title: Ultrasound-induced inactivation of gram-negative and gram-positive bacteria in secondary treated municipal wastewater.
abstract: The effect of 24kHz, high energy ultrasound in the presence and absence of titanium dioxide particles on the destruction of different bacteria groups was studied. Applying a total of 1500W/L for 60min (this corresponds to 5400kJ/L specific nominal energy), the mean destruction of gram-negative bacteria such as total coliforms, faecal coliforms and Pseudomonas spp. was 99.5%, 99.2% and 99.7%, respectively. More recalcitrant to sonolytic inactivation were the gram-positive bacteria Clostridium perfringens and faecal streptococci with a mean removal of 66% and 84%, respectively. The presence of 5g/L TiO(2) generally enhanced the destruction of gram-negative bacteria, yielding three to five logs reduction. On the other hand, the relatively weak sonochemical inactivation of gram-positive bacteria was only slightly affected by the presence of solid particles. Inactivation was found to follow first-order kinetics regarding bacteria population and was not affected significantly by the wastewater quality. Ultrasound irradiation at 4000kJ/L specific nominal energy and in the presence of 5g/L TiO(2) achieved less than 10(3) CFU/100mL total coliforms, thus meeting USEPA quality standards for wastewater reuse.
authors.affiliation: School of Agricultural Technology, Technological Educational Institute of Crete, Stavromenos, GR-71004 Heraklion, Greece.
authors.forename: S
authors.initials: S
authors.lastname: Drakopoulou
authors.forename: S
authors.initials: S
authors.lastname: Terzakis
authors.forename: M S
authors.initials: MS
authors.lastname: Fountoulakis
authors.forename: D
authors.initials: D
authors.lastname: Mantzavinos
authors.forename: T
authors.initials: T
authors.lastname: Manios
mesh_terms: D006090:Gram-Negative Bacteria; D006094:Gram-Positive Bacteria; D007700:Kinetics; D050296:Microbial Viability; D014465:Ultrasonics; D014865:Waste Disposal, Fluid / Q000379:methods*; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*