Adapting to seasonal temperature variations: A dynamic multi-subunit strategy for sulfur autotrophic denitrification bioreactors.

Elemental sulfur autotrophic denitrification (S ⁰ AD) processes are temperature-sensitive, presenting a substantial challenge for the practical implementation of S ⁰ AD bioreactors. In this study, a comprehensive methodology for designing and operating S ⁰ AD bioreactors was developed, effectively managing fluctuations in nitrogen removal efficiency caused by seasonal temperature variations. Initially, the nitrate removal rate was correlated with simulated on-site temperature and nitrate loading, revealing correlation coefficients of k ₁ , k ₂ , k ₃ , and A as 5.42×10 ^-4 , -0.41, 0.04, and 0.13, respectively, to establish a mathematical model for predicting S ⁰ AD efficiency. Subsequently, by considering influence factors such as dissolved oxygen and dynamic sulfur consumption, the model was employed to accurately design a pilot-scale S ⁰ AD bioreactor for a case study. By utilizing an alternative multi-subunit operation, a stable effluent nitrate concentration of less than 8 mg-N/L was maintained throughout the year. Importantly, this approach resulted in a substantial reduction of 76.8% in excessive nitrate removal, sulfur consumption, and sulfate production. This study aims to provide an optimal design and operation strategy for the practical application of S ⁰ AD bioreactors, thereby enhancing reliability and cost-effectiveness in the face of seasonal temperature changes.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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