Comparison of aerobic and anoxic phosphorus uptake in ndbepr systems (uct and enbnras)

2002 ◽  
Vol 46 (4-5) ◽  
pp. 201-207 ◽  
Author(s):  
S.M. Vermande ◽  
S. Sötemann ◽  
G. Aguilera Soriano ◽  
M. Wentzel ◽  
J.M. Audic ◽  
...  
Keyword(s):  
Nutrient Removal ◽  
Phosphorus Removal ◽  
Mass Fraction ◽  
Phosphorus Uptake ◽  
P Uptake ◽  
Biological Nutrient Removal ◽  
P Release ◽  
University Of Cape Town ◽  
The University ◽  
P Removal

Two Nitrification-Denitrification Biological Excess Phosphorus Removal (NDBEPR) systems have been operated for 8.5 months in order to compare their Biological Excess Phosphorus Removal (BEPR) performance. One of these systems, i.e. the University of Cape Town (UCT) system, exhibits mainly aerobic P uptake while the External Nitrification Biological Nutrient Removal Activated Sludge (ENBNRAS) system is characterised by high anoxic P uptake. It was observed that when operating with predominantly aerobic P uptake, the UCT system released more P than the ENBNRAS system, even though it had a lower anaerobic mass fraction. However, when the influent TKN/COD was high, i.e. >0.1, anoxic P uptake also occurred in the UCT system and P release dropped to lower levels than in the ENBNRAS. Accordingly, P uptake of the UCT system was 5 mg P/l influent higher than that of the ENBNRAS system, when it was predominantly aerobic, but 9 mg P/l influent lower when anoxic P uptake occurred. As a result, the UCT system achieved superior P removal when aerobic P uptake was predominant (23% higher), but when high influent TKN/COD promoted anoxic P uptake the P removal of the UCT system was poorer than that of the ENBNRAS system. This study clearly showed that anoxic P uptake is not beneficial to NDBEPR systems.

Effect of addition of anaerobic fermented OFMSW (organic fraction of municipal solid waste) on biological nutrient removal (BNR) process: preliminary results

1998 ◽  
Vol 38 (1) ◽  
pp. 327-334 ◽  
Author(s):  
P. Pavan ◽  
P. Battistoni ◽  
P. Traverso ◽  
A. Musacco ◽  
F. Cecchi
Keyword(s):  
Nutrient Removal ◽  
Fermentation Process ◽  
Organic Waste ◽  
Anaerobic Fermentation ◽  
Pilot Scale ◽  
Biological Nutrient Removal ◽  
Organic Fraction ◽  
P Release ◽  
Pure Methanol ◽  
P Removal

The paper presents results coming from experiments on pilot scale plants about the possibility to integrate the organic waste and wastewater treatment cycles, using the light organic fraction produced via anaerobic fermentation of OFMSW as RBCOD source for BNR processes. The effluent from the anaerobic fermentation process, with an average content of 20 g/l of VFA+ lactic acid was added to wastewater to be treated in order to increase RBCOD content of about 60-70 mg/l. The results obtained in the BNR process through the addition of the effluent from the fermentation unit are presented. Significant increase of denitrification rate was obtained: 0.06 KgN-NO3/KgVSS d were denitrified in the best operative conditions studied. -Vmax shows values close to those typical of the pure methanol addition (about 0.3 KgN-NO3/KgVSS d). A considerable P release (35%) was observed in the anaerobic step of the BNR process, even if not yet a completely developed P removal process.

