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A lab-scale anaerobic-aerobic-anoxic sequencing batch reactor was operated for 135 days with using acetate as sole carbon source to explore the contribution of denitrifying phosphate accumulating organisms to nitrogen and phosphorus removal in a post-anoxic system. The system was operated at an aerobic sludge age of 2.5 days and DO level greater th...
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... in each cycle. There were three cycles in a day, each 8 h long. During each cycle, 750 ml of synthetic wastewater was fed to the reactor with peristaltic pumps (Watson Marlow 323 S/D, USA). Hydraulic retention time (HRT) was 16 h. Temperature was main- tained at 22e23 C in an air conditioned room. A schematic dia- gram of the SBR is shown in Fig. 1. During the feeding period, nitrogen gas was introduced into the reactor head space to prevent oxygen entry. Reactor was subjected to anaerobic, oxic, and anoxic (post-denitrification) cycles during the treatment period. The reactor content was mixed with a mechanical stirrer at 200 ± 5 rpm to prevent ...
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The objective of this study was to investigate the ability of a culture highly enriched with the polyphosphate-accumulating organism, " Candidatus Accumulibacter phosphatis " clade IIC, to adjust their metabolism to different phosphate availabilities. For this purpose the biomass was cultivated in a sequencing batch reactor with acetate and exposed...
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... Biological nutrient removal (BNR) process has been widely used in many wastewater treatment plants (WWTPs) for N and P removal, and it is an economic and effective choice compared with traditional physical and chemical methods (Lu et al., 2021). Although the WWTP operation is stable, the removal of N and P requires a large amount of organic carbon, and the limited COD from influent affects the N and P removal for conventional WWTPs (Semerci et al., 2016). Manganese mainly exists in water environment in the form of Mn 2+ , and ingesting a large amount of manganese through drinking water is found to be toxic and has neurotoxic effects on health (Bai, 2021). ...
Effect of β-cyclodextrin (β-CD) on simultaneous removal of NH4+-N, NO3--N, COD, and phosphorus (P) in biogenic manganese oxides (BioMnOx) driven moving bed biofilm reactor (MBBR) was investigated. 58.64% and 86.32%, 79.65% and 98.39%, 62.45% and 97.30%, and 24.80% and 95.90% of TN and COD were removed in phases I-IV, indicating that simultaneous nitrification and denitrification (SND) efficiencies were 75.44%, 83.91%, 72.71%, and 35.83%, respectively. Composition and fluorescence spectral characteristics of extracellular polymeric substance (EPS) were evaluated including the removal kinetics of TN and COD. Metabolic activity of Mn2+, decolorization performance of BioMnOx, and reactive oxygen species (ROS) characteristics were determined in biofilm. Furthermore, intermediate Mn3+ and BioMnOx concentration were analyzed. Finally, the removal process of nitrogen (N) and P was proposed based on characterizations of elemental characterization, electrochemistry, and microbial community. This study provides new insights into the N and P removal mediated by BioMnOx and β-CD.
... SNDPR couples SND and EBPR in a single reactor Semerci and Hasilci, 2016). The abundant P accumulating bacteria, polysaccharide bacteria, nitrifying bacteria, and denitrifying bacteria in the reactor work together to increase the storage of internal glycogen obtained from influent wastewater in the anaerobic phase and use it as a carbon source and energy to uptake P in the aerobic/anoxic phase. ...
