Evaluation of UV-Chlorine Processes for Enhanced Disinfection in Drinking Water: case of study

The presence of natural organic matter (NOM) is the main cause for disinfection byproducts (DBP) formation, upon final chlorination. In this context, drinking water managers must maximize NOM removal and optimize chlorine dosage. In this study, water samples from surface reservoir and lab-scale treatment were combined with various unit operation and Advanced Oxidation Processes (AOPs) combinations. The impact of the experiments on the structure of the Natural Organic Matter (NOM) was evaluated as well as the formation of biodegradable compounds and the disinfection by-products (DBP) formation

Mathematical modelling of flow and adsorption in a gas chromatograph

In this paper, a mathematical model is developed to describe the evolution of the concentration of compounds through a gas chromatography column. The model couples mass balances and kinetic equations for all components. Both single and multiple-component cases are considered with constant or variable velocity. Dimensional analysis is employed to identify negligible terms and so reduce the problem to the solution of a single integral equation. From this the concentration profile for all components may be determined (since they are scaled versions of each other). The full governing equations are also solved numerically to verify the analytical approach. Finally the analytical results are compared with experimental data, showing excellent agreement. This novel method is highly efficient and is significantly faster and simpler than previous numerical approaches

Indoor CO2 direct air capture and utilization: Key strategies towards carbon neutrality

Direct air capture (DAC) is a promising technology that can help to remove carbon dioxide (CO2) from the air. One application of DAC is indoor CO2 direct air capture (iCO2-DAC). A wide range of materials with unique properties for CO2 capture have been investigated, including porous materials, zeolites, and metal-organic frameworks. The selection of suitable materials for iCO2-DAC depends on several factors, such as cost, CO2 adsorption capacity, and stability. The development of new materials with improved properties for iCO2-DAC is an active research area. The captured CO2 can serve as a renewable carbon source to produce biofuels for internal use (e.g., for heating purposes), decreasing the environmental impact of buildings. This review article highlights the importance of iCO2-DAC to improve indoor air quality in buildings and boost the circular economy. We discuss the available carbon capture technologies and materials, discussing their properties and focusing on those potentially applicable to indoor environments. We also provide a hypothetic scenario where CO2 is captured from different indoor environments and transformed into sustainable fuels by using an emerging carbon capture and utilization technology (microbial electrosynthesis). Finally, we evaluate the economic feasibility of such an innovative approach in comparison to the use of traditional, fossil-based fuels

Indoor CO2 direct air capture and utilization: Key strategies towards carbon neutrality

Direct air capture (DAC) is a promising technology that can help to remove carbon dioxide (CO2) from the air. One application of DAC is indoor CO2 direct air capture (iCO2-DAC). A wide range of materials with unique properties for CO2 capture have been investigated, including porous materials, zeolites, and metal-organic frameworks. The selection of suitable materials for iCO2-DAC depends on several factors, such as cost, CO2 adsorption capacity, and stability. The development of new materials with improved properties for iCO2-DAC is an active research area. The captured CO2 can serve as a renewable carbon source to produce biofuels for internal use (e.g., for heating purposes), decreasing the environmental impact of buildings. This review article highlights the importance of iCO2-DAC to improve indoor air quality in buildings and boost the circular economy. We discuss the available carbon capture technologies and materials, discussing their properties and focusing on those potentially applicable to indoor environments. We also provide a hypothetic scenario where CO2 is captured from different indoor environments and transformed into sustainable fuels by using an emerging carbon capture and utilization technology (microbial electrosynthesis). Finally, we evaluate the economic feasibility of such an innovative approach in comparison to the use of traditional, fossil-based fuels

CO2 in indoor environments: From environmental and health risk to potential renewable carbon source

In the developed world, individuals spend most of their time indoors. Poor Indoor Air Quality (IAQ) has a wide range of effects on human health. The burden of disease associated with indoor air accounts for millions of premature deaths related to exposure to Indoor Air Pollutants (IAPs). Among them, CO2 is the most common one, and is commonly used as a metric of IAQ. Indoor CO2 concentrations can be significantly higher than outdoors due to human metabolism and activities. Even in presence of ventilation, controlling the CO2 concentration below the Indoor Air Guideline Values (IAGVs) is a challenge, and many indoor environments including schools, offices and transportation exceed the recommended value of 1000 ppmv. This is often accompanied by high concentration of other pollutants, including bio-effluents such as viruses, and the importance of mitigating the transmission of airborne diseases has been highlighted by the COVID-19 pandemic. On the other hand, the relatively high CO2 concentration of indoor environments presents a thermodynamic advantage for direct air capture (DAC) in comparison to atmospheric CO2 concentration. This review aims to describe the issues associated with poor IAQ, and to demonstrate the potential of indoor CO2 DAC to purify indoor air while generating a renewable carbon stream that can replace conventional carbon sources as a building block for chemical production, contributing to the circular economy

CO2 in indoor environments: From environmental and health risk to potential renewable carbon source

In the developed world, individuals spend most of their time indoors. Poor Indoor Air Quality (IAQ) has a wide range of effects on human health. The burden of disease associated with indoor air accounts for millions of premature deaths related to exposure to Indoor Air Pollutants (IAPs). Among them, CO2 is the most common one, and is commonly used as a metric of IAQ. Indoor CO2 concentrations can be significantly higher than outdoors due to human metabolism and activities. Even in presence of ventilation, controlling the CO2 concentration below the Indoor Air Guideline Values (IAGVs) is a challenge, and many indoor environments including schools, offices and transportation exceed the recommended value of 1000 ppmv. This is often accompanied by high concentration of other pollutants, including bio-effluents such as viruses, and the importance of mitigating the transmission of airborne diseases has been highlighted by the COVID-19 pandemic. On the other hand, the relatively high CO2 concentration of indoor environments presents a thermodynamic advantage for direct air capture (DAC) in comparison to atmospheric CO2 concentration. This review aims to describe the issues associated with poor IAQ, and to demonstrate the potential of indoor CO2 DAC to purify indoor air while generating a renewable carbon stream that can replace conventional carbon sources as a building block for chemical production, contributing to the circular economy

Biogas Upgrading: Optimal Activated Carbon Properties for Siloxane Removal

A total of 12 commercial activated carbons (ACs) have been tested for the removal of octamethylcyclotetrasiloxane (D4) in dynamic adsorption experiments using different carrier gases and D4 concentrations. Characterization of the ACs included several physical and chemical techniques. The D4 adsorption capacities were strongly related with the textural development of the ACs. Results showed that the optimum adsorbent for D4 is a wood-based chemically activated carbon, which rendered an adsorption capacity of 1732 ± 93 mg g–1 using 1000 ppm (v/v) of D4 with dry N2 as the carrier gas. When the concentration of D4 was lowered to typical values found in biogas, the adsorption capacity was halved. The presence of major biogas compounds (i.e., CH4 and CO2) and humidity further reduced the D4 adsorption capacity. The polymerization of D4 over the surface of all ACs was found to be relevant after prolonged contact times. The extent of this phenomenon, which may negatively affect the thermal regeneration of the AC, correlated reasonably well with the presence of phenolic and carboxylic groups on the carbon surfaces