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There is a growing awareness of the valuable nutrients (nitrogen and phosphorus) being lost in conventional wastewater treatment systems. Although the removal of these nutrients has been well addressed, efforts for nutrient recovery have seen little development. As the emphasis on sustainability in the wastewater treatment industry increases, conventional wastewater treatment processes are being re-evaluated and new treatment systems developed. A possible nutrient recovery mechanism is the precipitation of magnesium ammonium phosphate hexahydrate (MgNH4PO4·6H2O), commonly known as struvite. Human urine has been identified as a rich source of nutrients in wastewater; hence the separate collection of urine is considered a viable method of enabling struvite recovery. Since dilution of urine to a certain degree is inevitable, reconcentration of urine beyond the solubility limit of struvite is critical. Currently available methods for reconcentration (e.g., evaporation, freeze-thaw, reverse osmosis and electrodialysis) are relatively expensive with high energy demand. Thus, the research here aims to demonstrate nutrient reconcentration from diluted urine and simultaneous organic removal by using the principles of microbial desalination cells (MDCs), where energy released from organic oxidation is partially used for the separation of nutrient ions. With reduced energy demand, a sustainable method for the utilization of source-separated urine is examined. The performance of bioelectrochemical systems relies on the activity of exoelectrogenic bacteria to transfer electrons to the anode. An examination of exoelectrogen sensitivity at various wastewater treatment conditions (i.e. ammonia and oxygen) is an important component of this research. Methanogenesis is considered the greatest challenge in achieving practical applications in anaerobic bioelectrochemical systems. An electrolytic oxygen production method is suggested for effective control of methanogenesis in a feasible and cost-effective manner. / Thesis / Master of Applied Science (MASc)

In 2012, mandatory effluent quality standards were established in Canada as part of the Wastewater Systems Effluent Regulations (WSER) with compliance deadlines starting in 2020. Maintaining the treatment process efficacy to meet these new stringent discharge regulations is extremely challenging at treatment facilities that treat wastewater from multiple industries due to the high variation in the composition of the incoming feed to the process. In this work, application of two new analytical tools, PeCOD® and Liquid Chromatography-Organic Carbon Detection (LC-OCD), for measurement and characterization of industrial wastewater organic pollution respectively, has been investigated. Organic pollution is commonly measured as Chemical Oxygen Demand via the dichromate method (CODCr) which requires 2-3 hours to complete. Thus this method is not suitable for applications that require rapid and frequent pollution monitoring. The Photoelectrochemical Oxygen Demand (peCOD) is an alternative parameter of organic pollution that can be measured in approximately 15 minutes via a method that utilizes the high oxidation potential of UV-irradiated TiO2 nano-particulates. Herein peCOD suitability to replace CODCr for analysis of industrial wastewater was investigated. The results indicated that for both untreated (i.e. incoming) and treated (i.e. effluent) industrial wastewater samples, peCOD results are lower than CODCr results. However, for the effluent samples, the two methods’ results are strongly correlated. Containing hard to oxidize materials (i.e. macromolecules) and high concentrations of chloride and nitrogenous compounds were identified as potential causes of difference between the results of the two methods. When there is variation in the composition of the incoming wastewater to a treatment process, information about the wastewater composition is required for process optimization. Thus optimization cannot be based solely on bulk measurements of organic pollution (e.g. COD). In this study, a novel combination of LC-OCD analysis with Design-Of-Experiments (DOE) methods was used to optimize the Fenton Advanced Oxidation (AO) treatment conditions in terms of chemical reagent concentrations, to develop statistical models of the process, and to identify potential mechanisms of COD removal. / Thesis / Master of Applied Science (MASc) / Many industrial facilities do not treat their wastewater on-site and instead ship it to specialized treatment facilities. Ensuring that the treated effluent meets the stringent discharge regulations is a challenging task for such facilities as the composition of the incoming feed to the treatment process changes with each shipment. In this work, application of two new analytical tools, PeCOD® and Liquid Chromatography-Organic Carbon Detection (LC-OCD), for measurement and characterization of industrial wastewater organic pollution respectively, has been investigated. The conventional method of measuring organic pollution, Chemical Oxygen Demand (COD), requires 2-3 hours to complete. Herein the suitability of an alternative parameter, Photoelectrochemical Oxygen Demand (peCOD), that can be measured in approximately 15 minutes for replacing COD analysis in industrial wastewater plants was investigated. Implementation of effective treatment processes that are operated at their optimum conditions is required to meet the stringent discharge regulations. Advanced Oxidation (AO) is an effective method of industrial wastewater treatment. Herein, optimum AO treatment conditions were studied via application of the LC-OCD analysis for organic pollution characterization.