Nitrogen and phosphorus contamination in wastewater is a serious environmental concern and poses a global threat to sustainable development. In this paper, a comprehensive review of the studies on simultaneous nitrogen and phosphorus removal (SNPR) during 1986–2022 (538 publications) was conducted using bibliometrics, which showed that simultaneous nitrification, denitrification, and phosphorus removal (SNDPR) is the most promising process. To better understand SNDPR, the dissolved oxygen, carbon to nitrogen ratio, carbon source type, sludge retention time, Cu²⁺ and Fe³⁺, pH, salinity, electron acceptor type of denitrifying phosphorus-accumulating organisms (DPAOs), temperature, and other influencing factors were analyzed. Currently, SNDPR has been successfully implemented in activated sludge systems, aerobic granular sludge systems, biofilm systems, and constructed wetlands; sequential batch mode of operation is a common means to achieve this process. SNDPR exhibits a significant potential for phosphorus recovery. Future research needs to focus on: (1) balancing the competitiveness between denitrifying glycogen-accumulating organisms (DGAOs) and DPAOs, and countermeasures to deal with the effects of adverse conditions on SNDPR performance; (2) achieving SNDPR in continuous flow operation; and (3) maximizing the recovery of P during SNDPR to achieve resource sustainability. Overall, this study provides systematic and valuable information for deeper insights into SNDPR, which can help in further research.
... The easily biodegradable matter is commonly removed in the anaerobic reactor of sequential anaerobic-oxic-anoxic systems, as also reported by Liu et al. [37] in a continuous anaerobic-aerobic-anoxic system treating synthetic domestic wastewater (initial COD of 300 mg L −1 ; HRT of 2 h); Alvarino et al. [34] with removal efficiency higher than 92% in a UASB reactor coupled to a hybrid aerobic membrane bioreactor treating municipal wastewater (organic loading rate 1.7 g COD L −1 d −1 , 1200 mg L −1 of TOC, HRT of 12 h); Ferro et al. [18] with removal efficiency higher than 82% in an AOA system treating synthetic wastewater (initial COD of 550 mg L −1 ; HRT of 8 h); and Table 3. Balance of alkalinity in the ammonification, nitrification, and denitrification processes in the AOA system. Semerci and Hasilci [38] with removal efficiency higher than 85% in a sequencing batch reactor operated under anaerobic-aerobic-anoxic conditions (initial COD of 200 mg L −1 ; HRT of 1.5 h). Moreover, the global COD removal efficiency of the AOA remained superior to 92% during the operation with concentration lower than 50 mg L −1 , representing average removal of 14.03 g d −1 and confirming the effectiveness of the system. ...
... Moreover, the global COD removal efficiency of the AOA remained superior to 92% during the operation with concentration lower than 50 mg L −1 , representing average removal of 14.03 g d −1 and confirming the effectiveness of the system. Similarly, Liu et al. [37], Alvarino et al. [34], Ferro et al. [18], and Semerci and Hasilci [38] obtained global removal efficiencies higher than 90%. ...
The constant presence of triclosan (TCS) in surface water and wastewater has been verified due to its application in several pharmaceutical and personal care products. Thus, removing this emerging contaminant is essential to minimize the contamination of water bodies. The anaerobic-aerobic-anoxic (AOA) system is an innovative alternative that combines the removal of nutrients and triclosan. This study focuses on the simultaneous removal of carbonaceous matter, nitrogen, phosphorus, and triclosan in a continuous pilot-scale AOA system from synthetic wastewater. The upflow system, in series, was operated at hydraulic retention time (HRT) of 8 h and a flowrate of 2.40 L h⁻¹. Glucose (190 mg L⁻¹) was added to the anoxic reactor as the external carbon source. Besides that, bacterial community structure was investigated using 16S rRNA sequencing in each of the reactors. The system achieved average removal efficiencies of 96% (14.03 g d⁻¹) for Chemical Oxygen Demand (COD), 85% (2.64 g d⁻¹) for Total Kjeldahl Nitrogen (TKN), 88% (1.40 g d⁻¹) for Total Ammonia Nitrogen (TAN), 20% (0.12 g d⁻¹) for Total Phosphorus (TP), and 93% (1.87 μg d⁻¹) for Triclosan (TCS). The phyla Proteobacteria, Firmicutes, Bacteroidetes, and Chloroflexi were found in greater abundance. The main genera identified were Anaeromusa, Aeromonas, Azospira, Clostridium, and Lactococcus. The organisms related to phylum and genus corroborate the involved processes and the removal performance achieved. In addition, Lactococcus, Thermomonas, Ferruginibacter, and Dechloromonas were involved in triclosan biodegradation. The anaerobic-oxic–anoxic system successfully removed carbonaceous, nitrogenous matter, and triclosan, with glucose increasing the denitrifying activity.
