Improving nitrogen removal in predenitrification-nitrification biofilters

2004 ◽  
Vol 48 (11-12) ◽  
pp. 419-428 ◽  
Author(s):  
L. Larrea ◽  
A. Abad ◽  
J. Gayarre
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Nitrogen Removal ◽  
Suspended Solids ◽  
Complete Removal ◽  
Cod Removal ◽  
Nitrification Rate ◽  
Removal Rates ◽  
N Removal ◽  
Activated Sludge Processes

The effect on NH4-N removal rates in nitrification biofilters of filtered biodegradable COD and particulate COD leaving predenitrification biofilters was studied in a lab scale plant configured with the separated system of biofilters for secondary nitrogen removal from urban wastewaters. Applying a typical COD load of 11 kg/m3.day to the predenitrification biofilter and maximizing its COD removal by adding nitrates or by operating an improved control of the internal recycle, only 60% removal of filtered biodegradable COD was found. This value corresponds to the complete removal of the readily biodegradable substrate (30% of influent filtered COD) and 36% of filtered slowly biodegradable substrate (50% of influent COD). The remaining 64% of the latter entered the nitrification biofilter, causing competition between heterotrophs and nitrifiers for dissolved oxygen in the inner layers of the biofilm. Consequently the nitrification rate had relatively low values (0.5 kgN/m3.d) at 14°C despite using dissolved oxygen levels of 6 mg/l. This behaviour may explain the lower nitrification rates obtained in some cases of nitrification biofilters compared to those in tertiary nitrification after activated sludge processes. The particulate COD entering the nitrification biofilter is associated with the suspended solids leaving the denitrification biofilter which are adsorbed by the external layers of the biofilm, increasing its thickness. The activity of the nitrifiers was affected because of a lack of oxygen when the thickness was left to grow considerably. Therefore no significant particulate COD effect is expected to occur as long as backwashing is carried out with the appropriate frequency.

Full-scale application of the BABE® technology

2004 ◽  
Vol 50 (7) ◽  
pp. 87-96 ◽  
Author(s):  
S. Salem ◽  
D.H.J.G. Berends ◽  
H.F. van der Roest ◽  
R.J. van der Kuij ◽  
M.C.M. van Loosdrecht
Keyword(s):  
Activated Sludge ◽  
Treatment Plant ◽  
Full Scale ◽  
Nitrification Rate ◽  
Stable Operation ◽  
Water Line ◽  
Ambient Temperatures ◽  
N Removal ◽  
Set Up ◽  
Activated Sludge Processes

Bio-augmentation can be used to obtain nitrification in activated sludge processes that operate at ub-optimal solid retention times. A side-stream process, the so-called BABE® process that incorporates Nremoval and augmentation of nitrifiers has been developed. The principle is to implement a nitrification reactor in the sludge return line, the so-called BABE reactor. This reactor can be fed with an internal N-rich flow (e.g. effluent from the sludge treatment). Hence the nitrification capacity of an activated sludge process can be augmented by the addition of nitrifiers cultivated in the BABE reactor. A full-scale test of the BABE technology has been at the treatment plant Garmerwolde in Groningen, the Netherlands. The set-up allowed comparing between three different lines: with the BABE reactor, without rejectwater and with untreated rejectwater. Based on this, the two important tasks (N-removal and inoculation) performed by the BABE reactor could be quantified. The results of the practical work in Garmerwolde showed a higher nitrification rate in the water line where the BABE reactor was implemented and also lower effluent ammonia. The experiments on a practical scale have demonstrated univocally the effective and stable operation of the BABE technology. In addition, sludge samples in different streams as well as from the BABE reactor were analysed with FISH technique. The FISH results illustrated the augmentation effect of the BABE reactor on the stream with the BABE reactor. A mathematical model, based on ASM1 model and implemented in AQUASIM was developed and used for simulating the treatment plant of Garmerwolde. The simulation results indicated that better effect of the BABE technology is expected at lower ambient temperatures and smaller volume of the BABE reactor. The BABE reactor could also allow for providing more space for de-nitrification in the main water line when nitrification is efficient enough.

Treatment of municipal wastewater in a hybrid process using a new suspended carrier with large surface area

2004 ◽  
Vol 49 (11-12) ◽  
pp. 207-214 ◽  
Author(s):  
M. Christensson ◽  
T. Welander
Keyword(s):  
Activated Sludge ◽  
Surface Area ◽  
Pilot Plant ◽  
Suspended Solids ◽  
Municipal Wastewater ◽  
Large Surface Area ◽  
Hybrid Process ◽  
Nitrification Rate ◽  
Suspended Carrier ◽  
Activated Sludge Processes

