This study was an extension of a project conducted by Cech and Hartman (1991) at the Academy of Sciences Laboratories in Ceske Budejouice, Czechoslovakia. During the 1991 study, an unidentified bacterial species dominated a biological phosphorous removal (BPR) system, causing the system to fail. The study indicated that feed composition may have been responsible for the bacteria population shift. The purpose of this study was to examine population shifts of polyphosphorous-removing (PP) bacteria and the unknown bacteria (G bacteria) in a bench-scale sequencing batch reactor (SBR), with emphasis on the effects of feed composition on the populations. The purpose of the study also included characterization and identification of the unknown bacterial species. Six SBRs were operated for three 8-hour cycles per day, over a time period greater than three sludge ages. Each 8-hour cycle included an influent/anaerobic, anoxic, aerobic, and settling/effluent stage. Different feed mixtures of acetate, glucose, and nutrient broth were fed to the reactors. Chemical and physical parameters were tested during each stage of an 8-hour cycle weekly, in addition to microscopic analysis of PP and G bacteria. The results of this study indicated that feed composition did not have as significant an effect on PP and G bacteria as hypothesized. G bacteria did not always dominate a system fed a glucose mixture, nor did PP bacteria always dominate a system fed only acetate. In terms of P-removal, bacteria numbers of either PP or G bacteria were not always indicative of P-removal in the reactor. Instead, the size of the PP cells and the amount of phosphorous inside the cells were better indicators of P-removal. G bacteria did not appear to be a controlling factor in PP population size; the reverse appeared to be true. Temperatures above 25C did have an adverse effect on G bacteria, and a positive effect on PP bacteria. No identification in terms of genus and species could be determined for the G bacteria. / Master of Science

The purpose of this study was to investigate selective operational parameters and their effect on activated sludge settling and dewatering rates. Several laboratory scale reactors were used in this study and fed with various synthetic substrates. The sludges produced from these reactors were used to examine sludge settling and dewatering characteristics as the selected operational parameters were varied. This study intended to determine if: (1) qualitative shock loadings affect sludge dewatering and settling and will biological systems recover quickly under various conditions; (2) aeration basin dissolved oxygen concentration affects sludge settling and dewatering characteristics; (3) biopolymer content can be correlated with sludge dewatering rates such that biopolymer content can be used as a parameter to monitor sludge dewatering characteristics. Results from this study indicated that the shock loadings considered here significantly alter the sludge settling and dewatering characteristics of an activated sludge population. Shock loadings may cause shifts in the bacterial population, allowing undesirable microorganisms to predominate but activated sludge systems can recover from shock loadings caused by the introduction of a different substrate. Also, it was seen that activated sludge dewatering is directly affected by the dissolved oxygen level in the aeration basin and the minimum level required is 2.0 mg/L in a completely-mixed system. A definite relationship was noted between biopolymer production and sludge dewatering with high biopolymer content correlating with poor sludge dewatering and low biopolymer content correlating with good sludge dewatering. / Master of Science / incomplete_metadata

The activated sludge (AS) process used for treating high-strength cellulose acetate wastewater of Celanese Corporation, Pearisburg, Virginia, produces a sludge with poor flocculation and settling characteristics, particularly during the periods of shock organic loadings. Pilot-scale treatment units were set up to study the effects of a fixed film pretreatment on the stability of the AS process, using a new type of trickling filter (TF) media consisting of long plastic strips. The pretreated activated sludge (PAS) unit was compared with a control activated sludge unit (CAS). Different hydraulic and organic loadings were applied to the TF. The study confirmed the ability of a TF to provide greater stability to subsequent AS processes during periods of shock organic loading. The TF did not significantly improve the PAS system effluent quality and organic removal performance, even though the PAS sludge had better settle ability in terms of Sludge Volume Index and had less filamentous growth than the CAS system. The TF pretreatment confirmed its ability to act as a roughing filter. During the study, it reduced the organic loading on the AS system by 26 to 43 %, oxygen requirement of AS system by 38 to 62 %, the aeration volume requirement by 17 to 47 %, and the sludge production by 0 to 37 %. The PAS system required fewer nutrients than the CAS system. / Master of Science

