Denitrification kinetics in an activated sludge system

1995 ◽  
Vol 32 (9-10) ◽  
pp. 323-330
Author(s):  
M. Roš
Keyword(s):  
Activated Sludge ◽  
Closed System ◽  
Open Systems ◽  
Aeration Tank ◽  
Activated Sludge System ◽  
Denitrification Kinetics ◽  
Closed Systems ◽  
Nitrate And Nitrite ◽  
Sludge Concentration

For all water bodies especially for sea, lakes, and ground waters it is very important that nutrient pollution is the least possible (minimal). From municipal and industrial waste waters where considerable amount of nutrients is expected it is possible to remove nutrients with biological treatment. The first step is usually aerobic activated sludge treatment and the second step is combined anaerobic-anoxic-aerobic step in different combinations. A very effective process for nitrogen removal is anoxic activated sludge system. It is very important that in the first aerobic step complete nitrification is achieved. In our laboratory denitrification kinetics was studied. The objective of this study was determination of denitrification velocity and attendance of different parallel phenomena such as nitrite, disappearance of nitrate and nitrite, sulphide formation, etc. Denitrification process was studied in two systems, in closed system (such as in closed reactors for denitrification) and in open systems (such as in open denitrification tanks). We found out that denitrification rate in closed systems was from about 8 to 52 mg/l.h and was dependent on activated sludge type, sludge concentration, and temperature of the system. In open system (such as in an anoxic aeration tank) the rate of denitrification was lower than in closed system; it was from 4 to 15 mg/l.h dependent on activated sludge type, sludge concentration, and temperature of the system. Experiments were carried out in the range of temperature from 20° to 30°C.

Evaluation of ozonation and cryptic growth for biosolids management in wastewater treatment

1999 ◽  
Vol 39 (10-11) ◽  
pp. 155-158 ◽  
Author(s):  
E. Egemen ◽  
J. Corpening ◽  
J. Padilla ◽  
R. Brennan ◽  
N. Nirmalakhandan
Keyword(s):  
Activated Sludge ◽  
Continuous Flow ◽  
Growth Conditions ◽  
Aeration Tank ◽  
Biomass Growth ◽  
Waste Sludge ◽  
Process Configuration ◽  
Activated Sludge System ◽  
Expensive Problems ◽  
Cryptic Growth

The ultimate disposal of biosolids has been and continues to be one of the most expensive problems faced by wastewater utilities. The objective of this research is to develop a process configuration for reducing the waste sludge generation in an activated sludge plant by promoting cryptic growth conditions (i.e., biomass growth on intracellular products). For this purpose, excess biosolids from a continuous flow activated sludge system were solubilized using ozone as the cell lysis agent, and then returned to the aeration tank. It is hypothesized that growth under such cryptic conditions will result in low net microbial yields, and hence, minimal net solids wastage. The results of these preliminary studies indicate that the proposed process configuration has the potential to reduce the waste sludge production by 40% to 60%.

E-Cigarettes: Policy Options and Legal Issues Amidst Uncertainty

2015 ◽  
Vol 43 (S1) ◽  
pp. 23-26 ◽  
Author(s):  
Nancy Kaufman ◽  
Margaret Mahoney
Keyword(s):  
Smoking Cessation ◽  
Propylene Glycol ◽  
Open System ◽  
Closed System ◽  
Open Systems ◽  
Delivery Systems ◽  
Legal Issues ◽  
Policy Options ◽  
Electronic Nicotine Delivery Systems ◽  
Closed Systems

E-cigarettes, sometimes referred to as ENDS (Electronic Nicotine Delivery Systems), include a broad range of products that deliver nicotine via heating and aerosolization of the drug. ENDS come in a variety of forms, but regardless of form generally consist of a solution containing humectant (e.g., propylene glycol or glycerol), flavorings, and usually nicotine (some solutions do not contain nicotine); a battery-powered coil that heats the solution into an aerosol (usually referred to as vapor) in an atomizing chamber; and a mouthpiece through which the user draws the vapor into the mouth and lungs. The devices may be closed systems containing prefilled cartridges, or open systems, where the user manually refills a 1-2 ml. tank with solution. What started as closed-system cigarette-shaped devices marketed as an adjunct for smoking cessation, has transitioned rapidly to literally thousands of hip and funky-designed open-system hookah pens, vape pens, and modifiable devices. For younger people, these forms are the “in” thing, while traditional cigarette-shaped devices are “out.”

