Doctor of Philosophy

dissertationBacteriophages are viruses that infect bacteria and are known to be a very important component of microbial ecology in aquatic environments. Bacteria are involved in removing organics, ammonia and phosphorus in activated sludge processes. Frequent upsets, however, were found in the activated sludge process such as nitrification failure and filamentous bulking, causing the deteriorated effluent quality. Those upsets are caused by either unwanted bacterial growth or the death of key bacteria in an activated sludge bioreactor. The prophage on the bacterial genome remains dormant, but can cause cell lysis under certain environmental conditions. The effect of various environmental stress factors was examined on the ammonia oxidation and prophage induction in a model ammonia oxidizing bacterium, Nitrosospira multiformis. The factors included in the study were pH, temperature, organic carbon, the presence of heavy metal and toxicity. The selected environmental factors are commonly encountered in wastewater treatment processes, where ammonia oxidizing bacteria play a pivotal role of converting ammonia into nitrite. All of the factors could induce prophage from N. multiformis, demonstrating that cell lysis due to prophage induction could be an important mechanism contributing to the frequent upset in ammonia oxidation efficiency in full-scale treatment plants. The lytic phage could be applied to control biomass bulking in the activated sludge process using model filamentous bacteria. The lytic phage especially infecting model iv filamentous bacteria was isolated from the mixed liquor of a wastewater treatment plant. Significant reduction of sludge volume index (SVI) was observed after the isolated phage addition. The phages were considerably stable after exposure to high temperature and pHs, emphasizing that phage can withstand the seasonal/operational fluctuations. The isolated phage showed no cross infectivity with other bacteria most commonly found in activated sludge systems, thus validating its suitability for biocontrol of filamentous bulking caused by filamentous bacteria. Following the application of bacteriophage-based biocontrol, successful reduction in SVI was achieved, indicating improved biomass settling. The phage application did not affect the nutrient removal efficiency of the biomass. The phage-based biocontrol, therefore, holds a great potentiality for large-scale applications as an economic agent in the mitigation of several water, wastewater and environmental problems

Bacterial Communities and Antibiotic Resistance Communities in a Full-Scale Hospital Wastewater Treatment Plant by High-Throughput Pyrosequencing

The community of whole microbes and antibiotic resistance bacteria (ARB) in hospital wastewater treatment plants (WWTP) receiving domestic wastewater (DWW) and hospital wastewater (HWW) was investigated. Samples from an influent of a secondary clarifier, at each treatment train, were characterized for the whole microbial community and ARB on the antibiotic resistance database, based on high-throughput pyrosequencing. The pyrosequencing analysis revealed that the abundance of Bacteroidetes in the DWW sample was higher (~1.6 times) than in the HWW sample, whereas the abundance of Proteobacteria in the HWW sample was greater than in the DWW sample. At the top twenty of the genus level, distinct genera were observed—Saprospiraceae in the DWW and Zoogloea in the HWW. Apart from the top twenty genera, minor genera showed various antibiotic resistance types based on the antibiotic resistance gene database

Power generation and oil sands process-affected water treatment in microbial fuel cells

Oil sands process-affected water (OSPW), a product of bitumen isolation in the oil sands industry, is a source of pollution if not properly treated. In present study, OSPW treatment and voltage generation were examined in a single chamber air-cathode microbial fuel cell (MFC) under the effect of inoculated carbon source and temperature. OSPW treatment with an anaerobic sludge-inoculated MFC (AS-MFC) generated 0.55 ± 0.025. V, whereas an MFC inoculated with mature-fine tailings (MFT-MFC) generated 0.41 ± 0.01. V. An additional carbon source (acetate) significantly improved generated voltage. The voltage detected increased to 20-23% in MFCs when the condition was switched from ambient to mesophilic. The mesophilic condition increased OSPW treatment efficiency in terms of lowering the chemical oxygen demand and acid-extractable organics. Pyrosequencing analysis of microbial consortia revealed that Proteobacteria were the most abundant in MFCs and microbial communities in the AS-MFC were more diverse than those in the MFT-MFC.</p

Biohydrogen Fermentation from Sucrose and Piggery Waste with High Levels of Bicarbonate Alkalinity

This study examined the influence of biohydrogen fermentation under the high bicarbonate alkalinity (BA) and pH to optimize these critical parameters. When sucrose was used as a substrate, hydrogen was produced over a wide range of pH values (5–9) under no BA supplementation; however, BA affected hydrogen yield significantly under different initial pHs (5–10). The actual effect of high BA using raw piggery waste (pH 8.7 and BA 8.9 g CaCO3/L) showed no biogas production or propionate/acetate accumulation. The maximum hydrogen production rate (0.32 L H2/g volatile suspended solids (VSS)-d) was observed at pH 8.95 and 3.18 g CaCO3/L. BA greater than 4 g CaCO3/L also triggered lactate-type fermentation, leading to propionate accumulation, butyrate reduction and homoacetogenesis, potentially halting the hydrogen production rate. These results highlight that the substrate with high BA need to amend adequately to maximize hydrogen production