Combined activated sludge-fixed film media treatment systems are an interesting innovation in treatment technology. By adding media into the aeration basin, increased biomass concentrations may be maintained with little or no increase in solids loading to the clarifier. The ideal combined system can treat higher organic and ammonia loadings than a conventional system, and is more resistant to temperature changes and shock loadings. Overloaded plants can be outfitted with media as an alternative to plant expansion, and initial designs of combined systems can result in smaller aeration basins and clarifiers in places of land scarcity. / Master of Science

The purpose of this research was to design, fabricate and test a 1 liter per minute pilot plant with a cascading sequence of continuously stirred tank reactors. The object of the research was to chemically decolorize selected reactive-dye bath concentrates resulting from exhaustive dyeing, and to remove metals and DOC using Fenton's Reagent or the reductive chemicals, thiourea dioxide and sodium hydrosulfite. For the Fenton's Reagent studies, ferrous sulfate was premixed with the dye waste concentrate before overflowing to the first reactor. A feedback control system based on color remaining in the discharge was used to regulate reactants added. Transmittance was measured at several wavelengths (590, 540, and 438 nm) and the American Dye Manufacturers Institute (ADMI) value calculated. The results demonstrated that ADMI measurements could not be made on dark solutions (over 3000 ADMI) in the pilot plant and, typically, one wavelength was used for control. DOC removal was used as a means of determining the biological activity in aerated reactors following color removal. The initial pilot plant studies were conducted using Navy 106 jet-dye waste. Reductive pretreatment with thiourea dioxide resulted in 92.2% color removal with color returning upon aeration for an overall color removal of 76.6%. Oxidative pretreatment with Fenton's chemistry resulted in 98.8% color removal with overall color removal after aerobic treatment at 96.8%. Dissolved Organic Carbon (DOC) removal in aerobic treatment improved with oxidative pretreatment relative to reductive pretreatment on Navy 106 jet-dye concentrate. On site operation of the pilot plant on other dye wastes showed color removals above 95% and DOC removals of 38% and 19% for an azo-based red dye waste concentrate and a copper-phthalocyanine-based dye, Ming Jade, respectively. The soluble copper concentration in the Ming Jade was decreased from 19.2 ppm to 4.5 ppm. This corresponded to a 3-fold increase in suspended solids from 0.575 g/L to 1.505 g/L. The results showed that continuous oxidative pretreatment with a 15-minute residence time was controllable and more effective than reductive treatment for color removal. Oxidative pretreatment also decreased the soluble copper concentration in a copper containing waste water, and did not hinder biological activity. / Master of Science

M.S.

A debate currently exists concerning whether or not oxygen uptake rate is a valid control parameter for monitoring the activated sludge process. A laboratory study was conducted to attempt to shed light on the controversy. Two bench-scale reactors were operated at steady state and under shock load. Oxygen uptake rate (OUR) was measured with the BOD bottle technique and with an on-line respirometer. The reliability of the results obtained from the BOD bottle technique was also of interest. No relationship could be deduced between effluent quality and oxygen uptake rate thereby suggesting that the latter would not be useful as a control parameter. As was concluded from the shock load data, the oxygen uptake rate varies very inconsistently at high organic loadings. It was found that the BOD bottle technique completely failed at very high organic loadings and gave meaningless results. The on-line respirometer, in spite of its high sensitivity, gave more realistic and consistent results. / M.S.

