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.

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.

Wastewater: Solids retention time control in wastewater treatment

2014 ◽  
Vol 51 (3) ◽  
pp. 12-17 ◽  
Author(s):  
Robert Smith ◽  
Sarah Elger ◽  
Scott Mleziva
Keyword(s):  
Wastewater Treatment ◽  
Retention Time ◽  
Time Control ◽  
Solids Retention Time ◽  
Solids Retention

Bulking and Foaming Organism Control at Phoenix, AZ WWTP

1992 ◽  
Vol 26 (3-4) ◽  
pp. 461-472 ◽  
Author(s):  
O. E. Albertson ◽  
P. Hendricks
Keyword(s):  
Wastewater Treatment ◽  
Nitrogen Removal ◽  
Retention Time ◽  
Oxygen Transfer ◽  
Average Rate ◽  
Oxygen Transfer Efficiency ◽  
Solids Retention ◽  
Total Nitrogen Removal ◽  
The Cost ◽  
The City

A 1630 L/s activated sludge plant at Phoenix was limited to an average rate of 1050 L/s and operated, at 400-600 mg/L MLSS and 0.8-1.3 day solids retention time (SRT) due to bulking sludge and limited clarification capacity. Higher SRTs also produced uncontrolled Nocardia foaming and low dissolved oxygen due to partial nitrification. The City retained the services of a team of consultants to resolve these problems as well as to upgrade the plant to provide nitrification and total nitrogen removal. An anoxic selector design was implemented within the existing basin and the clarifiers were modified to improve inlet design and sludge transport. The modified advanced wastewater treatment (AWT) plant operating at 1450 L/s has averaged an effluent of 7.6 mg/L BOD5, 8.2 mg/L TSS, 1.3 mg/L NH4N, 4.1 mg/L NO3N and 2.9 mg/L TP. Oxygen transfer efficiency has increased about 80% in the nitrification-denitrification (NdeN) mode. The cost of modification/upgrading to AWT was approximately $730,000 and a 400 L/s increase in hydraulic capacity was realized. Upgrading costs were $5.63/m3 ($0.02/gal.)

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