Microbial population response to changes of the operating conditions in a dynamic nutrient-removal sequencing batch reactor

Abstract

A nutrient-removal sequencing batch reactor operated with short anaerobic/aerobic cycles was subjected to different operating conditions, namely, cycle length, feeding pattern and feed composition. The changes in microbial population, as well as the contribution of microbial groups to the total nutrient removal, were estimated using the kinetic parameters obtained in this study. Denitrifying polyphosphate-accumulating organisms (DPAOs) were detected in the system, representing a fraction of 23% of phosphorus-accumulating organisms (PAOs). The results suggest that DPAOs and non-DPAOs are different microorganisms. The presence of nitrate in the feed stimulated DPAOs to predominate over non-DPAOs. Feeding the reactor with a mixture of organic substrates also stimulated DPAOs. Glycogen-accumulating organisms (GAOs) were likely to be present in the system and their development over PAOs was apparently favoured by increasing the aeration time and feeding during the aerobic phase. In contrast, the presence of propanoate in the feed apparently favoured PAOs over GAOs.

Characterization of the Denitrification-Associated Phosphorus Uptake Properties of “Candidatus Accumulibacter phosphatis” Clades in Sludge Subjected to Enhanced Biological Phosphorus Removal

“…This observation was slightly different from results reported in previous studies suggesting the presence of two PAO types, denitrifying PAOs and PAOs. These studies showed that denitrifying P uptake ceased, despite the presence of available nitrate due to internal PHA depletion of denitrifying PAOs, and P uptake by other PAOs continued again when oxygen was supplied (12,23,51,52). In the present study, our SBR operation showed that nitrite concentrations in the bulk solution increased concurrently with the decrease (Fig.…”

Anoxic–aerobic SBR system for nitrate, phosphate and COD removal from high-strength wastewater and diversity study of microbial communities

“…Enhanced Biological Phosphorus Removal (EBPR) processes enriched with DNPAOs have been under investigation as these microorganisms possess equal potential for simultaneous phosphate uptake and nitrate removal from wastewater [1][2][3]. DNPAOs are capable of utilizing nitrate as electron acceptor instead of oxygen hence the former have been enriched by introducing an anoxic Abbreviations: COD, chemical oxygen demand; DNPAO, denitrifying phosphate accumulating organisms; OHO, other denitrifying organisms; HRT, hydraulic retention time; N2O, nitrous oxide; OTU, operational taxonomic unit; PHB, poly hydroxy butyrate; PolyP, polyphosphate; RDP, ribosomal database project; SBR, sequencing batch rector; SDNR, specific denitrification rate; TSS, total suspended solid; VSS, volatile suspended solid; yHD, anoxic yield; MLSS, mixed liquor suspended solid.…”

Sequencing Batch Reactor for Wastewater Treatment: Recent Advances

“…A long-term anaerobic exposure to nitrate was demonstrated to diminish the number of certain group of PAOs showing that it may inhibit PAOs activity or activate the competition between PAOs and denitrifiers [35,36]. It was also found that a significant proportion of PAOs, known as denitrifying PAOs (DPAO), has the ability to simultaneously uptake phosphorus using nitrate as a terminal electron acceptor using stored PHAs in the anoxic zone [37,38]. The DPAOs are desirable because they, as they are able to remove nitrate and phosphorus simultaneously and also, have lower cell yield and sludge production [39].…”