Anaerobic digestion is a process that simultaneously treats waste and produces renewable energy in the form of biogas. Applications include swine and cattle waste management, which is still dominated by aerobic digestion, a less environmental alternative. The low adoption rates of anaerobic digestion is partly caused by the lack of modelling basis for the technology. This is due to the complexity of the process, as it involves dozens of interrelated biochemical reactions driven by hundreds of species of micro-organisms, immersed in a three-phase, non-Newtonian fluid. As a consequence, no practical computer models exist, and therefore, unlike most other engineering fields, the design process for anaerobic digesters still relies heavily on traditional methods such as trial and error. The current state-of-the-art model is Anaerobic Digestion Model No. 1 (ADM1), published by the International Water Association in 2001. ADM1 is a bulk model, therefore it does not account for the effects of concentration gradients, stagnation regions, and particle settling. To address this, this thesis works toward the creation of the first three-dimensional spatially resolved anaerobic digestion model, called Anaerobic Digestion Model with Multi-Dimensional Architecture (ADM-MDA), by developing a framework. The framework, called Coupled Reaction-Advection Flow Transient Solver (CRAFTS), is a general reaction solver for single-phase, incompressible fluid flows. It is a novel partial differential and algebraic equation (PDAE) solver that also employs a novel programmable logic controller (PLC) emulator, allowing users to define their own control logic. All aspects of the framework are verified for proper function, but still need validation against experimental results. The biochemistry from ADM1 is input into CRAFTS, resulting in a manifestation of ADM-MDA; however the numerical stiffness of ADM1 is found to conflict with the second order accuracy of CRAFTS, and the resulting model can only operate under restricted conditions. Preliminary results show spatial effects predicted by the CRAFTS model, and non-observable in the bulk model, impact the digester in a non-trivial manner and lead to measurable differences in their respective outputs. A detailed discussion of suggested work to arrive at a practical spatially resolved anaerobic digestion model is also provided.

The effectiveness of partial ozonation of return activated sludge for enhancing denitrification and waste sludge minimization were examined. A pair of nitrifying sequencing batch reactors was operated in either aerobic or alternating anoxic/aerobic conditions, with one control and one ozonated reactor in each set. The amount of solids decreased with the ozone dose. Biomass in the anoxic/aerobic reactor was easier to destroy than in the aerobic one, generating approximately twice as much soluble chemical oxygen demand (COD) by cell lysis. Increased COD favoured production of extracellular polymers in ozonated reactors, enhancing flocculation and improving settling. Floc stability was also strengthened in prolonged operation in alternating treatment, resulting in declined solids destruction. Dewaterability was better in alternating reactors than in aerobic ones indicating that incorporation of an anoxic zone for biological nutrient removal leads to improvement in sludge dewatering. The negative impact of ozonation on dewaterability was minimal in terms of the long-term operation. Ozone successively destroyed indicator estrogenic compounds, contributing to total estrogen removal from wastewater. Denitrification rate improved up to 60% due to additional carbon released by ozonation. Nitrification rates deteriorated much more in the aerobic than in the alternating reactor, possibly as a result of competition created by growth of heterotrophs receiving the additional COD. Overall, ozonation provided the expected benefits and had less negative impacts on processes in the alternating treatment, although after prolonged operation, benefits could become less significant. The alternating anoxic/aerobic reactor achieved twice the nitrification rates of its aerobic counterpart. Higher removal rates of estrogens were associated with higher nitrification rates, supporting the contention that the nitrifying biomass was responsible for their removal. The alternating treatment offered the better estrogen biodegradation. Microbial populations in both reactors were examined with fluorescent in situ hybridization. Dominance of rapid nitrifiers like Nitrosomonas and Nitrobacter (79.5%) in the alternating reactor, compared to a dominance of slower nitrifiers like Nitrosospira and Nitrospira (78.2%) in the aerobic reactor were found. The findings are important to design engineers, as reactors are typically designed based on nitrifiers’ growth rate determined in strictly aerobic conditions.

