Enhanced Biological Phosphorus Removal Activity Research Articles

Altered Carbon Flow by Polyphosphate‐Accumulating Organisms During Enhanced Biological Phosphorus Removal

The effect of carbon source availability during enhanced biological phosphorus removal (EBPR) was evaluated. To assess the EBPR activity of polyphosphate-accumulating organisms (PAOs), PAO-enriched sludge from a laboratory-scale sequencing batch reactor and activated sludge from a full-scale municipal wastewater treatment plant were used, and their EBRP performances were compared. Spiking with acetate (1000 mg/L chemical oxygen demand) during the aerobic phase disrupted the EBPR performance of both types of sludge; however, when the carbon source was removed, still in the aerobic phase, the EBPR performance of both types of sludge was restored. The PAO-enriched sludge showed 3 to 5 times greater glycogen restoration activity per biomass than the full-scale activated sludge. During high acetate loading in the anaerobic phase, PAOs are supposed to deplete internally stored polyphosphate, causing a "poly-phosphate limited condition". Under such a condition, unlike the full-scale activated sludge, the PAO-enriched sludge produced a higher fraction of poly-hydroxylvalerate. It was proposed that PAOs can use the glyoxylate pathway and the methymalonyl-CoA pathway through a full or partial tricarboxylic acid cycle under the anaerobic condition.

Factors affecting the microbial populations at full-scale enhanced biological phosphorus removal (EBPR) wastewater treatment plants in The Netherlands

The influence of operating and environmental conditions on the microbial populations of the enhanced biological phosphorus removal (EBPR) process at seven full-scale municipal activated sludge wastewater treatment plants (WWTPs) in The Netherlands was studied. Data from the selected WWTPs concerning process configuration, operating and environmental conditions were compiled. The EBPR activity from each plant was determined by execution of anaerobic–anoxic–aerobic batch tests using fresh activated sludge. Fractions of Accumulibacter as potential phosphorus accumulating organisms (PAO), and Competibacter, Defluviicoccus-related microorganisms and Sphingomonas as potential glycogen accumulating organisms (GAO) were quantified using fluorescence in situ hybridization (FISH). The relationships among plant process configurations, operating parameters, environmental conditions, EBPR activity and microbial populations fractions were evaluated using a statistical approach. A well-defined and operated denitrification stage and a higher mixed liquor pH value in the anaerobic stage were positively correlated with the occurrence of Accumulibacter. A well-defined denitrification stage also stimulated the development of denitrifying PAO (DPAO). A positive correlation was observed between Competibacter fractions and organic matter concentrations in the influent. Nevertheless, Competibacter did not cause a major effect on the EBPR performance. The observed Competibacter fractions were not in the range that would have led to EBPR deterioration. Likely, the low average sewerage temperature (12±2°C) limited their proliferation. Defluviicoccus-related microorganisms were seen only in negligible fractions in a few plants (<0.1% as EUB), whereas Sphingomonas were not observed.

Progress Toward Understanding the Distribution of Accumulibacter Among Full-Scale Enhanced Biological Phosphorus Removal Systems

This study investigated the role of Accumulibacter-related bacterial populations and factors influencing their distribution in enhanced biological phosphorus removal (EBPR) systems in the USA. For this purpose, five full-scale wastewater treatment facilities performing EBPR were surveyed. The facilities had different configurations but were all treating primarily domestic wastewater. Two facilities had history of poor EBPR performance. Batch-scale acetate uptake and inorganic phosphate (P(i)) release and uptake experiments were conducted to evaluate the EBPR activity of each sludge. Typical P(i) and acetate profiles were observed, and EBPR activity was found to be positively correlated to polyphosphate (polyP)-accumulating organism (PAO) abundance, as determined by staining intracellular polyP. The abundance of Accumulibacter-related organisms was investigated using fluorescent in situ hybridization. Accumulibacter-related organisms were present in all full-scale EBPR facilities, at levels ranging from 9 to 24% of total cells. More than 80% of Accumulibacter-related organisms were estimated to have high polyP content, confirming their involvement in EBPR in these five facilities. However, Accumulibacter-related PAOs were only a fraction (40-69%) of the total PAO population. The variation of Accumulibacter-related PAO abundance among these EBPR systems suggests that multiple interacting factors such as wastewater characteristics and operational conditions are structuring PAO communities.

