Life Cycle Assessment of Raw and Fe-Modified Biochars: Contributing to Circular Economy.

Biochar is a carbonaceous material, which can be decorated with metals, that has been garnering attention to be used in the treatment of water due to its contribution to waste management and circular economy. This study presents the life cycle assessment (LCA) regarding the generation of Pinus patula raw biochar and its modification with iron (Fe-modified biochar). SimaPro 9.3.0.3 software was used to simulate the environmental impacts of both carbonaceous materials. The potential environmental effects obtained from the production of Pinus patula raw biochar were mainly ascribed to the source of energy utilized during this process. The potential impacts demonstrated that the generation of gases and polycyclic aromatic hydrocarbons are the main concern. In the case of Fe-modified biochar, the potential environmental effects differed only in the stage of the biomass modification with the metal. These effects are associated with the extraction of Fe and the generation of wastewater. These findings provide an insight into the environmental effects linked to the production of raw and Fe-modified biochar. However, further LCA research should be performed concerning other materials and compounds than can be generated during the biomass thermochemical conversion.

Use of low frequency ultrasound for water treatment: Data on azithromycin removal.

Azithromycin (AZT) is a broad-spectrum antibiotic present in different aqueous matrices due to its incomplete removal using conventional water treatments. Ultrasound (US) is an advanced oxidation technology that has demonstrated its capacity to degrade different types of organic molecules due to the generation of cavitation bubbles or cavities that promote the generation of radicals. In this paper, data regarding the use of low-frequency US (40 kHz) in the removal of AZT are presented. Tests were carried out at lab scale for 60 min considering a reaction volume of 300 mL (pollutant initial concentration 1.0 mg L -1). The effect of operational parameters such as pH, ultrasound power, the presence of external agents like ferrous ions, hydrogen peroxide, and UV radiation were evaluated. In general, obtained data show that under the experimental reaction conditions, it is feasible to reach extents of AZT removal ∼50.0%, and that the presence of other species in the medium could inhibit the reaction, mainly due to scavenging effects. This information is relevant to future applications of US, at pilot or real scale, in the treatment of water with presence of AZT or similar organic pollutants.

Photolysis of a mixture of anthracene and benzo[a]pyrene at ultra-trace levels in natural water with disinfection purposes.

The photodegradation of anthracene (AN) and benzo[a]pyrene (BaP), two priority polycyclic aromatic hydrocarbons (PAHs), was examined at ultra-trace levels in surface water to elucidate their behaviour under several irradiance values and types of radiation. The emitting flux and the spectrum of the lamps were found to develop a crucial role in AN and BaP degradation since removal efficiencies of the target contaminants higher than 99% were found after 15 min of irradiation under an ultraviolet C (UVC) irradiance of 0.63 mW/cm2, corresponding to a fluence of 560.25 mJ/cm2. On the other hand, although ultraviolet A (UVA) lamps exhibited a higher irradiance compared to that of UVC lamps, they were not efficient for degrading the target PAHs. The removal kinetic studies corroborated these findings, being the AN elimination rate in surface water higher than that in deionized water at optimal operating conditions. Disinfection potential was also measured. A rapid microbial load inactivation, in terms of total coliforms naturally contained in the water matrix studied, was evidenced within 15 min of treatment for the fluence referred. However, after 24 hr in the dark, a regrowth was observed. Additionally, photolysis products more toxic than the parent compounds were found, which were not removed even by extending the treatment time. In this regard, it can be concluded that the individual action of UVC light for removing AN and BaP with disinfection purposes is not an efficient treatment; therefore, the use of radiation in combination with other kinds of treatments is required.

Total coliform inactivation in natural water by UV/H2O2, UV/US, and UV/US/H2O2 systems.

The presence of pathogens in drinking water can seriously affect human health. Therefore, water disinfection is needed, but conventional processes, such as chlorination, result in the production of dangerous disinfection by-products. In this regard, an alternative solution to tackle the problem of bacterial pollution may be the application of advanced oxidation processes. In this work, the inactivation of total coliforms, naturally present in a Colombian surface water by means of UV/H2O2, UV/US, and the UV/US/H2O2 advanced oxidation processes, was investigated. Under the investigated conditions, complete bacterial inactivation (detection limit equal to 1 CFU 100 mL-1) was found within 5 min of treatment by UV/H2O2 and UV/US/H2O2 systems. UV/US oxidation process also resulted in total bacterial load elimination, but after 15 min of treatment. Bacterial reactivation after 24 h and 48 h in the dark was measured and no subsequent regrowth was observed. This phenomenon could be attributed to the high oxidation capacity of the evaluated oxidation systems. However, the process resulting in the highest oxidation potential at the lowest operating cost, in terms of energy consumption, was UV/H2O2 system. Therefore, UV/H2O2 advanced oxidation system can be used for disinfection purposes, enabling drinking water production meeting the requirements of regulated parameters in terms of water quality, without incurring extremely high energy costs. Nonetheless, further researches are required for minimizing the associated electric costs.

Evaluation of the UV/H2O2 system for treating natural water with a mixture of anthracene and benzo[a]pyrene at ultra-trace levels.

