Assessment of Sidestream And Mainstream Anammox-Based Systems Using Experimental and Mathematical Modelling Tools

Anaerobic Ammonium Oxidation (ANAMMOX) process is an innovative alternative which is carried out by an entirely autotrophic method for shortcut N-removal in nitrogen cycle, in addition this technological advancement results in less aeration demand, decline in organic matter addition as well as nitrite reduction. Compared to conventional biological nitrogen removal processes, an ANAMMOX-based process can potentially save energy since it reduces oxygen requirement by around 60%, organic carbon utilization by 100%, and sludge production by approximately 90%. Due to low growth rates and cellular yields of autotrophic ammonia removal bacterial communities and their sensitivity to adverse environmental conditions, ANAMMOX reactor startup from conventional returned activated sludge has become a major challenge. This comprehensive study aimed to understand the engineering aspects and practical applications of ANAMMOX-based autotrophic nitrogen removal processes and overcome the current challenges. Fast start-up using micro-granular development of ANAMMOX reactor was investigated to evaluate ANAMMOX activity, population dynamics and core community members as well as the potential start-up options for mainstream municipal ANAMMOX process, in an upflow anaerobic sludge blanket (UASB) reactor seeded with municipal returned activated sludge (RAS). The micro-granular UASB reactor has been operated under steady-state conditions with average nitrogen loading rate ranging from 1.2 to 0.18 KgN /m3/day and the average SRT of the reactor ranged from 36 to 72 days. Subsequently, a set of manometric batch experiments to evaluate ANAMMOX performance efficiency in different conditions with a distinct emphasis on high-temperature mainstream conditions. To better assess the response and overall performance of the ANAMMOX system in a long-term operation period and to evaluate the possibility of using mathematical modelling for process prediction, intended for potential future scale-ups, a BioWin model was adapted. The results of this study, provide an alternative and efficient configuration for ANAMMOX cultivation and demonstrate the effectiveness and high performance efficiency of micro-sized granules in both sidestream and mainstream ANAMMOX processes. The section of the research focusing on mainstream processes highlights the factors monitoring and promoting the growth of ANAMMOX bacteria in mainstream wastewater treatment which can potentially guide the future implementation of ANAMMOX-based technologies. This study also confirms the reliability of ANAMMOX-based process modeling and high predictive ability with BioWin, being a valuable in enhancing the efficiency of UASB-ANAMMOX practical operation in an industrial scale.