Determination of the lower limits of antibiotic biodegradation and the fate of antibiotic resistant genes in activated sludge: Both nitrifying bacteria and heterotrophic bacteria matter

Although membrane bioreactors have attracted increasing attention in recent years, little research has been undertaken on the influence of the membrane separation on the microbial community composition. This paper compares the startup behaviour and the performance of the subsequent eight months of a membrane bioreactor with a conventional activated sludge pilot plant. Both plants were operated in parallel at the same sludge age and treated the same domestic wastewater. The identification of the nitrifying community composition using fluorescent in situ hybridization revealed only minor differences between the two reactors for both ammonia-oxidizing bacteria and nitrite-oxidizing bacteria. Accordingly, both systems exhibited the same maximum nitrification rates. Confocal laser scanning microscopy showed that the aggregates formed by nitrifying bacteria were located mostly in the inner part of the flocs and were overgrown by heterotrophic bacteria. It is concluded that the membrane separation itself does affect neither the nitrifying community composition nor the nitrification performance. However, impacts on kinetic parameters are emphasized.

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Respirometry for determination of the influents SS-concentration

Water Science & Technology ◽

10.2166/wst.1996.0031 ◽

1996 ◽

Vol 33 (1) ◽

pp. 311-323 ◽

Cited By ~ 2

Author(s):

A. Witteborg ◽

A. van der Last ◽

R. Hamming ◽

I. Hemmers

Keyword(s):

Experimental Design ◽

Activated Sludge ◽

Substrate Concentration ◽

Full Scale ◽

Activated Sludge Process ◽

Respiration Rates ◽

On Line ◽

Large Measurement ◽

Set Up

A method is presented for determining influent readily biodegradable substrate concentration (SS). The method is based on three different respiration rates, which can be measured with a continuous respiration meter which is operated in a cyclic way. Within the respiration meter nitrification is inhibited through the addition of ATU. Simulations were used to develop the respirometry set-up and decide upon the experimental design. The method was tested as part of a large measurement programme executed at a full-scale plant. The proposed respirometry set-up has been shown to be suitable for a semi-on-line determination of an influent SS which is fully based on the IAWQ #1 vision of the activated sludge process. The YH and the KS play a major role in the principle, and should be measured directly from the process.

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Quantification of the kinetic differences between communities isolated from completely mixed activated sludge systems operated with or without a selector using a novel respirometric method

Water Science & Technology ◽

10.2166/wst.1994.0567 ◽

1994 ◽

Vol 30 (11) ◽

pp. 255-261 ◽

Cited By ~ 5

Author(s):

Barth F. Smets ◽

Timothy G. Ellis ◽

Stephanie Brau ◽

Richard W. Sanders ◽

C. P. Leslie Grady

Keyword(s):

Oxygen Consumption ◽

Activated Sludge ◽

Physiological Changes ◽

Biodegradation Kinetics ◽

Substrate Removal ◽

Biomass Yields ◽

Selection For ◽

Single Oxygen ◽

Activated Sludge Systems

This study quantified the kinetic differences in microbial communities isolated from completely mixed activated sludge (CMAS) systems that were operated either with or without an aerobic selector preceding the main reactor. A new respirometric method was employed that allowed the determination of biodegradation kinetics from single oxygen consumption curves, thereby minimizing physiological changes to the examined communities during the assay. Results indicated that increased values for Ks and μmax for acetate, phenol, and 4-chlorophenol degradation were measured in the CMAS system operated with a selector. The biomass yields on acetate, phenol, and 4-chlorophenol were very similar in both systems. These findings indicate that the operation of CMAS systems with aerobic selectors may result in the selection for degrading populations with higher Ks and μmax values for both biogenic and xenobiotic organic compounds, and that substrate storage in the selector only partially contributes to increased substrate removal rates.

