Kozet Yapsakli

Identification and quantitative evaluation of nitrogen-converting organisms in a full-scale leachate treatment plant

The presence of ammonia nitrogen in landfill leachates poses a significant problem for treatment plant operators. The nitrification-denitrification process mostly carries out the nitrogen conversion in biological treatment systems. However, recent research shows that other processes by anaerobic ammonia-oxidizing bacteria (Anammox) and ammonia-oxidizing archaea (AOA) were also responsible for the removal of nitrogen in biological systems. In this study, the nitrogen-converting microorganisms in the Bursa Hamitler Leachate Treatment Plant were identified and monitored by using molecular tools. Fluorescent in situ hybridization (FISH) and slot-blot hybridization results showed that the Nitrosomonas and Nitrospira species were the dominant ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), respectively. Quantitative real-time PCR results indicated that AOB, NOB, AOA and Anammox bacteria exist in the leachate treatment plant. However, the removal of ammonia can be ascribed mainly to nitrification because AOB (1.5%) and NOB (11.3%) were predominant among all nitrogen-converting bacteria. The results of the phylogenetic analysis based on amoA and 16S rDNA gene revealed that the uncultured bacterium clone 4-24, Kuenenia stuttgartiensis genome fragment KUST_E and the uncultured Crenarchaeota clone NJYPZT-C1 belong to AOB, Anammox and AOA populations, respectively, and were the dominant species in their cluster.

Investigation of nitrogen converters in membrane bioreactor

In this study, the activity and diversity of nitrogen converters, ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), ammonia-oxidizing archaea (AOA) and Anammox bacteria in a pilot-scale membrane bioreactor (MBR) were investigated and monitored using amoA and 16S rDNA-based molecular tools. The pilot-scale MBR (100 m3/day) was located inside the full-scale Pasakoy Advanced Wastewater Treatment Plant (WWTP), and operated for approximately 5 months without sludge purge. During 148 days of operation, volatile suspended solids (VSS) concentration increased from 2,454 mg/L to 10,855 mg/L and the average organic carbon and ammonia nitrogen removal rates were 92% and 99%, respectively. Real-time PCR results indicated that the fraction of AOB increased from 2.94% to 4.05% when VSS concentration reached to 3,750 mg/L throughout 148 days of operation. At higher VSS concentrations, the fraction of AOB declined gradually to 1.15% while the fraction of Nitrospira population was varied between 8.23 and 13.01%. However, significant change or any positive and negative correlations between VSS concentration and Nitrospira population were not observed in this period. The phylogenetic analysis revealed that MBR harbored diverse AOB community which was related to the Nitrosomonas and Nitrosospira lineage. Candidatus Nitrospira defluvii was the only detected NOB in this study.

Co-occurrence of nitrogen-converting organisms in full-scale treatment plants

This study provides insights into nitrogen-converting microorganisms in three full-scale wastewater treatment plants (WWTPs), which were investigated and monitored according to their nitrification performance and the presence of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), ammonia-oxidizing archaea (AOA), and Anammox bacteria based on different molecular tools: fluorescent in situ hybridization (FISH), slot-blot hybridization, and quantitative real-time PCR. In situ hybridization clearly showed the Nitrosomonas species as the prevailing AOB, and Nitrospira-related species as the dominant NOB. Real-time PCR results exposed the Istanbul Pasakoy, Bursa West, and Bursa East WWTPs as harboring diverse nitrogen-converting microbial communities that include AOB, NOB, AOA, and Anammox bacteria. Nitrospira species had the highest fraction of nitrogen-converting organisms, which was up to 39.3% in the WWTPs throughout the two-year monitoring period. This study is the first molecular analysis of the simultaneous occurrence of these microorganisms.

Speciation of nickel and zinc, its short-term inhibitory effect on anammox, and the associated microbial community composition

This study provides insight into the short-term effects of nickel and zinc on anammox. The impacts of these heavy metals are evaluated based on their potentially bioavailable fractions, including the intracellular, surface-bound, soluble, free-ion, and weak (labile) complexes of heavy metals, in the presence of certain inorganic/organic species. Results showed that the IC50 values for soluble, intracellular, cell-associated, surface-bound, and free-ion Ni concentrations are 5.99, 0.250, 0.930, 0.680, and 1.36 mg/L, respectively. The inhibitory effect of Zn is found to be lower with respect to Ni, with IC50 values of 6.76, 11.9, 15.1, and 2.71 mg/L for the soluble, intracellular, cell-associated, and free-ion Zn concentrations, respectively. This is the first detailed evaluation of anammox inhibition based on the fractionation of heavy metals. Metagenomic analysis reveals that Candidatus Kuenenia constitute approximately 89% of the entire Planctomycetes population, whereas Candidatus Brocadia are detected in relatively low fractions (3%).

SHARON Prosesinin Sizinti Suyu Aritiminda Uygulanmasi

Conventional nitrification-denitrification processes are used extensively for the treatment of nitrogenous compounds in leachate treatment however; it results in high operational cost due to excessive oxygen requirement. Combination of SHARON-ANAMMOX processes are among the novel nitrogen removal technologies and are promising methods for cost-effective removal of these compounds. In the scope of this study, the applicability of SHARON process for the pre-treated leachate (a lab scale anaerobic + aerobic MBR treatment) taken from Komurcuoda Leachate is investigated in a chemostat reactor. The applicability of the system is first tested using synthetic wastewater and after stable operation is achieved, diluted leachate is given to the system. The experimental results showed that influent ammonia is converted to nitrite with 52% nitritation efficiency and 40% of influent remained as ammonia. Therefore, the effluent of the SHARON system is in suitable composition to be treated in the ANAMMOX reactor.