Difficulties and developments in biological nutrient removal technology and modelling

1999 ◽  
Vol 39 (6) ◽  
pp. 1-11 ◽  
Author(s):  
George A. Ekama ◽  
Mark C. Wentzel
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
P Uptake ◽  
Biological Nutrient Removal ◽  
Filamentous Bulking ◽  
Recent Developments ◽  
Removal Technology ◽  
Hydrolysis Of ◽  
Activated Sludge Systems ◽  
P Removal

Filamentous bulking and the long sludge age required for nitrification are two important factors that limit the wastewater treatment capacity of biological nutrient removal (BNR) activated sludge systems. A growing body of observations from full-scale plants indicate support for the hypothesis that a significant stimulus for filamentous bulking in BNR systems in alternating anoxic-aerobic conditions with the presence of oxidized nitrogen at the transition from anoxic to aerobic. In the DEPHANOX system, nitrification takes place externally allowing sludge age and filamentous bulking to be reduced and increases treatment capacity. Anoxic P uptake is exploited in this system but it appears that this form of biological excess P removal (BEPR) is significantly reduced compared with aerobic P uptake in conventional BNR systems. Developments in the understanding of the BEPR processes of (i) phosphate accumulating organism (PAO) denitrification and anoxic P uptake, (ii) fermentation of influent readily biodegradable (RB)COD and (iii) anaerobic hydrolysis of slowly biodegradable (SB)COD are evaluated in relation to the IAWQ Activated Sludge Model (ASM) No.2. Recent developments in BEPR research do not yet allow a significant improvement to be made to ASM No. 2 that will increase its predictive power and reliability and therefore it remains essentially as a framework to guide further research.

Combined denitrification and excess biological phosphorus removal in discontinuous operated biofilm systems

2002 ◽  
Vol 46 (4-5) ◽  
pp. 193-200 ◽  
Author(s):  
D. Brandt ◽  
C. Sieker ◽  
W. Hegemann
Keyword(s):  
Phosphorus Removal ◽  
P Uptake ◽  
Organic Substrate ◽  
Treated Wastewater ◽  
Biological Phosphorus Removal ◽  
P Release ◽  
Different Types ◽  
Immobilized Biomass ◽  
Biological Phosphorus ◽  
P Removal

The sorption-denitrification-P-removal (S-DN-P) process combines biological excess P-removal (BEPR) and denitrification using immobilized biomass. The accumulation of denitrifying polyP organisms is achieved by sequencing anaerobic/anoxic conditions. The immobilized biomass is in alternating contact with primary treated wastewater (anaerobic sorption-phase) and nitrified wastewater (denitrification phase). In the sorption phase, P-release takes place and readily biodegradable organic substrate, e.g. volatile fatty acid, is taken up and stored by polyP accumulating organisms (PAO). In addition to this, other organic matter is physically/chemically adsorbed in the biofilm structures. In the denitrification phase, the biomass denitrifies the stored and adsorbed organic substrate and, at the same time, P-uptake and polyP formation occurs. This paper presents results of investigations at laboratory and half-technical scale. At laboratory scale different types of carriers were tested regarding their suitability for the S-DN-P-process. In half-technical scale a biofilter and a moving bed reactor (MBR) were tested. In the biofilter a stable removal of nitrate and phosphate was achieved. However, it was not possible to achieve similar results in the MBR process. Especially the release and uptake of phosphate showed no clear tendency although the uptake of acetate was good. Reasons for this could be the accumulation of glycogen accumulating organisms which impair the metabolism of PAO.

Effect of continuous addition of an organic substrate to the anoxic phase on biological phosphorus removal

1998 ◽  
Vol 38 (1) ◽  
pp. 97-105 ◽  
Author(s):  
J. Meinhold ◽  
H. Pedersen ◽  
E. Arnold ◽  
S. Isaacs ◽  
M. Henze
Keyword(s):  
Phosphorus Removal ◽  
Phosphate Uptake ◽  
P Uptake ◽  
Organic Substrate ◽  
Organic Substrates ◽  
Biological Phosphorus Removal ◽  
P Release ◽  
Influence Of Substrate ◽  
Biological Phosphorus ◽  
P Removal

