Yang Yan, Perez Calleja Patricia, Liu Yiwen, Nerenberg Robert, Chai Hongxiang
Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400045, PR China.
Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States.
Environ Sci Technol. 2022 Aug 16;56(16):11760-11770. doi: 10.1021/acs.est.2c03937. Epub 2022 Aug 3.
There is increasing interest in thiosulfate-driven denitrification for low C/N wastewater treatment, but the denitrification performance varies with the thiosulfate oxidation pathways. Models have been developed to predict the products of denitrification, but few consider thiosulfate reduction to elemental sulfur (S), an undesirable reaction that can intensify electron competition with denitrifying enzymes. In this study, the model using indirect coupling of electrons (ICE) was developed to predict S formation and electron competition during thiosulfate-driven denitrification. Kinetic data were obtained from sulfur-oxidizing bacteria (SOB) dominated by the branched pathway and were used to calibrate and validate the model. Electron competition was investigated under different operating conditions. Modeling results reveal that electrons produced in the first step of thiosulfate oxidation typically prioritize thiosulfate reduction, then nitrate reduction, and finally nitrite reduction. However, the electron consumption rate for S formation decreases sharply with the decline of thiosulfate concentration. Thus, a continuous feeding strategy was effective in alleviating the competition between thiosulfate reduction and denitrifying enzymes. Electron competition leads to nitrite accumulation, which could be a reliable substrate for anammox. The model was further evaluated with anammox integration. Results suggested that the branched pathway and continuous supply of thiosulfate are favorable to create a symbiotic relationship between SOB and anammox.
硫代硫酸盐驱动的反硝化用于处理低C/N废水越来越受到关注，但反硝化性能会因硫代硫酸盐的氧化途径而异。已经开发出模型来预测反硝化产物，但很少有模型考虑硫代硫酸盐还原为元素硫（S）这一不良反应，该反应会加剧与反硝化酶的电子竞争。在本研究中，开发了使用电子间接耦合（ICE）的模型来预测硫代硫酸盐驱动的反硝化过程中硫的形成和电子竞争。动力学数据取自以分支途径为主的硫氧化细菌（SOB），并用于校准和验证该模型。研究了不同运行条件下的电子竞争情况。建模结果表明，硫代硫酸盐氧化第一步产生的电子通常优先用于硫代硫酸盐还原，然后是硝酸盐还原，最后是亚硝酸盐还原。然而，随着硫代硫酸盐浓度的下降，用于硫形成的电子消耗速率急剧下降。因此，连续进料策略有效地缓解了硫代硫酸盐还原与反硝化酶之间的竞争。电子竞争导致亚硝酸盐积累，这可能是厌氧氨氧化的可靠底物。通过厌氧氨氧化整合对该模型进行了进一步评估。结果表明，分支途径和硫代硫酸盐的连续供应有利于在SOB和厌氧氨氧化之间建立共生关系。
