The combination of moving bed biofilm reactors and membrane bioreactors (MBBR-MR) can compensate for the drawbacks of both of these systems and further increase their acceptance and application in wastewater treatment industries. Despite the potential benefits of a MBBR-MR technology there has only been limited study of this configuration. The present study consisted of an overall assessment of the performance of a combined MBBR-MR system under high and low loading rates. Since colloidal matter in mixed liquor suspended solid (MLSS) is considered as one of the important contributors to membrane fouling, pre-treatment of membrane feed by coagulation was investigated for improving membrane performance. The performance of the MBBR-MR was assessed based on its chemical oxygen demand (COD) removal efficiency and membrane fouling mechanisms. The study was carried out using pilot-scale MBBR and bench-scale batch membrane filtration setups (Millipore Inc. Bedford, MA). The pilot MBBR had a working volume of 1.8 m3 and a 30% carrier fill fraction. The MBBR was operated with loading rates of 160 ± 44 g/m2/d (hydraulic residence time (HRT) of 4.6 h) and 223 g/m2/d (HRT of 2.6 h). The MBBR feed was obtained from a starch recovery line in a potato chip processing factory. The carriers were mixed by coarse bubble aeration and the dissolved oxygen (DO) was maintained above 2 mg/l. Preliminary jar test trials (based on turbidity removal) were performed in order to obtain an optimal dosage of coagulants for subsequent ultrafiltration (UF) tests. The efficiency of three coagulants (alum, ferric chloride and a blend of polyaluminum chloride and polyamine) was evaluated. The membranes were composed of polyethersulfone (PES) and had a pore size of 0.05 microns. The results of this study indicate that the combination of MBBR with membrane filtration can be operated at relatively high loading rates to yield a constant high quality permeate that is suitable for water reuse purposes. Fouling of the membrane by the wastewater was found to be substantially reduced by treatment with the MBBR. The reversible and irreversible fouling of the MBBR effluent were 56 and 63%, respectively, of that observed with the raw wastewater. The MBBR Loading-rate was found to affect treatment efficiency of the MBBR-MR and membrane performance. Operation under the elevated loading-rate conditions HRT = 2.6 hours) resulted in an increase in the irreversible fouling of the membranes (60% on average). The addition of all the coagulants in this study was found to decrease the fouling of the membrane. However, the extent of the pre-coagulation effect on membrane fouling was found to strongly depend on the type and dosage of the coagulant and the MBBR effluent characteristics. All the coagulants were effective in decreasing membrane fouling at their optimal dosages which was determined in preliminary jar tests. Ferric chloride performed the best as a pretreatment coagulant compared to alum (Aluminum sulfate) and the coagulant blend with reductions in both reversible and irreversible fouling (43-86% and 51-71%, respectively) and increased consistency (in decreasing fouling) as compared to the other coagulants. Alum had no effect on irreversible fouling and the coagulant blend significantly increased irreversible fouling in some trials (up to 196% or by a factor of 3 when overdosed). Additionally, alum and the blend were, on average, 29% and 7%, less effective than ferric chloride in reducing reversible fouling under the conditions and dosages tested.