Pollution created by textile dyeing operations attracts significant attention because an effluent containing a complex mixture of coloured and potentially toxic compounds can be released with the discharged water. Developing dyes and dyeing conditions to reduce the amount of residual dye contained in any effluent has been one of many approaches to minimise this environmental impact. However, the presence of coloured discharge cannot be totally eliminated using only this strategy. Thus, development of efficient post-dyeing wastewater treatment methods capable of removing coloured products from the water is of paramount importance. TiO2-mediated photocatalytic degradation of organic dye molecules via oxidation is the focus of the study reported in this thesis. TiO₂ significantly increases the rate of photodegradation of a wide range of organic dyes under mild operating conditions, and is able to mineralise a wide spectrum of organic contaminants. TiO₂ is also one of the very few substances appropriate for the industrial applications. One of primary aims of this thesis is to test the hypothesis that augmenting standard TiO₂ photocatalysts with Au nanoparticles could increase performance of a catalyst, while immobilizing TiO₂ on SiO₂ support may improve the cost of the process efficiency, i.e. more photocatalytic degradation per particle of TiO₂. Combining TiO₂ doped with gold nanoparticles on SiO₂ support has the potential to provide the highest photocatalytic ability at the lowest cost. The first half of the thesis is concerned with establishing and optimizing experimental conditions for monitoring photodegradation via UV-Visible spectroscopy. Effects of various conditions such as temperature, sequence of addition of reagents, exposure to light vs. experiments in dark, sampling methods, and the use of quenching agent were examined. The main conclusions from this study are that light-induced photodegradation using titanium dioxide nanoparticles catalysts is comparatively more efficient than purely chemical catalytic (e.g. non-light mediated) degradation, even if the latter is performed at elevated temperature. Further, the rate of dye degradation is affected considerably by the parameters of the system. The degradation rate depends strongly on the pH of the solution, due to charges on both the catalyst surface and in the dye. In general, at pH ≤ 6.8, which is the zero charge point for TiO₂, reactions proceeded faster than those at higher pH. Six dyes from four different classes of dyes used in industry were used in this study, and all showed different photodegradation behaviour. The second half of thesis tests the photocatalytic abilities of various TiO₂-based catalysts: pure TiO₂ (commercial and custom-made in our laboratory), TiO₂-supported gold nanoparticles (Au/TiO₂), SiO₂-supported TiO₂ (TiO₂/SiO₂), and SiO₂-supported Au/TiO₂. The best photocatalytic performance was observed for the custom-made TiO₂ code-named as e-TiO₂, which was synthesized using the sol-gel method in dry ethanol. TiO₂-supported Au55 nanoparticles showed a similar level of catalytic ability but are significantly more expensive. It was observed that dye adsorption played a significant role in the case of SiO₂-immobilized photocatalysts.

The increasing cost of effluent treatment in the wool scouring industry is rapidly becoming a determining factor in the viability of existing scouring operations and new installations alike. This thesis details the development of an integrated effluent treatment process capable of treating the worst polluted effluent from a wool scour "heavy flow-down", to the point where it can either be economically discharged to local trade waste sewer, or directly discharged to river or ocean outfall with minimal environmental impact. The existing proprietary chemical flocculation process, Sirolan CF™, was improved by the addition of a bio-flocculation stage and turbidity monitoring and control, and the product from this process fed to an aerobic biological treatment system based upon the traditional activated sludge process. The biological treatment process was found to remove up to 98% of the BOD5 loading from the pre-treated liquor with a hydraulic residence time of at least 50 hours being required in the aerobic digestion vessels. A residual biorefractory COD of approximately 3,600mg/L was identified which could not be removed by biological treatment. When operating continuously, the biological process was observed to metabolically neutralise the pH 3.0 - 4.5 feed from the chemical flocculation system to pH &gt 7.0 without the need for supplemental addition of neutralising agents such as sodium hydroxide. This in itself provides a significant economic incentive for implementation of the process. Kinetic analysis of the biological process carried out under controlled laboratory conditions using a Bioflo 3000 continuous fermentor showed that the bio-chemical process followed substrate inhibition kinetics. An appropriate kinetic model was identified to represent the behaviour of the substrate degradation system, and modified by inclusion of a pseudo toxic concentration to account for the effect of pH inhibition upon the biological growth rate. The process was verified both at pilot plant scale and at demonstration plant scale at an operational wool scour. The demonstration plant was of sufficient size to handle the full heavy effluent flow-down from a small wool scour. At the time of publishing three full-scale effluent treatment systems based on this research had been sold to both domestic and international clients of ADM Group Ltd. who funded the research.

