Integration of ozonation with water treatment for pharmaceuticals removal from Arroio Diluvio in southern Brazil.

Pharmaceutical compounds can reach water bodies through sewage systems. The process of water treatment is insufficient for the removal of these contaminants. The ozonation has great potential to be integrated into the treatment, since it promotes the reduction of pharmaceuticals, reduces the generation of disinfection byproducts and can reduce operational costs. In this work, the integration of the ozonation process with water treatment was studied. The ozone was applied in the pre-oxidation and intermediate ozonation stages, to evaluate the dependence of different variables. Water samples were collected from Arroio Diluvio, a river of the city of Porto Alegre (Brazil). The doses of ozone were maintained between 0.5 and 1.0 mgO3 L-1 while the coagulant was between 25 and 150 mg·L-1. Pre-ozonation resulted in a removal of pharmaceuticals at pH 10.0, time of 15 min and coagulant concentration of 52.5 mgL-1. The intermediate ozonation provided a removal with pH 10.0 and a time of 5 min of bubbling. Based on the results, it was confirmed that the synergy of the ozonation process with conventional water treatment is an effective, sensitive and fast method for the removal of pharmaceuticals from the aqueous medium.

Use of ozonation technology to combat viruses and bacteria in aquatic environments: problems and application perspectives for SARS-CoV-2.

COVID-19 is a global health threat with a large number of confirmed cases and deaths worldwide. Person-to-person transmission through respiratory droplets and contact with aerosol-infected surfaces are the main ways in which the virus spreads. However, according to the updated literature, the new coronavirus (SARS-CoV-2) has also been detected in aqueous matrices, with the main route of transmission being feces and masks from patients diagnosed with the disease. Given the emergence of public health and environmental protection from the presence of lethal viruses and bacteria, this review article aims to report the major challenges associated with the application of ozonation in water contaminated with viruses and bacteria, in order to clarify whether these communities can survive or infect after the disinfection process and if it is efficient. Available data suggest that ozonation is able to increase the inactivation effect of microorganisms by about 50% in the logarithmic range, reducing infectivity. In addition, the evidence-based knowledge reported in this article is useful to support water and sanitation safety planning and to protect human health from exposure to cited contaminants through water.

Determination of optimal operating parameters for tetracycline removal by adsorption from synthetic and real aqueous solutions.

Among all emerging contaminants, pharmaceutical compounds as tetracycline (TC) can cause potential environmental impact in water quality. In this work, the removal of TC drug on activated carbon from aqueous solution was studied and the best operating parameters were obtained. In addition, a real aqueous matrix was enriched with TC and the optimized conditions were applied to study the adsorption process efficiency. For this, the influence of pH, contact time between phases and dosage of adsorbent solid was evaluated. The investigation of kinetics, equilibrium and thermodynamic was also performed. The adsorbent material was characterized by SEM analysis and N2 adsorption/desorption isotherms to confirm its properties. Batch experiments showed that the most suitable experimental conditions for adsorption in aqueous solution were: pH 4.0, contact time 90 min and dosage of adsorbent solid 30 g.L-1. Under these conditions, it was possible to obtain 92.7% of TC removal with predominance of a spontaneous, favorable and endothermic chemisorption process. Adsorption experiments with real aqueous matrix provided 99.4% TC removal. These results show the potential of adsorption as a wastewater treatment applied to remove emerging pollutants as TC from real aqueous contaminated water.

Use of functinalized adsorbents for tetracycline removal in wastewater: adsorption mechanism and comparison with activated carbon.

The present study investigated the application of functinalized adsorbents in the removal of tetracycline in water by adsorption. Activated carbon was impregnated with iron chloride, copper sulfate and hydrogen peroxide, in order to improve its adsorption properties. The solids were characterized by adsorption/desorption isotherms N2, XRD, FTIR and SEM. The influence of pH, adsorbent concentration and contact time parameters was evaluated. The results using activated carbon as adsorbent and initial TC concentration of 20 mg.L-1 showed that 93% TC removal was achieved at pH 4.0, contact time of 120 minutes and 30 g.L-1 adsorbent concentration. Experiments applying the functionalized solids showed a faster initial adsorption kinetics. Also, no pH adjustment was required (pH 6.0). In addiction, a minimum of 50% reduction in adsorbent mass (15, 10 and 5 g.L-1 for CA-H2O2, CA-Fe and CA-Cu, respectively) was observed, compared to the untreated solid. The pseudo-second-order kinetic model was chosen as the optimal model for the study. The application of FeCl3, CuSO4 and H2O2 composites as adsorbent solids are technically feasible for the removal of tetracycline in wastewater treatment.