Optimizing ozone treatment for pathogen removal and disinfection by-product control for potable reuse at pilot-scale.

Reclaimed water poses environmental and human health risks due to residual organic micropollutants and pathogens. Ozonation of reclaimed water to control pathogens and trace organics is an important step in advanced water treatment systems for potable reuse of reclaimed water. Ensuring efficient pathogen reduction while controlling disinfection byproducts remains a significant challenge to implementing ozonation in reclaimed water reuse applications. This study aimed to investigate ozonation conditions using a plug flow reactor (PFR) to achieve effective pathogen removal/inactivation while minimizing bromate and N-Nitrosodimethylamine (NDMA) formation. The pilot scale study was conducted using three doses of ozone (0.7, 1.0 and 1.4 ozone/total organic carbon (O3/TOC) ratio) to determine the disinfection performance using actual reclaimed water. The disinfection efficiency was assessed by measuring total coliforms, Escherichia coli (E. coli), Pepper Mild Mottle Virus (PMMoV), Tomato Brown Rugose Fruit Virus (ToBRFV) and Norovirus (HNoV). The ozone CT values ranged from 1.60 to 13.62 mg min L-1, resulting in significant reductions in pathogens and indicators. Specifically, ozone treatment led to concentration reductions of 2.46-2.89, 2.03-2.18, 0.46-1.63, 2.23-2.64 and > 4 log for total coliforms, E. coli, PMMoV, ToBRFV, and HNoV, respectively. After ozonation, concentrations of bromate and NDMA increased, reaching levels between 2.8 and 12.0 µg L-1, and 28-40.0 ng L-1, respectively, for average feed water bromide levels of 86.7 ± 1.8 µg L-1 and TOC levels of 7.2 ± 0.1 mg L-1. The increases in DBP formation were pronounced with higher ozone dosages, possibly requiring removal/control in subsequent treatment steps in some potable reuse applications.

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.

Evaluation of efficiency and capacity of thermal, chemical and ultrasonic regeneration of tetracycline exhausted activated carbon.

Emerging pollutants have received increasing attention because of their potential environmental risks. As conventional treatment processes are not able to completely remove emerging pollutants, such as drugs, for example, the adsorption process is considered a complementary treatment. However, after some time of use, the adsorbent solids used in this type of process become saturated and there may be a higher demand for replacement of these materials, resulting in a large amount of solid waste. In this context, the objective of this study was to evaluate regeneration techniques of adsorbent solid depleted with emerging tetracycline pollutant. For this, tests were performed using three regenerative methods - thermal, chemical and ultrasonic, where through them were analyzed the influence of temperature, type of solvent and sonification time, respectively. Virgin, saturated and regenerated solids were characterized by their physical structure, micro and mesopore distribution and scanning electron microscopy. For all techniques employed, the regeneration efficiency reached values ⁣⁣above 85%. Thermal treatments at 200°C, 100% methanol solution, 100% deionized water with 60 °C heating and ultrasonic treatment at 5 and 20 minutes were chosen as the most viable methods for the study of adsorption/desorption cycles. Compared to the others, the heat treatment at 200°C remained with consistent results until the sixth cycle, presenting a regenerative capacity of 90%. Therefore, it has been selected as the most suitable regenerative agent, ensuring that CAG can be regenerated and used repeatedly in the treatment of tetracycline contaminated waters.

Evaluation of zinc adsorption through batch and continuous scale applying Bayesian technique for estimate parameters and select model.

This work aims to study the efficiency of zinc adsorption onto granular-activated carbon, predicting the mathematical models that best describe the adsorption behavior in a fixed bed column. First, batch scale experiments were performed to evaluate the influence of pH (3 to 6), contact time (5 to 60 min), and absorbent concentration (5 to 25 g L-1) using synthetic effluent. Fixed bed column experiments were performed by varying the adsorbent concentration (10, 13, 20, and 40 g L-1) and the effluent flow rate (15 and 20 mL min-1). Markov Chain Monte Carlo and Bayesian criteria information were applied to describe the phenomena using Langmuir, Freundlich, Temkin, Redlich-Peterson, Sips, Toth, Khan, Radke-Prausnitz, for isotherm models, and Thomas; Yoon-Nelson; Yan; Clark models for breakthrough curve. Adsorption operating best conditions were pH 5, 20 g L-1 of solid, and 50 min of contact time. These parameters allowed 80% of Zn removal, being better described by the Tempki model. In tests on a pilot plant, the Yan model was able to predict the second-order kinetic model, with an increase in the effluent flow and a 50% increase in the bed saturation time with a greater amount of adsorbent solid.