The conventional wastewater treatment of today was developed aiming to mitigate problems occurring in wastewater recipients such as oxygen depletion and eutrophication. The focus of wastewater management has however broadened and major concern is now focused on the sustainability of the wastewater treatment process itself. Algae based wastewater treatment is an alternative to conventional treatment. It has the potential to yield an acceptable effluent quality at a lower ecological cost. This Degree Project was conducted as part of MOBIT, a project at Mälardalen University. The MOBIT project was aimed at the development of an algae based wastewater treatment process in an activated sludge environment. The aim of this Degree Project was to propose a model describing the dynamics of such a system. The model was constructed in Simulink, based on the River Water Quality Model no. 1. The River Water Quality Model no. 1 was chosen as the basis for modelling because it included the state variables and processes necessary to describe the dynamics of bacteria, algae and pH. The River Water Quality Model no. 1 was, as the name suggests, developed to describe a river system. It was hence considered important to evaluate if the model was applicable to an activated sludge environment. A major obstacle was the fact that no algae based activated sludge system had been studied prior the start of the MOBIT project, the project was pioneering. The lack of system understanding and of measurement data aggravated the evaluation. However, the proposed model was compared to the Activated Sludge Model No. 1 which was known to describe an activated sludge system accurately. The model structure of the River Water Quality Model no. 1 was considered a good starting point for future modelling of the algae based activated sludge process. However, the model set-up proposed in this report does not describe the system sufficiently well. Better system understanding and measurement data is needed in order to develop and calibrate the model. / Dagens konventionella avloppsvattenrening har utvecklats för att minimera utsläpp av näringsämnen och kolföreningar då sådana utsläpp medför övergödning och syrebrist i mottagande vatten. På senare tid har reningsprocessen i sig hamnat i fokus då den är såväl energi- som resurskrävande. Algbaserad avloppsvattenrening är ett alternativ som har potential att ge tillfredsställande rening med ett betydligt mindre ekologiskt fotavtryck. Det här examensarbetet var en del av MOBIT, ett projekt vid Mälardalens högskola. MOBIT syftade till att utvärdera algbaserad avloppsvattenrening i form av en aktivslamprocess. Syftet med examensarbetet var att ta fram en modell för det planerade systemet. Modellen byggdes i Simulink och den baserades på en befintlig modell, River Water Quality Model no. 1. Den befintliga modellen valdes för att den inkluderade alla önskvärda tillståndsvariabler och processer, bland annat de som krävs för att beskriva alg-, bakterie- och pH-dynamik. Som namnet antyder utvecklades River Water Quality Model no. 1 för att beskriva ett flodsystem. Det var därför angeläget att utvärdera huruvida modellen var tillämpbar i en aktivslammiljö. Utvärderingen försvårades av att det vid tiden för examensarbetets utförande ännu inte fanns någon existerande algbaserad aktivslamprocess. Kunskapen om systemet var därför begränsad och det fanns ingen mätdata att kalibrera eller evaluera mot. I brist på mätdata jämfördes den framtagna modellen med en annan modell som var utvecklad för att beskriva just avloppsvattenrening, Activated Sludge Model No. 1. Arbetet resulterade i slutsatsen att River Water Quality Model no. 1 utgör en bra grund för modellering av den algbaserade aktivslamprocessen. Men, den modellkonfiguration som tas fram i denna rapport beskriver inte systemet särskilt bra. Bättre systemförståelse samt tillförlitlig mätdata krävs för att omarbeta och kalibrera den föreslagna modellen. / MOBIT