... The phosphorus at anaerobic end phase reduced from 71.15 to 58.67 mg/L. Due to the lower aeration intensity and the appearance of fine particle (Fig. 2), the micro-anoxic zone stimulated the denitrification and limited the P release of PAOs (Semerci and Hasılcı, 2016). At stage III, the aeration intensity was reduced to 8.25-9.00 ...
Extracellular polymeric substances (EPS) with high molecular weights, secreted from microorganisms, play a critical functional role in the aerobic granular sludge (AGS). To investigate the level and function of EPS during the granulation of aerobic sludge and in the mature AGS, a sequencing batch reactor (SBR) was operated for 70 days. Aerobic granules with average diameters of 0.25 mm were obtained with reduced settling time of sludge. Simultaneous removals of COD, nitrogen and phosphorus by the mature AGS exceeded 90, 95 and 90%, respectively. The EPS content increased significantly to above 333 mg/g MLVSS during the initial stage, and after that, it stabilized at about 240 mg/g MLVSS as the mature AGS formed, higher than that of the seed sludge (212 mg/g MLVSS). The increased EPS contents showed a negative correlation with SVI values, while a strong positive relationship with the formation of the AGS. The protein/polysaccharide (PN/PS) ratio in the EPS increased from 1.42 to 4.17, and TP/MLSS increased to about 6%, with the formation of AGS. The proportion of extracellular-P increased with the increase of EPS, and then maintained stable at about 20%, indicating EPS promoted the removal of phosphorus. Furthermore, the results from the Standards, Measurements and Testing (SMT) and X-Ray Diffraction (XRD) showed that phosphorus in the AGS mainly existed in the form of inorganic phosphorus (IP) and the proportion of Ca5(PO4)3(OH) in IP was up to 92%. This investigation demonstrated that EPS had a positive relationship with the sludge granulation and nutrients removal.
... Generally, sequencing anaerobic and aerobic conditions is necessary to achieve efficient biological phosphorus removal [8]. However, the competition for insufficient organic carbon sources between polyphosphate accumulating organisms (PAOs) and denitrifying bacteria inevitably occurs in the anaerobic phase of WWTPs [9]. This unavoidable drawback would be overcome if biological phosphorus removal was separated from nitrogen removal when re-engineering a typical EBPR process. ...
The increasing concerns on resource and energy recovery call for the modification of the current wastewater treatment strategy. This study synthetically evaluates the feasibility of the short sludge retention time approach to improve the energy recovery potential, but keeping steady biological phosphorus removal and system stability simultaneously. SBRS-SRT and SBRcontrol that simulated the short sludge retention time and conventional biological phosphorus removal processes, respectively, were set up to treat real domestic sewage for 120 d. SBRS-SRT achieved an efficient COD (91.5 ± 3.5%), PO43−-P (95.4 ± 3.8%), and TP (93.5 ± 3.7%) removal and maintained the settling volume index around 50 mL/gSS when the sludge retention time was 3 d, indicating steady operational stability. The poor ammonia removal performance (15.7 ± 7.7%) and a few sequences detected in samples collected in SBRS-SRT indicated the washout of nitrifiers. The dominant phosphorus accumulating organisms Tetrasphaera and Hydrogenophaga, which were enriched with the shortened sludge retention time, was in line with the excellent phosphorus performance of SBRS-SRT. The calculated methanogenic efficiency of SBRS-SRT increased significantly, which was in line with the higher sludge yield. This study proved that the short sludge retention time is a promising and practical approach to integrate biological phosphorus removal in A-stage when re-engineering a biological nutrient removal process.