Efficiency evaluation of thermal, ultrasound and solvent techniques in activated carbon regeneration.

The regeneration of diclofenac saturated activated carbon was studied and compared by thermal, solvent and ultrasound techniques in this work. Thermal regeneration was performed at 673 K in atmospheric air for one hour. Different proportions of solvents (ethanol, ethyl acetate and H2O) were used to evaluate the regeneration of the sorbent solid. Ultrasound treatment was tested by varying the time (5 and 15 min) and bath temperature (298 and 323 K). With the highest levels of regeneration for each technique employed, regeneration cycle tests were conducted. With the adsorption capacity recovery limit set at 60%, 8 regeneration cycles were achieved. At the end of the 8th regeneration cycle, the thermal technique made it possible to maintain the adsorption capacity at 75%. Using the water/ethanol (50:50) solvent mixture, after 8 cycles, 64% of solid regeneration was obtained. With the ultrasound technique, in the 5th cycle the solid regeneration capacity was reduced to 65%, remaining constant until 8°. The sorbent solid was characterized by TGA, N2 adsorption, FTIR and sem.

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.

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.

Comparison of different advanced oxidation processes for the removal of amoxicillin in aqueous solution.

Amoxicillin (AMX) is a widely used penicillin-type antibiotic whose presence in the environment has been investigated. In this work, the degradation of the AMX in aqueous solutions by ozonation, ozonation with UV radiation (O3/UV), homogeneous catalytic ozonation (O3/Fe2+) and homogeneous photocatalytic ozonation (O3/Fe2+/UV) was investigated. The performance results have been compared in terms of removal of amoxicillin and total organic carbon (mineralization efficiency). In all processes, complete amoxicillin degradation was obtained after 5 min. However, low mineralization was achieved. For the best available process, the potential toxicity of AMX intermediates formed after ozonation was examined using a Fish Embryo Toxicity test. Results reveal that O3 in alkaline solution and O3/Fe2+/UV provide the highest mineralization rates. Ecotoxicity showed that no acute toxicity was observed during the exposure period of 96 h.

Electrochemical regeneration of phenol-saturated activated carbon - proposal of a reactor.

An electrochemical process was used to investigate the activated carbon regeneration efficiency (RE) saturated with aromatics. For this purpose, an electrochemical reactor was developed and the operational conditions of this equipment were investigated, which is applied in activated carbon regeneration process. The influence of regeneration parameters such as processing time, the current used, the polarity and the processing fluid (electrolyte) were studied. The performance of electrochemical regeneration was evaluated by adsorption tests, using phenol as adsorbate. The increase in current applied and the process time was found to enhance the RE. Another aspect that indicated a better reactor performance was the type of electrolyte used, showing best results for NaCl. The polarity showed the highest influence on the process, when the cathodic regeneration was more efficient. The electrochemical regeneration process developed in this study presented regeneration capacities greater than 100% when the best process conditions were used, showing that this form of regeneration for activated carbon saturated with aromatics is very promising.

Consumption-based approach for pharmaceutical compounds in a large hospital.

Hospital wastewater contains a great variety of pharmaceutical compounds (PhCs), mainly due to excretion by patients. These PhCs, called emerging pollutants, are not fully eliminated in treatment plants, and are consequently detected in various environmental matrices, contributing to bacterial resistance and adverse environmental impacts on water resources. This study explores a consumption-based approach to predict the contribution of PhCs to a Brazilian hospital's wastewater. This approach identifies the consumption of major pharmaceutical classes in the studied hospital. Overall, this approach demonstrates a unique opportunity to screen PhCs used in hospitals and identify priority pollutants in hospital wastewater.

Hospital and Municipal Wastewater: Identification of Relevant Pharmaceutical Compounds.

The interest in the presence of pharmaceutical compounds (PhC) in the environment has increased significantly because of their potential impact on human health. Many studies have demonstrated that PhCs can be found in hospital and municipal wastewaters, mainly due to the inefficiency of the treatment plants. However, the question is how significant the hospital contribution represents in the total municipal wastewater generated. Therefore, the objective of this paper is to perform a comparison between hospital and municipal wastewaters based on literature review, serving as a base for the implementation of more efficient management policies in hospitals and municipal wastewater treatment plants. Results indicate that there are some compounds found in higher concentrations in hospital effluents than in municipal inffluent, particularly the class of antibiotics.