When continuous monitoring devices such as the electrolytic respirometer are used for performing biodegradation experiments, cumulative data are acquired. The structure of these observations limits the reliable application of existing methodologies for analyzing cumulative respirometric biodegradation trends, because the resulting error terms are likely to be highly autocorrelated. To overcome these limitations it is proposed that the Oxygen Uptake Rate (OUR) should be used as the data source for further analysis, because the dependence of the error terms is then removed. To model uniform reaction rate respirometric biodegradation OUR data trends, 1st and 2nd-order OUR models are proposed. Theoretical and practical assessment of these models in comparison with their cumulative counterparts indicates that (a) they are likely to have improved nonlinear behaviour, (b) their parameters will have more reliable confidence interval estimates, and (c) the optimal duration of an experiment performed to estimate the OUR model parameters is shorter compared to that required for estimating similar parameters in the case of cumulative biodegradation data. During respirometric biodegradation studies, data trends with distinct microbial growth periods often appear as well. In order to describe such observations a new diphasic OUR model is proposed, which provides valuable information for each phase in the form of 1st-order reaction rate coefficients and the duration of the first phase. Application of this model to a number of data cases indicates that this model can be regarded as a practical alternative for modelling diphasic respirometric data trends. A similar conclusion was drawn for a proposed two-stage respirometric biodegradation model. In the present study an approach is also suggested for performing statistical comparisons between biodegradation curves which have been obtained under different experimental conditions. This approach is based on the proposed OUR models, t

Four type of suspensions were dewatered by electroosmosis alone or by electroosmosis combined with other methods: (1) Clay (Bentonite or hydrocol)--electroosmosis with constant voltage continuous DC or square wave interrupted power. In the interrupted mode, a constant voltage was applied for t$ sb1$ seconds (the on-time) followed by a short circuit for t$ sb2$ seconds (the off-time). (2) Food waste--electroosmosis (continuous DC only) alone or in combination with expression (pressure of 207 kPa). (3) Titanium oxohydrate slurry--electroosmosis (similar to (1)) alone or in combination with a vacuum (absolute pressure of 89 kPa). (4) Pyrite slurry--electroosmosis (similar to (1)) in combination with vacuum (similar to (3)). The major independent variables were applied voltage, t$ sb1$ and t$ sb2,$ and initial bed height. The dependent variables were the amount of water removed and the electric current. / For clay and titanium oxohydrate there was an optimum off-time for a fixed on-time. For $ rm t sb1=30$ s, the most water was removed from clay with $ rm t sb2=0.1$ s while for titanium oxohydrate the most water was removed for $ rm t sb2=3.5$ s. For suspensions (2), (3) and (4), the combination of electroosmotic dewatering with vacuum or expression increased the amount of water removed. In general, interrupted power removed more water than continuous power electroosmosis. For suspensions (3) and (4), only the combined modes were able to achieve dewatering targets set by industry.

This paper investigates the effects of water quality parameters on fouling rates of UV lamp sleeves, through the results of various published studies performed by different groups as well as by the author. / As part of this study, a pilot UV system was installed at the effluent line of two different biological wastewater treatment plants. The first plant included biofilters supplemented by alum addition during the summer for phosphorus removal. The second plant used an oxidation ditch and no coagulants were added. Iron was added to the UV pilot system influent in both cases to simulate post-coagulation of phosphorus. The Trojan UV System 3000 pilot consisted of three separate channels each containing 2 lamps. Two channels were used as controls by having just the sleeves (without UV lamps) in one of them and non-UV lamps (i.e. lamps with visible light output only) in the other. The third channel contained sleeves with two low-pressure UV lamps. The flow in each channel was maintained around 1--1.5 L/s and the ferric chloride concentration was varied from 0 to 6 mg/L. (Abstract shortened by UMI.)

