Fate of tetracycline resistant bacteria as a function of activated sludge process organic loading and growth rate

2007 ◽  
Vol 55 (1-2) ◽  
pp. 291-297 ◽  
Author(s):  
S. Kim ◽  
J.N. Jensen ◽  
D.S. Aga ◽  
A.S. Weber
Keyword(s):  
Growth Rate ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Tetracycline Resistance ◽  
Organic Loading Rate ◽  
Resistant Bacteria ◽  
Activated Sludge Process ◽  
Organic Loading ◽  
Specific Growth Rates ◽  
Evaluation Parameters

The objective of this research was to elucidate the fate of tetracycline resistant bacteria as a function of activated sludge organic loading rate and growth rate. Techniques employed to evaluate the effect of these factors on the fate of tetracycline resistant bacteria were: (1) resistant bacteria concentrations in the SBR biomass; (2) production of tetracycline resistant bacteria as measured by a combination of effluent efflux and intentional solids wasting; (3) net specific growth rates as determined by an SBR population balance; and (4) percentage of resistance as determined by normalising resistant concentrations to total concentrations. Based on these evaluation parameters, increases in organic loading and growth rate both resulted in amplification of tetracycline resistance. These trends were observed for activated sludge reactors loaded with typical municipal background tetracycline concentrations (∼1 μg/L) and those receiving influent augmented with 250 μg/L tetracycline. Accordingly, biological wastewater treatment plants, such as the activated sludge process, may be significant sources of antibiotic resistance to the environment.

Effect of loading rate and intermittent aeration cycle on nitrogen removal in membrane separation activated sludge process

2002 ◽  
Vol 46 (8) ◽  
pp. 119-126 ◽  
Author(s):  
H. Nagaoka ◽  
C. Kudo
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Loading Rate ◽  
Membrane Separation ◽  
Organic Loading Rate ◽  
Aeration Tank ◽  
Activated Sludge Process ◽  
Intermittent Aeration ◽  
Organic Loading ◽  
Mixed Liquor

The performance of the submerged membrane separation activated sludge process with intermittent aeration was investigated in a laboratory scale experiment by changing organic loading rate and intermittent aeration cycle. A rectangular PVC tank was used as an aeration tank, in which a flat-sheet type Micro-Filtration membrane made of poly-olefin with a pore size of 0.2 mm was submerged. Organic loading rate to the reactor was set at 0.3 and 0.8 g-TOC/L/day. C/N ratio in the feed was set at around 5.0 for every condition. Aeration cycle was changed from 10 min-10 min (aeration - stop) to 120 min-120 min in different organic loading conditions. Flux through the membrane was set at 0.25 m/day. Membrane fouling proceeded rapidly in 0.8 g-TOC/L/day conditions. However, when organic loading rate was 0.3 g-TOC/L/day, bacterial metabolic substances were degraded rapidly compared to the production, thereby decreasing viscosity in mixed liquor. Nitrogen removal rate was between 60% and 80% for 0.8 g-TOC/L/day loading, and between 50% and 65% for 0.3 g-TOC/L/day loading. And the nitrogen removal was highest in 40 min to 60 min aeration cycle conditions. Too short aeration cycle did not result in sufficiently long anoxic periods for denitrification while too long a cycle resulted in unnecessary anaerobic periods after depletion of nitrate. Intermittent aeration was effective also for decreasing viscosity in mixed liquor.

Interpretation of Experimental Data with Regard to the Activated Sludge Model No.1 and Calibration of the Model for Municipal Wastewater Treatment Plants

1992 ◽  
Vol 25 (6) ◽  
pp. 167-183 ◽  
Author(s):  
H. Siegrist ◽  
M. Tschui
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Municipal Wastewater Treatment ◽  
Activated Sludge Model

The wastewater of the municipal treatment plants Zürich-Werdhölzli (350000 population equivalents), Zürich-Glatt (110000), and Wattwil (20000) have been characterized with regard to the activated sludge model Nr.1 of the IAWPRC task group. Zürich-Glatt and Wattwil are partly nitrifying treatment plants and Zürich-Werdhölzli is fully nitrifying. The mixing characteristics of the aeration tanks at Werdhölzli and Glatt were determined with sodium bromide as a tracer. The experimental data were used to calibrate hydrolysis, heterotrophic growth and nitrification. Problems arising by calibrating hydrolysis of the paniculate material and by measuring oxygen consumption of heterotrophic and nitrifying microorganisms are discussed. For hydrolysis the experimental data indicate first-order kinetics. For nitrification a maximum growth rate of 0.40±0.07 d−1, corresponding to an observed growth rate of 0.26±0.04 d−1 was calculated at 10°C. The half velocity constant found for 12 and 20°C was 2 mg NH4-N/l. The calibrated model was verified with experimental dam of me Zürich-Werdhölzli treatment plant during ammonia shock load.

Controlling Activated Sludge Process Using EFOR

1992 ◽  
Vol 26 (3-4) ◽  
pp. 783-790
Author(s):  
J. Pedersen
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Simulation Program ◽  
Activated Sludge Process ◽  
Activated Sludge Model

A newly developed simulation program, based on the Activated Sludge Model No. 1, has been investigated for its controlling abilities. The program is capable of simulating most of the control types which have been applied to wastewater treatment plants. The program was tested on a nitrifying and a denitrifying treatment plant. The results showed that the model makes good simulations of the applied controls.