Abundance of Candidatus 'Accumulibacter phosphatis' in Enhanced Biological Phosphorus Removal Activated Sludge Acclimatized with Different Carbon Sources

In the present study, the abundance of Candidatus ‘Accumulibacter phosphatis’ and the accumulation of polyphosphate were investigated in five enhanced biological phosphorus removal (EBPR) activated sludge reactors operated with different carbon sources. Fluorescence in situ hybridization (FISH) in combination with 4',6-diamidino-2-phenylindole (DAPI) staining for polyphosphate granules confirmed the accumulation of polyphosphate by Candidatus ‘Accumulibacter phosphatis’ in all the reactors. The abundance of Candidatus ‘Accumulibacter phosphatis’ was determined from the FISH images. When EBPR activity was high and phosphorus content made up around 9% or more of mixed liquor volatile suspended solids (MLVSS), Candidatus ‘Accumulibacter phosphatis’ accounted for over 20% of the eubacteria in the reactors acclimatized with acetate, aspartate, or glucose. Whereas this value was as low as around 10% in the reactors acclimatized mainly with yeast extract, peptone, or glutamate. In these reactors, bacteria affiliated with Actinobacteria were found to accumulate polyphosphate and to contribute to phosphorus removal. Candidatus ‘Accumulibacter phosphatis’ takes part in the removal of phosphorus by using various carbon sources, but its abundance varies according to the type of carbon source.

Simultaneous removal of organic and strong nitrogen from sewage in a pilot-scale BNR process supplemented with food waste

As the sewerage system is incomplete, sewage in Korea lacks easily biodegradable organics for nutrient removal. In this country, about 11,400 tons of food waste of high organic materials is produced daily. Therefore, the potential of food waste as an external carbon source was examined in a pilot-scale BNR (biological nutrient removal) process for a half year. It was found that as the supply of the external carbon increased, the average removal efficiencies of T-N (total nitrogen) and T-P (total phosphorus) increased from 53% and 55% to 97% and 93%, respectively. VFAs (volatile fatty acids) concentration of the external carbon source strongly affected denitrification efficiency and EBPR (enhanced biological phosphorus removal) activity. Biological phosphorus removal was increased to 93% when T-N removal efficiency increased from 78% to 97%. In this study, several kinds of PHAs (poly-hydroxyalkanoates) in cells were observed. The observed PHAs was composed of 37% 3HB (poly-3-hydroxybutyrate), 47% 3HV (poly-3-hydroxyvalerate), 9% 3HH (poly-3-hydroxyhexanoate), 5% 3HO (poly-3-hydroxyoctanoate), and 2% 3HD (poly-3-hydroxydecanoate).

生物学的リン除去機能の発現過程における嫌気好気回分式活性汚泥のキノンプロファイル解析

A bench-scale anaerobic/oxic sequencing batch reactor (SBR) was operated for 35 days with peptone and acetate fed as carbon sources during the start-up phase. In order to find quinone biomarkers representing bacteria the play important roles in priming the enhanced biological phosphorus removal (EBPR) process, the time variations of 12 quinone species and EBPR activities were quantitatively compared in the SBR. Both phosphate release rate and specific phosphate release rate increased at the beginning of the operation and reached maximum on the 21st day. It was interpreted kinetically that the concentration of phosphate-accumulating organisms (PAOs) in the reactor and the fractional percentage of PAOs in the sludge increased in the first 21 days. Only MK-10 showed a good correlation with EBPR activity through out this period, and therefore, MK-10 could be a candidate biomarker. Since Q-9 and MK-7 showed good correlations only in the first seven days, these two quinone species may be present in bacteria that play certain roles during the early phase of EBPR development.

Diversity and distribution of a deeply branched novel proteobacterial group found in anaerobic-aerobic activated sludge processes.

A novel coccobacilli group found previously in enhanced biological phosphorus removal (EBPR) systems was further revealed to have a high degree of diversity and distribution in various activated sludge systems. Phylogenetic analysis based on 14 existing and 18 newly retrieved 16S rRNA sequences revealed that these sequences formed a novel cohesive cluster with seven subgroups in the gamma-Proteobacteria. Fluorescence in situ hybridization with a set of probes designed specifically targeting the novel group at different hierarchical levels showed that the novel group with a coccoid (2-4 micro m) to occasionally long-rod (up to 20 micro m) shape widely distributed and in some cases predominated in sludge samples taken from nine lab- and full-scale EBPR systems (10-50% of total cells) and four conventional activated sludge systems (1-10%). Variation of predominance was also observed among those subgroups in systems showing deteriorated or effective EBPR activity.