Evaluation of an Ozone Chamber as a Routine Method to Decontaminate Firefighters' PPE.

Ozone chambers have emerged as an alternative method to decontaminate firefighters' Personal Protective Equipment (PPE) from toxic fire residues. This work evaluated the efficiency of using an ozone chamber to clean firefighters' PPE. This was achieved by studying the degradation of pyrene and 9-methylanthracene polycyclic aromatic hydrocarbons (PAHs). The following experiments were performed: (i) insufflating ozone into PAH solutions (homogeneous setup), and (ii) exposing pieces of PPE impregnated with the PAHs to an ozone atmosphere for up to one hour (heterogeneous setup). The ozonolysis products were assessed by Fourier Transform Infrared Spectroscopy (FTIR), Thin-Layer Chromatography (TLC), and Mass Spectrometry (MS) analysis. In the homogeneous experiments, compounds of a higher molecular weight were produced due to the incorporation of oxygen into the PAH structures. Some of these new compounds included 4-oxapyren-5-one (m/z 220) and phenanthrene-4,5-dicarboxaldehyde (m/z 234) from pyrene; or 9-anthracenecarboxaldehyde (m/z 207) and hydroxy-9,10-anthracenedione (m/z 225) from 9-methylanthracene. In the heterogeneous experiments, a lower oxidation was revealed, since no byproducts were detected using FTIR and TLC, but only using MS. However, in both experiments, significant amounts of the original PAHs were still present even after one hour of ozone treatment. Thus, although some partial chemical degradation was observed, the remaining PAH and the new oxygenated-PAH compounds (equally or more toxic than the initial molecules) alerted us of the risks to firefighters' health when using an ozone chamber as a unique decontamination method. These results do not prove the ozone-advertised efficiency of the ozone chambers for decontaminating (degrading the toxic combustion residues into innocuous compounds) firefighters' PPE.

Petroleum-contaminated soil: using sonolysis to improve mineralization and biodegradation potential of Fenton reaction and ozonolysis process.

The degradation efficiency of the Fenton reaction or ozonolysis (O3) to treat soil contaminated by crude petroleum was studied in association with the sonolysis process. To quantify oxidation efficiency, total organic carbon (TOC) and chemical oxygen demand (COD) were measured, while biochemical oxygen demand (BOD5) was measured to estimate biodegradation potential. TOC removal efficiency ranged from 9 to 52% to the Fenton reaction without sonolysis, and 18% and 78% with sonolysis for reagent concentrations of 1% H2O2-100 mM Fe2+ and 20% H2O2-1 mM Fe2+, respectively. For ozonolysis (after 10 and 60 min of treatment), the reduction in TOC ranged from 9 to 43% without sonolysis and 15 to 61% with sonolysis. The Fenton reaction without sonolysis increased the biodegradability in relation to the non-oxidized sample by 6% (1% H2O2-100 mM Fe2+) and 26% (20% H2O2-1 mM Fe2+), and with sonolysis the corresponding values were 13% and 42%, respectively. The biodegradation potential under ozonolysis without sonolysis increased from 0.18 (10 min of treatment) to 0.38 (30 min of treatment), and with sonolysis these values were 0.26 and 0.58, respectively. Optimization of the remediation processes is essential to determine sequential treatment order and efficiency.

Properties and possible applications of ozone-modified potato starch.

In this work, different properties of potato starch modified by ozone oxidation were evaluated and described aiming to represent different possibilities of industrial application. The most promising results were observed regarding the pasting properties and the gel texture of the starch samples ozonated for 15 and 30 min. These samples presented a higher apparent viscosity and a higher gel strength when gelatinized at 65 and 70 °C, if compared to the native sample. Furthermore, the 15 and 30-min samples retained more water at mild temperatures (~60 °C) than the other samples. These results could be related to the less compact structure of the oxidized starches after the ozone processing due to the cleavage of their glycosidic bonds and the presence of electronegative groups. Not only do these characteristics facilitate the water absorption and gelatinization of the samples at mild temperatures, they also favour the granular disruption at higher temperatures (above 85 °C). The data reported in this work broadens the understanding of the ozone-modification process, as well as suggesting possibilities of industrial applications using ozonated potato starch.

Production of biogas (methane and hydrogen) from anaerobic digestion of hemicellulosic hydrolysate generated in the oxidative pretreatment of coffee husks.

Ozone pretreatment of coffee husks (CH) was evaluated to generate hydrolysates for biogas production and to preserve cellulose of the solid phase for 2G ethanol production. Pretreatment variables included liquid-to-solid ratio (LSR), pH and specific applied ozone load (SAOL). Considering single-stage anaerobic digestion (AD), the highest methane production (36 NmL CH4/g CH) was achieved with the hydrolysate generated in the experiment using LSR 10 mL/g, pH 11 and SAOL 18.5 mg O3/g CH, leading to 0.064 kJ/g CH energy recovery. Due to the presence of toxic compounds in the hydrolysate, the addition of powdered activated carbon (4 g/L) to the reactor enhanced biogas production, leading to 86 NmL CH4/g CH yield and 0.58 kJ/g CH energy recovery. When two-stage AD was applied, methane production resulted in 49 NmL CH4/g CH, with additional 19 NmL H2/g CH production, resulting in a net 0.26 kJ/g CH energy recovery.

Ozonolysis combined with ultrasound as a pretreatment of sugarcane bagasse: Effect on the enzymatic saccharification and the physical and chemical characteristics of the substrate.

Sugarcane bagasse (SCB) was treated in three stages using ozone oxidation (O), washing in an alkaline medium (B) and ultrasonic irradiation (U). The impact of each pretreatment stage on the physical structure of the SCB was evaluated by its chemical composition, using an infrared technique (FTIR-ATR), and using thermogravimetric analysis (TGA/DTG). The pretreatment sequence O, B, U provided a significant reduction of lignin and hemicellulose, which was confirmed by changes in the absorption bands corresponding to these compounds, when observed using infrared. Thermogravimetric analysis confirmed an increased thermal stability in the treated sample due to the removal of hemicellulose and extractives during the pretreatment. This pretreatment released 391mg glucose/g from treated SCB after the enzymatic hydrolysis, corresponding to a yield of 94% of the cellulose available.

Genetic material present in hospital wastewaters: Evaluation of the efficiency of DNA denaturation by ozonolysis and ozonolysis/sonolysis treatments.

Hospital wastewater treatments must ensure that all genetic material is destroyed, since nuclear and extra-nuclear DNA can show antimicrobial resistance and contain recombinant genes, which promote vertical and/or horizontal gene transfer, amplifying the current problem of the emergence of antibiotic-resistant microorganisms. In this study, we investigated whether ozonolysis or ozonolysis/sonolysis in combination can denature genetic material, i.e., destroy the integrity of DNA molecules, present in hospital wastewaters. To achieve this goal, hospital wastewaters were treated by ozonolysis or ozonolysis/sonolysis in combination (at 70 and 100 W L(-1)) and both raw and treated wastewaters were analyzed in terms of disinfection and DNA denaturation efficiency quantified by viable cell counts and by agarose gel electrophoresis. In the ozonolysis treatment, the agarose gel electrophoresis technique showed that the ozone-treated samples contained DNA molecules, while combined ozonolysis/sonolysis destroyed the DNA in a power density-dependent manner (64% at 70 W L(-1) and 81% at 100 W L(-1)). Care must be taken by environmental managers to distinguish disinfection processes from DNA denaturation processes, since these two terms are not synonymous.