José Roberto Guimarães

Reverse osmosis is widely applied as an advanced treatment technology due to its high efficiency in removing organic micropollutants from wastewater. However, this process inevitably produces a residue with a high contaminant load, posing environmental challenges and requiring effective post-treatment strategies. In this study, the photoperoxidation process was investigated for the degradation of six pharmaceuticals (acetaminophen, caffeine, naproxen, progesterone, sulfathiazole, and testosterone) in reverse osmosis concentrate and other complex aqueous matrices to assess matrix-driven effects on process efficiency. Experiments in ultrapure water showed negligible removal by UVA photolysis and H ₂ O ₂ alone, whereas UVC irradiation promoted compound-dependent degradation. UVC-photoperoxidation significantly enhanced removal efficiency, and under optimized conditions (UVC/H ₂ O ₂ 0.87 mmol L ⁻¹ ), all pharmaceuticals were degraded within 40 min. Matrix composition strongly governed degradation efficiency. In reverse osmosis concentrate, all compounds were efficiently degraded within 30 min. Similar rapid degradation was observed in the post-Membrane Bioreactor effluent. In contrast, matrices with high dissolved organic matter content, such as surface water and solutions containing elevated humic acid concentrations, strongly inhibited degradation due to UV light attenuation and radical scavenging. Low humic acid accelerated degradation, underscoring dissolved organic matter’s dual role. Naproxen was the least persistent compound, whereas acetaminophen was the most persistent. In saline matrix such as reverse osmosis concentrate, efficient degradation was observed despite elevated conductivity, suggesting the contribution of additional oxidative pathways. Overall, the results show that the matrix composition plays a decisive role in degradation efficiency, emphasizing the need to consider the characteristics of the water when evaluating advanced oxidation processes.

New technologies and processes have been developed, searching for higher efficiency to improve the treatment of effluents discharged into the environment. This work presents the performances, advantages, and disadvantages of two of these processes, the MBR (Membrane Bioreactor) and the MABR (Membrane-Aerated Biofilm Reactor), considering that there is not enough literature available for MABR design and for comparing both processes when is needed to choose one of it. To run the experimental study, a 1.2 m3/d MABR pilot plant was installed in parallel with a MBR full-scale sewage treatment plant, in the same place, using the same raw sewage source. The results presented that the MBR had higher removal efficiencies for Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS) and Total Phosphorus (TP). For Total Kjeldahl Nitrogen (TKN), both processes obtained similar values. However, the MABR was more efficient concerning the indicators of energy consumption and COD and TKN load removed per reactor volume. In addition, it was verified the total suspended solids had an essential impact on the performance of the MABR, concluding that it is necessary to have an efficient system to control and remove the TSS from the reactor as well one separation downstream step such as a filtration or sedimentation system.

This study aimed to investigate the efficiency of ozone and peroxone for the disinfection of water containing Giardia duodenalis cysts. Dechlorinated tap water (TW) and spring water (SW) samples were inoculated with a purified commercial suspension containing 105 cysts of Giardia duodenalis. The membrane filtration method was employed for cyst concentration, with average recovery efficiencies of 43.3% in TW and 73.3% in SW. Visualization of the cysts was carried out by Immunofluorescence Assay (IFA). The use of ozone as a disinfectant in SW showed a concentration-dependent increase in cyst damage, reaching 98% non-viability at the highest ozone concentration (5 mg L-1). The addition of hydrogen peroxide (H2O2) improved the process, as 2.5 mg L-1 of ozone at an H2O2 / O3 ratio of 0.3 caused morphological damage to 99% of the cysts. The data indicated that the lower H2O2 / O3 ratio resulted in better overall performance in terms of cyst damage. In TW, the oxidation behavior differed, with no clear difference observed between the lowest and highest ozone concentrations causing cyst wall damage. The presence of alkalinity in TW negatively affected the disinfection process, likely due to the scavenger effect of alkalinity compounds on hydroxyl radicals. The use of peroxone process with an H2O2 / O3 ratio of 0.5 yielded the highest damage to cysts in TW. The findings contribute to the understanding of factors influencing the efficacy of oxidation techniques and provide insights for developing effective disinfection strategies for water treatment systems.

