Prevalence of Escherichia coli in surface waters of Southeast Asian cities

Surface water samples were collected from rivers which fed into large urban areas within Vietnam, Indonesia, Cambodia, and Thailand and were processed to enumerate Escherichia coli. Selected isolates were further characterized using PCR to detect the presence of specific virulence genes. Analyzing the four countries together, the approximate mean cfu/100 ml for E. coli counts in the dry season were log 4.3, while counts in the wet season were log 2.8. Of the 564 E. coli isolates screened for the presence of pathogenic genes, 3.9 % possessed at least one virulence gene. The most common pathogenic types found were Shiga toxin-producing E. coli isolates. These results reinforce the importance of monitoring urban surface waters for fecal contamination, that E. coli in these water environments may serve as opportunistic pathogens, and may help in determining the impact water usage from these rivers have on the public health of urban populations in Southeast Asia.     

Bioregeneration by mixed microorganisms of granular activated carbon loaded with a mixture of phenols

The role of mixed microorganisms on the bioregeneration of granular activated carbon (GAC) loaded with a mixture of phenol and 2,4-dichlorophenol was investigated. In a biological activated-carbon, sequencing batch reactor (BAC-SBR), bioregeneration efficiency for phenol was enhanced from 39 to 48% and for 2,4-dichlorophenol from 38 to 43% by increasing solid retention time from 3 to 8 days. Prolonging the sludge retention time induced both progressive desorption of adsorbates due to biodegradation in the bulk solution and direct assimilation of adsorbates on GAC by attached microorganisms.