Establishment of Anammox wastewater treatment process in the Expanded Bed Biofilm Reactor (EBBR) with ABDite

Anyanwu, Comfort Chinyere (2023) Establishment of Anammox wastewater treatment process in the Expanded Bed Biofilm Reactor (EBBR) with ABDite. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

The anaerobic ammonia oxidation (Anammox) process plays a vital role in wastewater treatment by removing up to 90% nitrogen at a lower cost: due to reductions in energy and oxygen consumptions by 60%. The Anammox process has successfully been used by different bioreactors at laboratory, pilot, and industrial scale to treat wastewater that originated from agricultural, domestic, and industrial sources amongst others. The aim of this thesis is to determine whether the Anammox wastewater treatment process could be established using the lab scale expanded bed biofilm reactor (EBBR) successful at high-rate nitrification of wastewater. In a series of studies, the research will: i) establish the Anammox process in the EBBR; ii) optimize the EBBR-Anammox process pH and temperature conditions; iii) Examine the EBBR ABDite biofilm and compare the EBBR-Anammox performance with other available Anammox process technologies; and iv) identify key Anammox bacteria in the established Anammox process. Results indicated that the established lab scale EBBR-Anammox process achieved a maximum nitrogen removal rate (NRR) of 6.1 Kg N m-3 d-1 from a loading rate of the 9.8 Kg N m-3 d-1 with 80 – 100 % nitrogen removal efficiency (NRE). The optimization results suggested that pH 8.2, at 28 ºC as the optimum condition for the EBBR-Anammox process: with 2.23 ± 0.07 kg N m-3 EBBR d-1 NRR. SEM analysis detected biofilm with cauliflower structure, alongside filamentous, rod and cocci-like bacteria cell consistent with reported characteristic of Anammox bacteria; and yeasts-like communities on the EBBR ABDite bioparticles. Using molecular biology techniques, 3 Anammox bacteria genera (Candidatus Brocadia, Candidatus Kuenenia and Candidatus Jettenia) were identified in the established Anammox EBBR . Also identified were ammonia oxidizer Nitrosomonas, complete ammonia oxidizer Nitrospira, nitrite oxidizer Nitrobacter, ammonia oxidizing Archaea Nitrosarchaeum limnium; nitrate reducing bacteria Nitratireductor, anaerobic het erotrophic bacteria Anaerolinea thermolimosa, yeasts and others The EBBR achieved comparable nitrogen removal rate and nitrogen removal efficiency, developed similar Anammox granules, cauliflower biofilm and key bacterial communities reported by other Anammox technologies. These results suggest that the Anammox process was established in the EBBR and opens the possibility of further research in adapting the EBBR system to the complete Anammox process for wastewater treatment.