Water infrastructure on Aboriginal communities in Canada, and specifically Northern Manitoba is in sub-standard condition. A recent Government of Canada study indicated that an estimated $1.5 billion would need to be spent to improve this infrastructure. September 2003 through July 2004, an examination of the effectiveness of a membrane bioreactor (MBR) in a Northern Manitoban Aboriginal community took place. This study was intended to identify and test an appropriate and effective solution for the lack of adequate wastewater treatment in these communities. The MBR system, employing a Zenon ZW-10 ultrafiltration membrane, was designed and constructed at the University of Manitoba. It was installed and tested in two phases at the Opaskwayak Cree Nation Reserve in Northern Manitoba. Phase I was a direct comparison between the pilot-scale MBR and the community’s existing Sequencing Batch Reactor (SBR) with sand filter. This phase occurred from September 2003 until December 2003. The MBR, with an SRT of 20-days and an HRT of 10 hours, outperformed the SBR in every category despite 2 mechanical/electrical failures that resulted in the loss of biomass from the MBR. The SBR/Sand filter combination had BOD, TSS, and TKN concentrations of 30.3 mg/L, 27.5 mg/L, and 8.4 mg/L, respectively. By comparison, the BOD, TSS, and TKN concentrations in the MBR effluent were <6 mg/L, <5 mg/L, and 1.3 mg/L respectively. Phase II, from March 2004 through July 2004, tested the overall MBR efficacy and intended to assess a novel remote control and monitoring system. The MBR SRT was adjusted to 40-days and, as expected, the MBR MLVSS concentration increased to a relatively stable 5000 mg/L. The MBR continued to provide high quality effluent with some exceptions. Despite the 0.034 μm pore size, the total coliforms and TSS measured in the effluent were higher than in Phase I. This indicates a compromised membrane, faulty sampling procedures, or biological regrowth downstream of the membrane. This failure could point to the need for some form of tertiary disinfection. Also in Phase II, a remote control and monitoring program was implemented. The controlling PC was controlled via the internet using pcAnywhere software. The software allowed for real-time monitoring and complete control of the pilot system. In conclusion, the pilot-scale MBR yielded consistent, high quality wastewater effluent and this would benefit the pristine environments existing in Manitoba’s north. The potential hands-free operation could be utilized to provide support to communities lacking sufficient wastewater treatment know-how.

Anaerobic digestion is a process that simultaneously treats waste and produces renewable energy in the form of biogas. Applications include swine and cattle waste management, which is still dominated by aerobic digestion, a less environmental alternative. The low adoption rates of anaerobic digestion is partly caused by the lack of modelling basis for the technology. This is due to the complexity of the process, as it involves dozens of interrelated biochemical reactions driven by hundreds of species of micro-organisms, immersed in a three-phase, non-Newtonian fluid. As a consequence, no practical computer models exist, and therefore, unlike most other engineering fields, the design process for anaerobic digesters still relies heavily on traditional methods such as trial and error. The current state-of-the-art model is Anaerobic Digestion Model No. 1 (ADM1), published by the International Water Association in 2001. ADM1 is a bulk model, therefore it does not account for the effects of concentration gradients, stagnation regions, and particle settling. To address this, this thesis works toward the creation of the first three-dimensional spatially resolved anaerobic digestion model, called Anaerobic Digestion Model with Multi-Dimensional Architecture (ADM-MDA), by developing a framework. The framework, called Coupled Reaction-Advection Flow Transient Solver (CRAFTS), is a general reaction solver for single-phase, incompressible fluid flows. It is a novel partial differential and algebraic equation (PDAE) solver that also employs a novel programmable logic controller (PLC) emulator, allowing users to define their own control logic. All aspects of the framework are verified for proper function, but still need validation against experimental results. The biochemistry from ADM1 is input into CRAFTS, resulting in a manifestation of ADM-MDA; however the numerical stiffness of ADM1 is found to conflict with the second order accuracy of CRAFTS, and the resulting model can only operate under restricted conditions. Preliminary results show spatial effects predicted by the CRAFTS model, and non-observable in the bulk model, impact the digester in a non-trivial manner and lead to measurable differences in their respective outputs. A detailed discussion of suggested work to arrive at a practical spatially resolved anaerobic digestion model is also provided.

Water infrastructure on Aboriginal communities in Canada, and specifically Northern Manitoba is in sub-standard condition. A recent Government of Canada study indicated that an estimated $1.5 billion would need to be spent to improve this infrastructure. September 2003 through July 2004, an examination of the effectiveness of a membrane bioreactor (MBR) in a Northern Manitoban Aboriginal community took place. This study was intended to identify and test an appropriate and effective solution for the lack of adequate wastewater treatment in these communities. The MBR system, employing a Zenon ZW-10 ultrafiltration membrane, was designed and constructed at the University of Manitoba. It was installed and tested in two phases at the Opaskwayak Cree Nation Reserve in Northern Manitoba. Phase I was a direct comparison between the pilot-scale MBR and the community’s existing Sequencing Batch Reactor (SBR) with sand filter. This phase occurred from September 2003 until December 2003. The MBR, with an SRT of 20-days and an HRT of 10 hours, outperformed the SBR in every category despite 2 mechanical/electrical failures that resulted in the loss of biomass from the MBR. The SBR/Sand filter combination had BOD, TSS, and TKN concentrations of 30.3 mg/L, 27.5 mg/L, and 8.4 mg/L, respectively. By comparison, the BOD, TSS, and TKN concentrations in the MBR effluent were <6 mg/L, <5 mg/L, and 1.3 mg/L respectively. Phase II, from March 2004 through July 2004, tested the overall MBR efficacy and intended to assess a novel remote control and monitoring system. The MBR SRT was adjusted to 40-days and, as expected, the MBR MLVSS concentration increased to a relatively stable 5000 mg/L. The MBR continued to provide high quality effluent with some exceptions. Despite the 0.034 μm pore size, the total coliforms and TSS measured in the effluent were higher than in Phase I. This indicates a compromised membrane, faulty sampling procedures, or biological regrowth downstream of the membrane. This failure could point to the need for some form of tertiary disinfection. Also in Phase II, a remote control and monitoring program was implemented. The controlling PC was controlled via the internet using pcAnywhere software. The software allowed for real-time monitoring and complete control of the pilot system. In conclusion, the pilot-scale MBR yielded consistent, high quality wastewater effluent and this would benefit the pristine environments existing in Manitoba’s north. The potential hands-free operation could be utilized to provide support to communities lacking sufficient wastewater treatment know-how.

