Pretreatment of waste activated sludge (WAS) and the subsequent near-critical water gasification (NCWG) is a potential avenue to convert WAS into value added products. Part one of the research investigated thermal and thermochemical pretreatments. No difference was observed in the percentage of sludge liquefied beyond 10min between 200°C to 300°C. It was found that pretreated activated sludge supernatant (PASS) doubled the gas yield compared to untreated sludge when gasified. The order of effectiveness for sludge treatment was thermo-alkali > thermal > thermo-acid for hydrogen production in NCWG. Part two investigated NCWG parameters to identify optimal conditions. High gasification yields were obtained using a commercial catalyst (Raney nickel), with hydrogen content of 65-75% of the gas phase products. Thermo-alkali treated PASS was found to perform well at subcritical temperatures with 25% higher yields than thermally treated PASS. Increased catalyst loading had little additional effect on gas yields above 0.075g.

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The desirability of effective control of anaerobic digesters as a means of avoiding imbalance in the microbial population has become clearer and this can be seen from the literature in recent years. A number of published control strategies have been encouragingly successful, however the non-linear and time varying nature of the process generally requires a bespoke, engineered system dependant on the characteristics of the system. The 'cost of knowing' in employing control systems, is generally high. The ideal scenario for operators would be the availability of a generic control system at reasonable cost, which would be applicable to a large group of high rate reactor designs, operating on a limited (but broad) variety of waste streams. The system would be able to control from commissioning through to steady state and should be able to cope with reasonable expected shock loading conditions, albeit perhaps at some degree of sub-optimality. The aim of this work is to develop a control strategy, which will lead in future to this end. Bicarbonate alkalinity (BA) is a key parameter which indicates the buffering capacity of the anaerobic digestion system and which has the potential for helping to maintain a stable system in the face of changing organic and toxic load. This is particularly the case when used in association with other informative on-line parameters such as gas production rate, %CO2 concentration in the gas, TOC, pH and volatile fatty acids. All but the last of these have been investigated using a fluidised bed reactor and the degree to which the anaerobic process is non-linear and time varying has been assessed, as the level of complexity required to represent anaerobic digestion 'well enough' was not clear. Simple linear black box models of low order were investigated, predicting over a limited horizon and relying on current and recent data values to refine the prediction. Independent black box ARX models were identified for gas production rate, % CO 2 , bicarbonate alkalinity and Total Organic Carbon using on-line data from a fluidised bed reactor at varying organic load. Model predictions looked ahead one sample step (30 minutes) and when validated using data obtained in a different time period (separated by 4-8 weeks) gave significant predictions in each case. The non-linear nature of the process was found to have little effect over the operating conditions investigated. Also the variation of the process within 4-8 weeks period was not sufficient to cause the models to predict badly. The performance of three black box models which were parameterised and validated using data collected from the same laboratory scale fluidised bed anaerobic digester, were compared. The models investigated were all ARX (auto regressive with exogenous input) models, the first being a linear single input single output (SISO) model, the second a linear multi-input multi-output (MIMO) model and the third a non-linear neural network based model. The performances of the models were compared and it was found that the SISO model was the least able to predict the changes in the reactor parameters (bicarbonate alkalinity, gas production rate and % CO2 ). The MIMO and neural models both performed reasonably well. Though the neural model was shown to be superior overall to the MIMO model, the simplicity of the latter should be a consideration in choosing between them. A simulation with a horizon approaching 48 hours was performed using this model and showed that the method was not sufficiently accurate for use in situations where pure simulation was required. This thesis includes the use of a two population deterministic model calibrated using data from a fluidised bed reactor operating on a simulated yeast waste, in the development of a Model Reference Adaptive Control (MRAC) strategy. The strategy uses a three term adaption mechanism, which is described in the thesis as a Fast Adaption Trajectory (FAT) strategy, as it was found to be necessary to respond to catastrophic events over short time scales, in order to maintain the viability of the bacterial population. Numerical optimisation in a simulation environment was used to parameterise the controller, and this was done on the basis of only basic design information being available for the reactor which was to be controlled. The controller was tested on a significantly different Expanded Granular Sludge Blanket (EGSB) reactor operated on a sucrose based feed and which did not inform the controller design process beyond basic physical information. Two actuation strategies were explored over several months of operation, using a single on-line bicarbonate alkalinity monitor, which in the event proved to have significant reliability problems. Not withstanding the problems with the alkalinity monitor, which was dominant in determining the success or failure of the control strategy, it was found that the control strategy was able to maintain control during start-up, which was the ambition of this part of the experimentation. Both actuation methodologies showed promise although the variation of loading rate was not adequately tested by the experimentation, which was conducted. The actuation by dosing with bicarbonate proved to be better at maintaining control in the face of repeated and severe perturbations caused by failure in the bicarbonate monitor system. It is believed that the FAT controller is likely to be a transferable technique provided that unmodelled dynamics are not excessively dominant and that the reactor system is comparable to a CSTR design with predominantly soluble waste in the feed.