There is an urgent need to develop ammonia removal treatment systems for municipal and industrial wastewater treatment due to the increasingly stringent ammonia effluent discharge regulations implemented by Canada, the United States, and the European Union. The objective of this dissertation is to develop new understanding and advance the current design and operation of total ammonia nitrogen (TAN) removal via the moving bed biofilm reactor technology (MBBR) for municipal and industrial wastewaters. The first specific objective is to develop a passive, low operationally intensive, efficient and robust design strategy for municipal wastewater treatment to achieve partial nitritation (PN) as a pre-treatment to anammox treatment without using control strategies such as operating at low dissolved oxygen, or the use of inhibitors. This first objective includes developing new knowledge of the biofilm, biomass and microbiome of attached growth PN systems. The second specific objective is to investigate the impact of defining a maximum biofilm thickness, via bio-carrier design, to enhance the effects of free nitrous acid inhibition for PN of municipal wastewaters. The third objective is to investigate the effect of influent copper concentration on nitrifying MBBR systems over long-term operations, to demonstrate the feasibility of the nitrifying MBBR as a solution for TAN removal from gold mining wastewaters. The results pertaining to the first objective, achieved via a study investigating the operation of a nitrifying moving bed biofilm reactor at elevated TAN surface area loading rates (SALRs) of 3, 4, 5, and 6.5 g TAN/m²∙d with the aim of achieving passive PN, demonstrates that operating at a TAN SALR value of 6.5 g TAN/m²∙d can achieve PN without restricting dissolved oxygen or using inhibitors. Operating at a TAN SALR value of 6.5 g TAN/m²∙d achieves a TAN surface area removal rate (SARR) of 3.5 g TAN/m²∙d, and a nitrite accumulation of 99.8% of the oxidized TAN, demonstrating the suppression of nitrite oxidizing bacteria (NOB) activity, while achieving elevated TAN SARR values. At the molecular-scale, there is a statistically significant change in the ammonia oxidizing bacteria (AOB) to NOB ratio from 1:2.6 to 8.7:1 as the TAN SALR increases from 3 to 6.5 g TAN/m²∙d; however, even at a TAN SALR value of 6.5 g TAN/m²∙d there is an NOB abundance of approximately 2%; thus demonstrating that NOB remain present in the biofilm, while their activity is suppressed by operation at elevated TAN SALR values. Furthermore, this system was shown to achieve stable PN consistently for over a period of 10 months of operation, demonstrating a robust, passive, low operational strategy for attached growth PN. The second objective of this dissertation is addressed through a study that compared the carrier design of defined maximal biofilm thickness (z-prototype carrier) to undefined maximal biofilm thickness (chip-prototype carrier) for PN via free nitrous acid inhibition of tertiary, low carbon, municipal wastewaters. The study demonstrates that defined maximal biofilm thickness is a preferred design choice to achieve attached growth PN. The chip-prototype carrier shows biofilm thicknesses and biofilm mass values that are ten-fold higher than the z-prototype carrier, which is shown to contribute to the impact of free nitrous acid on AOB and NOB activities. The z-prototype carrier shows PN is achieved after 3 hours of exposure to free nitrous acid while the chip-prototype carrier does not achieve PN within this same time of exposure. Therefore, the defined maximal biofilm thickness carrier is identified in this research as the preferred design option to achieve attached growth PN for municipal, low carbon, tertiary wastewater treatment. The results of the third objective, achieved via a study investigating the effects of influent copper concentrations on nitrifying MBBR during long term operations to gold mining wastewaters, demonstrates that there is no AOB inhibition in attached growth systems exposed to 0.1, 0.3, 0.45, and 0.6 mg Cu/L for long exposure times. A trend of increasing nitrite accumulation with increasing influent copper concentrations is shown, indicating that NOB inhibition occurs at influent copper concentrations of 0.3 mg Cu/L and greater, with the greatest NOB inhibition observed with an influent copper concentration of 0.6 mg/L. There is no statistically significant difference in biofilm characteristics at the copper concentrations tested; however, there is a trend of increasing biofilm thickness and biofilm roughness with increasing copper concentrations. This study demonstrates the resilience of the nitrifying biofilm to copper inhibition and demonstrates that the nitrifying MBBR is a promising system for removing TAN in mining wastewater in the presence of copper.