The continuous introduction of a biological phosphorus removal (BPR) promoting organic substrate to the denitrifying reactor of a BPR process is examined through a series of batch experiments using acetate as model organic substrate. Several observations are made regarding the influence of substrate availability on PHA storage/utilization and phosphate uptake/release. Under anoxic conditions PHB is utilized and phosphate is taken up, indicating that at least a fraction of the PAO can denitrify. The rates of anoxic P-uptake, PHB utilization and denitrification are found to increase with increasing initial PHB level. At low acetate addition rates the P-uptake and PHB utilization rates are reduced compared to when no acetate is available. At higher acetate addition rates a net P-release occurs and PHB is accumulated. For certain intermediate acetate addition rates the PHB level can increase while a net P-release occurs. Whether the introduction of BPR promoting organic substrates to the denitrifying reactor is detrimental to overall P-removal appears to be dependent on the interaction between aerobic P-uptake, which is a function of PHB level, and the aerobic residence time.

Biological nitrogen and phosphorus removal in UCT-type MBR process

2009 ◽  
Vol 59 (11) ◽  
pp. 2093-2099 ◽  
Author(s):  
H. Lee ◽  
J. Han ◽  
Z. Yun
Keyword(s):  
Phosphorus Removal ◽  
P Uptake ◽  
Biological Nutrient Removal ◽  
Anoxic Zone ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Nitrate Inhibition ◽  
Biological Nitrogen ◽  
P Removal ◽  
Production Characteristics

A lab-scale UCT-type membrane bio-reactor (MBR) was operated for biological nitrogen (N) and phosphorus (P) removal simultaneously. In order to examine biological nutrient removal (BNR) characteristics of MBR, the lab unit was fed with a synthetic strong and weak wastewater. With strong wastewater, a simultaneous removal of N and P was achieved while application of weak wastewater resulted in a decrease of both N and P removal. Recycled nitrate due to the limited organic in weak wastewater operation probably caused a nitrate inhibition in anaerobic zone. In step feed modification with weak wastewater, both N and P removal capability recovered in the system, indicating that the allocation of COD for denitrification at anoxic zone was a key to increase the biological P removal. In addition, the analysis on the specific P uptake rate in anoxic zone demonstrated that denitrifying phosphorus accumulating organism (dPAO) played an important role to remove up to 40% of P along with N. The sludge production characteristics of UCT-type MBR were similar to ordinary activated sludge with BNR capability.

Enhancing nitrogen and phosphorus removal in the BUCT–IFAS process by bypass flow strategy

2015 ◽  
Vol 72 (4) ◽  
pp. 528-534 ◽  
Author(s):  
Yang Bai ◽  
Xie Quan ◽  
Yaobin Zhang ◽  
Shuo Chen
Keyword(s):  
Carbon Source ◽  
Removal Efficiency ◽  
Phosphorus Removal ◽  
P Uptake ◽  
Flow Mode ◽  
Bypass Flow ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
University Of Cape Town ◽  
P Removal

A University of Cape Town process coupled with integrated fixed biofilm and activated sludge system was modified by bypass flow strategy (BUCT–IFAS) to enhance nitrogen and phosphorus removal from the wastewater containing insufficient carbon source. This process was operated under different bypass flow ratios (λ were 0, 0.4, 0.5, 0.6 and 0.7, respectively) to investigate the effect of different operational modes on the nitrogen (N) and phosphorus (P) removal efficiency (λ = 0 was noted as common mode, other λ were noted as bypass flow mode), and optimizing the N and P removal efficiency by altering the λ. Results showed that the best total nitrogen (TN) and total phosphorus (TP) removal performances were achieved at λ of 0.6, the effluent TN and TP averaged 14.0 and 0.4 mg/L meeting discharge standard (TN < 15 mg/L, TP < 0.5 mg/L). Correspondingly, the TN and TP removal efficiencies were 70% and 94%, respectively, which were 24 and 41% higher than those at λ of 0. In addition, the denitrification and anoxic P-uptake rates were increased by 23% and 23%, respectively, compared with those at λ of 0. These results demonstrated that the BUCT–IFAS process was an attractive method for enhancing nitrogen and phosphorus removal from wastewater containing insufficient carbon source.