Philosophiae Doctor - PhD / Actinomycetes are ubiquitous in many environments such as soil, activated sludge and water.Besides the genus Streptomyces, which has been extensively exploited, members of other genera including Micromonospora have been shown to be a promising source of novel secondary metabolites and enzymes.The biocatalytic conversion of 5-monosubstituted hydantoin derivatives to optically pure amino acids involves two reaction steps. The first step, catalysed by a hydantoinase, yields an N-carbamylamino acid intermediate, which is subsequently broken down by an Ncarbamoylase to the amino acid. This process has been successfully applied in industry for the production of optically pure amino acids which are used in the synthesis of pharmaceuticals,insecticides, hormones, and food additives. The need for novel hydantoinases to hydrolyse a wider variety of substrates is increasing. This thesis describes the search for a novel hydantoinase from environmental isolates obtained from two Zambian hot-springs. The aim of this study was to isolate, characterise and screen novel actinobacteria for industrially relevant enzymes including hydantoinases. Fifty one actinobacteria were isolated. Isolates were characterized by a polyphasic approach using standard methods, combining phylogenetic analysis of the 16S rRNA gene, chemotaxonomic and phenotypic characterization. Results revealed that these sites were dominated by actinobacteria belonging to the family Micromonosporaceae, and a potentially novel Verrucosispora species was identified. Screening the isolate identified a Streptomyces species which has hydantoinase, carbamoylase, amidase and nitrilase activities.The Streptomyces sp. hydantionase was cloned and functionally expressed in E.coli. The recombinant enzyme showed 49 % similarity to a crystallised hydantoinase from a Bacillus species. Homology modelling revealed that the enzyme had the TIM barrel topology which is characteristic of hydantoinases. Amino acid residues predicted to be involved in the catalytic activity as well as substrate orientation were identified. The partially purified hydantoinase was characterised and showed optimally activity at 45 °C and pH 8. This study revealed that hot springs may represent a previously unexplored source of novel actinobacterial diversity. However, it also revealed that novel secondary metabolites are not only limited to novel organisms but that some of the answers for the challenges we face today maybe found in organisms we have already encountered and characterised.

Mathematical models elaborated for removal of microconstituents (MCs) in activated sludge (AS) system have not incorporated developments in International Water Association (IWA) models. In this thesis, sorption and biodegradation kinetic models that can be applied to describe transformation of MCs in an AS process were evaluated (volatilization and photodegradation were considered negligible). Bisphenol-A (BPA), 17α-ethinylestradiol (EE2), and triclosan (TCS) have been selected as target compounds in this thesis. Sorption batch tests were conducted to retrieve kinetic and equilibrium data. Nine lab-scale continuous flow porous-pot bioreactors operating at various solids retention times (SRTs) and hydraulic retention times (HRTs) were studied for biodegradation of MCs. The effects of SRT, HRT and the biomass concentration on sorption and removal of MCs were also investigated and the results of each phase were incorporated into MCs fate models. Freundlich and linear sorption isotherms and pseudo-second-order kinetic models with different kinetic rates were found to best fit the sorption and desorption results. The result of biodegradation study in the presence of 20 µg/L of MCs demonstrated 90-98, 63-91 and 97-98% mean removal rates of BPA, EE2 and TCS, respectively, in systems operating at SRT of 5–15 d and HRT of 4-10 h. Calculation of mass fluxes of selected MCs in the dissolved and particulate phases showed that biotransformation was the principal removal mechanism of targeted MCs. The fate models for the degradation mechanism of selected MCs were evaluated by applying various mathematical models. The pseudo-second-order model was found to best fit the results when active MCs degraders (XC) were used in the model. It was found that biodegradation studies should incorporate XC and not mixed liquor suspended solids concentration in their kinetic formulations. Therefore, the result of this study could be seen in the context, where the active MCs degraders are proposed to reduce the variability of biodegradation kinetic rates in AS systems operating at different operational conditions. Finally nitrification inhibitors, allylthiourea (ATU) were added to reactors and it was found that although nitrification process affects the fate of MCs in AS system, heterotrophs were most likely responsible for the biotransformation of the targeted MCs.