Determination of ozone adsorption in activated sludge system and its effect on sludge properties

2014 ◽  
Vol 54 (13) ◽  
pp. 3575-3581 ◽  
Author(s):  
Sara Rezaee ◽  
Mohammad-Hossein Sarrafzadeh ◽  
Mohammad-Reza Mehrnia ◽  
Ahmad-Reza Mohammadi ◽  
Farshid Pajoum-Shariati
Keyword(s):  
Activated Sludge ◽  
Activated Sludge System ◽  
Sludge Properties

Asymptotic expansions of moments of the waiting time in closed and open processor-sharing systems with multiple job classes

1983 ◽  
Vol 15 (4) ◽  
pp. 813-839 ◽  
Author(s):  
Debasis Mitra ◽  
J. A. Morrison
Keyword(s):  
Waiting Time ◽  
Open System ◽  
Closed System ◽  
Asymptotic Expansions ◽  
Queueing Networks ◽  
Open Systems ◽  
Asymptotic Series ◽  
Processor Sharing ◽  
Single Class ◽  
Closed Systems

We present new results based on novel techniques for the problem of characterizing the waiting-time distribution in a class of queueing networks. We give effective methods for computing, for each of possibly several job-classes, the second moment of the equilibrium waiting time for closed systems as well as for open systems. Both open and closed systems have a CPU operating under the processor-sharing (‘time-slicing') discipline in which service-time requirements may depend on job-class. The closed system also includes a bank of terminals grouped according to job-classes, with the class structure allowing distinctions in the user's behavior in the terminal. In the contrasting open system, the job streams submitted to the CPU are Poisson with rate parameters dependent on job-classes.Our results are exact for the open system and, for the closed system, in the form of an asymptotic series in inverse powers of a parameter N. In fact, the result for open networks is simply the first term in the asymptotic series. For larger closed systems, the parameter N is larger and thus fewer terms of the series need be computed to achieve a desired degree of accuracy. The complexity of the calculations for the asymptotic expansions is polynomial in number of classes and, importantly, independent of the class populations. Only the results on the single-class systems, closed and open, were previously known.

scholarly journals Ammonia and Phosphorous removal in municipal wastewater treatment plant with extended aeration.

2013 ◽  
Vol 1 (1) ◽  
pp. 47-53
Keyword(s):  
Activated Sludge ◽  
Municipal Wastewater ◽  
Combined Treatment ◽  
Cell Formation ◽  
Treatment Plant ◽  
Mean Value ◽  
Aeration Tank ◽  
Municipal Wastewater Treatment ◽  
Denitrification Kinetics ◽  
The Mean

Samples were taken from Metamorphosis/Attica combined treatment plant for municipal wastewater and septage, which treats about 12000 m3 d-1 of municipal wastewater and 8000 m3 d-1 of septage, and analyzed for solids, COD, ammonia, nitrate, orthophosphate, polyphosphate and total phosphorus. Ammonia is almost completely eliminated within the plant. Orthophosphates show a removal of about 28%, while total phosphorus is removed by about 15%. The mean value of the ratio (phosphorus eliminated)/(COD eliminated) in mg g-1 is 8. Assuming suspended-growth nitrification and denitrification kinetics as proposed in literature, the percentage of nitrifiers in the activated sludge population is estimated at 1.1%. Assuming that phosphorus removal in the aeration tank is proportional to cell formation, which in turn is proportional to substrate elimination, the phosphorus content of the activated sludge is estimated at 0.031 gP (gVSS)-1.

