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The research demonstrated that an easily cultivated fungus was screened from filter materials of fresh water recycle aquaculture system. A fungus, characterized as being able to remediate multiple nitrogenous wastes, was identified as Aspergillus niger NBG5. A. niger NBG5 was developed as superior fungus through bioreactor so as to establish a nitrogenous removal system of single tank stirred tank reactor (SSTR). A. niger NBG5¡¦s remediative responses were tested under various temperatures. The experiment showed that specific nitrogen consumption rate was 0.047 g-N g-cell-1 day-1 at 30¢J which were better than nitrite nitrogen and protein nitrogen consumption. When the artificial wastes¡¦ ammonium concentration was set as 50 mg L-1, its ammonium consumption rate was 4.8 mg m-2 day-1. The ammonium consumption rate reached 0.32 mg m-2 day-1 with aquaculture wastes. The result revealed that SSTR removed nitrogen from aquaculture wastes by A. niger NBG5 and achieved a purpose of decreasing ammonium within aquaculture wastes. The research simulated ammonium variable numerals between SSTR and BSTR (the system of bi-tank stirred tank reactor). Through BSTR, regression formula with water flow rate and ammonium removal efficiency rate was y = 5.7219x-0.9616 when the ammonium concentration was set as 50 mg L-1. SSTR simulated a phenomenon¡Xthe more ammonium concentration aquaculture wastes reached, the much waste water volume of aquaculture tank it had. Based on the same requirements, a better water flow rate would be concluded through various water flow rate simulation tests. SSTR numerical simulation system could simulate ammonium production rate of fish tank to get consumption trends of ammonium concentration in fish tank and reactor. The simulation results would be able to decide later system design, water flow rate, feed timing and similar research references.

Thesis (Ph.D.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 201-209.

The membrane bioreactor (MBR) is becoming increasingly popular for wastewater treatment, mainly due to its capability of producing high quality effluent with a relatively small footprint. However, high plant maintenance and operating costs due to membrane fouling limit the wide spread application of MBRs. Membrane fouling generally depends on the interactions between the membrane and, the activated sludge mixed liquor, which in turn, are affected by the chosen operating conditions. The present research study aimed to explore the process performance and membrane fouling in the membrane enhanced biological phosphorus removal (MEBPR) process under different operating conditions by, (1) comparing two MEBPRs operated in parallel, one with constant inflow and another with a variable inflow, and by, (2) operating the MEBPRs with different solids retention times (SRT). On-line filtration experiments were conducted simultaneously in both MEBPR systems by using test membrane modules. From the transmembrane pressure (TMP) data of the test membrane modules, it was revealed that fouling propensities of the MEBPR mixed liquors were similar in both parallel reactors under the operating conditions applied, although the fouling propensity of the aerobic mixed liquors of both reactors increased when the SRT of the reactors was reduced. Routinely monitored reactor performance data suggest that an MEBPR process with a varying inflow (dynamic operating condition) performs similarly to an MEBPR process with steady operating conditions at SRTs of 10 days and 20 days. Mixed liquor characterization tests were conducted, including critical flux, capillary suction time (CST), time to filter (TTF) and, bound and soluble extracellular polymeric substances (EPS) were quantified, to evaluate their role on membrane fouling. The tests results suggest that the inflow variation in an MEBPR process did not make a significant difference in any of the measured parameters. With decreased SRT, an increase in the concentrations of EPS was observed, especially the bound protein, and the bound and soluble humic-like substances. This suggests that these components of activated sludge mixed liquors may be related to membrane fouling. No clear relationship was observed between membrane fouling and other measured parameters, including critical flux, normalized CST and normalized TTF.

While tissue-engineering approaches of heart valves have made great strides towards creating functional tissues in vitro, the instruments used, named bioreactors, cannot efficiently integrate multiple stimuli to accurately emulate the physiological microenvironment. To address this, we conceptually designed and built a bioreactor system that applied a range of mechanical tension conditions, modulated matrix stiffness, and introduced biochemical signals in a combinatorial and high-throughput manner. Proof-of-concept experiments on PAVIC-seeded hydrogels were performed to assess the independent and combined effects of tensile strain, matrix stiffness and TGF-β1 on myofibroblast differentiation by measuring α-SMA expression, a marker that indicates a disease-associated phenotype. We found that matrix stiffness and TGF-β1 significantly increased α-SMA levels (p < 0.001), while the effect of mechanical strain was only significant on soft gels (~12 kPa) without TGF-β1. This study therefore demonstrated independent and integrated effects of multiple stimuli in regulating key cellular events in the aortic valve.