A lab-scale study of anoxic-aerobic digestion of waste activated sludge was performed, using 6 litre digesters, and operated in a semi - continuous (fed-once-a-day) manner with solids retention times (SRTs) of 20, 15 and 10 days and mixed-liquor temperatures of 20 °C and 10 °C. Raw sludge was obtained from a pilot-scale biological phosphorus removal facility operating at U.B.C. Fresh sludge was obtained daily and digested by three different digestion modes: anoxic-aerobic, aerobic with lime addition and aerobic. Two aerobic control digesters were run in parallel with the anoxic-aerobic digesters. One of the aerobic digesters received a daily dose of lime slurry. All three digesters were operated under identical conditions (except for the cycling of air supply to the anoxic-aerobic digesters) so that direct comparison could be made between the three digestion modes. Comparisons were made on the basis of five main parameters related to: (1) digestion kinetics, (2) digested sludge characteristics, (3) supernatant quality, (4) ORP monitoring, and (5) an overall rating system. Percent volatile suspended solids (VSS) reduction was used as one performance variable. Despite using only 42 percent of the air required by the two controls, anoxic-aerobic digestion showed comparable percent VSS reductions. All three digestion modes showed increased solids reduction with increasing SRT and temperature. There was a linear relationship between percent TVSS and the product of SRT and temperature. All three digestion modes had a propensity to retain their percent nitrogen and phosphorus within their solids. However, with respect to retaining phosphorus, the aerobic controls were the least effective. Anoxic-aerobic digestion maintained neutral mixed-liquor pH (MLpH) throughout. Lime controls were maintained at MLpH close to neutral. Aerobic digestion, in general, resulted in MLpH levels below 5.0, however, there were periods when the MLpH of the aerobic digesters varied widely between 4.2 and 6.8. Supernatant quality was superior for the anoxic-aerobic digesters. Due to the incorporation of non-aerated periods, there was almost 100 percent denitrification of nitrates produced during the aerated time. This nitrification-denitrification resulted in very low soluble nitrogen levels in the effluent, as well as considerable removal of nitrogen gas. Neither of the controls showed this ability. The lime and aerobic controls produced high levels of effluent nitrates, as well as occasional measurements of ammonia and nitrite. Phosphorus levels were lowest for the lime control and anoxic-aerobic digesters. Presumably, due to reduced pH levels, the soluble phosphorus levels from the aerobic digesters were 2 to 3 times those in the lime or anoxic-aerobic digesters. Alkalinity was conserved in the anoxic-aerobic digesters as well as the lime control. However, the purely aerobic digesters consumed alkalinity until very little buffering capacity remained. Oxidation-reduction potential (ORP) was used as a means of monitoring the anoxic-aerobic digesters on a real time basis. ORP was particularly useful during the non-aerated periods, due to the fact that, at those times, dissolved oxygen was undetectable. Characteristic real time ORP profiles were revealed. Slope changes correlated well with events of theoretical and engineering interest; the' disappearance of ammonia and nitrates, as well as the (dis)appearance of detectable dissolved oxygen, could be predicted by these slope changes. As a result of the findings, ORP may prove to be an ideal parameter for the control of the anoxic-aerobic digestion process. Finally, an overall rating system was developed. The results of this study suggest that, for the digestion of waste activated sludge, anoxic-aerobic digestion out-performed both lime-control and conventional digestion modes. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Diploma thesis Effect of emergent micropolutants on the denitrification process through activated sludge is focused on three specific substances. The substances under investigation are atrazine, terbutylazine and sulfametaxazole. Atrazine and terbutylazine are pesticides, particularly herbicides. Sulfametaxazole was chosen as a common antibiotic. The thesis is summarized into 10 chapters and conclusion. The work consists essentially of theoretical and practical part. Part of the theoretical part of the thesis is legislation that deals with the matters of the problem with micropolutants. The next chapter is an introduction to the issue, where we want to familiarize the reader with the current situation. There are also chapters on emergent micropolutants, denitrification and investigated substances. If we look at the practical part, there are chapters on sampling, evaluation of BATCH tests and evaluation of inhibition tests. There are also chapters on BATCH tests and respiratory inhibition test, which describe procedures of how we performed this test. Laboratory test reports are included in the Annex.