The Effect of Organic Compounds on Biological Phosphorus Removal

1991 ◽  
Vol 23 (4-6) ◽  
pp. 585-594 ◽  
Author(s):  
Z. H. Abu-ghararah ◽  
C. W. Randall
Keyword(s):  
Organic Acids ◽  
Organic Compounds ◽  
Phosphorus Removal ◽  
Phosphorus Uptake ◽  
Phosphorus Release ◽  
Biological Nutrient Removal ◽  
Biological Phosphorus Removal ◽  
University Of Cape Town ◽  
Biological Phosphorus ◽  
Removal System

The effect of influent organic compounds on the performance of a biological nutrient removal system was investigated using a pilot plant system operated as a UCT (University of Cape Town) process. The system was fed domestic sewage and operated at a sludge age of 13 days. The effects of separate addition of formic, acetic, propionic, butyric, isobutyric, valeric, and isovaleric acid on phosphorus release under anaerobic conditions, and phosphorus uptake under aerobic conditions, were studied. The effects of the organic acid additions on the removal of nitrogen and COD, and changes in SOUR and MLSS, were also studied. All added substrates, except formic acid, caused significant increases in phosphorus release in the anaerobic stage, and subsequent phosphorus uptake in the aerobic stage with an increase in phosphorus removal efficiency. It was also found that the branched organic acids, isobutyric and isovaleric, caused more phosphorus release in the anaerobic stage and better phosphorus removal efficiencies in the system, compared with the nonbranching forms of the same organic acids. The most recent biochemical model, proposed by Comeau et al. (1986) and Wentzel et al. (1986) was also tested using the data collected in this investigation. Both models, in most cases, overestimated the ratios of phosphorus release to volatile fatty acid utilized. All added substrates caused no change in either COD or TKN removals. For engineering applications, it is suggested by this research, that at least 20 mg COD equivalent of acetic acid is needed for the removal of 1 mg phosphorus.

Effects of SRT and DO on nutrient removal in a combined AS-biofilm process

1997 ◽  
Vol 36 (12) ◽  
pp. 19-27 ◽  
Author(s):  
S. H. Chuang ◽  
C. F. Ouyang ◽  
H. C. Yuang ◽  
S. J. You
Keyword(s):  
Dissolved Oxygen ◽  
Nutrient Removal ◽  
Phosphorus Removal ◽  
High Efficiency ◽  
Phosphorus Uptake ◽  
Experimental Results ◽  
Biological Nutrient Removal ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Biofilm Process

This study examines the effects of sludge retention time (SRT) and dissolved oxygen (DO) on COD, nitrogen and phosphorus removal in a combined activated sludge - biofilm process. Various SRT (5, 10, 12 and 15 days) and dissolved oxygen (0.1, 0.5, 1.0 and 2.0 mg/l in aerobic stage) conditions are performed during the hybrid process. Experimental results indicate that SRT significantly affects the behavior of nitrogen and phosphorus removal, although the variation of COD removal is only slight in different SRT experiments. The SRT should be controlled for longer than 10 days to achieve efficient nitrogen removal. However, a SRT less than 12 days is deemed necessary to complete the phosphorus removal. The process displays similar characteristics when dissolved oxygen is operated between 1.0 to 2.0 mg/l in the aerobic stage. Moreover, analyzing polyhydroxyalkanoates (PHAs) reveals that phosphorus release and uptake are closely related to PHAs accumulation and utilization, respectively, during anaerobic, anoxic and aerobic stages of the process. The ratio of phosphorus uptake and PHAs utilized, rP/PHAs, denotes a dissimilar trend during anoxic and aerobic stages. The sludge has a high efficiency in utilizing PHAs for phosphorus uptake in anoxic stage when it is under lower COD-SS loading conditions. The value of rP/PHAs ranges from approximately 0.1 to 1.0 mg P/mg PHAs. In addition, experimental results also demonstrate that anoxic phosphorus uptake can improve phosphorus removal in biological nutrient removal processes.

