Enhancing bio-P removal by phosphate recovery from anaerobic supernatant

2006 ◽  
Vol 6 (6) ◽  
pp. 11-18
Author(s):  
X.-D. Hao ◽  
J. Dai ◽  
M.C.M. van Loosdrecht
Keyword(s):  
Ph Value ◽  
Phosphate Removal ◽  
Biological Nutrient Removal ◽  
Effluent Quality ◽  
Phosphate Recovery ◽  
Previous Modeling Study ◽  
Modeling Prediction ◽  
Minor Form ◽  
A Minor ◽  
P Removal

A previous modeling study predicted that phosphate removal and recovery could be combined in biological nutrient removal (BNR) processes, which would be beneficial for either improving bio-P removal effluent quality or lowering the influent COD/P ratio required for bio-P removal. To confirm the modeling prediction, an experiment with a traditional A2/O process was initiated. The experimental results were qualitatively in agreement with the modeling prediction. The minimal COD/P ratio required for the effluent standard (1 mg P/L) could be lowered from 35 to 25 with a stripping ratio of 20% at a phosphate recovery efficiency of 34%, which means a COD saving of 25–30% in bio-P removal. A practical experiment for phosphate recovery in a WWTP identified that HAP was a major form of precipitated compounds and that MAP was a minor form. Due to the higher contents of Ca2 +  and Mg2 +  in the influent to the WWTP (with groundwater mainly used for portable water), it was unnecessary to dose any extra chemicals for phosphate precipitation, and a pH value increased to ≥9 in the supernatant was all to be done.

Model-based evaluation of struvite recovery from an in-line stripper in a BNR process (BCFS)

2006 ◽  
Vol 53 (3) ◽  
pp. 191-198 ◽  
Author(s):  
X.-D. Hao ◽  
M.C.M. van Loosdrecht
Keyword(s):  
Nutrient Removal ◽  
Phosphate Concentration ◽  
Phosphate Removal ◽  
Carbon Oxidation ◽  
P Efficiency ◽  
Effluent Quality ◽  
P Recovery ◽  
Struvite Precipitation ◽  
Removal And Recovery ◽  
P Removal

Phosphate removal and recovery can be combined in BNR processes. This may be realised by struvite precipitation from the supernatant of the sludge in anaerobic compartments. This can be beneficial for either improving bio-P removal effluent quality or lowering the influent COD/P ratio required for bio-P removal. For this reason, a patented BNR process, BCFS®, was developed and applied in The Netherlands. Several questions relating to P-recovery and behaviour of the system remain unclear and need to be ascertained. For this purpose, a modelling technique was employed in this study. With the help of a previous developed model describing carbon oxidation and nutrient removal, three cases were fully simulated. The simulations demonstrated that there was an optimal stripping flow rate and P-recovery would increase in costs and bio-P activity might be negatively affected due to decreased bio-P efficiency if this value was exceeded. The simulations indicated that the minimal CODbiod/P ratio required for the effluent standard (1 g P/m3) could be lowered from 20 to 10 with 36% of P-recovery. A simulation with dynamic inflow revealed that the dynamic influent loads affected slightly the anaerobic supernatant phosphate concentration but the effluent phosphate concentration would not be affected with regular P-recovery.

Kinetics of Simultaneous Ammonium and Phosphate Recovery by Natural Zeolite

2021 ◽  
Vol 5 (4) ◽  
pp. 68
Author(s):  
Sandro Pesendorfer ◽  
Markus Ellersdorfer
Keyword(s):  
Ion Exchange ◽  
Natural Zeolite ◽  
Large Scale ◽  
Ph Value ◽  
Exchange Process ◽  
Phosphate Removal ◽  
Synthetic Wastewater ◽  
Nutrient Recovery ◽  
Phosphate Recovery ◽  
Kinetics Of

Nowadays, fertilizers containing nitrogen and phosphorus are indispensable for medium and large-scale industrial agriculture. To meet the growing demand of nutrients and reduce the accompanied ecological footprint of primary fertilizer production, processes and technologies for nutrient recovery are necessary and have to be developed. This study represents the basis of an extension of the ion-exchange-loop-stripping process (ILS), which is a combined stripping and ion exchange process using natural zeolite for nitrogen recovery. In batch experiments with a special zeolite filled stirrer, the mechanism and kinetics of simultaneous ammonium and phosphate recovery by natural zeolite were determined. Zeolite loadings of 6.78 mg PO43− g−1 were reached and after regeneration, phosphate recovery rates up to 75% of the initial concentration were achieved. The speed of phosphate precipitation is mostly controlled by the pH value of synthetic wastewater. Phosphate removal in simultaneous experiments does not affect ammonium sorption onto zeolite. These findings and the different removal mechanisms of ammonium and phosphate lead to versatile applications in wastewater treatment and reveal great potential of natural zeolite in simultaneous nutrient recovery processes.

scholarly journals Optimizing water and resource recovery facilities (WRRF) for energy generation without compromising effluent quality

