Solids retention time-dependent phototrophic growth and microbial population dynamics in wastewater treatment

2013 ◽  
Author(s):  
Qi Shen
Keyword(s):  
Population Dynamics ◽  
Wastewater Treatment ◽  
Retention Time ◽  
Microbial Population ◽  
Time Dependent ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Microbial Population Dynamics ◽  
Phototrophic Growth

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.

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