A conventional membrane bioreactor (MBR) and two moving bed bioreactors coupled with ultrafiltration membrane filtration were operated for close to six months to investigate biological nutrient removal and potential fouling inducing parameter mitigation. Unique to one of the moving bed membrane bioreactors (MBMBR) was a newly designed media that incorporated a hydrodynamic exterior carrier with a highly porous interior packing. Preliminary investigation indicates that nitrogen compounds were superiorly removed in the two MBMBRs when compared with the MBR. This is a result of denitrification processes occurring in anoxic micro-zones found within the depths of the biofilm affixed to media. Fouling propensity was found to be increased by over four times in the MBMBR systems as compared to the MBR. Mixed liquor, permeate and filtrate analysis, membrane fibre examination and permeability tests indicated that colloidal organic carbon, as well as soluble microbial products were the dominant fouling inducing compounds. / Manuscript format / The Natural Sciences and Engineering Research Council of Canada

PhD. (Department of Biotechnology, Faculty of Applied and Computer Sciences), Vaal University of Technology. / South Africa utilises more antiretroviral (ARV) compounds per capita than any other nation in the fight against Human Immune Deficiency Virus (HIV) or acquired immunodeficiency syndrome (AIDS). Considering the main entrance pathways of antiviral drugs into the urban water cycle, excretions via urine or faeces from treated individuals play a dominant role. Due to the limited efficiency of conventional biological treatment (activated sludge), ARVs were detected in South African wastewater treatment plant effluents and surface waters. This poses a threat to aquatic environments due to the toxicity of ARVs and can be a potential contributor to ARV resistance due to persistent low level ARV exposure in the general population. This study investigated the efficacy of a moving bed biofilm reactor (MBBR) for ctybtri8nthe elimination of five ARV compounds i.e., tenofovir, emtricitabine, nevirapine, ritonavir and efavirenz from synthetic wastewater. Furthermore, the study also looked at the shift in microbial community compositions of biofilms in the MBBR due to exposure to the ARV compounds. Lastly, the ecotoxicity of the MBBR’s influent and effluent along with the actual ARV compounds were examined. The capacity of ARV degradation by the MBBR was investigated by spiking synthetic wastewater influent with 10 μg/L of five ARV compounds. Actual removal during treatment was assessed by sampling the inlets and outlets of the reactor. A targeted solid phase extraction method with Ultra High Pressure Liquid Chromatography coupled to quadrupole time of flight mass spectrometry (LC-MS/MS) was used to quantify the five ARV compounds. Microbial diversity (alpha-diversity) of seeded sludge from a full-scale municipal WWTP and biofilm samples from a laboratory scale MBBR system during pre- and post-introduction of ARV compounds was investigated by Illumina sequencing of the 16S rRNA gene. Ecological toxicity of the MBBR’s influent and effluent along with the five ARV compounds was determined using the Vibrio fischeri, Daphnia magna and Selenastrum capricornutum toxicity test kits and measured as EC50. After MBBR treatment; Nevirapine, Tenofovir, Efavirenz, Ritonavir and Emtricitabine all showed marked reduction in concentration between the influent and effluent of the MBBR. On average, the percentage removed for Nevirapine, Tenofovir, Efavirenz, Ritonavir and Emtricitabine was 62.31%, 74.18%, 93.62%, 94.18% and 94.87% respectively. Microbial diversity results demonstrated that the introduction of antiretroviral drugs affects the bacterial community composition and diversity considerably. For instance, Nitrosomonas, Nitrospira and Alicycliphilus were found to be higher in post introduction of ARV compounds biofilm samples than in biofilm samples before the introduction of ARV compounds. The EC50 for Tenofovir, Emtricitabine, Nevirapine, Ritonavir and Efavirenz were 82.5, 41.7, 39.3, 60.3 and 0.21 mg/L respectively for S. capricornutum; 81.3, 50.7, 49, 87.1 and 0.43 mg/L respectively for D. magna; and 73.5, 55.1, 41.3, 83.6 and 0.55 mg/L respectively for V. fischeri. The EC50 of the influent and effluent were found to be above 100% concentration, therefore they could not be specifically determined. The ecotoxicity results show that ARV compounds are potentially toxic to the environment, with efavirenz being more toxic than the other four ARV compounds tested. Since there were no toxic effects observed from the effluent, it can be assumed that mineralisation has occurred, or the transformation products are of less or equal toxicity to the influent (because the influent did not show any toxic effects to the model organisms tested).