Effect of hydraulic retention time on effluent pH in anammox bioreactors: Characteristics of effluent pH and pH as an indicator of reactor performance

摘要

In order to assess the performance of anaerobic ammonium oxidation (anammox) bioreactors, it is necessary to study the stoichiometry of the anammox reaction and pH. This study focused on the effect of the hydraulic retention time (HRT) on the effluent pH in anammox-upflow anaerobic sludge blanket (UASB) bioreactors. Anammox-UASB bioreactors with and without a recirculation system were used to investigate the effluent pH and bioreactor performance. It was concluded that under varying HRT conditions, the decrease in effluent pH did not indicate the deterioration of nitrogen removal, but did indicate that the nitrogen removal efficiency was reduced owing to a sudden increase in the nitrogen loading rate resulting from the decrease in HRT. Moreover, the results showed that the HRT directly affected the concentration of OH-, which affected the increase/decrease in effluent pH. This study demonstrated that effluent pH is a more powerful tool than previous techniques used to assess bioreactor performance. We suggest that the effluent pH could be used for preliminary assessment.

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