An activated sludge/biofilm hybrid process treating municipal wastewater was studied in pilot plant trials. A new type of suspended carrier, with large effective surface area, was employed in the process with the aim of enhancing nitrification. The pilot plant was operated for 1.5 years in five different configurations including pre-denitrification in all five and enhanced biological phosphorus removal in the final two. The wastewater temperature ranged between 11°C and 20°C, and the nominal dissolved oxygen (DO) level was 5-6 mg/L. The nitrification rate obtained on the new carrier within the hybrid stage was in the range of 0.9-1.2 g NH4-N/m2/d corresponding to a volumetric rate of 19-23 g NH4-N/m3/h (total nitrification including nitrification in the suspended solids). More than 80% of the total nitrification took place on the carrier (and the remainder in the suspended solids). The nitrification rate was shown to correlate with DO, decreasing when the DO was decreased. The results supported the idea of using the new carrier as a tool to upgrade plants not having nitrification today or improve nitrification in activated sludge processes not reaching necessary discharge levels. The large surface area present for nitrification makes it possible to obtain high nitrification rates within limited volumes. The possibility to keep the total suspended solid content low (<3 g/L) and avoiding problems with the filament Microthrix parvicella, are other beneficial properties of the hybrid process.

Application of Three Step-Biological Pond with the Use of Aquatic Plant for Post Treatment of Petroleum Wastewater in Vietnam

1991 ◽  
Vol 23 (7-9) ◽  
pp. 1503-1507 ◽  
Author(s):  
L. M. Triet ◽  
N. T. Viet ◽  
T. V. Thinh ◽  
H. D. Cuong ◽  
J. C. L. van Buuren
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Residence Time ◽  
Aquatic Plants ◽  
Water Hyacinth ◽  
Aquatic Plant ◽  
Post Treatment ◽  
Cod Removal ◽  
Sludge Treatment ◽  
Purification Efficiency

The effluent from activated sludge treatment of petroleum wastewater was treated with the aid of a ponding system using aquatic plants (Water Hyacinth, Chlorella, Reed). A good result was obtained in this study. Pilot pond system shows that the purification efficiency depends on the residence time of about 14 days. The petroleum removal waa 97-98 %, the COD removal was from 88-93 %. The dissolved oxygen amount (with Chlorella) increased from 0.7 mg/l to 9.8 mg/l and the pH increased from 6.9 to 8-8.6. The application of 3 step biological pond with the use of Water Hyacinth, Chlorella, Reeds for post treatment of petroleum wastewater is appropriate in Vietnam.

Floc size distribution and bacterial activities in membrane separation activated sludge processes for small-scale wastewater treatment/reclamation

1997 ◽  
Vol 35 (6) ◽  
pp. 37-44 ◽  
Author(s):  
Boran Zhang ◽  
Kazuo Yamamoto ◽  
Shinichiro Ohgaki ◽  
Naoyuki Kamiko
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Membrane Separation ◽  
Small Scale ◽  
Nitrification Rate ◽  
Floc Size ◽  
Denitrification Activity ◽  
Concentration Changes ◽  
Activated Sludge Processes

Activated sludges taken from full-scale membrane separation processes, building wastewater reuse system (400m3/d), and two nightsoil treatment plants (50m3/d) as well as laboratory scale membrane separation bioreactor (0.062m3/d) were analyzed to characterize membrane separation activated sludge processes (MSAS). They were also compared with conventional activated sludges(CAS) taken from municipal wastewater treatment plants. Specific nitrification activity in MSAS processes averaged at 2.28gNH4-N/kgMLSS.h were higher than that in CAS processes averaged at 0.96gNH4-N/kgMLSS.h. The denitrification activity in both processes were in the range of 0.62-3.2gNO3-N/kgMLSS.h without organic addition and in the range of 4.25-6.4gNO3-N/kgMLSS.h with organic addition. The organic removal activity in nightsoil treatment process averaged at 123gCOD/kgMLSS.h which was significantly higher than others. Floc size distributions were measured by particle sedimentation technique and image analysis technique. Flocs in MSAS processes changed their sizes with MLSS concentration changes and were concentrated at small sizes at low MLSS concentration, mostly less than 60 μm. On the contrary, floc sizes in CAS processes have not much changed with MLSS concentration changes and they were distributed in large range. In addition, the effects of floc size on specific nitrification rate, denitrification rate with and without organic carbon addition were investigated. Specific nitrification rate was decreased as floc size increased. However, little effect of floc size on denitrification activity was observed.