The presence of polycyclic aromatic hydrocarbons, such as anthracene (AN) and benzo[a]pyrene (BaP), in water has become a problem of great concern due to the detrimental health effects caused to humans and living beings. In this work, the efficiency of the UV/H2O2 system for degrading the target compounds at ultra-trace levels in surface water has been evaluated. For this purpose, a previous optimization step using a face-centered central composite experimental design has been conducted, considering the effect of the UV-C irradiance and the initial concentration of H2O2. It was evidenced that under optimal operating conditions (11 mg L-1 H2O2 and 0.63 mW cm-2 irradiance), AN and BaP removal percentages were higher than 99.8%. Additionally, 69.3% of the organic matter, in terms of total organic carbon, was mineralized without the production of transformation by-products more harmful than the parent compounds. These findings demonstrate the oxidation capacity of the examined system in a natural matrix for degrading micropollutants that cannot be converted through conventional treatment processes. Consequently, new horizons are opened for the effective use of the UV/H2O2 system for drinking water production, providing the accomplishment of other regulated parameters related to water quality.

Direct large-volume injection analysis of polycyclic aromatic hydrocarbons in water / Análisis de inyección directa en gran volumen de hidrocarburos aromáticos policíclicos en agua / Análise de injeção direta de grande volume de hidrocarbonos aromáticos policíclicos em água

Abstract Due to the health risks for both humans and living beings caused by polycyclic aromatic hydrocarbons (PAHs), the monitoring of these compounds in environmental matrices is mandatory. This work proposes an analytical method for analyzing anthracene (AN) and benzo[a]pyrene (BaP), two of the most representative PAHs, at ultra-trace concentrations in water, employing direct injection of large volumes of samples coupled with reversed-phase high-performance liquid chromatography. For this purpose, principal component analysis was used to examine the behavior of AN and BaP within the chromatographic system. Results showed that AN and BaP chromatographic behavior can be described by three models representing their identification, the quantification of AN and that of BaP, respectively. The factors affecting the obtained models, such as the injection volume, column temperature, flow rate, strength of the mobile phase, and the excitation and emission wavelengths, were examined and optimized by means of design of experiments. Finally, the analytical method was validated, obtaining promising limits of detection and quantification. The developed analytical method was demonstrated to be useful for a sensitive analysis of the target analytes in relatively clean natural water matrices.

Resumen Los hidrocarburos aromáticos policíclicos (HAPs) causan problemas en la salud de los seres humanos y seres vivos, por lo que se requiere un monitoreo de estos compuestos en matrices ambientales. Este trabajo propone un método analítico para analizar el antraceno (AN) y el benzopireno (BAP), los hidrocarburos más representativos en concentraciones de ultra trazas en el agua, empleando inyección directa en grandes volúmenes en muestras acopladas a la fase inversa con cromatografía líquida de alto rendimiento. Por tal razón, se utilizó el análisis de componentes principales para examinar el comportamiento de AN y BAP en el sistema cromatográfico. Los resultados mostraron que el comportamiento cromatográfico de AN y BAP podría describirse por medio de tres modelos que representan su identificación, la cuantificación de AN y de BAP, respectivamente. Se examinaron los factores que afectan a los modelos obtenidos, como el volumen de inyección, la temperatura de la columna, la tasa de flujo, la fuerza de la fase móvil, y las longitudes de las ondas de excitación y emisión, y se optimizaron mediante el diseño de experimentos. Finalmente, se validó el método analítico, obteniendo límites de detección y cuantificación. Se demostró que el método analítico desarrollado fue útil para el análisis sensible de los analitos en matrices de agua natural relativamente limpia.

Resumo Devido aos riscos para a saúde tanto para humanos como para os seres vivos em geral causados pelos hidrocarbonos aromáticos policíclicos (HAPs), o monitoramento de estes compostos em matrizes ambientais é prioritário. Este trabalho propõem um método analítico para analisar antraceno (AN) e benzo[a]pireno (BaP), dois dos hidrocarbonos mais representativos, em concentrações de ultra traços em água, empregando injeções diretas de grandes volumes de amostra acoplada a cromatografia líquida de alta eficiência em fase reversa. Usando Análises por Componentes Principais e desenho experimental, foram avaliados os efeitos de diversos fatores que afetam o sistema cromatográfico, tais como o volume de injeção, a temperatura da coluna, fluxo, forca da fase móvel e comprimentos de onda de excitação e emissão. Os resultados demonstraram que o comportamento cromatográfico de AN e BaP pode ser descrito por meio de três que representam sua identificação, quantificação de AN e de BaP, respectivamente. Os resultados mostraram que o comportamento cromatográfico de NA e BAP poderia ser descrito por meio de três modelos que representam sua identificação, a quantificação de NA e de BAP, respectivamente. Examinaram-se os fatores que afetam aos modelos obtidos, como o volume de injeção, a temperatura da coluna, a taxa de fluxo, a forca da fase móvel, e as longitudes das ondas de excitação e emissão, e se otimizaram mediante o desenho experimental. Finalmente, se validou o m todo analítico, obtendo os limites de detecção e quantificação. O método analítico desenvolvido demonstrou ser útil para uma análise sensível para os compostos de interesse em matrizes de água natural relativamente limpas.

Removal of polycyclic aromatic hydrocarbons in aqueous environment by chemical treatments: a review.

Due to their carcinogenic, mutagenic and teratogenic potential, the removal of polycyclic aromatic hydrocarbons (PAHs) from aqueous environment using physical, biological and chemical processes has been studied by several researchers. This paper reviews the current state of knowledge concerning PAHs including their physico-chemical properties, input sources, occurrence, adverse effects and conventional and alternative chemical processes applied for their removal from water. The mechanisms and reactions involved in each treatment method are reported, and the effects of various variables on the PAH degradation rate as well as the extent of degradation are also discussed. Extensive literature analysis has shown that an effective way to perform the conversion and mineralization of this type of substances is the application of advanced oxidation processes (AOPs). Furthermore, combined processes, particularly AOPs coupled with biological treatments, seem to be one of the best solutions for the treatment of effluents containing PAHs.