Application of slightly acidic electrolyzed water (SAEW) for surface disinfection in waste sorting and sewage treatment plants: a pilot study

TL;DR

This study tests slightly acidic electrolyzed water (SAEW) as a disinfectant in waste and sewage plants, finding it effective against bacteria but less so against fungi compared to alcohol-based disinfectants.

Contribution

Demonstrates SAEW's potential as an alternative disinfectant in organic dust-contaminated environments, with concentration-dependent effectiveness.

Findings

SAEW at 300 mg/l achieved the highest bacterial log reduction values (LRV) in both waste sorting and sewage treatment plants.

Commercial alcohol-based disinfectants were more effective against fungi than SAEW or silver nanoparticle mixtures.

Mixtures of SAEW and silver nanoparticles showed the lowest biocidal effectiveness.

Abstract

The objective of this study was to evaluate the effectiveness of surface disinfection using slightly acidic electrolyzed water (SAEW), concerning microorganisms detected in organic dust at a municipal waste sorting plant (WSP) and a sewage treatment plant (STP).

Five sampling sites were selected at each facility. Four disinfectants used in the tests included: SAEW solutions with active chlorine concentrations of 100 mg/l and 300 mg/l; a mixture of SAEW (100 mg/l) and silver nanoparticles (25 mg/l); and a commercially available disinfectant, a mixture of alcohols. Surface swab samples were collected to evaluate microbial contamination and compare bacterial and fungal levels after disinfection.

Analysis of the control samples (with no disinfectant application) revealed significant microbiological contamination of the surface tested. The tested disinfectants showed varying effectiveness against the microorganisms under study. For the aerobic and anaerobic bacteria, the highest decrease in concentrations was achieved when SAEW (300 mg/l) was applied. For the sampling sites in WSP, the log reduction values (LRV) were 2.32 and 1.99, respectively. For samples from the STP, the LRVs were 2.57 and 2.42. The most significant decrease in fungal concentration was induced by a commercial disinfectant made from a mixture of alcohols. For the samples collected at WSP, the LRV was 2.06, while for those from STP, it was 0.95. The lowest biocidal effectiveness was found for the preparation consisting of a mixture of SAEW and silver nanoparticles, for which the LRV values did not usually exceed 1.00.

The results indicate that SAEW can be a promising alternative to the traditional alcohol-based disinfectants in occupational environments contaminated with organic dust. However, more comprehensive project should be conducted that would include a wider variety of work surfaces to be tested and a broader range of active chlorine concentrations.

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