... The Evikon E6115 pH meter was used for pH measurement. FNA was calculated based on pH, temperature and NO 2 − concentration according formula shown in Semerci and Hasilci (2016). P-removal, COD removal, TNREs and TNRRs were calculated based on the feed flow rate, influent and effluent parameters, and the flow rate into the reactor. ...
... Higher nitrate concentration (500 mg NO 3 − −N L −1 ) did not ameliorate nitrite inhibition further, probably due to excess amount of NO 3 − most likely having osmotic effect by KNO 3 − to cause inhibition to bacteria (Li et al., 2016). Semerci and Hasilci (2016) have shown similar FNA contents (0.01-2.27 μg HNO 2 -N L −1 ) as our applied FNA content of 1.12 μg HNO 2 -N L −1 (for test done at 5 mg NO 2 − -N L −1 ) to be inhibiting Puptake. The accumulation of GAOs over PAOs has also been associated with FNA-inhibited conditions present in the systems (Semerci and Hasilci, 2016). ...
... Semerci and Hasilci (2016) have shown similar FNA contents (0.01-2.27 μg HNO 2 -N L −1 ) as our applied FNA content of 1.12 μg HNO 2 -N L −1 (for test done at 5 mg NO 2 − -N L −1 ) to be inhibiting Puptake. The accumulation of GAOs over PAOs has also been associated with FNA-inhibited conditions present in the systems (Semerci and Hasilci, 2016). For the PAOs-containing SBR, the degree of inhibition on P-uptake has been observed to be 65% at 10 mg NO 2 − -N L −1 (Sin et al., 2012). ...
Lowered air supply and organic carbon need are the key factors to reduce wastewater treatment costs and thereby, avoid eutrophication. Denitrifying PO4³⁻- removal (DPR) process using nitrate instead of oxygen for PO4³⁻ uptake was started up in the sequencing batch reactor (SBR) at a nitrate dosing rate of 20–25 mg N L⁻¹ d⁻¹. Operation with a real municipal wastewater supplied with CH3COONa, K2HPO4 and KNO3 succeeded in the cultivation of biomass containing denitrifying polyphosphate accumulating organisms (DPAOs). The durations of SBR process anaerobic/anoxic/oxic cycles were 1.5 h, 3.5 h and 1 h, respectively. SBR operation resulted in a maximum PO4³⁻-P uptake of 17 mg PO4³⁻-P g⁻¹ MLSS. The highest TN and PO4³⁻ removal efficiencies were observed during the first half of reactor operation at 77 (±10) % and 71 (±5) %, respectively. An average COD removal rate of 172 (±98) mg g⁻¹ MLSS and a high average removal efficiency of 89 (±4) % were achieved.
Nitrite effect with/without nitrate as DPR electron acceptor was investigated in batch-scale to show possibilities to use high nitrite and nitrate contents simultaneously as electron acceptors for the anoxic phosphate uptake. Nitrate attenuation against nitrite toxicity can be economically justified in full-scale treatment applications in which wastewater has a high nitrogen content. Nitrate attenuated nitrite toxicity (caused by nitrite content at 5–100 mg NO2⁻-N L⁻¹) when using supplemental additions of nitrate (at concentrations of 45–200 mg NO3⁻-N L⁻¹) in batch tests. Illumina sequencing emphasized that during biomass adaption microbial community changed by lowered aerobic cycle length and by lowered nitrate dosing towards representation of key DPAO/PAO- organisms, such as Candidatus Accumulibacter, Xanthomonadaceae, Comomonadaceae, Saprospiraceae and Rhodocyclaceae. This study showed that DPAO biomass adaption to nitrate maintained an efficient COD, nitrogen and phosphorus removal and the biomass can be applied for treatment of wastewater containing high nitrite and nitrate content.