Factors affecting nitrogen removal from domestic wastewater using immobilized bacteria

1998 ◽  
Vol 38 (1) ◽  
pp. 193-202 ◽  
Author(s):  
Vasanthadevi Aravinthan ◽  
Satoshi Takizawa ◽  
Kenji Fujita ◽  
Kazuya Komatsu
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Nitrate Nitrogen ◽  
Domestic Wastewater ◽  
Nitrification Rate ◽  
Factors Affecting ◽  
Immobilized Bacteria ◽  
Bulk Oxygen ◽  
Micro Organisms ◽  
Nitrogen Loadings

The parameters affecting the nitrogen removal process by the immobilized bacteria in the anoxic-oxic process have been studied by investigating two bench scale Runs A and B. The hollow polypropylene pellets have been dosed into the anoxic reactor in Run A and into the oxic reactors of both Runs up to 24% of volume. Run B was operated with no pellets in the anoxic reactor as a control. The maximum nitrification rate of 0.4 kg NH4-N/m3d was achieved in sufficient DO (6.5 mg/l) at 15°C in the reactor with both activated sludge and immobilized micro-organisms. The volumetric nitrification rate was found to be greatly dependent on bulk oxygen concentration especially when the DO was maintained below 4 mg/l. A mathematical model developed successfully simulated the experimental results showing the variation of nitrification rate with DO. In the case of denitrification, the contribution of immobilized bacteria was prominent when lesser concentration of MLSS was present in the activated sludge in the combined immobilized and activated sludge system. The presence of immobilized bacteria in the anoxic reactor will be effective when higher nitrate nitrogen loadings are expected and the maintenance of higher MLSS than 2 g/l in an activated sludge facility is not feasible.

A comparison of NH4/NO3 control strategies for alternating activated sludge processes

1999 ◽  
Vol 39 (4) ◽  
pp. 93-102 ◽  
Author(s):  
L. J. S. Lukasse ◽  
K. J. Keesman ◽  
A. Klapwijk ◽  
G. van Straten
Keyword(s):  
Activated Sludge ◽  
Time Delays ◽  
Control Strategies ◽  
Treatment Plant ◽  
Biological Processes ◽  
Effluent Quality ◽  
N Removal ◽  
Activated Sludge Reactor ◽  
The Difference ◽  
Activated Sludge Processes

Four control strategies for N-removal in alternating activated sludge plants (ASP's) are compared: 1. timer-based, 2. switching the aeration on/off when depletion of nitrate/ammonium is detected, 3. switching the aeration on/off when ammonium crosses an upper/lower-bound, 4. the newly developed adaptive receding horizon optimal controller (ARHOC) as presented in Lukasse et al. (1997). The comparison is made by simulating the controllers' application to an alternating continuously-mixed activated sludge reactor preceded by a small anoxic reactor for predenitrification. The biological processes in the reactors are modelled by the activated sludge model no. 1. Realistic influent patterns, measured at a full-scale wastewater treatment plant, are used. The results show that three totally different controllers (timer-based, NH4-bounds based and ARHOC) can achieve a more or less equal effluent quality, if tuned optimally. The difference mainly occurs in the sensitivity to suboptimal tunings. The timer-based strategy has a higher aeration demand. The sensitivity of the ARHOC controller to sub-optimal tuning, known measurement time delays and changing plant loads is significantly less than that of the other controllers. Also its tuning is more natural and explicit.

Full-scale evaluation of an integrated fixed-film activated sludge (IFAS) process for enhanced nitrogen removal

1996 ◽  
Vol 33 (12) ◽  
pp. 155-162 ◽  
Author(s):  
Clifford W. Randall ◽  
Dipankar Sen
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Plug Flow ◽  
Treatment Plant ◽  
Nitrification Rate ◽  
A Value ◽  
Fixed Film ◽  
Control Section ◽  
The Media ◽  
Retrofit Design

One of the two trains of the 37,000 m3/d Annapolis, Maryland step aeration activated sludge treatment plant was modified for single-sludge anoxic-aerobic operation, and then fixed-film media were integrated into the aerobic zone to enhance nitrification. Rope-like Ringlace media was selected for integration, and 30,000 meters were installed in a volume of 475 m3 for a pilot demonstration. The purpose of the integrated fixed-film media was to upgrade the short hydraulic retention time (HRT) basin (6 hrs nominal) for efficient, year-round nitrogen removal without construction to increase basin volume. An engineering study had concluded that upgrading the facility for year round complete nitrification, without nitrogen removal, would cost US$24 million. The modified train was operated for 12 months, six in the plug-flow MLE configuration, and six in a step-feed configuration. The integrated Ringlace media increased the nitrification rate per unit volume to 225% of that observed in the control section, attaining a value of 1.75 kg/d NH3-N per linear meter at 15°C. The media also increased denitrification in the aerobic media section to the extent that between 30 and 88% of the nitrates formed in the section were denitrified within it, permitting a potential 25% or more reduction in the volume of the anoxic zone. An IFAS retrofit design was developed which incorporated step-feed operation, and reduced the projected construction cost to US$9.2 million.

Hierarchical dissolved oxygen control for activated sludge processes

2008 ◽  
Vol 16 (1) ◽  
pp. 114-131 ◽  
Author(s):  
R. Piotrowski ◽  
M.A. Brdys ◽  
K. Konarczak ◽  
K. Duzinkiewicz ◽  
W. Chotkowski
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Oxygen Control ◽  
Dissolved Oxygen Control ◽  
Activated Sludge Processes
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