While the terms reduce, reuse, and recycle are common concepts in minimizing resource waste, most people do not think twice about energy as a resource or the large amounts of wasted energy in wastewater treatment and industrial processes. Recovery of wasted energy or reducing the net energy consumption of such processes would save resources and reduce energy costs. This research investigated emerging energy systems for handling wastewater (bioelectrochemical systems) and waste heat (ion exchange membrane systems) to elucidate and quantify thermodynamic and kinetic phenomena in biological and electrochemical reactions. Bioelectrochemical systems utilize exoelectrogenic microorganisms for wastewater treatment energy recovery in the form of electricity or biogas. The substrate utilization and electron transfer by exoelectrogens to the bioanode have not been clearly explained and thus there are no commonly accepted models for bioanode performance. A comprehensive model for bioanode operation was proposed including equilibrium, kinetics, and microbiological characteristics. The utilization and preference of different organic substrates were also assessed with electrochemical techniques and it was found that linear sweep voltammetry and exchange current are good indicators of whether a substrate is directly or indirectly utilized by exoelectrogenic microorganisms. This research also investigated ion exchange membrane systems for energy recovery from waste-grade heat, such as that wasted in the steel refinery and power industries, using concentration gradients of ammonium bicarbonate solutions. Estimation of the junction potential (amount of concentration gradient energy) has significant technical difficulties for highly concentrated ammonium bicarbonate solutions (e.g., unknowns in equilibrium speciation and activity coefficient determination). A straightforward estimation method was proposed and found to be able to reliably determine the junction potential across an ion exchange membrane based on conductivity measurement, simplifying the model for junction potential determination. / Thesis / Doctor of Philosophy (PhD)

Heavy metals are a growing environmental concern as they are unable to be metabolized in the environment, leading to bioaccumulation in the food chain and impacting human health. Treating heavy metals is difficult and expensive. Current methods include precipitation (which generates sludge that is costly to dispose of) or requires the use of a membrane, which fouls and requires regeneration. Microbial electrolysis cells (MECs) represent an alternative for treating heavy metal contaminated wastewater. Reactor components are cheap, and operation requires only a small amount of electricity. The electrically active biofilm oxidizes organics in the wastewater while transferring electrons first to the anode, then to the cathode, where aqueous metals are reduced to a solid deposit, a mechanism called electrodeposition. Few studies have been conducted to investigate the best operational conditions for heavy metal removal in MECs. In this study, the effects of hydrodynamics, applied voltage, and initial metal concentration on heavy metal removal mechanisms are investigated, and the best operational practices are determined on a high level. Mixing in the cathode chamber increased electrodeposition by 15%, decreased the cathode potential by -0.06 V, and increased current generation between 10-30%. Increasing the applied voltage from 0.6 V to 1.2 V increased electrodeposition by 22%. With both mixing and higher voltage applied, 93.35% of cadmium was removed from the catholyte in 24 hours. Although high voltage application maximized electrodeposition for short-term treatment, long-term treatment indicated lower applied voltage resulted in healthier MEC reactors, better overall metal recoveries, along with a more stable cathode potential. / Thesis / Master of Applied Science (MASc)

Anaerobic digester design and operation influences the biomass degradation efficiency performed by complex and diverse microbial communities. Optimum anaerobic digester design and operational parameters in residential on-site wastewater treatment sites (OWTS) establishes physiochemical environments suitable for the growth and stability of the microbial communities responsible for organic waste degradation. A comparative study of the microbial communities and their functional profiles between different OWTS designs and operational parameters have not been done despite their functional importance in residential organic waste removal. Using whole-metagenome shotgun sequencing, microbial community compositions and functions were compared between two digester designs: conventional box septic tanks and septic tanks equipped with a novel closed-conduit tube called the InnerTubeTM. Wastewater was sampled along the length of each digester to explore the microbial community stratification during the anaerobic digestion treatment process. Additionally, the effect of effluent, aerobic recirculating-lines on the digester microbiome was also explored. Physiochemical characteristics in the form of oxygen demand, nitrogen and solids content was used as endpoints and correlated with microbial community and functional gene abundances to explore the microbes driving anaerobic digestion. Conventional digesters were characterized by syntrophic proprionate-oxidizing microbes and acetoclastic methanogens, while InnerTube™ digesters were characterized by syntrophic sulfate-reducing microbes and hydrogenotrophic methanogens. Recirculating digesters were enriched with denitrifying microbial consortia in syntrophy with hydrogenotrophic methanogens. Microbial communities were organized according to hydrolytic, acidogenic, acetogenic, and methanogenic groups along the digester treatment process. Insight into the core microbiome of OWTS can inform bioaugmentation and digester design and operation optimization strategies to improve the treatment of decentralized residential sewage sources. / Thesis / Master of Science (MSc) / Anaerobic digesters are used throughout North America to treat residential sewage. Despite their prevalence, the composition and function of the microbial communities driving sewage degradation in residential digesters has not been studied. We used DNA sequencing to compare the microbial communities and functional genes in different anaerobic digester designs across Southern Ontario. Our findings suggest there are successive microbial groups along the length of septic tanks and that different septic tank designs harbor characteristic sulfidogenic and methanogenic microbes. Characterization of these microbes could inform septic tank bioaugmentation, design and operational optimization strategies to improve sewage treatment performance.