Carvone is a flavor and fragrance compound that is prominent in nature and is found in the essential oils of many plants. Carvone exists as two enantiomers, (R)-(-)-carvone which has a spearmint aroma and (S)-(+)-carvone which has a caraway aroma and can be used in a variety of applications: as a common food additive, as an antimicrobial/antifungal agent and as a potato sprout inhibitor. Carvone is currently produced by the extraction of essential oils from plants where the yield and quality of the extracted oil depends largely on successful agricultural production of dill, spearmint and caraway plants. Biotechnological production can offer a constant supply of carvone that is independent of several agricultural limitations. In this study, it was confirmed that the substrate and product of the microbial biotransformation of trans-carveol to (R)-(-)-carvone by Rhodococcus erythropolis DCL14 can be inhibitory to the cells at high concentrations. As such, a two phase partitioning bioreactor was employed where the function of the second phase (immiscible organic solvent or solid polymer beads) was to partition the inhibitory substrate into the aqueous phase at a rate governed by the metabolic demand of the cells and uptake the inhibitory product as it accumulated in the aqueous phase. Rational selection strategies were employed when determining the appropriate organic solvent and solid polymer to be used as the second phase. The performance of the reactor was evaluated based on volumetric productivity, length of biotransformation and total volume of substrate added to the reactor. The most successful reactor configuration was one in which styrene/butadiene copolymer beads were used as a second phase in the reactor and the fermentation medium was continuously circulated through an external extraction column packed with Hytrel® 8206 polymer beads. The volumetric productivity, length of biotransformation and total volume of substrate added to this reactor were 99 mg/L.h, 48.75 h and 35 mL, respectively whereas in the single phase benchmark reactor the performance indicators were only 31 mg/L.h, 15.25 h and 5 mL, respectively. These results clearly show the advantage of employing a partitioning bioreactor configuration for the biotechnological production of high value chemical species that exhibit cytotoxicity. / Thesis (Master, Chemical Engineering) -- Queen's University, 2008-01-24 10:20:09.589

The purpose of this thesis was to compare ethinylestradiol (EE2) and nitrogen removal in a conventional membrane bioreactor (C-MBR) and a simultaneous nitrification-denitrification membrane bioreactor (SND-MBR). Two MBRs were operated in parallel for 450 days; various MBR operating parameters, total nitrogen removal, and estrogenic activity removal (EA) were measured. The SND-MBR was able to remove 59% of influent TN with an additional 21% removed via sludge wasting; the C-MBR had a TN removal efficiency of only 31%. The C-MBR and SND-MBR removed 57% and 58% of influent EA, respectively. Biodegradation was the dominant removal mechanism for both reactors with KBIO coefficients of 1.5 ± 0.6 and 1.6 ± 0.4 days-1 for the C-MBR and the SND-MBR, respectively. Adsorption removed approximately 1% of influent EA in each reactor. This indicates that SND was able remove greater amounts of TN with no observable impact on EA reduction and membrane operations.

Bioartificial Liver (BAL) is a term for medical devices designed to replace natural liver functions. The idea behind the use of artificial livers is to either externally support an injured liver to recovery or bridge a patient with a failing liver to transplantation. Central to all BAL systems is a bioreactor for culturing liver cells. The main function of this reactor is to provide a cell adhesion matrix and supply the necessary nutrient solution. A high cellular oxygen uptake rate combined with low solubility in aqueous media makes oxygen supply to the liver cells the most constraining factor in current reactor designs. Devices with parallel-plate channel geometry promise high efficiency for blood detoxification and liver metabolism. However, due to their specific flow regime oxygen depletion in the medium is a major problem in these devices. This thesis explores a unique method of controlling and measuring dissolved oxygen in BAL cell-culture bioreactors and lab-on-a-chip devices. Testing is performed using simulations, prototype bioreactor devices and in-vitro measurement of dissolved oxygen. Several strategies developed to fabricate the bioreactors and integrate oxygen sensing are presented. Emphasis is placed on techniques that provide compatibility with commonly used microfabrication processes, while allowing for laterally-resolved measurement of oxygen in a re-usable, low-cost setup. The most significant contribution presented is the development and assessment of the tapered cell-culture bioreactor with integrated PtOEPK/PS oxygen sensor. The combination adopts a unique approach to oxygen control. Bioreactor shape is used to modulate the oxygen supplied to cells via the resulting shear-stress function. By linearly increasing the shear-stress oxygen concentration can be maintained constant over the length of the reactor. Using the integrated oxygen sensor, the resulting concentration profile can be monitored in real-time with high lateral resolution. The advantage of the device over existing techniques is that no additional oxygenation inside the reactor chamber is required to maintain a certain concentration profile and that oxygen concentration can be mapped in-situ without having to introduce further chemicals into the perfusion medium. This thesis presents a number of other contributions: a grayscale mask process, development of the PtOEPK/PS sensor patterning method and signal optimization regime, demonstration of the multi-stream flow application, an experimental setup for sensor calibration and a process to pattern cell-adhesion proteins simultaneously with the oxygen sensor, a multi-layer BAL prototype and the results of a brief experiment to test an approach using vertically aligned carbon nanotube bundles as fluidic conduits for bile drainage.

