Inactivation of Geobacillus stearothermophilus spores by alkaline hydrolysis applied to medical waste treatment

Abstract

Although alkaline hydrolysis treatment emerges as an alternative disinfection/sterilization method for medical waste, information on its effects on the inactivation of biological indicators is scarce. The effects of alkaline treatment on the resistance of Geobacillus stearothermophilus spores were investigated and the influence of temperature (80 o C, 100 o C and 110 o C) and NaOH concentration was evaluated. In addition, spore inactivation in the presence of animal tissues and discarded medical components, used as surrogate of medical waste, was also assessed. were approximately 3 times lower than those at 100 o C (8.8e1.6 min). Independent of the presence of animal tissues and discarded medical components, 6 log10 reduction times varied between 66 and 5 min at 100 o C-0.1 M NaOH and 110 o C-1 M NaOH, respectively. The alkaline treatment may be used in future as a disinfection or sterilization alternative method for contaminated waste.

Characteristics of effluents from healthcare waste treatment with alkaline hydrolysis

“…These results were similar to those obtained in others studies (Kaye et al 1998;Thacker 2004;Pinho et al 2015b). According to previous studies, the solid fraction has no infectious character (Kaye et al 1998;Franke-Whittle & Insam 2013;Pinho et al 2015a) and, thus, can be further disposed of in municipal solid waste landfills. Nevertheless, the alkaline hydrolysis treatment generates an effluent with high pH, and depending on the type of wastes treated, it is expected to contain different types and concentrations of organic compounds.…”

“…; Franke‐Whittle & Insam ; Pinho et al . ) and, thus, can be further disposed of in municipal solid waste landfills.…”

“…The selection of these conditions, that is temperature, NaOH concentration and time of contact, was based on previous studies (Pinho et al . ) showing to be possible the complete inactivation of Geobacillus stearothermophillus and the complete destruction of the AT.…”

“…; Pinho et al . ) have been proved. Thereby, this treatment has been shown to have significant advantages when compared to other treatments, because it sterilizes and destroys at once and reduces the total waste volume.…”

“…In this context, alkaline hydrolysis may be an alternative treatment process for HCW in some countries (Health Care Without Harm 2004). The successful decontamination of the prion (Murphy et al 2009;McDonnell et al 2013) and inactivation of potentially infectious agents including virus, bacteria, fungi and protozoa (Kaye et al 1998;Neyens et al 2003;Murphy et al 2007;Dixon et al 2012;Pinho et al 2015a) have been proved. Thereby, this treatment has been shown to have significant advantages when compared to other treatments, because it sterilizes and destroys at once and reduces the total waste volume.…”