Modelling of simultaneous nitrogen and thiocyanate removal through coupling thiocyanate-based denitrification with anaerobic ammonium oxidation

摘要

Thiocyanate (SCN-)-based autotrophic denitrification (AD) has recently been demonstrated as a promising technology that could be integrated with anaerobic ammonium oxidation (Anammox) to achieve simultaneous removal of nitrogen and SCN-. However, there is still a lack of a complete SCN--based AD model, and the potential microbial competition/synergy between AD bacteria and Anammox bacteria under different operating conditions remains unknown, which significantly hinders the possible application of coupling SCN--based AD with Anammox. To this end, a complete SCN--based AD model was firstly developed and reliably calibrated/validated using experimental datasets. The obtained SCN--based AD model was then integrated with the well-established Anammox model and satisfactorily verified with experimental data from a system coupling AD with Anammox. The integrated model was lastly applied to investigate the impacts of influent NH4+-N/NO2--N ratio and SCN- concentration on the steadystate microbial composition as well as the removal of nitrogen and SCN-. The results showed that the NH4+-N/NO2--N ratio in the presence of a certain SCN- level should be controlled at a proper value so that the maximum synergy between AD bacteria and Anammox bacteria could be achieved while their competition for NO2- would be minimized. For the simultaneous maximum removal (>95%) of nitrogen and SCN-, there existed a negative relationship between the influent SCN- concentration and the optimal NH4+-N/NO2--N ratio needed. (C) 2019 Elsevier Ltd. All rights reserved.