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Concept: Peroxy acid


There is still an important interest in controlling bacterial endospores. The use of chemical disinfectants and notably oxidising agents to sterilize medical devices is increasing. With this in mind hydrogen peroxide (H2O2) and peracetic acid (PAA) have been used in combination but until now there has been no explanation for the observed increased in sporicidal activity. This study provides information on the mechanism of synergistic interaction of PAA and H2O2 against bacterial spores. The investigations of the efficacy of different combinations, including pre-treatments with the two oxidisers were performed against wild-type and a range of spore mutants deficient in their spore coat or small acid-soluble spore proteins. The concentrations of the two biocides were also measured in the reaction vessels enabling the assessment of any shift from H2O2 to PAA formation. This study confirmed the synergistic activity of H2O2 and PAA combination. However, we observed that the sporicidal activity of the combination is largely due to PAA and not H2O2. Furthermore, we observed that the synergistic combination was based on H2O2 compromising the spore coat, which was the main spore resistance factor, likely allowing better penetration of PAA, resulting in the increased sporicidal activity.

Concepts: Peroxy acid, Peracetic acid, Disinfectant, Disinfectants, Peroxide, Chlorine, Hydrogen peroxide, Oxygen


The inactivation of Bacillus anthracis spores on subway and used subway railcar materials was evaluated using fogged peracetic acid/hydrogen peroxide (PAA) and hydrogen peroxide (H2O2). A total of 21 separate decontamination tests were conducted using bacterial spores of both B. anthracis Ames (B.a.) and Bacillus atrophaeus (B.g.) inoculated onto several types of materials. Tests were conducted using commercial off-the-shelf fogging equipment filled with either PAA or H2O2 to fumigate a ∼15 cubic meter chamber under uncontrolled ambient relative humidity and controlled temperature (10 or 20 °C) from 8 to 168 h. For the present study, no conditions were found that resulted in complete inactivation of either B.a. Ames or B.g. on all test materials. Approximately 41% and 38% of the decontamination efficacies for B.a. and B.g., respectively, exhibited ≥6 log10 reduction (LR); efficacy depended greatly on the material. When testing at 10 °C, the mean LR was consistently lower for both B.a. and B.g. as compared to 20 °C. Based on the statistical comparison of the LR results, B.g. exhibited equivalent or greater resistance than B.a. for approximately 92% of the time across all 21 tests. The efficacy data suggest that B.g. may be a suitable surrogate for B.a. Ames when assessing the decontamination efficacy of fogged PAA or H2O2. Moreover, the results of this testing indicate that in the event of B.a. spore release into a subway system, the fogging of PAA or H2O2 represents a decontamination option for consideration.

Concepts: Endospore, Relative humidity, Peroxy acid, Peracetic acid, Oxygen, Bacillus anthracis, Bacillus, Hydrogen peroxide


The effect of thermal treatments and several biocides on the viability of Lactobacillus virulent phage P1 was evaluated. Times to achieve 99% inactivation (T99) of phage at different treatment conditions were calculated. The thermal treatments applied were 63, 72, and 90°C in 3 suspension media (de Man, Rogosa, Sharpe broth, reconstituted skim milk, and Tris magnesium gelatin buffer). Phage P1 was completely inactivated in 5 and 10 min at 90 and 72°C, respectively; however, reconstituted skim milk provided better thermal protection at 63°C. When phage P1 was treated with various biocides, 800 mg/L of sodium hypochlorite was required for total inactivation (∼7.3 log reduction) within 60 min, whereas treatment with 100% ethanol resulted in only a ∼4.7 log reduction, and 100% isopropanol resulted in a 5.2-log reduction. Peracetic acid (peroxyacetic acid) at the highest concentration used (0.45%) resulted in only a ∼4.-log reduction of phage within 60 min. The results of this study provide additional information on effective treatments for the eradication of potential phage infections in dairy plants.

Concepts: Milk, Ethanol, Bacteriophage, Disinfectants, Chlorine, Peroxy acid, Peracetic acid, Hydrogen peroxide


Because manual cleaning is often suboptimal, there is increasing interest in use of automated devices for room decontamination. We demonstrated that an ultrasonic room fogging system that generates submicron droplets of peracetic acid and hydrogen peroxide eliminated Clostridium difficile spores and vegetative pathogens from exposed carriers in hospital rooms and adjacent bathrooms.