Upset events due to the inflow of toxic chemicals are a critical issue for wastewater treatment facilities. Understanding the source-effect relationship of toxic chemicals can facilitate the prevention or improved reaction to upset events. Part one of this study was conducted to investigate the source of upset events at a regional industrial wastewater treatment plant (WWTP). Part two of this study determined the process performance effects of two chemical shocks, cyanide (zinc-cyanide complex) and pH, on nitrifying and non-nitrifying activated sludge. A modified respirometric assay protocol was developed to allow the industrial WWTP to screen industrial wastewaters for inhibitory properties. All five industrial wastewaters tested revealed inhibitory properties. Large day-to-day variations were found, illustrating the need for a large database of results for comparison over time. Additionally, a small volume contributor, that was thought by the utility to be an unlikely source of problems, contributed significantly to the wastewater oxygen demand and demonstrated inhibitory properties. The modified respirometric procedure enabled the WWTP to identify possible industrial sources that could cause an upset event. Lab-scale sequencing-batch reactors were used to determine the effects of cyanide and pH shock on activated sludge. Three reactors were shocked with increasing weak-acid complexed zinc cyanide or pHs of 5, 9, and 11. The resulting effects were compared to an un-shocked control reactor. It was found that respiration and nitrification were affected by the zinc cyanide complex, while COD removal, effluent TSS and dewaterability were not. Recovery was seen in less than 2 X solids residence time (SRT) for the nitrifying biomass and within 3 X SRT for the non-nitrifying biomass. The results of the pH experiment showed that the pH 11 shock affected the settleability, nitrification, COD removal, and effluent TSS levels of the reactors, while pH 5 and pH 9 shocks had no effect. Recovery was seen within 3 X SRT for both the nitrifying and non-nitrifying systems. / Master of Science

abstract: The production and applications of engineered nanomaterials (ENM) has increased rapidly in the last decade, with release of ENM to the environment through the sewer system and municipal wastewater treatment plants (WWTPs) being of concern. Currently, the literature on ENM release from WWTPs and removal of ENM by WWTPs is insufficient and disorganized. There is little quantitative data on the removal of multi-walled carbon nanotubes (MWCNTs), graphene oxide (GO), or few-layer graphene (FLG), from wastewater onto biomass. The removal of pristine and oxidized MWCNTs (O-MWCNTs), graphene oxide (GO), few-layer graphene (FLG) and Tween™ 20-coated Ag ENM by the interaction with biomass were determined by programmable thermal analysis (PTA) and UV-Vis spectrophotometry. The removal of pristine and O-MWCNTs was 96% from the water phase via aggregation and 30-min settling in presence or absence of biomass with an initial MWCNT concentration of 25 mg/L. The removal of 25 mg/L GO was 65% with biomass concentration at or above 1,000 mg TSS/L. The removal of 1 mg/L FLG was 16% with 50 mg TSS/L. The removal of Tween™ 20 Ag ENM with concentration from 0.97 mg/L to 2.6 mg/L was from 11% to 92% with biomass concentration of 500 mg TSS/L to 3,000 mg TSS/L, respectively. A database of ENM removal by biomass was established by analyzing data from published papers, and non-linear solid-liquid distribution functions were built into the database. A conventional activated sludge (CAS) model was built based on a membrane bioreactor (MBR) model from a previous paper. An iterative numeric approach was adapted to the CAS model to calculate the result of non-linear adsorption of ENM by biomass in the CAS process. Kinetic studies of the CAS model showed the model performance changed mostly in the first 10 days after changing influent chemical oxygen demand (COD) concentration, and reached a steady state after 11 days. Over 60% of ENMs which have distribution coefficients in the database reached higher than 50% removal by the CAS model under general operational conditions. This result suggests that traditional WWTP which include the CAS process can remove many known types of ENMs in certain degree. / Dissertation/Thesis / Masters Thesis Civil and Environmental Engineering 2015