A Fixed-Film Pressurized Tubular Bioreactor (FFPTB), which used the inner surface of a tube as the support surface, was evaluated under laboratory conditions to treat synthetic wastewater where glucose was used as the carbon source. Dissolved oxygen (DO) at the entrance of the tube was supplied in proportion to the influent chemical oxygen demand (COD) or total organic carbon (TOC) through a pressurized dissolution tank where compressed air or oxygen from a liquid oxygen cylinder was applied. Key variables included tube length and diameter, liquid flow rate, initial organic strength and gas pressure. / The bioreactor was a coiled tube, 15 to 30 m long and 6.4 or 8 mm in diameter. It was a closed system operated under pressure at constant temperature (20$ sp circ$C) and pH (7.0). The hydraulic retention time (HRT) in the gas dissolution tank was 13 minutes, and the pressure applied was 210 to 350 kPa. The tube HRTs ranged from 16 to 38 minutes, and organic loadings from 2.29 to 11.46 g COD/m$ sp2$-d (the area being the inside surface area of the tube), depending on the liquid flows and initial waste concentrations. / The FFPTB performed well (80-85% organic removal) under COD loadings of up to 7.64 g/m$ sp2$-d at relatively short HRTs (40-45 minutes) using the compressed air supply. When pure oxygen was used, the raw wastewater with an initial COD varying between 80-120 mg/L could be treated with even higher efficiency (90-95% organic removal). / It was observed that the COD, TOC and DO decreased dramatically over the initial portion of the tube, then decreased more slowly. Biofilm thickness along the tube varied in similar fashion, with the greatest thickness (350-750 $ mu$m when the compressed air was used, and 1,900 $ mu$m with the pure oxygen supply) registered at the beginning of the tube and decreasing to 90 to 345 $ mu$m at the end. The biofilm thickness at the beginning of the tube was found to be proportional to the initial strength of the wastewater used. Furthermore, as the influent substrate concentration increased, the pressure had to increase appropriately to maintain a sufficient DO level for aerobic respiration in the system. The application of elevated pressures appeared to reduce the thickness of the liquid diffusion layer, thereby increasing the mass transfer rate, and consequently increasing the substrate utilization rate in the biofilm. / Besides the experimental investigations, a mathematical model based on Monod-type kinetics, molecular diffusion, liquid layer mass transport, bacterial growth and decay as well as shear stress under steady-state conditions was developed and verified for the FFPTB. Based upon numerical simulations, for a given bulk substrate concentration, the model would give a solution for substrate flux into the biofilm and predict the TOC concentration along the tube. The model was also able to predict the biofilm thickness along the tube with reasonable accuracy. / The system appears to be particularly suitable for high rate treatment of wastewaters, especially at low initial concentrations and for small systems. The high level of efficiency of the system could be achieved with short detention times and confined gaseous emissions as well as a low production of sludge.

It is known that the use of batch experiments for the estimation of kinetic coefficients is a better alternative than continuous flow reactors, in terms of the time needed to perform the experiments. / In this study a new methodology to estimate the four Monod-kinetic parameters from batch reactor data set is presented. This method fits biomass and substrate plots simultaneously via nonlinear least-squares analysis. The nonlinear equations are solved via the secant method. / The methodology performed satisfactorily with two synthetic data sets. It was also applied to seven batch reactor data sets available in the literature and to ten data sets from batch experiments using wastewater and sludge from the municipality wastewater treatment plant in Granby, Quebec. The constants estimated vary considerable among themselves, and some were not within the range of values commonly found in the literature. The methodology proposed yields parameter estimates which produce the minimum sum of squares residuals. / It is believed that further studies are needed if one is to attempt estimating the four Monod-kinetics constants using batch reactors experiments.