... A similar behavior was also observed by Semerci and Hasılcı (2016) in an SBR operated in an anaerobic/aerobic/anoxic regime aiming at nutrient removal from low-strength wastewater. According to Semerci and Hasılcı (2016), the system achieved extensive dissolved oxygen (DO) consumption for P-uptake during the aerated stage. ...
... A similar behavior was also observed by Semerci and Hasılcı (2016) in an SBR operated in an anaerobic/aerobic/anoxic regime aiming at nutrient removal from low-strength wastewater. According to Semerci and Hasılcı (2016), the system achieved extensive dissolved oxygen (DO) consumption for P-uptake during the aerated stage. Thus, the authors inferred that, even in the aerated phase, denitrification occurred in the formed anoxic microniches, leading to the removal of 60% of the total-N during the aerated phase. ...
Biological nitrogen and phosphorus removal often requires an external carbon source to be effective during wastewater treatments. The purpose of this work was to evaluate a sequencing batch reactor (SBR) operated in a non-conventional anoxic/aerated (An/O) regime (alternated condition) treating synthetic wastewater simulating secondary anaerobic effluent mainly composed by P-phosphate and N-nitrate. The focus was to report the achieved biological efficiency removal of phosphorus and nitrate from the synthetic inlet when adding pre-fermented glycerol as the sole external carbon source. Experimental phase I aimed at the glycerol fermentation in batch reactors, leading to the formation of ethanol and volatile fatty acids. During experimental phase II, a non-acclimated (C1) and an acclimated biomass (C2) were used as inoculum of the SBR operated in the (An/O) regime. The anoxic phase was set to couple denitrification and P-release/uptake. The aerated phase was set to remove any remaining phosphorus. The fermented glycerol was applied in 15 gCOD g−1 N-NO3− and 29 gCOD g−1P-PO4−3 ratios in a sequential batch reactor during a non-aerated phase. This operation favored the development and maintenance of phosphorus-accumulating organisms (PAO), as well as denitrifying organisms, resulting in approximately 90 ± 11% and 98 ± 3% for phosphorus and nitrogen removal, respectively. The study showed that the fermented glycerol can be successfully applied as an electron donor for biological nitrogen and phosphorus removal during wastewater treatments.
... Simultaneous nitrification and denitrification (SND) efficiency was calculated using Eq. (1) [18]: ...
... The improvement in the ratio of P release/NaAc uptake indicated that phosphorus accumulation was substantially enhanced over the morphological transformation from floc to granular sludge. Semerci and Hasilci [18] found that the fastest rate of P release/HAc uptake was 0.14 in anaerobic/aerobic/anoxic modes, which is far below our result under high DO. After granulation, the strength of phosphorus release was gradually enhanced in response to accumulating Accumulibacter, and the rate of P release/NaAc uptake exhibited slight variation, which also revealed increased glycogen accumulation. ...
... The decrease in NOBs might have led to weaker nitrate reduction efficiency and therefore nitrite accumulation in the preliminary phase. The increase in DNPAOs and the existence of GAOs followed the enhancement of TP removal and substantial organic metabolism in the anaerobic period, as depicted by [18,11]. The enrichment of EPS producers suggests microbial adaptation to different states, such as a high DO environment [45]. ...
AGS technology has been studied for decades, and many successful experimental research approaches and full-scale processes have been proposed. However, a precise, comprehensive understanding of the granulation mechanism remains lacking. In this study, sequencing batch reactors were partially inoculated with (S1) or without AGS (S2) to explore aerobic granulation performance in simulative low-strength wastewater. The COD, NH4⁺-N removal efficiency and SND rate were 91.61%, 92.47%, and 84%, respectively, in S1 and higher in this reactor than in S2 (86.76%, 85.21%, and 75%, respectively), indicating the superiority of partial inoculation with AGS. The ratios of P release/NaAc uptake both increased to nearly 0.250, revealing the robust capacity for phosphorus enrichment. Moreover, the increment of EPS content in S2 (31.73 mg/g MLSS) was 47% higher than that in S1 (21.54 mg/g MLSS) and was contributed mainly by PS, which increased to 30.17 mg/g MLSS (S2). These findings indicated active sludge for granulation was more sensitive to the ambient conditions, and secrete greater PS. FTIR and 3D-EEM revealed that numerous hydroxyl groups were assembled within EPS upon granulation, and humic acid-like substances first increased and then decreased over the operation, implying robust cohesion and positive microbial activities. Microbial community analysis demonstrated that Paracoccus and unclassified_Cytophagales dominated in both reactors, accounting for 29.42% and 10.87%, respectively, of the community in S1 and 26.62% and 18.54%, respectively, of the community in S2. Metabolic pathway analysis revealed enhancement of microbial metabolism, cellular processes, and signaling pathways, such as methanol oxidation, methylotrophy, and nitrite denitrification pathways.