The rate of anaerobic digestion (AD) often depends on the rate-limiting hydrolysis step that makes organics available to microorganisms. To achieve efficient conversion of particulates to soluble materials and finally methane, the biomass in the digester must be provided with optimal operational conditions that will allow for biomass retention and substrate metabolism. Two approaches were employed in this study to improve the ultimate biodegradability of waste activated sludge (WAS) - Pre-treatment (PT) and operation using an Anaerobic Membrane Bioreactor (AnMBR). PT of WAS is one way of speeding up hydrolysis. It has been proposed that PT leads to the lysis of cells, which in turn causes the release and solubilisation, and thus availability of intracellular matter to microorganisms for microbial growth and metabolic activities. This study compared the effect of thermal, sonication, and sonication + hydrogen peroxide PT on chemical oxygen demand (COD) solubilisation of WAS. Based on the soluble COD (SCOD) release, it was concluded that combined chemi-sonic treatment resulted in better WAS degradation rather than individual ultrasonic pre-treatment and thermal PT. The highest solubilisation rate was observed at a chemi-sonic PT of 50gH2O2/kgTS and sonication duration of 60 minutes. At this PT, a COD solubilisation of 40% was observed which was significantly different than PT involving only sonication and no pre-treatment (0.88%) at 95% confidence. Therefore a peroxide-sonic PT was chosen to treat WAS in this study as it was expected to result in the greatest improvement in WAS biodegradability. In addition to PT, biodegradability of WAS can also be improved by coupling PT with an AnMBR. AnMBRs prevent biomass washout by decoupling the solids retention time (SRT) from the hydraulic retention time (HRT). Thus, a long SRT can be used to provide sufficient duration for biological activities without increasing the volume of the reactor. In this study, a 4.5L AnMBR with an HRT and SRT of 3 and 20 days, respectively was used to treat raw and PT WAS. In order to compare the biodegradability of PT and raw WAS, the AnMBR was operated in three phases. Phase 1 was operated with raw WAS, Phase 2 was operated with WAS pre-treated with 50 gH2O2/kgTS and 20 minutes ultrasound (US), and Phase 3 was operated with WAS pre-treated with 50 gH2O2/kgTS and 60 minutes US. The anaerobic biodegradability of WAS following a combination of ultrasonic pre-treatment and H2O2 addition was significantly improved, with Phase 3 resulting in the greatest improvement. The COD destruction for phases 1, 2, and 3 were 49%, 58%, and 63%, respectively whereas the volatile suspended solids (VSS) destruction for phases 1, 2, and 3 were 46%, 71%, and 77% respectively. Organic Nitrogen (Org-N) destruction increased from 44% to 52% for phases 1 and 2 respectively. A further increase of 18% in Org-N destruction was observed in phase 3. This improvement in biodegradability of WAS was attributed to the high solubilisations of COD, VSS, and ON and conversion of non-biodegradable materials to biodegradable fractions. In order to determine the effect of PT of WAS on membrane performance, the transmembrane pressure (TMP) and fouling rate were monitored throughout the operation of the AnMBR. Negligible variation in membrane performance was observed over all three phases. At a constant low flux of 2.75 litres/m2/hour (LMH), the TMP and the fouling rate remained low over the course of operation. In order to maintain the performance of the membrane, maintenance cleaning with 50 ml of 2g/L critic acid solution followed by 50 ml of 0.2 g/L sodium hypochlorite was performed three times a week. In addition, a gas sparing rate of 2 L/minute and a permeation cycle of 10 minutes with 8 minutes of operation followed by 2 minutes of relaxation was employed. During phase 2 of this study, a new membrane was installed due to a faulty gas sparging pump. A slight decrease of TMP was observed with the installation of the new membrane; however the decrease was minimal. In addition critical flux for phases 2 and 3 were determined to be in the range of 6 to 12 LMH. In conclusion, the incorporation of H2O2-US PT with AD could allow treatment plants to substantially reduce the mass flow of solids and organics and thus result in a decrease in requirements for downstream sludge processing. With sufficient maintenance, steady operation could be achieved for a hollow fibre AnMBR with a total solids concentration range of 20-25 g/L, an HRT of 3 days, and an SRT of 20 days. It was found that PT could be successfully integrated with AnMBR to substantially reduce the HRT required for digestion when compared to conventional designs.

The purpose of this thesis was to compare ethinylestradiol (EE2) and nitrogen removal in a conventional membrane bioreactor (C-MBR) and a simultaneous nitrification-denitrification membrane bioreactor (SND-MBR). Two MBRs were operated in parallel for 450 days; various MBR operating parameters, total nitrogen removal, and estrogenic activity removal (EA) were measured. The SND-MBR was able to remove 59% of influent TN with an additional 21% removed via sludge wasting; the C-MBR had a TN removal efficiency of only 31%. The C-MBR and SND-MBR removed 57% and 58% of influent EA, respectively. Biodegradation was the dominant removal mechanism for both reactors with KBIO coefficients of 1.5 ± 0.6 and 1.6 ± 0.4 days-1 for the C-MBR and the SND-MBR, respectively. Adsorption removed approximately 1% of influent EA in each reactor. This indicates that SND was able remove greater amounts of TN with no observable impact on EA reduction and membrane operations.