Die-off of E. coli as fecal indicator organism on different surfaces after urban floods

• Published in: Journal of environmental management 2019-11, Vol.250, p.109516-109516, Article 109516
• Main Authors: Scoullos, Iosif Marios, Lopez Vazquez, Carlos M., van de Vossenberg, Jack, Brdjanovic, Damir
• Format: Article
• Language: English
• Subjects: Solar inactivation; Surfaces; Urban floods; Water-borne diseases
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2019.109516

A better understanding of the effects of different urban and recreational surfaces on the die-off of water-borne pathogens that can cause infections after urban floods if released from surcharged combined sewers and other sources of fecal contamination is needed. The die-off of fecal indicator Escherichia coli was studied under controlled exposure to simulated sunlight on a range of different surfaces found in urban environments: gravel, sand, asphalt, pavement blocks, concrete, playground rubber tiles and grass, using glass as control. The surfaces were inoculated with artificial flooding water containing 105 colony forming units (CFU) of E. coli per mL and sampled periodically using the sterile cotton swab technique, after lowering the water level. The results show that dark inactivation was not statistically significant for any surface, suggesting that chemical composition and pH (varying between 6.5 ± 0.8 and 9.2 ± 0.4) did not affect the die-off rates. The highest light-induced die-off rates for E. coli after the floodwater recession, observed on rubber (>3.46 h−1) and asphalt (2.7 h−1), were attributed to temperature stress and loss of surface moisture. [Display omitted] •For E. coli die-off the effect of sunlight on soil moisture was critical.•High temperatures on dark surfaces are inducing loss of moisture and E. coli die-off.•The close to neutral pH of weathered surfaces had a minor contribution on die-off.