This research investigated the origins and formations of permanent fouling. Four instrumental analyses were employed. They were Sleeve UV Transmittance (SUVT), Atomic Force Microscope (AFM), X-Ray Fluorescence (XRF), and Scanning Electron Microscope (SEM) combined with Energy Dispersive X-ray Microanalysis (EDX). / It was verified that permanent foulants were trapped initially by the inherent holes and peaks on sleeve surfaces. After long term periodical chemical/mechanical cleaning, the wipers of cleaning systems would damage sleeve surfaces severely, causing scratches or holes with wide surface areas, which may be termed mechanical deterioration of the sleeves. Thus, foulants would be trapped more easily by these scratches, and would be attached tightly to the surfaces of these scratches or to each other. Using instrumental analyses, the compositions of permanent foulants were found to be site specific. In general, iron, aluminum, calcium, magnesium and phosphorus composed the majority of the components of the permanent foulants. / This research attempted to correlate permanent fouling to the site-specific wastewater quality. However, although it seemed that wastewater quality could affect permanent fouling to some extent, there was no robust relationship between them. Thus, wastewater quality parameters cannot be used at this stage to predict the future influence of that wastewater on permanent fouling.

The inactivation of pathogens in sewage sludge reduces the risks of infection through contaminant pathways associated with handling and disposal. Domestic sludge sourced from a rural treatment plant was found to contain high levels of the indicator microoganisms E. coli and fecal coliforms and pathogenic bacteria Salmonella spp., Shigella spp., and C. perfringens. An effective and simple approach to enhance pathogen removal in a rural treatment setting was desired. Existing literature suggested that draw/fill staged configurations tended to yield better inactivation rates. Other literature suggested that the build-up of inhibitory compounds such as VFAs were detrimental to pathogens and that VFAs could be accumulated in higher temperature microaerobic conditions. The investigation of microaerobic pretreatment was trialed as a novel approach to staged digestion for improved pathogen removal. Microaerobic pretreatment of aerobically digested sludge improved inactivation of aerobic bacteria but the inactivation of persistent spores of C. perfringens were inconclusive. Microaerobic pretreatment alone was investigated in three phases of the experiments and did not result in inactivation greater than one log reduction for any bacteria monitored. In Phase I where feed solids concentration was varied across four reactors, the lowest solids loading of 1.1% TS showed the best removal rates of pathogens. In Phase II, contact time was evaluated in terms of feeding frequency and residence time. It was found that less frequent feeding and longer residence times were more effective in removing pathogens as expected from the reactor kinetics and suggested by the literature. The impact after digestion was found to be significant in Phase III for fecal coliforms, E. coli, Salmonella spp. and Shigella spp. It appeared that changes to the sludge matrix in microaerobic pretreatment improved digester performance in terms of pathogen removal. Operating variables were monitored to gain an understanding of the factors impacting performance. Statistical analyses were performed at the 90% confidence interval to determine which if any factors differed significantly between systems and stages. The major findings were that mesophilic pretreatment (35°C) with air supplied at 0.06vvm yielded significantly higher ammonia levels after pretreatment than did pretreatment at ambient temperatures. This was hypothesized to account for the significantly greater extent of nitrification observed in downstream aerobic digestion over the effluents from digestion without pretreatment and those that were pretreated under ambient microaerobic conditions. Accordingly, the pH in those digesters was significantly lower than after digestion without pretreatment and after digestion with ambient microaerobic pretreatment. This enhanced depression in pH was hypothesized to account for the significantly enhanced inactivation in pathogens.

