Hydraulic Residence Time Effects on Performance of an Activated Sludge Unit Treating Wastewater Containing Dichlorophenol

2006 ◽  
Vol 78 (7) ◽  
pp. 686-690 ◽  
Author(s):  
Serkan Eker ◽  
Fikret Kargi
Keyword(s):  
Activated Sludge ◽  
Residence Time ◽  
Hydraulic Residence Time ◽  
Time Effects

Integration of performance, molecular biology and modeling to describe the activated sludge process

1998 ◽  
Vol 37 (4-5) ◽  
pp. 223-229 ◽  
Author(s):  
V. Urbain ◽  
B. Mobarry ◽  
V. de Silva ◽  
D. A. Stahl ◽  
B. E. Rittmann ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Molecular Biology ◽  
Activated Sludge ◽  
Residence Time ◽  
Municipal Wastewater ◽  
Treated Wastewater ◽  
Integrated Analysis ◽  
Activated Sludge Process ◽  
Hydraulic Residence Time ◽  
Technical Problems

To study process performance and population dynamics in activated sludge, a pilot-scale Membrane Bioreactor (MBR) was installed in a municipal wastewater treatment plant (Aubergenville, France). Since no solids losses occur in the MBR effluent, the sludge residence time (SRT) can be: i) easily controlled by means of the sludge withdrawal, and ii) dissociated from the hydraulic residence time (HRT). A complete characterization of this activated sludge system was performed at three sludge ages (5, 10 and 20 days). Raw and treated wastewater quality, as well as sludge concentration, was analyzed, nucleic probe analysis was performed to determine the heterotrophic and nitrifier populations, and the results were compared to the output from a multispecies model that integrates substrate removal kinetics and soluble microbial products (SMP) production/consumption. This paper presents an integrated analysis of the activated sludge process based on chemical, molecular biology, and mathematical tools. The model was able to describe the MBR system with a high degree of accuracy, in terms of COD removal and nitrification, as well as sludge production and population dynamics through the ratio of active nitrifiers/bacteria. Both steady-state and transient conditions could be described accurately by the model, except for technical problems or sudden variations in the wastewater composition.

Enhancing nitrification in North American activated sludge plants

2000 ◽  
Vol 41 (9) ◽  
pp. 97-105 ◽  
Author(s):  
G.T. Daigger ◽  
D.S. Parker
Keyword(s):  
Activated Sludge ◽  
Residence Time ◽  
North American ◽  
Biological Process ◽  
Full Scale ◽  
Activated Sludge Process ◽  
Hydraulic Residence Time ◽  
Nitrification Process ◽  
Mechanistic Basis ◽  
Space Requirements

Many plant owners, operators and designers consider the nitrifying activated sludge process as being a high hydraulic residence time (HRT) process. However, in recent years a number of techniques have been developed to enhance the performance of activated sludge plants for nitrification. The result, when the proper combination of these techniques is used, can be a significant reduction in the biological process hydraulic residence time and a corresponding reduction in facility costs and space requirements. Several of these factors are discussed in this paper, including a discussion of the mechanistic basis for each technique and its impact on nitrification process sizing. Some full-scale North American examples are also discussed.

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.

Suspended carrier technology allows upgrading high-rate activated sludge plants for nitrogen removal via process intensification

2000 ◽  
Vol 41 (4-5) ◽  
pp. 5-12 ◽  
Author(s):  
E.v. Münch ◽  
K. Barr ◽  
S. Watts ◽  
J. Keller
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Residence Time ◽  
Nitrogen Removal ◽  
Wastewater Treatment Plant ◽  
Pilot Plant ◽  
Treatment Plant ◽  
Carbon Removal ◽  
Suspended Carrier ◽  
Plastic Media

The Oxley Creek wastewater treatment plant is a conventional 185,000 EP BOD removal activated sludge plant that is to be upgraded for nitrogen removal to protect its receiving water bodies, the Brisbane River and Moreton Bay. Suspended carrier technology is one possible way of upgrading this activated sludge wastewater treatment plant for nitrogen removal. Freely moving plastic media is added to the aeration zone, providing a growth platform for nitrifying bacteria and increasing the effective solids residence time (SRT). This paper presents the results from operating a pilot plant for 7 months at the Oxley Creek WWTP in Brisbane, Australia. Natrix Major 12/12 plastic media, developed by ANOX (Lund, Sweden), was trialed in the pilot plant. The pilot plant was operated with a mixed liquor suspended solids concentration of 1220 mg/L and a total hydraulic residence time of 5.4 hours, similar to the operating conditions in the full-scale Stage 1&2 works at the Oxley Creek WWTP. The plastic carriers were suspended in the last third of the bioreactor volume, which was aerated to a DO setpoint of 4.0 mg/L. The first third of the bioreactor volume was made anoxic and the second third served for carbon removal, being aerated to a DO setpoint of 0.5 mg/L. The results from the pilot plant indicate that an average effluent total inorganic nitrogen concentration (ammonia-N plus NOx−N) of less than 12 mg/L is possible. However, the effluent ammonia concentrations from the pilot plant showed large weekly fluctuations due to the intermittent operation of the sludge dewatering centrifuge returning significant ammonia loads to the plant on three days of the week. Optimising denitrification was carried out by lowering the DO concentration in the influent and in the carbon removal reactor. The results from the pilot plant study show that the Oxley Creek WWTP could be upgraded for nitrogen removal without additional tankage, using suspended carrier technology.

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