Water SA ◽  
2021 ◽  
Vol 47 (2 April) ◽  
Author(s):  
George A Ekama
Keyword(s):  
Activated Sludge ◽  
Energy Generation ◽  
Resource Recovery ◽  
Biological Nutrient Removal ◽  
Effluent Quality ◽  
P Content ◽  
Primary Separation ◽  
The Impact ◽  
Final Effluent ◽  
P Removal

The primary separation unit (PSU) splits the organic load on the water and resource recovery facility (WRRF) between the primary sludge (PS) anaerobic digester (AD), where energy can be generated, and the biological nutrient removal (BNR) activated sludge (AS) reactor, where energy is consumed. With a CHONP element mass-balanced plant-wide stoichiometric and kinetic steady-state model, this paper explores quantitatively the impact of four cases of increasing organics removal efficiencies in the PSU on (i) settled wastewater characteristics, (ii) balanced solids retention time (SRT) of the Modified Ludzack-Ettinger (MLE) and University of Cape Town/Johannesburg (UCT/JHB) systems for lowest economical effluent N and P concentrations, (iii) reactor volume, (iv) energy consumption for aeration, pumping and mixing, (v) energy generation by AD of PS and waste activated sludge (WAS), (vi) N&P content of the PS and WAS AD dewatering liquor (DWL) and (vii) final effluent N and P concentrations with and without enhanced biological P removal (EBPR), and looks for an optimum WRRF layout for maximum energy recovery without compromising effluent quality. For the low biogas yield from the WAS AD, decreasing as the SRT of the BNRAS system gets longer and with the added complexity of N&P removal from the digested sludge DWL, makes AD of WAS undesirable unless P recovery is required. Because the wastewater biodegradable particulate organics (BPO) have a low N&P content, it is better to divert more biodegradable particulate organics to the PSAD with enhanced primary separation than digest WAS – the PSAD DWL can be returned to the influent with relatively small impact on final effluent N and P concentration.

Considerations in the Process Design of Nutrient Removal Activated Sludge Processes

1983 ◽  
Vol 15 (3-4) ◽  
pp. 283-318 ◽  
Author(s):  
G A Ekama ◽  
I P Siebritz ◽  
G V R Marais
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
Concentration Ratio ◽  
Oxygen Demand ◽  
Biological Nutrient Removal ◽  
Nitrogen And Phosphorus ◽  
Effluent Quality ◽  
Biological Nitrogen ◽  
Activated Sludge Processes ◽  
P Removal

The average influent wastewater characteristics - (i) the COD concentration, (ii) the TKN/COD concentration ratio, (iii) the rapidly biodegradable COD concentration, (iv) the maximum specific growth rate of the nitrifiers at 20°C attainable in the wastewater, (v) the maximum and minimum temperatures, and (vi) the P/COD concentration ratio - are shown to govern the design of, and effluent quality from single sludge activated sludge processes for both biological nitrogen and phosphorus removal. The TKN/COD ratio governs the selection of the process type: For the Phoredox process, complete denitrification is essential to obtain excess P removal, and this is shown to be feasible only for TKN/COD ratios less than 0,07 to 0,08 mgN/mgCOD; as the TKN/COD ratio increases above 0,08, complete denitrification becomes increasingly unlikely, and the UCT or Modified UCT processes are appropriate because in these processes complete denitrification is not essential to achieve excess P removal - in these processes N and P removal can be traded off against each other depending on the critical nutrient to be removed. Primary sedimentation significantly reduces the biological nutrient removal potential of activated sludge process because it increases the TKN/COD and P/COD ratios and reduces the COD load; however it significantly reduces the process volume and total oxygen demand.

A Promising Combination of Two Phosphate Removal Techniques: Biological P-Removal and the Crystalactor

1991 ◽  
Vol 24 (10) ◽  
pp. 329-332
Author(s):  
P. M. J. Janssen ◽  
J. H. Rensink ◽  
E. Eggers
Keyword(s):  
Phosphate Removal ◽  
P Removal

Survey of filamentous populations in nutrient removal plants in four European countries

1998 ◽  
Vol 37 (4-5) ◽  
pp. 281-289 ◽  
Author(s):  
Dick H. Eikelboom ◽  
Andreas Andreadakis ◽  
Kjaer Andreasen
Keyword(s):  
Nutrient Removal ◽  
Seasonal Pattern ◽  
Plug Flow ◽  
Phosphate Removal ◽  
Particulate Fraction ◽  
Biological Nutrient Removal ◽  
Process Conditions ◽  
Minor Importance ◽  
Filamentous Microorganisms ◽  
Short Period