Effects of Cr3+ on Chromium Adsorption of SBR Activated Sludge System under Different Chromium Loads and Different Initial SVIs

2013 ◽  
Vol 838-841 ◽  
pp. 2735-2738
Author(s):  
Guo Ri Dong ◽  
Jian She Liu
Keyword(s):  
Activated Sludge ◽  
Toxic Effect ◽  
Load Level ◽  
Adsorption Rate ◽  
Tolerance Range ◽  
Chromium Ion ◽  
Activated Sludge System ◽  
Process System ◽  
Chromium Adsorption

In allusion to Cr3+s toxic effect on activated sludge in SBR process system, by determination of the Cr3+adsorption rate, mlvss under different initial SVIs and different chromium loads, the Cr3+s toxic effect on activated sludge and the Cr3+s influence on chromium adsorption of activated sludge were studied. The research shows that within tolerance range, the activated sludge of SBR system can adsorb 60% chromium ion within 10min reaction. Moreover, with the increase of chromium load, the final chromium remnant rate decreases; within tolerance range, the increase of chromium load contributes to the adsorption of chromium ion and the acceleration is subject to initial SVI. Within non-tolerance range, the ability of SBR process system to adsorb chromium decreases greatly; The whole curve of chromium remnant rate shifts upward with the increase of chromium load level. Within 10mins reaction, the adsorption rate of chromium is about 50% under best condition.

A Pilot-Plant Study to Salvage a Full-Scale Treatment Plant

1992 ◽  
Vol 25 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Y. H. Yu ◽  
K. S. L. Lo
Keyword(s):  
Activated Sludge ◽  
Pilot Plant ◽  
Settling Tank ◽  
Treatment Plant ◽  
Chemical Precipitation ◽  
Aeration Tank ◽  
Treatment Unit ◽  
Activated Sludge System ◽  
High Metal ◽  
Pilot Plant Study

Kwei-Shan Wastewater Treatment Plant is the second oldest treatment plant ever designed and operated in Taiwan, to treat the combined industrial wastewater collected from various kinds of factories located in Kwei-Shan Industrial Park. From the beginning the treatment plant has been suffering from influents containing a spectrum of various pollutants harmful to the activated-sludge system of the plant. Extreme pH measurements (1.4-12.0), jumpy organic contents (COD 104-6660 mg/l), high metal concentrations (Cu up to 19 mg/l, Zn up to 37 mg/l), and high grease concentrations (up to 470 mg/l) were unbelievably found in tne plant influents, while a traditional plain primary settling tank was the only shield to protect the aeration basin from damage. In a dilemma like this, a pilot-plant study was undertaken to save the efficiency of the existing biological treatment plant from those various fatal influent constituents. A flow equalization tank and a chemical treatment unit were first built to damp out pH and COD variations, Ca(OH)2 was added to remove the toxic metals as well as part of the grease. The effluent after the above treatment was then neutralized and sent to the downscaled activated sludge system containing one aeration tank and one settling tank. The results indicated that equalization and chemical precipitation by using the existing space of the roughing filter and the sedimentation tank could produce much safer influents to the activated sludge system.

Asymptotic expansions of moments of the waiting time in closed and open processor-sharing systems with multiple job classes

1983 ◽  
Vol 15 (04) ◽  
pp. 813-839 ◽  
Author(s):  
Debasis Mitra ◽  
J. A. Morrison
Keyword(s):  
Waiting Time ◽  
Open System ◽  
Closed System ◽  
Asymptotic Expansions ◽  
Queueing Networks ◽  
Open Systems ◽  
Asymptotic Series ◽  
Processor Sharing ◽  
Single Class ◽  
Closed Systems

We present new results based on novel techniques for the problem of characterizing the waiting-time distribution in a class of queueing networks. We give effective methods for computing, for each of possibly several job-classes, the second moment of the equilibrium waiting time for closed systems as well as for open systems. Both open and closed systems have a CPU operating under the processor-sharing (‘time-slicing') discipline in which service-time requirements may depend on job-class. The closed system also includes a bank of terminals grouped according to job-classes, with the class structure allowing distinctions in the user's behavior in the terminal. In the contrasting open system, the job streams submitted to the CPU are Poisson with rate parameters dependent on job-classes. Our results are exact for the open system and, for the closed system, in the form of an asymptotic series in inverse powers of a parameter N. In fact, the result for open networks is simply the first term in the asymptotic series. For larger closed systems, the parameter N is larger and thus fewer terms of the series need be computed to achieve a desired degree of accuracy. The complexity of the calculations for the asymptotic expansions is polynomial in number of classes and, importantly, independent of the class populations. Only the results on the single-class systems, closed and open, were previously known.

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