Bacteriological Quality of Reclaimed Wastewater Used for Irrigation of Public Parks in the United Arab Emirates

Abstract

Bacteriological quality of reclaimed wastewater used for irrigation of thirty public parks located in Dubai and Sharjah was evaluated. Bacterial contaminants (Escherichia coli, Salmonella, Shigella and Enterobacter aerogenes) were tested by membrane filtration technique using Bismuth Sulphite Agar (BSA) and Violet Red Bile Agar (VRBA) media. The results showed the presence of Salmonella, Shigella, E. coli, Entereobacter aerogenes and other unidentified bacterial species on various selective media with different occurrence rates. The most common type of bacteria observed on the BSA media were Shigella (63%), E. coli (30%), Salmonella (10%) and a large percentage of unidentified bacteria (97%). Whereas on VRBA media the most common bacteria detected were E. coli (83%), unidentified bacteria (76%) followed by Enterobacter aerogenes (70%). The overall results obtained in the present study demonstrated that only 40% of the reclaimed wastewater samples examined complied with the local and widely accepted international standards of less than 1000 fecal coliforms/100mL for unrestricted irrigation. Further studies are recommended to determine the survival rate of Salmonella and other coliform group bacteria in the soil irrigated by reclaimed wastewater. In addition, detailed research should be conducted to establish the identity of Salmonella, Shigella (up to the species and sub-species level) and other unidentified bacteria which were detected in most of the reclaimed water samples.