... Hence, it is of great practical significance to take full advantage of the influent carbon source. The anaerobic-aerobic-anoxic (AOA) sequencing batch reactor (SBR) system is widely used due to the its simplicity and because it takes advantage of carbon sources in raw wastewater [1,2]. In the anaerobic stage, the carbon source is stored by phosphorus accumulating organisms (PAOs) with PO 4 3− -P release and by denitrifying glycogen accumulating organisms (GAOs). ...
Endogenous denitrification (ED) is an effective approach to achieve advanced nitrogen removal for low COD/N (C/N) municipal wastewater, in which internal carbon sources are used for denitrification. However, phosphorus-accumulating organisms (PAOs) and denitrifying ordinary heterotrophic organisms (DOHOs) outcompeting glycogen-accumulating organisms (GAOs) for carbon sources decreases total inorganic nitrogen (TIN) removal efficiency. This study proposed a novel side-stream sludge treatment strategy, i.e., through phosphorus famine, to selectively strengthen GAOs. Two sequencing batch reactors (SBR) were used, with one served as an anaerobic/aerobic/anoxic SBR (AOA-SBR) and the other as a side SBR. Side-stream phosphorus famine treatment was conducted three times during 140 days’ experiment, of which 20–30% of the sludge collected from the AOA-SBR was imposed to phosphorus famine condition in the side SBR for 4 days (24 cycles). Results showed that the average TIN and phosphorus removal efficiencies were 88.76% and 95.31%, and the average TIN and phosphorus in the effluent were 8.01 and 0.30 mg/L, respectively, treating low C/N (∼3.25) municipal wastewater in the AOA-SBR. The relative abundance of PAOs decreased from 3.23% to 2.15% and that of DOHOs reduced by 62.78%. In contrast, the abundance of GAOs increased from 3.09% to18.25%, which should be the key reason for the improvement of the ED efficiency. Moreover, the enrichment of GAOs promoted ED simultaneously using glycogen and poly-β-hydroxyalkanoates (PHA) as carbon sources. The strategy of side-stream treatment proved the potential of rapid proliferation of GAOs while achieving improved nitrogen removal.
... The phosphorus removal rate is high and the treatment effect is stable. And the sludge will not re-release phosphorus during the treatment and disposal process, causing secondary pollution [6][7]. ...
Beaker coagulation experiments were carried out using polyaluminium chloride (PAC), polyferric sulfate (FPS), polyacrylamide (PAM), polyaluminum chloride (PAFC), polyaluminum sulfate (PAFS) and polyacrylamide (PAFC). The phosphorus removal effects of several flocculants were compared. The best combination coagulant PAM-PAC/PFS with high efficiency and economy was selected. The best ratio of PAC/PFS is 1:1, and the dosage of PAM is 1mg/L. The experiment determined the optimal hydraulic conditions: fast agitation and addition of PAC/PFS at a speed of 400 r/min for 1 min. PAM was added during slow agitation at a speed of 100 r/min for 6 min. The phosphorus removal system has a good effect on the removal of total phosphorus and other water quality indicators in the mine drainage of many phosphate mines, and all of them can meet the discharge standards.