Biodegradation of oil sands process affected water in sequencing batch reactors and microbial community analysis by high-throughput pyrosequencing

Two sequencing batch reactors (SBR) were constructed and filled with different inocula of activated sludge (AS) and mature fine tailings (MFT) to treat oil sands process-affected water (OSPW). The COD was reduced by 82% in the AS-SBR and 43% in the MFT-SBR during phase I using 10% OSPW and 90% synthetic wastewater as reactor feed. However, COD removal reached 12% and 20% in the AS-SBR and the MFT-SBR, respectively, when 100% raw OSPW was fed into the reactors. Maximum removal of acid-extractable organics (AEO) was 8.7% and 16.6% in the AS-SBR and the MFT-SBR, respectively with a hydraulic retention time of one day. Pyrosequencing analysis revealed that Proteobacteria was the dominant phylum and beta- and gamma-Proteobacteria were dominant classes in both reactors. Evidence of a microbial community change was observed when influent raw OSPW was switched from 50 to 100%. More significant changes in the AS-SBR community were detected.</p

Phage-Based Biocontrol of Antibiotic-Resistant Bacterium Isolated from Livestock Wastewater Treatment Plant

The presence of antibiotic-resistant bacteria (ARB) in receiving water can severely threaten the aquatic environment and human health. The treated effluent containing ARB in some livestock wastewater treatment plants (WWTPs) is returned to the municipal WWTP to reduce the residual ammonia and phosphorus concentrations. ARBs are widespread through wastewater treatment processes and are discharged into river and lake. This study highlights that the isolated lytic phage could reduce ARB isolated from livestock WWTPs and apply phage-based biocontrol in mixed cultures. ARB and lytic phages were isolated from livestock wastewater and used in a batch reactor with diverse cultures. The isolated bacterium was from the Aeromonas species and was resistant to various antibiotics (penicillin, tetracycline, colistin, and kanamycin), indicating multi-drug resistance and biofilm formation. The isolated lytic phage successfully infected Aeromonas species in pure culture and was relatively stable in terms of pH, temperature, and toxic chemicals. The multiplicity of infection (MOI) was examined to determine the proper phage number to kill the host bacterium. The optimal number to control the isolated ARB was a 1:100 phage-to-host ratio. Scanning electron microscopy showed that lytic phages reduced bacterial growth and biofilm formation. Phage-mediated biocontrol was applied in a batch reactor with mixed cultures. Pyrosequencing data from the batch reactor indicated that lytic phages reduced the proportion of the isolated ARB from 65.7 to 20% in 24 h. This study provides evidence for the possible application of lytic phages to control ARB in treated wastewater and an alternative method to prevent the widespread exposure of ARB without producing chemical byproducts

Biological fixed film

The review includes literature published during the year 2012 regarding the use of biofilms and bioreactors to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular polymeric substance and its extraction from biofilms; biofilm consortia and quorum sensing; biofilm imaging techniques; biofilm reactors and modeling.</p

Effect of reactor configuration and microbial characteristics on biofilm reactors for oil sands process-affected water treatment

Batch and continuous biofilm reactors (BBR and CBR) were operated to treat raw and ozone-treated oil sands process-affected water (OSPW). In raw OSPW, the BBR removed less (24% vs. 29%) chemical oxygen demand (COD) than did the CBR. The CBR removed 14% of the acid-extractable fraction (AEF) from raw OSPW and 51% from ozonated OSPW, whereas the BBR had lower AEF removal efficiencies of 6.2% and 37% for raw and ozonated OSPW, respectively. NAs with low molecular weight were preferentially degraded over those with high molecular weight, and classical NA degradation was more effective in the CBR than in the BBR. CBR operation with ozone-treated OSPW allowed a favorable growth of bacteria due to the high bioavailability of low molecular weight compounds. Scanning electron micrographs showed that distinct biofilm and extracellular polymeric substances (EPS) were formed under continuous flow conditions, and that the biofilm was thicker in the CBR than in the BBR. Microbial community analysis using denaturing gradient gel electrophoresis (DGGE) revealed more bands in BBR biomass samples; 23 strains were identified in the BBR compared to 21 in the CBR. The continuous flow mode removed organic compounds more favorably than the batch mode from raw and ozonated OSPW.</p

Biological fixed film

The review includes literatures published in the year of 2014 regarding the uses of biofilm and bioreactor to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular polymeric substance from biofilms; biofilm consortia and quorum sensing; biofilm reactors and biofilm in bioelectrochemical systems.</p

Biological fixed film

The review includes literatures published in the year of 2014 regarding the uses of biofilm and bioreactor to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular polymeric substance from biofilms; biofilm consortia and quorum sensing; biofilm reactors and biofilm in bioelectrochemical systems.</p