Date

2023-1-20

Author

Harb, Rayaan

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Recently, the implementation of next-generation biological nutrient removal techniques aimed at recycling nutrients such as nitrogen and phosphorus while generating energy, producing value-added products and mitigating greenhouse gas emissions, in wastewater treatment plants is being emphasized. In this regard, investigating the development and applicability of a DAMO-Anammox co-culture and a novel DAMO-Anammox-Microalgae sequential treatment unit in the treatment of anaerobic digester (AD) effluent was the main goal of this PhD research. A DAMO-Anammox co-culture is capable of oxidizing methane into carbon dioxide, oxidizing ammonium and reducing nitrite and nitrate into nitrogen gas. A DAMO-Anammox co-culture was enriched in an SBR and the effect of hydraulic retention time (HRT), thus nitrogen loading rate was assessed on the co-culture performance. The relative abundance in the microbial consortium of the target phyla were 8% Planctomycetota, 0.5% NC10, and 0.16% Euryarchaeota. Since the co-culture was Anammox dominated, the reduction in HRT from 6 to 4 days did not allow the DAMO microorganisms, especially DAMO bacteria any chance of competition with the Anammox bacteria. The short-term effect of ammonium to dissolved methane ratios (0, ¼, 1), which has not been investigated in the current literature, was assessed in batch reactors. The results illustrated DAMO bacteria dominance at ratios less than 1, and Anammox dominance at ratio of 1 constraining the DAMO bacteria activity in turn facilitating the increase in DAMO archaea activity. The effect of various combinations of nitrogen sources on the enrichment of the DAMO microorganisms and the DAMO-Anammox co-culture were researched. The results revealed that in the absence of a dominant Anammox culture, the DAMO (DAMO bacteria and DAMO archaea) activity was prominent which may allow a shorter enrichment period of a DAMO culture. A DAMO-Anammox co-culture consisting of 7% Planctomycetota, 0.2% NC10 and 0.3% Euryarchaeota was employed to treat an AD effluent with concentrations of about 222±8 mg TN/L (166±15 mg TAN/L and 56±6 mg NO2--N/L), achieving a TN removal rate of 12.1±2.6 mg N/L·day. The DAMO-Anammox-Microalgae system was successful in completely removing nitrogen and phosphorus from an AD effluent. Regarding the promising nature of this integrated system, an innovative wastewater treatment system was further proposed.

Subject Keywords

DAMO, Anammox, microalgae, anaerobic, denitrification

URI

https://hdl.handle.net/11511/102018

Collections

Graduate School of Natural and Applied Sciences, Thesis