This work investigates the degradation of Reactive Gray BF-2R dye (a blend of reactive yellow 145, reactive orange 122 and reactive black 5 dyes) using UV/H₂O₂, Fenton, and photo-Fenton-advanced oxidative processes, with artificial sunlight and UV-C radiations. The photo-Fenton process employing UV-C radiation was the most efficient under the conditions studied. The ideal conditions for the degradation of the dye, determined using a factorial design 2³ and a study of the concentration of hydrogen peroxide ([H₂O₂]), were [H₂O₂] equal to 40 mg L⁻¹, iron concentration [Fe] of 1 mg L⁻¹, and pH between 3 and 4. The Chan and Chu non-linear kinetic model predicted the kinetic data with a degradation of over 98% for color and 68% for aromatics after 60 min. The behavior of the chemical oxygen demand fitted the first-order kinetic model well, with a degradation of 64% after 60 min. The Multilayer Perceptron 7-11-2 artificial neural network model enabled to model the degradation process of the aromatics and accurately predict the experimental data. Toxicity tests indicated that the post-treatment samples were non-toxic for Escherichia coli bacteria, and Portulaca grandiflora and Basil sabory seeds. However, they inhibited the growth of Lactuca sativa seeds and Salmonella enteritidis bacteria. The photo-Fenton process with UV-C radiation degraded the dye studied efficiently and the degradation percentages were, on average, 7% and 5% higher for color than those observed when employing the Fenton and UV/H₂O₂ processes, respectively. With the aromatic, however, they were 84% and 62% higher, thus justifying the use of this process.

The food industry is considered to be one of the greatest sources of environmental contamination produced by dyes. Moreover, a large number of commercial food dyes and their by-products have been shown to be toxic, having chronic effects on human health. The search for efficient processes with which to treat these compounds is, therefore, necessary. In this work, the photo-peroxidation and photo-Fenton processes using UV-C and sunlight radiations were evaluated in order to degrade two synthetic dyes commonly found in food industry wastewater, sunset yellow and tartrazine, in an aqueous mixture. The preliminary results showed that the photo-Fenton/UV-C system was the most efficient. The ANOVA analysis results indicated a good fit of the model. The higher degradations were obtained using 50 mg L⁻¹ of [H₂O₂], 1 mg L⁻¹ of [Fe], a pH of 3.5, and a lower surface area/volume ratio (0.02 cm² mL⁻¹). In the kinetic study, a good fit was found for the kinetic model proposed by Chan and Chu. Degradations higher than 99% and 78% were obtained for the chromophore and aromatic groups, respectively, in 180 min. Toxicity tests showed that post-treatment samples did not interfere in the development of Lactuca sativa seeds and Escherichia coli and Salmonella enteritidis bacteria strains. The photo-Fenton/UV-C system can, therefore, be considered an efficient treatment for the degradation of the mixture of sunset yellow and tartrazine dyes under the conditions evaluated.

The non-steroidal anti-inflammatory pharmaceuticals ketoprofen, meloxicam, and tenoxicam were degraded by photo-assisted peroxidation (hv/H₂O₂) and photo-Fenton processes under simulated solar radiation (sunlight) and UV-C. Preliminary studies showed that the processes under UV-C and sun-photo-Fenton radiation showed similar degradation results. The sun-photo-Fenton was less sensitive to the concentration variation of the H₂O₂ oxidant. Given that, in general, the highest percentages of degradation were achieved using the sun-photo-Fenton system and that this radiation resembles solar radiation, this process was selected for further studies. From the results of a factorial design 2³, in duplicate, the highest degradation condition within the studied levels was 400 mg L⁻¹ of [H₂O₂], 1.75 mg L⁻¹ of [Fe], and pH at 3–4 range. The kinetic degradation curve, monitored by the chemical oxygen demand (COD), could be represented by the pseudo-first-order model, and after 120 min the COD concentrations reached values below 2% of the initial demand. Degradation products from the three drugs were identified by high-performance liquid chromatography with coupled mass spectrometry (UCLAE-EM) and verified the toxicity of Escherichia coli and Salmonella enteritidis bacteria and of lettuce seeds (Lettuce Veneranda), indicating the formation of compounds that have lower molecular mass and can be more easily degraded, using this process as one of the stages of a system of treatment.

Nontyphoidal Salmonella (NTS) is a relevant pathogen involved in gastroenteritis outbreaks worldwide. In this study, we determined the capacity to combine the most probable number (MPN) and multiplex polymerase chain reaction (PCR) methods to characterize the most important Salmonella serotypes in raw sewage. A total of 499 isolates were recovered from 27 raw sewage samples and screened using two previously described multiplex PCR methods. From those, 123 isolates were selected based on PCR banding pattern—identical or similar to Salmonella Enteritidis and Salmonella Typhimurium—and submitted to conventional serotyping. Results showed that both PCR assays correctly serotyped Salmonella Enteritidis, however, they presented ambiguous results for Salmonella Typhimurium identification. These data highlight that MPN and multiplex PCR can be useful methods to describe microbial quality in raw sewage and suggest two new PCR patterns for Salmonella Enteritidis identification.

A comparative study of the phagovars, antimicrobial susceptibility patterns, and plasmid profiles of 119 strains of Salmonella Enteritidis isolated from food poisoning was carried out to determine the most adequate markers in epidemiological investigations. An epidemiological pattern (consisting of a phagovar 4 and 60kb plasmid) emerged as the predominant pattern in Nagano prefecture during the study period.