New technologies and processes have been developed, searching for higher efficiency to improve the treatment of effluents discharged into the environment. This work presents the performances, advantages, and disadvantages of two of these processes, the MBR (Membrane Bioreactor) and the MABR (Membrane-Aerated Biofilm Reactor). The data were collected in a comparative study between a full-scale MBR plant and an MABR pilot plant installed in the same place, using the same raw sanitary sewage source. The MBR presented higher efficiencies for Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD). However, the MABR was more efficient concerning the indicators of electric energy consumption per COD load removed and COD load removed per reactor volume. It also was verified the need for and importance of having an efficient system to control and remove the suspended solids in the MABR reactor, being an impacting factor in the pollutant removal efficiency results.

In a post-pandemic scenario, indoor air monitoring may be required seeking to safeguard public health, and therefore well-defined methods, protocols, and equipment play an important role. Considering the COVID-19 pandemic, this manuscript presents a literature review on indoor air sampling methods to detect viruses, especially SARS-CoV-2. The review was conducted using the following online databases: Web of Science, Science Direct, and PubMed, and the Boolean operators “AND” and “OR” to combine the following keywords: air sampler, coronavirus, COVID-19, indoor, and SARS-CoV-2. This review included 25 published papers reporting sampling and detection methods for SARS-CoV-2 in indoor environments. Most of the papers focused on sampling and analysis of viruses in aerosols present in contaminated areas and potential transmission to adjacent areas. Negative results were found in 10 studies, while 15 papers showed positive results in at least one sample. Overall, papers report several sampling devices and methods for SARS-CoV-2 detection, using different approaches for distance, height from the floor, flow rates, and sampled air volumes. Regarding the efficacy of each mechanism as measured by the percentage of investigations with positive samples, the literature review indicates that solid impactors are more effective than liquid impactors, or filters, and the combination of various methods may be recommended. As a final remark, determining the sampling method is not a trivial task, as the samplers and the environment influence the presence and viability of viruses in the samples, and thus a case-by-case assessment is required for the selection of sampling systems.

Sulfaquinoxaline (SQX) has been detected in environmental water samples, where its side effects are still unknown. To the best of our knowledge, its oxidation by Fenton and photo-Fenton processes has not been previously reported. In this study, SQX oxidation, mineralization, and toxicity (Escherichia coli and Staphylococcus aureus bacteria) were evaluated at two different setups: laboratory bench (2 L) and pilot plant (15 L). The experimental design was used to assess the influence of the presence or absence of radiation source, as well as different H₂O₂ concentrations (94.1 to 261.9 mg L⁻¹). The experimental conditions of both setups were: SQX = 25 mg L⁻¹, Fe(II) = 10 mg L⁻¹, pH 2.8 ± 0.1. Fenton and photo-Fenton were suitable for SQX oxidation and experiments resulted in higher SQX mineralization than reported in the literature. For both setups, the best process was the photo-Fenton (178.0 mg L⁻¹ H₂O₂), for which over 90% of SQX was removed, over 50% mineralization, and bacterial growth inhibition less than 13%. In both set-ups, the presence or absence of radiation was equally important for sulfaquinoxaline oxidation; however, the degradation rates at the pilot plant were between two to four times higher than the obtained at the laboratory bench.

Photoperoxidation (UV/H₂O₂) was used to degrade three of the worldwide most consumed antidepressant pharmaceuticals—bupropion, escitalopram, and fluoxetine—in ultrapure water, drinking tap water, surface water, and reclaimed water. The study was performed with antidepressants in concentration levels in which these compounds usually occur in the water matrices. Online solid-phase extraction coupled to UHPLC-MS/MS was used to quantify the analytes during degradation studies. The UV/H₂O₂ process was able to degrade bupropion and fluoxetine in ultrapure water, using 0.042 mmol L⁻¹ of H₂O₂ and 1.9 kJ of UV-C irradiation. Nevertheless, escitalopram, which had the most recalcitrant character among the studied antidepressants, needed a tenfold more oxidant and UV-C irradiation. The primary metabolites of the antidepressants were identified as the major by-products generated by the UV/H₂O₂ process, and they persisted in the solution even when the parent compound was degraded. The residual toxicity of the solution was evaluated for two different trophic levels. The UV/H₂O₂ process reduced the toxicity of the solution to Raphidocelis. subcapitata microalgae after 30 min of reaction. On the other hand, the toxicity of the residual solution increased over the reaction time to the marine bacteria Vibrio fischeri (reaching up to 48.3% of bioluminescence inhibition after 60 min of reaction). Thus, our results evidenced that the toxicity against different trophic levels and the monitoring of the by-products formed are important aspects to be considered regarding the safety of the treated solution and the optimization of the treatment process.