Study of factors affecting simultaneous nitrification and denitrification (SND)

1999 ◽  
Vol 39 (6) ◽  
pp. 61-68 ◽  
Author(s):  
Klangduen Pochana ◽  
Jürg Keller
Keyword(s):  
Carbon Source ◽  
Activated Sludge ◽  
Physical Phenomenon ◽  
Treatment Plant ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Factors Affecting ◽  
Floc Size ◽  
Sludge Flocs ◽  
Activated Sludge Systems

Experiments have been performed to gain an understanding of the conditions and processes governing the occurrence of SND in activated sludge systems. Sequencing batch reactors (SBRs) have been operated under controlled conditions using the wastewater from the first anaerobic pond in an abattoir wastewater treatment plant. Under specific circumstances, up to 95% of total nitrogen removal through SND has been found in the system. Carbon source and oxygen concentrations were found to be important process parameters. The addition of acetate as an external carbon source resulted in a significant increase of SND activity in the system. Stepwise change of DO concentration has also been observed in this study. Experiments to determine the effect of the floc size on SND have been performed in order to test the hypothesis that SND is a physical phenomenon, governed by the diffusion of oxygen into the activated sludge flocs. Initial results support this hypothesis but further experimental confirmation is still required.

Dynamic mathematical modelling of sequencing batch reactors with aerated and mixed filling period

1997 ◽  
Vol 35 (1) ◽  
pp. 105-112 ◽  
Author(s):  
L. Novák ◽  
M. C. Goronszy ◽  
J. Wanner
Keyword(s):  
Activated Sludge ◽  
Batch Reactor ◽  
Major Elements ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Nitrogen And Phosphorus ◽  
Sludge Flocs ◽  
Solids Concentration ◽  
A Minor ◽  
Selection Of

Sequencing batch reactors (SBRs) can be successfully operated for both carbon and nutrient removal, including nitrogen and phosphorus. The major elements of design that accomplish population dynamics control to prevent filamentous sludge bulking, cycle time, oxygen supply, biological nitrification, denitrification, phosphorus removal and solids-liquid separation need to be set in such a way that sufficiently optimal conditions are provided to permit the reactions and processes to take place. SBR processing using cyclic activated sludge technology employs biological selectors in the inlet part of the SBR system and a minor sludge recycle stream to ensure influent wastewater is mixed with activated sludge flocs to create favourable conditions for kinetic and metabolic selection of microorganisms producing floccules. Reaction volume, in addition to the designated bottom water level volume, is variable through time fed-batch reactor mode of operation. A mathematical model that describes volume changes and simultaneously the biodegradation kinetics has been developed. The model describes theoretical behaviour of selected parameters of volume, suspended solids concentration, OUR, ammonia and nitrate nitrogen in the selector compartment and the main aerated basin in ideally mixed and filled reactors of the cyclic system during the phase of mixed-fill (selector) and aerated and non-aerated fill (main aeration reactor basin).

Effects of increased influent nitrogen load on a part-time aerated activated sludge system

2013 ◽  
Vol 8 (1) ◽  
pp. 18-26
Author(s):  
T. Weinpel ◽  
V. Bakos ◽  
A. Jobbágy
Keyword(s):  
Carbon Source ◽  
Activated Sludge ◽  
Treatment Plant ◽  
Ammonia Concentration ◽  
Content Increase ◽  
The North ◽  
Mathematical Simulations ◽  
Part Time ◽  
Anoxic Zones ◽  
Activated Sludge Systems

Part-time aeration is frequently applied in activated sludge systems in order to decrease treatment costs by achieving nitrification and denitrification in the same basin. However, measurements and mathematical simulations carried out at the North-Budapest Wastewater Treatment Plant (Budapest, Hungary), clearly show that especially in the increasingly characteristic shortage of readily biodegradable carbon-source, this technique may lead to high effluent nitrate and/or ammonia concentrations at decreased temperatures. This situation may be worsened when co-digestion of external wastes with high N-content increase the ammonia concentration of sludge processing return flows. In these cases, denitrification should rather be enhanced in pre-anoxic zones. Pronounced pre-denitrification leads to better usage of the influent carbon-source and to considerably less methanol demand when dosing external carbon-source proves to be necessary.

The Concept of Soluble Residual Product Formation in the Modelling of Activated Sludge

1989 ◽  
Vol 21 (4-5) ◽  
pp. 339-350 ◽  
Author(s):  
D. Orhon ◽  
N. Artan ◽  
Y. Cimşit
Keyword(s):  
Organic Matter ◽  
Activated Sludge ◽  
Product Formation ◽  
Cellular Materials ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Soluble Organic Matter ◽  
Residual Product ◽  
Hydrolysis Of ◽  
Activated Sludge Systems

The soluble effluent COD of a well operated activated sludge plant is likely to be composed almost entirely of organic matter generated by microbial activity. There is evidence to show that a significant portion of this soluble organic matter is non-degradable and may be due to similar microbial mechanisms. A model for the formation of these soluble residual products, (SRP), is propose'd, relating the SRP formation to the hydrolysis of non-viable cellular materials in the reactor. The set of equations describing the model are successfully calibrated and verified for a set of representative experimental data derived from Sequencing Batch Reactors. The model is found to explain and predict COD accumulation at the end of each cycle of these activated sludge systems.

