Solids retention time, influent antibiotic concentrations, and temperature as selective pressures for antibiotic resistance in activated sludge systems

2017 ◽  
Vol 3 (5) ◽  
pp. 883-896 ◽  
Author(s):  
Majid Neyestani ◽  
Eric Dickenson ◽  
Jean McLain ◽  
Victoria Obergh ◽  
Oscar Quinones ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Retention Time ◽  
Biological Wastewater Treatment ◽  
Selective Pressures ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Activated Sludge Systems

This paper evaluates changes in antibiotic resistance during biological wastewater treatment.

Nitrogen removal in activated sludge systems including denitrification in secondary clarifiers

1994 ◽  
Vol 30 (6) ◽  
pp. 101-111 ◽  
Author(s):  
H. Siegrist ◽  
W. Gujer
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Retention Time ◽  
Secondary Clarifier ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Activated Sludge Systems

Denitrification in the secondary clarifier can contribute substantially to the nitrogen removal of activated sludge systems. This is illustrated on two treatment plants with different secondary clarifier systems. A model to estimate denitrification capacity and to design activated sludge systems for nitrogen removal is developed and verified with data from two treatment plants. The model includes denitrification in the secondary clarifier, wastewater composition (soluble readily biodegradable COD, particulate degradable COD), oxygen input into the anoxic volume, temperature, and solids retention time (SRT). The influence of aerated grit chambers and primary sedimentation on denitrification is discussed.

Electron density-based transformation of trimethoprim during biological wastewater treatment

2012 ◽  
Vol 65 (4) ◽  
pp. 689-696 ◽  
Author(s):  
Taewoo Yi ◽  
William Barr ◽  
W. F. Harper
Keyword(s):  
Wastewater Treatment ◽  
Electron Density ◽  
Retention Time ◽  
Biological Wastewater Treatment ◽  
Hydroxylation Reaction ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Biological Transformation

This research investigated the biological transformation of trimethoprim (TMP). Partial TMP removal was observed in the presence of ammonia and toluene, and increasing the solids retention time from 20 days to 60 days improved TMP removal in both the nitrifying and heterotrophic bioreactors. Two TMP-related metabolites were identified, the first (5-(3,4,5-trimethoxybenzyl) pyrimidine-2,4-diamine, 5-hydroxyl) showing that a hydroxylation reaction took place, and the second (5-(1-carboxyl, 1-methoxy, 5-methoxy 1-,4-pentene) pyrimidine-2,4-diamine, 5-hydroxyl) showing that the trimethoxybenzyl ring was cleaved. This research is the first that we are aware of to report these two TMP-related byproducts. TMP metabolites show that initiating reactions take place where the electron density is highest, and that these initiating reactions shift the electron density of TMP, likely affecting the course of transformation.

scholarly journals The influence of solids retention time on activated sludge bioflocculation and membrane fouling in a membrane bioreactor (MBR)

2012 ◽  
Vol 401-402 ◽  
pp. 48-55 ◽  
Author(s):  
R. Van den Broeck ◽  
J. Van Dierdonck ◽  
P. Nijskens ◽  
C. Dotremont ◽  
P. Krzeminski ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Solids Retention Time ◽  
Solids Retention
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