A joint EU research project aimed at solving activated sludge bulking in nutrient removal plants was initiated in 1993. The project started with a survey of the size and composition of the filamentous population in nutrient removal plants in Denmark, Germany, Greece and the Netherlands. The results show that biological nutrient removal process conditions indeed favour filamentous microorganisms in their competition with floc forming organisms. An increase in the size of the filamentous population resulted in a deterioration of the settling properties of the biomass, except for plants with Bio-P removal conditions. It is assumed that in the latter case the dense clusters of Bio-P bacteria increase the weight of the flocs, and compensate for the effect of the larger number of filaments. Although exceptions frequently occur, the following sequence in decreasing filamentous organism population size was observed for the process conditions indicated: - completely mixed + simultaneous denitrification; - completely mixed + intermittent aeration/denitrification; - alternating anoxic/oxic process conditions, with an anaerobic tank for biological phosphate removal (Bio-Denipho); - alternating anoxic/oxic process conditions (Bio-Denitro); - predenitrification The surveys provided little information about the effect of nutrient removal in plants with plug flow aeration basins. Simultaneous precipitation with aluminium salts nearly always resulted in a low number of filaments and a good settling sludge. The size of the filamentous organism population showed a seasonal pattern with a maximum in winter/early spring and a minimum during summer (in Greece: during autumn). This seasonal variation is primarily caused by the effect of the season on the population sizes of M. parvicella, N. limicola and Type 0092. M. parvicella is by far the most important filamentous species in nutrient removal plants. In Denmark only, Type 0041 also frequently dominates the filamentous population, but seldom causes severe bulking. Considering their frequency of occurrence, approx. 10 other filamentous micro-organisms are of minor importance. Growth of some of these species, viz. those which use soluble substrate, can be prevented by the introduction of Bio-P process conditions. M. parvicella and Type 0041 (and probably also Actinomycetes and the Types 1851 and 0092) seem to compete for the same substrates i.e. the influent particulate fraction. Most of the differences in composition of the filamentous microorganism population can be explained by whether or not premixing of influent and recycled sludge is used. In general, premixing for a short period of time followed by anoxic conditions favours Type 0041. M. parvicella seems to proliferate if the particulate fraction is first hydrolysed or if it enters the plant via an oxic zone. It is concluded that bulking in nutrient removal plants is mainly caused by filamentous species requiring the particulate fraction for their growth.

Model based evaluation of plant improvement strategies for biological nutrient removal

1999 ◽  
Vol 39 (4) ◽  
pp. 45-53 ◽  
Author(s):  
H. M. van Veldhuizen ◽  
M. C. M. van Loosdrecht ◽  
F. A. Brandse
Keyword(s):  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
P Uptake ◽  
Biological Nutrient Removal ◽  
Adequate Description ◽  
Control Scheme ◽  
Detailed Simulation ◽  
High Fraction ◽  
Biokinetic Parameters ◽  
P Removal

An activated sludge model for biological N- and P-removal was developed, which describes anoxic and aerobic P-uptake based on bacterial metabolism. This model was tested in practice on two wastewater treatment plants, which are BCFS®-processes, which contain activated sludge with a high fraction of denitrifying P-removing bacteria (DPB's). The model appeared to be able to give an adequate description of the performance of these treatment plants under different conditions. If the process parameters are well defined almost no calibration of the biokinetic parameters was necessary. In the simulation of Dalfsen wwtp, which has a complex control scheme, it was possible to give an adequate simulation of the control actions and the concentration profiles in a rather simple way, showing that detailed simulation of these controllers was not necessary. With the calibrated model it was possible to analyse bottlenecks and give suggestions for upgrading of the concerned treatments plants. The simulation results were used in decisions on investments.

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.

Improvment of nitrogen and phosphorus removal in the anaerobic-oxic-anoxic-OXIC (AOAO) process by stepwise feeding

2000 ◽  
Vol 42 (3-4) ◽  
pp. 89-94 ◽  
Author(s):  
H.Y. Chang ◽  
C.F. Ouyang
Keyword(s):  
Carbon Source ◽  
Phosphorus Removal ◽  
Removal Rate ◽  
Feeding Strategy ◽  
Synthetic Wastewater ◽  
Biological Nutrient Removal ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Kjeldahl Nitrogen ◽  
P Removal

This investigation incorporated a stepwise feeding strategy into the biological process containing anaerobic/oxide/anoxic/oxide (AOAO) stages to enhance nitrogen and phosphorus removal efficiencies. Synthetic wastewater was fed into the experimental reactors during the anaerobic and anoxic stages and the substrates/nutrients were successfully consumed without recycling either nitrified effluent or external carbon source. An intrinsic sufficient carbon source developed during the anoxic stage and caused the NOx (NO2-N+NO3-N) concentration to be reduced from 11.85mg/l to 5.65mg/l. The total Kjeldahl nitrogen (TKN) removal rate was between 81.81%∼93.96% and the PO4-P removal ratio ranged from 93%∼100%. The substrate fed into the anaerobic with a Q1 flow rate and a Q2 into the anoxic reactor. The three difference experiments contained within this study produced Q1/Q2 that varied from 7/3, 8/2, and 9/1. The AOAO process saved nearly one-third of the energy compared with typical biological nutrient removal (BNR) system A2O processes.

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