Concepts: Chlorine, Peroxy acid, Peracetic acid, Hygiene, Rooms, Oxygen, Hydrogen peroxide, Clostridium difficile


Extracellular polymeric substances (EPS) are highly hydrated biopolymers and play important roles in bioflocculation, floc stability, and solid-water separation processes. Destroying EPS structure will result in sludge reduction and release of trapped water. In this study, the effects of combined process of peracetic acid (PAA) pre-oxidation and chemical re-flocculation on morphological properties and distribution and composition of EPS of the resultant sludge flocs were investigated in detail to gain insights into the mechanism involved in sludge treatment. It was found that sludge particles were effectively solubilized and protein-like substances were degraded into small molecules after PAA oxidation. A higher degradation of protein-like substances was observed at acid environments under PAA oxidation. Microscopic analysis revealed that no integral sludge floc was observed after oxidation with PAA at high doses. The floc was reconstructed with addition of inorganic coagulants (polyaluminium chloride (PACl) and ferric chloride (FeCl3)) and PACl performed better in flocculation due to its higher charge neutralization and bridging ability. Combined oxidative lysis and chemical re-flocculation provide a novel solution for sludge treatment.

Concepts: Aluminium chlorohydrate, Peroxy acid, Peracetic acid, Iron(III) chloride, Hydrochloric acid, Iron, Hydrogen peroxide, Flocculation


This study was conducted to evaluate the efficacy of four different peroxyacids, namely peracetic (PAA), perpropionic (PPA), perlactic (PLA), and percitric (PCA) for inactivating viruses in suspension or attached to stainless steel or polyvinyl chloride surfaces. The test virus was a proxy for human norovirus, namely murine norovirus 1. Plaque-forming units in suspension (10(7) per mL) were treated with 50-1,000 mg L(-1) peroxyacid (equilibrium mixture of organic acid, hydrogen peroxide, peroxyacid, and water) for 1-10 min. Inactivation was measured by plaque assay. PAA and PPA were the most effective, with a 5 min treatment at 50 mg L(-1) being sufficient to reduce viral titer by at least 3.0 log10, whether the virus was in suspension or attached to stainless steel or polyvinyl chloride disks under clean or fouled conditions. Combinations of organic acid and hydrogen peroxide were found ineffective. Similar inactivation was observed in the case of virus in artificial biofilm (alginate gel). These short super-oxidizers could be used for safe inactivation of human noroviruses in water or on hard surfaces.

Concepts: Acid, Hydrogen, Chlorine, Peracetic acid, Peroxy acid, Corrosion, Hydrogen peroxide, Oxygen


We investigated the possibility of applying performic acid (PFA) and peracetic acid (PAA) for disinfection of combined sewer overflow (CSO) in existing CSO management infrastructures. The disinfection power of PFA and PAA towards Escherichia coli (E. coli) and Enterococcus was studied in batch-scale and pre-field experiments. In the batch-scale experiment, 2.5mgL(-1) PAA removed approximately 4 log unit of E. coli and Enterococcus from CSO with a 360min contact time. The removal of E. coli and Enterococcus from CSO was always around or above 3 log units using 2-4mgL(-1) PFA; with a 20 min contact time in both batch-scale and pre-field experiments. There was no toxicological effect measured by Vibrio fischeri when CSO was disinfected with PFA; a slight toxic effect was observed on CSO disinfected with PAA. When the design for PFA based disinfection was applied to CSO collected from an authentic event, the disinfection efficiencies were confirmed and degradation rates were slightly higher than predicted in simulated CSO.

Concepts: Peracetic acid, Peroxy acid, Units of measurement, Combined sewer, Disinfectants, Proteobacteria, Escherichia coli, Hydrogen peroxide


Peracetic acid is gaining usage in numerous industries who have found a myriad of uses for its antimicrobial activity. However, rapid high throughput quantitation methods for peracetic acid and hydrogen peroxide are lacking. Herein, we describe the development of a high-throughput microtiter plate based assay based upon the well known and trusted titration chemical reactions. The adaptation of these titration chemistries to rapid plate based absorbance methods for the sequential determination of hydrogen peroxide specifically and the total amount of peroxides present in solution are described. The results of these methods were compared to those of a standard titration and found to be in good agreement. Additionally, the utility of the developed method is demonstrated through the generation of degradation curves of both peracetic acid and hydrogen peroxide in a mixed solution.

Concepts: Peroxy acid, Peroxides, Peracetic acid, Peroxide, Chemical reaction, Chemistry, Oxygen, Hydrogen peroxide


The palladium-catalyzed diacetoxylation and trifluoromethanesulfonic acid-catalyzed diacetoxylation using inexpensive and environmentally friendly hydrogen peroxide and peracetic acid were successfully conducted with the help of microchemical technology. Excellent yield and selectivity were achieved in significantly shortened reaction times without the decomposition of explosive oxidants and further transformation of unstable products, offering a safe and efficient alternative to traditional methods for alkene diacetoxylation.

Concepts: Peroxy acid, Hydrogenation, Peracetic acid, Peroxide, Alkene, Chlorine, Hydrogen peroxide, Oxygen