion desulfurization of coal was investigated by photochemical methods and by the application of a novel pyrite depressant in froth flotation. Semiconductor photoelectrochemical catalysis was extensively examined. As much as 41% of the organic sulfur was removed and 72% overall desulfurization of micronized Illinois No. 2 coal was obtained. Zinc oxide, in colloidal suspension, produced a small increase in the overall desulfurization at longer reaction times when compared to direct photolysis. The major limiting factor in organic sulfur removal from coal appears to be accessibility rather than reactivity. Kinetic experiments conducted with the model organosulfur compound, dibenzothiophene, showed high photochemical reactivity with nearly complete conversion occurring in 5 minutes in a saturated solution at 25°C. Scanning electron microscopic examination of product coals showed empty casts in places once occupied by iron pyrite. Additionally, a novel process was developed for separating clean coal from metal sulfide minerals such as pyrite and marcasite. The process comprises depressing the metal sulfide minerals with a reagent resulting from the alkaline oxidation and polymerization of a polyphenol or a quinone, and selectively floating clean coal from the depressed metal sulfide minerals. The process was investigated using microflotation, conventional Denver cell flotation, and microbubble column flotation. Up to 90% pyritic sulfur rejection was achieved from a coal and coal pyrite synthetic mixture. The process efficiency is a function of pH with greater improvements generally occurring at acidic pH when compared with the results obtained in the absence of the quinonoid reagent. However, in the case of microbubble column flotation with micronized coals, the largest overall pyritic sulfur and ash rejection occurred under alkaline conditions. Data from x-ray photoelectron spectroscopy and calorimetry indicate the quinonoid reagent modified the surface properties of minerals by reversible adsorption.
A productivity study of the Roanoke River above Niagra Dam in Virginia
Sherrard, Joseph H.; Hoyle, Joyce L. (Water Resources Research Center, Virginia Polytechnic Institute and State University, 1977)
Deterioration of the water quality in the upper end of the Roanoke River of Smith Mountain Lake due to eutrophication has caused much concern. The Smith Mountain Lake impoundment was constructed in 1965 as a pump storage facility to generate electrical energy and has served as a major recreational area for Southwestern Virginia. Eight sampling stations were established along the length of the Roanoke River from an agricultural area in Montgomery County through the urban area of Roanoke-Salem to Niagra Dam above Smith Mountain Lake. On 12 different occasions, approximately once a month, grab samples. were taken at the sampling stations. Samples were analyzed for general chemical parameters and for nitrogen and phosphorus. The Algal Assay Procedure Bottle Test [Environmental Protection Agency, 1971] was conducted with the samples, and in addition, with samples in which phosphorus and/or nitrogen spikes were added to determine potential productivity and to determine which element was limiting productivity. ResuIts of this investigation demonstrate that the algal assay bottle test is usefuI in correlating phosphorus concentrations with algal growth rate. Phosphorus was found to limit the algal growth in the Roanoke River above the Roanoke wastewater treatment plant for Selenastrum capricornutum and Anabaena flos-aquae, the two algal species used in this study. Maximum specific growth rates tended to increase with in- creasing phosphorus concentration.
Removal of organic contaminants from groundwater by reverse osmosis
Robinson, Michael A. (Virginia Tech, 1990)
The performance of a poly(ether/urea) membrane has been evaluated in a full scale reverse osmosis system. A series of experiments were conducted with six aromatic compounds - anthracene, pyrene, fluorene, 2-chlorobiphenyl, 2,4,6 trichlorophenol, and pentachlorophenol- and four volatile compounds - trichloromethane, bromodichloromethane, dibromochloromethane, and trichloroethene - as single and multi-solute contaminants. The objectives of the experiments were to determine if poly(ether/urea) membranes could produce a permeate that met maximum contaminant levels (MCL) set by the Safe Drinking Water Act (SDWA) and to correlate membrane performance with physical/chemical properties of the solute contaminants. Aromatic contaminants were removed to concentrations below the current MCLs. However, volatile contaminants were not sufficiently rejected by the membrane to meet either the MCL for total trihalomethanes or trichloroethene. Sorption onto the poly(ether/urea) was found to occur for several of the aromatic compounds tested in this research. This prevented developing any relationship between membrane performance and physical/chemical properties of the solute.
The removal of pesticides and heavy metals by reverse osmosis
Chong, Brian S. H. (Virginia Tech, 1990-03-10)
In the past few years, the contamination by pesticides and heavy metals in surface water and groundwater has increased. Reverse osmosis is a unit process that has demonstrated capacity to remove dissolved pesticides and heavy metals from aqueous solution, and it is therefore worthwhile to consider this treatment process as a potential removal technique for hazardous constituents. The purpose of this investigation was to determine the effectiveness of a field scale reverse osmosis unit, with a spiral wound poly(ether/urea) membrane, in removing pesticides and heavy metals from a contaminated source. The removal efficiency for a single contaminant alone and a part of a mixture was examined. The performance of new and used membranes over time was also investigated. The average removal of pesticides was better than 99 percent. Reverse osmosis separation of pesticides was found to be dependent on the characteristics of the membrane and the physical/chemical properties of the pesticides. Pesticides in the mixed solution were found to behave independently. Sorption of the pesticides onto the reverse osmosis membrane was found to play a major role in the overall removal efficiency. Better than 99 percent average removal was achieved for all the metals except arsenic. The importance of the physical/chemical properties of the metal ions such as solubility, ionic radius, and electronegativity were determined. In tests to compare removal efficiency between new membrane and membrane which had been used, virtually no differences occurred.

Browsing by Author "Sherrard, Joseph H."

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