An investigation was conducted using in situ lysimeters (1.5 m x 2.3 m) to determine Cd, Cu, Ni, and Zn availabilities for barley (Hordeum vulgare L.) and corn (Zea mays L.) grown on four sludge-amended soils. These lysimeters were constructed in Acredale silt loam (Typic Ochraqualf), Bojac loamy sand (Typic Hapludult), Davidson clay loam (Rhodie Paleudult), and Groseclose silt loam (Typic Hapludult) soils. An aerobically digested sewage sludge from a sewage system with major industrial inputs was applied at rates of 0, 42, and 84 dry Mg ha-t to the lysimeters in the poorly-drained Acredale soil. Rates of 0, 42, 84, 126, 168, and 210 dry Mg ha-1 were applied to the lysimeters in the well-drained Bojac, Davidson, and Groseclose soils. Tissue metal concentrations were determined in 1984 and 1985 for a three crop rotation, which consisted of corn, barley, and corn on the Acredale soil. Increases in sludge-borne Ni and Zn led to increases in Ni and Zn concentrations in corn earleaf, corn grain, and barley silage. Copper concentration was increased in barley silage but not in corn grain and stover. On this poorly-drained soil, metal movement did not occur below the Ap horizon even when Cu was applied in excess of USEPA guidelines. Although there were increases in metal levels, all four metals were within the range considered normal for corn and barley growth. Soil, corn, and barley plants were sampled in 1984 and 1985 to determine Cd, Cr, Cu, Ni, and Zn availabilities for crops grown on the sludge-amended Bojac, Davidson, and Groseclose soils. Levels of DTPA-extractable Cd, Cu, Ni, and Zn in the Ap horizon of these soils increased linearly with sludge rate. Corn grain and stover yields were not decreased on the Bojac, Davidson, and Groseclose soils when 4.5, 5105, 760, 43.0, 135, and 620 kg ha-1 of Cd, Cr, Cu, Ni, Pb, and Zn were added as a sludge-amendment. Copper and Zn applied in excess of 480 and 60 kg ha- 1 of USEPA guidelines, respectively on the Bojac, Davidson, and Groseclose soils were not phytotoxic to corn plants in 1984. Corn and barley tissue sampled for three consecutive seasons had Cr concentrations <2.8 mg kg-1. / Ph. D.

The effects of varied concentrations of a natural sewage grease on the oxidative activities of activated sludge were investigated in an effort to determine the feasibility of using activated sludge as a treatment method for wastes high in grease content. The method employed to measure the oxidative activities of the activated sludge was the standard Warburg respirometer technique. Cumulative net BOD curves were plotted to determine the magnitude of the oxidation. Total grease analyses were performed throughout the test period to establish a definitive pattern of depletion by oxidation. The experimental results indicated that the grease was completely assimulated within 24 hours and that there were no adverse pH changes during the course of oxidation. On the basis of the experimental evidence activated sludge shows great promise as a treatment method for wastes high in grease content. / Master of Science

Wastewater samples were collected from both the secondary settling and the chlorine contact tanks at a secondary sewage treatment plant (trickling filter) in Blacksburg, Virginia and analyzed for fecal coliforms using three procedures. Physical parameters including total suspended solids, DO, pH, turbidity, temperature and total chlorine residual were measured in effort to ascertain their effect on fecal coliform recoveries. The three procedures employed included the multiple-tube fermentation technique that yields the most probable number (MPN), the standard MF technique (SF-MF), and a modified MF technique (IF-MF) which consisted of a lactose overlay and a 5-hour incubation period at 44.5°C. A statistical analysis of the data showed that the means of the recoveries by the IF-MF technique were significantly greater (0.01 level) than those by the SF-MF technique in both the secondary settling tank and the chlorine contact tank samples. Recoveries by the IF-MF technique were comparable to those by the MPN technique when samples from the secondary settling basin were analyzed, but not in samples from the chlorine contact tank. However, the means of the IF-MF recovery procedure were within the 95 percent confidence interval associated with the MPN. No relationships could be established between the observed variations in the physical and chemical characteristics of the treated sewage samples and the fecal coliform densities. / Master of Science