Effect of salinity on the activity, settling and microbial community of activated sludge in sequencing batch reactors treating synthetic saline wastewater

2008 ◽  
Vol 58 (2) ◽  
pp. 351-358 ◽  
Author(s):  
G. Wu ◽  
Y. Guan ◽  
X. Zhan
Keyword(s):  
Microbial Community ◽  
Activated Sludge ◽  
Volume Index ◽  
Synthetic Wastewater ◽  
Utilization Rate ◽  
Yield Coefficient ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Saline Wastewater ◽  
Sludge Flocs

The effects of salinity on the activity in nutrient removal, settling and microbial community of activated sludge in sequencing batch reactors (SBRs) treating synthetic saline wastewater were investigated. Two SBRs, one treating synthetic saline wastewater (the N-Reactor, with NaCl addition) and the other treating fresh synthetic wastewater (the C-Reactor, without NaCl addition), were operated for 68 days. Three salinities (in terms of concentrations of NaCl)—10, 20 and 40 g NaCl/l—were examined. The microbial activity described with the specific glucose utilization rate, specific nitritation and nitratation rates, and specific phosphorus release and uptake rates, was inhibited in the N-Reactor, in comparison with that in the C-Reactor, except that the specific nitritation and nitratation rates were improved at the salinity of 10 g NaCl/l. The sludge yield coefficient decreased at salinities of 10 and 20 g NaCl/l but it rose at the salinity of 40 g NaCl/l. The settling of activated sludge flocs, in terms of the sludge volume index (SVI), was improved by adding NaCl. Particularly in the first 5 minutes during the SVI measurement, activated sludge flocs in the N-Reactor settled much faster than those in the C-Reactor. However, the effluent from the N-Reactor contained higher suspended solids than the effluent from the C-Reactor. The microbial diversity decreased with increasing the salinity, and the microbial community structure was greatly influenced by the salinity. Bacteriodetes and Actinobacteria were the dominant phylums detected with molecular fingerprinting techniques.

Aerobic granular sludge technology: an alternative to activated sludge?

2004 ◽  
Vol 49 (11-12) ◽  
pp. 1-7 ◽  
Author(s):  
L.M.M. de Bruin ◽  
M.K. de Kreuk ◽  
H.F.R. van der Roest ◽  
C. Uijterlinde ◽  
M.C.M. van Loosdrecht
Keyword(s):  
The Netherlands ◽  
Activated Sludge ◽  
Sewage Treatment ◽  
Treatment Plant ◽  
Granular Sludge ◽  
Primary Treatment ◽  
Aerobic Granular Sludge ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Effluent Standards

Laboratory experiments have shown that it is possible to cultivate aerobic granular sludge in sequencing batch reactors. In order to direct future research needs and the critical points for successful implementation at large scale, a full detailed design of a potential application was made. The design was based on the laboratory results, and two variants of a full-scale sewage treatment plant based on Granular sludge Sequencing Batch Reactors (GSBRs) were evaluated. As a reference a conventional treatment plant based on activated sludge technology was designed for the same case. Based on total annual costs both GSBR variants proved to be more attractive than the reference alternative (7-17% lower costs). From a sensitivity analysis it appeared that the GSBR technology was less sensitive to the land price and more sensitive to a rain weather flow (RWF). This means that the GSBR technology becomes more attractive at lower permissible RWF/DWF ratios and higher land prices. The footprint of the GSBR variants was only 25% compared to the reference. However, the GSBR with primary treatment only cannot meet the present effluent standards for municipal wastewater in The Netherlands, mainly because of a too high suspended solids concentration in the effluent. A growing number of sewage treatment plants in the Netherlands are going to be faced with more stringent effluent standards. In general, activated sludge plants will have to be extended with a post treatment step (e.g. sand filtration) or be transformed into Membrane Bioreactors. In this case a GSBR variant with primary treatment as well as post treatment can be an attractive alternative.

scholarly journals Sulphide Biooxidation in Activated Sludge Diffusion Process: Microbiological and Biochemical Effects

Proceedings ◽  
2018 ◽  
Vol 2 (11) ◽  
pp. 646 ◽  
Author(s):  
Massimo Blonda ◽  
Angelantonio Calabrese ◽  
Raffaele Palumbo ◽  
Elvira Giorgio
Keyword(s):  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Batch Reactors ◽  
Biological Processes ◽  
Sequencing Batch Reactors ◽  
Diffusion Test ◽  
Biochemical Activity ◽  
Sludge Flocs ◽  
Biochemical Effects ◽  
Odorous Compound

Sulphide was adopted as odorous compound in a simulation of AS Diffusion, an interesting process to treat odors at wastewater treatment plants by diffusing odorous air into aerobic basins. Its behaviour were experimentally evaluated along with its effects on the biomass and the biological processes supposed by some author in an AS diffusion test. Two bench scale sequencing batch reactors (SBRs) were fed in parallel on real primary sewage and monitored after adding increasing concentrations of sulphide to one of them. In this reactor, an average sulphide removal of 94% was measured. Microbial biochemical activity and composition did not show relevant variations after the addition of sulphide, and the good features of activated sludge flocs were maintained also in terms of sludge settleability.