The Monod or hyperbolic kinetic formulation became the de facto kinetic descriptor in activated sludge models in the '80s-'90s. It still plays a prominent role in activated sludge models; however, a dual hyperbolic formulation (with respect to both substrate and active biomass) that implicitly accommodates storage as well as more rationally describes metabolic kinetics is more prominent in governing metabolic functions in activated sludge models (ASMs) promulgated by working groups under the aegis of the International Water Association (IWA). There are other kinetic formulations used in the models of this group as well as models of the activated sludge process formulated by others. There is lack of consistency in the choice of kinetic formulations for various processes even within the IWA family of models. This thesis examined the basis for the common Monod and dual-hyperbolic formulations and puts forward theoretical justifications of them based on various considerations of mass transfer, storage and metabolic rate formulation. Other models were developed based on major governing principles. Models used in biological wastewater treatment are Eulerian gross descriptors of a process involving mass transfer, many substrates, and metabolic pathways and their enzymes, contained within many microorganisms. Any model at this level is merely a fit of mathematical formulations to data. As number of processes in biotreatment models increases along with mathematical descriptors and their associated coefficients, fitting an overall model improves to a point. But beyond this there has been little justification of the Monod or other kinetic expressions. Since a variety of formulations have been proposed for two of the primary metabolic processes which are hydrolysis of complex substrates and then metabolism of resulting readily degradable (or simple) substrates, the primary objective of this study was to examine these processes by experiment and determine the most appropriate models for each step. A chemostat was used in this study to culture active biomass acclimatized to a feed containing starch, a complex substrate requiring hydrolysis, and glucose which is readily biodegradable and also a product of starch hydrolysis. Active mass samples were taken from the chemostat and placed in batch reactors where varying concentrations of active mass were exposed to varying concentrations of either glucose or starch. Before adding any substrate to the batch reactors the active mass was aerated for a period of time until DO change was not observed to ensure that any stored or extraneous substrate was metabolized. After addition of one or the other substrate, the rate of dissolved oxygen (DO) uptake was monitored over the initial 15 minutes in the batch culture. Rapidly changing conditions dictated the necessity of using DO as a surrogate for either starch or glucose. Over 249 models were examined for their ability to describe glucose metabolism for 16 different batch experiments. The Monod model gave a good fit to the data. Other models that were equally applicable were too complex or made no scientific sense. Another series of batch tests were conducted using only starch as a substrate. Again substrate concentration and active mass concentration were varied in the batch tests in six different batch runs. The results from these experiments were again used to determine the adequacy of 249 starch hydrolysis models. The Monod type relationship and a dual hyperbolic relation again proved to be the most reasonable choices. Also a first-order model based on starch concentration was applicable. However no general set of coefficients that applied to all experiments was found for any model; it is necessary to calibrate either model to environmental conditions. All of these models are fairly simple in terms of concept as well as determination of parameters and have scientific sensibility in describing hydrolysis of SBCOD. Keywords: wastewater, activated sludge, dissolved oxygen, modeling

A membrane activated sludge bench-scale system was used to treat a complex synthetic wastewater over a wide range of operating conditions ranging 1 to 15 day(s) solids retention time (SRT) and 4 to 12 hours hydraulic retention time (HRT). Although the membrane reactor was able to provide good to excellent separation of particulates from the liquid in the mixed liquor over these operating conditions, the membrane failed, primarily due to clogging at operating conditions outside of these ranges. Various techniques, such as coagulant addition, were attempted to further expand the operating range but they failed. All runs were conducted until steady state conditions existed at which time data for modelling were collected. Performance of the system primarily for carbon and nitrogen removal is described for conditions where solids loss or clogging was nonproblematic. Different mathematical models to predict the behaviour of an activated sludge system and to estimate stoichiometric and kinetics parameters are presented. (Abstract shortened by UMI.)

The impact of hydraulic shockloads on UASB reactors operating at mesophilic conditions (T = 35°C) was studied. The wastewater, landfill leachate, was pretreated by filtering it through peat moss. The reactor was 1/2 filled with sludge previously acclimated from a pulp mill wastewater treatment facility. The shockloads imposed on the reactor were hydraulic where the flowrate of the influent wastewater was increased by 2--3 times the initial flow rate at quasi steady-state (corresponding to a change of HRT from 2.5--3 to 1--1.5 d) where the influent concentration was maintained around 10 g COD/L. Two modes of shock-loading were compared: continuous versus intermittent for a total duration of 3 hours, where the intermittent operation distributed the flowrate increase over 9 hours to make a total of 3 hours. The results showed that a UASB reactor can endure a single shockload of OLR close to 9.6 +/- 1.8 g COD/L.d and recover to pre-shock conditions in a period not exceeding 30 hours. Intermittent shock feeding resulted in better effluent quality; nonetheless, it took a longer time to recover, and was more prone to solids washout. (Abstract shortened by UMI.)