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Operational Determination of the Activated Sludge Process Using Neural Networks

Water Science & Technology ◽

10.2166/wst.1992.0762 ◽

1992 ◽

Vol 26 (9-11) ◽

pp. 2461-2464 ◽

Cited By ~ 2

Author(s):

R. D. Tyagi ◽

Y. G. Du

Keyword(s):

Neural Network ◽

Neural Networks ◽

Steady State ◽

Activated Sludge ◽

Feedforward Neural Network ◽

Training Data ◽

Activated Sludge Process

A steady-statemathematical model of an activated sludgeprocess with a secondary settler was developed. With a limited number of training data samples obtained from the simulation at steady state, a feedforward neural network was established which exhibits an excellent capability for the operational prediction and determination.

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Distribution of nitrifying bacteria in a shallow stream

Water Science & Technology ◽

10.2166/wst.1997.0660 ◽

1997 ◽

Vol 36 (8-9) ◽

pp. 161-166 ◽

Cited By ~ 1

Author(s):

Ivana Jancarkova ◽

Tove A. Larsen ◽

Willi Gujer

Keyword(s):

Field Experiments ◽

Heterotrophic Bacteria ◽

Pollution Source ◽

Nitrifying Bacteria ◽

Channel Water ◽

River Bed ◽

Hydraulic Conditions ◽

Major Floods ◽

Shallow Stream ◽

Stream Bed

A project investigating the dynamics of self-purification processes in a shallow stream is carried out. Effects of the concentration gradient due to the distance to the pollution source, of hydraulic conditions in the river bed and of storm floods on the distribution of nitrifying bacteria were studied with the help of laboratory and field experiments. Nitrifiers density on the surface of the stream bed increased rapidly up to a distance of 300 m from the WWTP indicating possible competition of the nitrifiers with the heterotrophic bacteria close to the WWTP. Afterwards a slight decrease in the downstream direction was observed. In vertical profiles, higher bacterial densities were found at sites with rapid infiltration of channel water to the stream bed than at sites with no exchange between channel water and stream bed water or where stream bed water exfiltrated. A major flood event scoured the nitrifiers nearly totally from the surface of the river bed. Major floods belong so to the most dominant processes controlling self-purification in shallow streams. Minor floods, however, don't scour bacteria in the depth of the stream bed that could then be important for the self-purification processes.

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A Rapid Method for Determination of Buprenorphine and Norbuprenorphine in Urine by UPLC-MS/MS

Current Pharmaceutical Analysis ◽

10.2174/1573412916999200627010536 ◽

2020 ◽

Vol 16 ◽

Author(s):

Aykut Kul ◽

Murat Ozdemir ◽

Selma Ozilhan ◽

Olcay Sagirli

Keyword(s):

Forensic Science ◽

Rapid Method ◽

Proficiency Testing ◽

Mass Spectrometer ◽

Illicit Market ◽

Analysis Methods ◽

Accuracy And Precision ◽

Lower Limits

Background: Buprenorphine is quite common in the illicit market. Buprenorphine-containing drugs abuse is frequently encountered in patients. The analysis methods used to determine the abuse of buprenorphine and norbuprenorphine are important for forensic science. Buprenorphine is metabolized to norbuprenorphine by the liver. Objective: Therefore, the determination of buprenorphine and norbuprenorphine in urine is one of the methods to determine the abuse of buprenorphine. Methods: In this study, we have developed a precise, simple, and rapid ultra-performance liquid chromatographytandem mass spectrometer method for the determination of buprenorphine and norbuprenorphine simultaneously. Results: The developed method was validated in terms of selectivity and linearity, which was in the range of 9–1800 ng/mL for both buprenorphine and norbuprenorphine. The intra-assay and inter-assay accuracy and precision were found within acceptable limits of the EMA guideline. Lower limits of quantitation were 9 ng/mL for both buprenorphine and norbuprenorphine. Conclusion: The developed method was successfully applied for the determination of both analytes in the proficiency testing samples.

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