Spatial arrangement of the components of activated sludge flocs

1994 ◽  
Vol 30 (11) ◽  
pp. 243-250 ◽  
Author(s):  
F. Zartarian ◽  
C. Mustin ◽  
J. Y. Bottero ◽  
G. Villemin ◽  
F. Thomas ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Laser Scanning ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Spatial Arrangement ◽  
Municipal Sewage ◽  
Cellular Division ◽  
Floc Size ◽  
Sludge Flocs

The purpose of this work was to observe the internal structure of activated sludge flocs and the relationship between the different components. Activated sludge flocs from the municipal sewage treatment plant at Nancy (France) were physically stabilized and solidified in an epoxy resin. The flocs were sliced into 0.1 μm thick sections and stained for characterisation of components and exopolymers by transmission electron microscopy. One small floc (10 μm × 20 μm), embedded in resin, was chosen and studied using a laser scanning confocal microscope. The focal plane was incremented in steps of 2 μm along the z axis of the microaggregate. In order to extract quantitative data (number of cells, floc size) a numerical treatment of the images was applied. A typical floc exhibits an unhomogeneous distribution of the mass of the exocellular polymer matrix (mainly polysaccharides). This matrix maintains the integrity of the floc and connects most of the components. These components are isolated bacteria, waste and debris inherited from the effluent and microcolonies. The structure of the microflocs is fractal with a fractal dimension Df ≈ 3. This large value implies that the growth of the small aggregates is possibly generated by cellular division and polymer production.

Stress protein expression in domestic activated sludge in response to xenobiotic shock loading

2001 ◽  
Vol 43 (1) ◽  
pp. 123-130 ◽  
Author(s):  
C. B. Bott ◽  
A. J. Duncan ◽  
N. G. Love
Keyword(s):  
Activated Sludge ◽  
Shock Loading ◽  
Treatment Process ◽  
Stress Proteins ◽  
Stress Protein ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Analysis Method ◽  
Consistent Increase ◽  
Activated Sludge Systems

Using the Western blot immunochemical analysis method, the heat shock protein, GroEL, was found to be either induced or repressed in activated sludge microorganisms exposed to a range of xenobiotics. At the EC25 concentration, pentachlorophenol (PCP), cadmium, nickel, 2,4-dichloroaniline, benzoquinone, 2,4-dinitrophenol, and 1,1,1-trichloroethane all rapidly induced measurable GroEL expression, even though the time-dependent response for each of these compounds was somewhat varied. Toluene and hydroquinone resulted in repression of GroEL expression to levels below that measured in the control mixed liquor. For PCP concentrations at or exceeding the EC25, there was a significant and consistent increase in effluent volatile suspended solids from activated sludge sequencing batch reactors relative to unstressed controls. These preliminary results indicate that stress proteins may serve as sensitive and rapid indicators of toxicity which can adversely impact treatment process performance in activated sludge systems.

scholarly journals N2O Reduction During Denitrifying Phosphorus Removal With Propionate as Carbon Source

2021 ◽  
Author(s):  
Li Cong ◽  
Qian Wang ◽  
Wenlin Jia
Keyword(s):  
Carbon Source ◽  
Phosphorus Removal ◽  
Dominant Factor ◽  
Nitrite Accumulation ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
N2o Reduction ◽  
Denitrifying Phosphorus Removal ◽  
Factors Affecting ◽  
Mixed Carbon Source

Abstract Denitrifying phosphorus removal was realized in sequencing batch reactors using different carbons sources (acetate, propionate, and a mixture of acetate/propionate). Nutrient removal and N2O production were investigated, and the factors affecting N2O production were explored. Nitrogen removal was 40.6% lower when propionate was used as the carbon source instead of acetate, while phosphorus removal was not significantly different. N2O production was greatly reduced when propionate was used as the carbon source instead of acetate. The emission factor in the propionate system was only 0.43%, while those in the acetate and mixed-carbon source system were 16.3% and 1.9%, respectively. Compared to the propionate system, ordinary heterotrophic organisms (i.e., glycogen-accumulating organisms) were enriched in the acetate system, explaining the higher N2O production in the acetate system. The lower nitrite accumulation in the propionate system compared to the acetate system was the dominant factor leading to the lower N2O production.

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