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Zeng T.,Hunan University | Wang D.,Jiangsu Tongyan Environmental Production Science and Technology Co. | Li X.,Hunan University | Ding Y.,Hunan University | And 3 more authors.
Biochemical Engineering Journal | Year: 2013

Lately, we have proved that biological phosphorus (P) removal can be achieved in the aerobic/extended-idle (AEI) regime using glucose as the sole carbon source, which might develop a potential simple strategy for simultaneous removal of P and organic substrates from wastewater. Since acetate and propionate are the two most common substrates present in real domestic wastewater, this paper further assesses the P removal performances in the AEI process using acetate and propionate as the sole carbon source. The results showed that 3.91 and 3.64. mg of P/g of total suspended solids were, respectively, removed in the acetate-reactor and propionate-reactor after 50 days, respectively. After 90 days P removal in the propionate-reactor increased to 4.91. mg P/g of total suspended solids whereas that in the acetate-reactor kept in the same level (3.98. mg/g). Though both acetate and propionate could be used as carbon sources for P removal in such a novel system, the latter was more effective after long-term operation. Further investigations showed that, after 90 days' acclimatization, sludge poly-P content in the propionate-system was more than that in the acetate-system, which was the primarily reason for the propionate-system showing higher P removal. © 2012 Elsevier B.V. Source


Chen H.,Hunan University | Wang D.,Hunan University | Wang D.,Jiangsu Tongyan Environmental Production Science and Technology Co. | Li X.,Hunan University | And 3 more authors.
Biochemical Engineering Journal | Year: 2013

Recently, it has been reported that biological phosphorus removal (BPR) could be achieved in a sequencing batch reactor (SBR) with aerobic/extended-idle (A/EI) regime using synthetic medium. This paper first examined the feasibility and stability of the A/EI regime treating real domestic wastewater. The results showed that the A/EI-SBR removed 1.32. ±. 0.03-3.55. ±. 0.04. mg of phosphorus per g of volatile suspended solids during the steady-state operation, suggesting that BPR from domestic wastewater could be well realised in the A/EI regime. Then, another SBR operated as the conventional anaerobic/oxic (A/O) regime was conducted to compare the soluble orthophosphate (SOP) removal with the A/EI regime. The results clearly showed that the A/EI regime achieved higher SOP removal than the A/O regime. Finally, the mechanism for the A/EI-SBR driving superior SOP removal was investigated. It was found that the sludge cultured by the A/EI regime had more polyphosphate accumulating organisms and less glycogen accumulating organisms than that by the A/O regime. Further investigations showed that the A/EI-SBR had a lower glycogen transformation and a higher PHB/PHV ratio, which correlated well with the superior phosphorus removal. © 2013 Elsevier B.V. Source


Wang D.,Hunan University | Wang D.,Jiangsu Tongyan Environmental Production Science and Technology Co. | Xu Q.,Hunan University | Yang W.,Hunan University | And 6 more authors.
Biochemical Engineering Journal | Year: 2014

Recently, it has been reported that the aerobic/extended-idle (AEI) regime can achieve a satisfied biological phosphorus removal (BPR). Although the AEI regime has exhibited some merits, its main drawback that the extended-idle phase (e.g., 210-450. min) is much longer than the anaerobic phase (e.g., 60-120. min) performed in the aerobic/oxic (A/O) regime requires to be addressed. In this study, a new configuration of sequencing batch reactor (SBR) with sludge tank halved (STH-SBR) was therefore designed. After stable operation, 96.9. ±. 0.5% of total phosphorus was removed in the STH-SBR, which was higher than that in the AEI-SBR (86.9. ±. 0.8%) and A/O-SBR (84.7. ±. 1.3%). Further investigations showed that the biomass cultured in the STH-SBR contained more polyphosphate accumulating organisms but less glycogen accumulating organisms than that in the AEI-SBR and A/O-SBR. In the STH-SBR, the aerobic glycogen accumulation was lower than that in the A/O-SBR while the average idle phosphorus release was greater than that in the AEI-SBR. Finally, the key enzyme activities in the AEI and A/O regimes were compared for the first time, and the reasons for the AEI regime showing lower exopolyphosphatase and polyphosphate kinase activities were also discussed. © 2014 Elsevier B.V. Source


Zhao J.,Hunan University | Wang D.,Hunan University | Wang D.,Tongji University | Wang D.,University of Queensland | And 7 more authors.
Scientific Reports | Year: 2015

Free nitrous acid (FNA), which is the protonated form of nitrite and inevitably produced during biological nitrogen removal, has been demonstrated to strongly inhibit the activity of polyphosphate accumulating organisms (PAOs). Herein we reported an efficient process for wastewater treatment, i.e., the oxic/anoxic/oxic/extended-idle process to mitigate the generation of FNA and its inhibition on PAOs. The results showed that this new process enriched more PAOs which thereby achieved higher phosphorus removal efficiency than the conventional four-step (i.e., anaerobic/oxic/anoxic/oxic) biological nutrient removal process (41 ± 7% versus 30 ± 5% in abundance of PAOs and 97 ± 0.73% versus 82 ± 1.2% in efficiency of phosphorus removal). It was found that this new process increased pH value but decreased nitrite accumulation, resulting in the decreased FNA generation. Further experiments showed that the new process could alleviate the inhibition of FNA on the metabolisms of PAOs even under the same FNA concentration. Source


Zeng T.-J.,Hunan University | Yang G.-J.,Hunan University | Wang D.-B.,Tongji University | Wang D.-B.,Jiangsu Tongyan Environmental Production Science and Technology Co. | And 5 more authors.
Water Science and Technology | Year: 2013

Recently, it has been found that biological phosphorus removal can be achieved in an aerobic/extended-idle (AEI) process using both glucose and acetate as the sole substrate. However, the microbial consortiums involved in glucose-fed and acetate-fed systems have not yet been characterized. Thus the aims of this paper were to investigate the diversities and dynamics of bacterial communities during the acclimation period, and to quantify polyphosphate- accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs) in the systems. The phylogenetic analysis showed that the microbial communities were mainly composed of phylum Proteobacteria, Bacteroidetes, Chlorobi and another six kinds of unclassified bacteria. Fluorescence in-situ hybridization (FISH) analysis revealed that PAOs and GAOs accounted for 43±7 and 16 ± 3% of all bacteria in the glucose-fed system, and 19 ± 4 and 35 ± 5% of total bacteria in the acetate-fed system, respectively. The results showed that the conventional PAOs could thrive in the AEI process, and a defined anaerobic zone was not necessarily required for putative PAOs growth. © IWA Publishing 2013. Source

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