Application of cigarette filter rods as biofilm carrier in an integrated fixed-film activated sludge reactor

2013 ◽  
Vol 67 (8) ◽  
pp. 1793-1801 ◽  
Author(s):  
Ahmad Sabzali ◽  
Mahnaz Nikaeen ◽  
Bijan Bina
Keyword(s):  
Activated Sludge ◽  
Loading Rate ◽  
Oxygen Demand ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Cigarette Filter ◽  
Biofilm Reactors ◽  
Biofilm Carrier ◽  
Fixed Film ◽  
Activated Sludge Reactor

Bio-carriers are an important component of integrated fixed-film activated sludge (IFAS) processes. In this study, the capability of cigarette filter rods (CFRs) as a bio-carrier in IFAS processes was evaluated. Two similar laboratory-scale IFAS systems were operated over a 4-month period using Kaldnes-K3 and CFRs as IFAS media. The process performance was studied by using chemical oxygen demand (COD). The organic loading rate was in the range 0.5–2.8 kgCOD/(m3·d). The COD average removal efficiencies were 89.3 and 93.9% for Kaldnes-K3 (reactor A) and cigarette filters (reactor B), respectively. The results demonstrate that the performance of the IFAS reactor containing CFRs was comparable to the reactor using Kaldnes. The CFRs, which have a high porous surface area and entrapment ability for microbial cells, could be successfully used in biofilm reactors as a bio-carrier.

Iterative design of a nitrate controller using an external carbon source in an activated sludge process

1998 ◽  
Vol 37 (12) ◽  
pp. 95-102 ◽  
Author(s):  
Pericles R. Barros ◽  
Bengt Carlsson
Keyword(s):  
Carbon Source ◽  
Activated Sludge ◽  
High Performance ◽  
Controller Design ◽  
Wastewater Treatment Plants ◽  
Design Procedure ◽  
Pole Placement ◽  
Activated Sludge Process ◽  
Suggested Approach ◽  
External Carbon Source

More stringent effluent and cost requirements are increasing the need for better control of wastewater treatment plants. In an activated sludge process, the nitrogen removal efficiency may be improved by adding an external carbon source. In this paper, automatic control of the nitrate level by regulating external carbon flow is discussed. More specifically, an iterative tuning procedure for the controller is outlined. Iterative controller design schemes aim at tuning high performance controllers of low complexity using closed loop data. The basic strategy used in this paper is an iterative pole placement controller design procedure. The suggested approach is compared with conventional design in a simulation study.

Removal Characteristics of Human Antibiotics during Wastewater Treatment in Japan

2006 ◽  
Vol 1 (3) ◽  
Author(s):  
Y. Kobayashi ◽  
M. Yasojima ◽  
K. Komori ◽  
Y. Suzuki ◽  
H. Tanaka
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Treatment Method ◽  
Batch Experiment ◽  
Aqueous Environment ◽  
Activated Sludge Process ◽  
Conventional Activated Sludge ◽  
Conventional Activated Sludge Process

Pharmaceuticals resident in sewage and in the aqueous environment has begun to attract attention. The objectives of this research were to clarify the behaviour of selected human antibiotics in wastewater treatment plants, namely levofloxacin (LVFX), clarithromycin (CAM) and azithromycin (AZM) which are much used in Japan. The concentrations in raw influent of LVFX, CAM, AZM were respectively 425~981ng/L, 340~573ng/L, ND(<190 ng/L)~371ng/L. The averages of removal ratio were about 50 % for all selected antibiotics. It was suggested that selected antibiotics was not too much removed in the conventional creature processing like the conventional activated sludge process. The remarkable removals in activated sludge tank using high class treatment method were confirmed about all selected antibiotics. The rise of the concentrations of CAM and AZM was confirmed after the addition of chemical coagulants in one wastewater treatment plant. From the result of batch experiment with activated sludge, it was suggested that LVFX and AZM were removed from water mainly by the absorption to activated sludge. Also, in batch experiment with chemical coagulants, it was suggested that LVFX was removed from water and CAM, AZM were eluted a little in water by adding sulphuric acid band.

Anaerobic co-digestion of sludge with other organic wastes and phosphorus reclamation in wastewater treatment plants for biological nutrients removal

2006 ◽  
Vol 53 (12) ◽  
pp. 177-186 ◽  
Author(s):  
D. Bolzonella ◽  
P. Pavan ◽  
P. Battistoni ◽  
F. Cecchi
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Biogas Production ◽  
Organic Wastes ◽  
Organic Loading Rate ◽  
Waste Activated Sludge ◽  
Nutrients Removal ◽  
Nitrogen And Phosphorus ◽  
Biological Nutrients Removal

This paper deals with the performances obtained in full scale anaerobic digesters co-digesting waste activated sludge from biological nutrients removal wastewater treatment plants, together with different types of organic wastes (solid and liquid). Results showed that the biogas production can be increased from 4,000 to some 18,000 m3 per month when treating some 3–5 tons per day of organic municipal solid waste together with waste activated sludge. On the other hand, the specific biogas production was improved, passing from 0.3 to 0.5 m3 per kgVS fed the reactor, when treating liquid effluents from cheese factories. The addition of the co-substrates gave minimal increases in the organic loading rate while the hydraulic retention time remained constant. Further, the potentiality of the struvite crystallisation process for treating anaerobic supernatant rich in nitrogen and phosphorus was studied: 80% removal of phosphorus was observed in all the tested conditions. In conclusion, a possible layout is proposed for designing or up-grading wastewater treatment plants for biological nutrients removal process.

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