Biological nutrient removal in membrane bioreactors: denitrification and phosphorus removal kinetics

2007 ◽  
Vol 56 (6) ◽  
pp. 125-134 ◽  
Author(s):  
V. Parco ◽  
G. du Toit ◽  
M. Wentzel ◽  
G. Ekama
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
Phosphorus Removal ◽  
Biological Nutrient Removal ◽  
Specific Rate ◽  
Mixed Liquor ◽  
Batch Tests ◽  
The Impact ◽  
Substrate Concentrations ◽  
P Removal

The impact of including membranes for solid liquid separation on the kinetics of nitrogen and phosphorus removal was investigated. To achieve this, a membrane bioreactor (MBR) biological nutrient removal (BNR) activated sludge system was operated. From batch tests on mixed liquor drawn from the MBR BNR system, denitrification and phosphorus removal rates were delineated. Additionally the influence of the high total suspended solids concentrations present in the MBR BNR system and of the limitation of substrate concentrations on the kinetics was investigated. Moreover the ability of activated sludge in this kind of system to denitrify under anoxic conditions with simultaneous phosphate uptake was verified and quantified. The denitrification rates obtained for different mixed liquor (ML) concentrations indicate no effect of ML concentration on the specific denitrification rate. The denitrification took place at a single specific rate (K2) with respect to the ordinary heterotrophic organisms (OHOs, i.e. non-PAOs) active mass. Similarly, results have been obtained for the P removal process kinetics: no differences in specific rates were observed for different ML or substrate concentrations. From the P removal batch tests results it seems that the biological phosphorus removal population (PAO) consists of 2 different sets of organisms denitrifying PAO and aerobic PAO.

Denitrification kinetics in biological N and P removal activated sludge systems treating municipal wastewaters

1999 ◽  
Vol 39 (6) ◽  
pp. 69-77 ◽  
Author(s):  
George A. Ekama ◽  
Mark C. Wentzel
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
P Uptake ◽  
Active Fraction ◽  
Batch Tests ◽  
P Release ◽  
Denitrification Kinetics ◽  
Nd Systems ◽  
Activated Sludge Systems ◽  
P Removal

The denitrification kinetics at 12, 20 and 30°C in nitrification denitrification biological excess phosphorus removal (NDBEPR) systems were delineated in batch tests on sludge harvested from laboratory scale M/UCT systems. In some investigations, it was found that the P release and uptake were confined exclusively (>95%) to the anaerobic and aerobic reactors respectively and the observed P removal conformed to the BEPR model of Wentzel et al. In these investigations, due to an absence of anoxic P uptake (substantiated by PHB measurements), it could be inferred that the phosphate accumulating organisms (PAOs) did not significantly contribute to the denitrification. The ordinary heterotrophic organism (OHO) and PAO groups were separated with the aid of the BEPR model of Wentzel et al. Ascribing the denitrification to the OHO group performing this process, the specific rates of denitrification associated with the utilization of slowly biodegradable COD (SBCOD) in the primary (K′2) and secondary (K′3) anoxic reactors were calculated and compared with the rates in ND systems (K2 and K3). In other investigations it was found that P release and uptake were not confined exclusively to the anaerobic and aerobic reactors respectively and the observed P removal was only about 60% of that expected from the BEPR model of Wentzel et al. In these investigations significant P uptake under anoxic conditions was observed so the PAOs may have been involved with the denitrification. However, the denitrification rates were calculated as before by attributing it exclusively to the OHOs. Widely varying K'2 rates were observed at 20°C, ranging from 0.071 to 0.335 mgNO3-N/(mgAHVSS.d). The variation in K' rate is mainly due to widely varying OHO active fraction estimates for NDBEPR systems.

Sign in / Sign up

Export Citation Format

Share Document