The effectiveness of partial ozonation of return activated sludge for enhancing denitrification and waste sludge minimization were examined. A pair of nitrifying sequencing batch reactors was operated in either aerobic or alternating anoxic/aerobic conditions, with one control and one ozonated reactor in each set. The amount of solids decreased with the ozone dose. Biomass in the anoxic/aerobic reactor was easier to destroy than in the aerobic one, generating approximately twice as much soluble chemical oxygen demand (COD) by cell lysis. Increased COD favoured production of extracellular polymers in ozonated reactors, enhancing flocculation and improving settling. Floc stability was also strengthened in prolonged operation in alternating treatment, resulting in declined solids destruction. Dewaterability was better in alternating reactors than in aerobic ones indicating that incorporation of an anoxic zone for biological nutrient removal leads to improvement in sludge dewatering. The negative impact of ozonation on dewaterability was minimal in terms of the long-term operation. Ozone successively destroyed indicator estrogenic compounds, contributing to total estrogen removal from wastewater. Denitrification rate improved up to 60% due to additional carbon released by ozonation. Nitrification rates deteriorated much more in the aerobic than in the alternating reactor, possibly as a result of competition created by growth of heterotrophs receiving the additional COD. Overall, ozonation provided the expected benefits and had less negative impacts on processes in the alternating treatment, although after prolonged operation, benefits could become less significant. The alternating anoxic/aerobic reactor achieved twice the nitrification rates of its aerobic counterpart. Higher removal rates of estrogens were associated with higher nitrification rates, supporting the contention that the nitrifying biomass was responsible for their removal. The alternating treatment offered the better estrogen biodegradation. Microbial populations in both reactors were examined with fluorescent in situ hybridization. Dominance of rapid nitrifiers like Nitrosomonas and Nitrobacter (79.5%) in the alternating reactor, compared to a dominance of slower nitrifiers like Nitrosospira and Nitrospira (78.2%) in the aerobic reactor were found. The findings are important to design engineers, as reactors are typically designed based on nitrifiers’ growth rate determined in strictly aerobic conditions.

Visible light-driven photocatalysis has shown considerable potential in the area of clean and renewable energy, as well as in wastewater treatment. This thesis describes the synthesis, characterization and applicability of a visible-light active photocatalyst, bismuth oxybromide (BiOBr). The photocatalytic activity of BiOBr was investigated through its preparation via hydrothermal and solvothermal synthesis routes under various conditions. Hydrothermal catalyst was prepared using non template based method while for solvothermal synthesis CTAB was used as a template. Parameters of temperature and time of thermal treatment were optimized for each synthesis method and overall tests for catalyst dosage and recyclability were performed. An overall optimal route leading to high photocatalytic performance was also proposed based on the obtained results. Studies were also conducted to examine the applicability of optimally synthesized BiOBr in drinking water applications by studying catalyst-mediated disinfection of E. coli and degradation of phenol. Favourable results were obtained, confirming the prospective application of BiOBr as a viable photocatalyst for disinfection. Furthermore, the potential of enhancing BiOBr to further improve its performance is described through synthesis of a novel PdCl2/BiOBr based photocatalyst. Overall, the performance of BiOBr under various conditions in this study establishes its potential as a holistic photocatalyst and merits further development.