Browsing by Author "Rodriguez, Carolina"

Now showing 1 - 12 of 12
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    Arsenic removal mediated by acidic ph neutralization and iron precipitation in microbial fuel cells
    (2018) Leiva, Eduardo; Leiva-Aravena, Enzo; Rodriguez, Carolina; Serrano, Jennyfer; Vargas Cucurella, Ignacio Tomás; CEDEUS (Chile)
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    Cost-Benefit Evaluation of Decentralized Greywater Reuse Systems in Rural Public Schools in Chile
    (2020) Rodriguez, Carolina; Sanchez, Rafael; Rebolledo, Natalia; Schneider, Nicolas; Serrano, Jennyfer; Leiva, Eduardo
    Water scarcity is one of the most important climatic threats in recent times. In Chile, the north and north-central areas, with predominantly arid or semi-arid climates, have been strongly affected by the low availability of water, as well as by overexploitation of water resources derived from the negative effect caused by some sectors of the economy such as agriculture and mining. Only 53% of households in rural areas in Chile have access to drinking water from a public network. To date, some pilot greywater treatment systems have been implemented in rural public schools. This paper presents an economic analysis of pilot systems for greywater treatment from three case studies. The results showed that the implementation of these systems would not be economically feasible, since the initial investment costs can exceed USD 5200, which is not offset by the water savings. However, other benefits, such as thermal regulation, better life quality, and the feeling of well-being and satisfaction of students and teachers should be considered to be paramount for the evaluation of treatment systems. In addition, current levels of treated greywater could allow irrigation of 6.24, 5.68, and 3.56 m(2)/person in the Alejandro Chelen, El Guindo, and Pedro de Valdivia schools, respectively. These results contribute to a better understanding of the social role that should be applied to the evaluation of ecological systems that save water and improve the well-being of the population.
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    Coupling of the Feammox - Anammox pathways by using a sequential discontinuous bioreactor
    (2024) Gonzalez, Macarena; Cerda, Ambar; Rodriguez, Carolina; Serrano, Jennyfer; Leiva, Eduardo
    Treating nitrogenous compounds in wastewater is a contemporary challenge, prompting novel approaches for ammonium (NH4+) conversion to molecular nitrogen (N2). This study explores the classic anaerobic ammonium oxidation process (Anammox) coupled to the iron-dependent anaerobic ammonium oxidation process (Feammox) in a sequential discontinuous bioreactor (SBR) for NH4+ removal. Feammox and Anammox cultures were individually enriched and combined, optimizing the coupling, and identifying key variables influencing the enrichment process. Adding sodium acetate as a carbon source significantly reduces Fe3+ to Fe2+, indicating Feammox activity. Both Anammox and Feammox processes were successfully operated in SBRs, achieving efficient NH4+ removal (Anammox: 64.6 %; Feammox: 43.4 %). Combining these pathways in a single SBR enhances the NH4+ removal capacity of 50.8 %, improving Feammox efficiency. The Feammox process coupled with Anammox may generate the nitrite (NO2-) needed for Anammox. This research contributes to biotechnological advancements for sustainable nitrogenous compound treatment in SBRs.
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    Feammox Bacterial Biofilms as an Alternative Biological Process for the Removal of Nitrogen from Agricultural Wastewater
    (2023) Cerda, Ambar; Gonzalez, Macarena; Rodriguez, Carolina; Serrano, Jennyfer; Leiva, Eduardo
    The excessive deposition of ammonium (reactive nitrogen) in the environment has led to losses of biodiversity and the eutrophication of ecosystems. Anthropogenic sources contribute twice the natural rate of terrestrial reactive nitrogen and provide about 45% of the total amount of it produced annually on Earth. Recently, a biological process that anaerobically metabolizes ammonium and facilitates iron reduction, termed Feammox, was discovered. The use of Feammox activity together with hollow fiber membrane bioreactors (HFMB), for which the latter are based on the formation of biofilms of bacterial communities, constitutes an efficient and sustainable method for the removal of ammonium from agriculturally derived wastewater. To implement the use of HFMB with Feammox activity, the formation of Feammox bacterial biofilms from wastewater sludge samples from a brewery was evaluated. The cultures were enriched with two different carbon sources, namely, sodium acetate and sodium bicarbonate; then, ferrous iron and ammonium concentrations, which were used as indicators of reactive nitrogen removal, were measured. The measurements revealed that the ammonium removal level reaches 20.4% when sodium acetate is used as carbon source. Moreover, an increase in the ferrous iron concentration of +Delta 84.6 mg/L was observed, indicating that Feammox activity had been generated. Biofilm formation was observed under Feammox conditions on the hollow fibers. These results showed that Feammox bacteria can form biofilms and efficiently remove ammonium from wastewater, constituting an essential feature with which to scale up the process to HFMBs. Overall, these results contribute to a better understanding of the Feammox process that can be used to implement these processes in agriculture and thus progress towards a more sustainable industry.
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    Graphene Oxide-ZnO Nanocomposites for Removal of Aluminum and Copper Ions from Acid Mine Drainage Wastewater
    (MDPI, 2020) Rodriguez, Carolina; Tapia, Camila; Leiva Aravena, Enzo; Leiva, Eduardo
    Adsorption technologies are a focus of interest for the removal of pollutants in water treatment systems. These removal methods offer several design, operation and efficiency advantages over other wastewater remediation technologies. Particularly, graphene oxide (GO) has attracted great attention due to its high surface area and its effectiveness in removing heavy metals. In this work, we study the functionalization of GO with zinc oxide nanoparticles (ZnO) to improve the removal capacity of aluminum (Al) and copper (Cu) in acidic waters. Experiments were performed at different pH conditions (with and without pH adjustment). In both cases, decorated GO (GO/ZnO) nanocomposites showed an improvement in the removal capacity compared with non-functionalized GO, even when the pH of zero charge (pH(PZC)) was higher for GO/ZnO (5.57) than for GO (3.98). In adsorption experiments without pH adjustment, the maximum removal capacities for Al and Cu were 29.1 mg/g and 45.5 mg/g, respectively. The maximum removal percentages of the studied cations (Al and Cu) were higher than 88%. Further, under more acidic conditions (pH 4), the maximum sorption capacities using GO/ZnO as adsorbent were 19.9 mg/g and 33.5 mg/g for Al and Cu, respectively. Moreover, the removal percentages reach 95.6% for Al and 92.9% for Cu. This shows that decoration with ZnO nanoparticles is a good option for improving the sorption capacity of GO for Cu removal and to a lesser extent for Al, even when the pH was not favorable in terms of electrostatic affinity for cations. These findings contribute to a better understanding of the potential and effectiveness of GO functionalization with ZnO nanoparticles to treat acidic waters contaminated with heavy metals and its applicability for wastewater remediation.
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    Highly Efficient Removal of Cu(II) Ions from Acidic Aqueous Solution Using ZnO Nanoparticles as Nano-Adsorbents
    (2021) Leiva, Eduardo; Tapia, Camila; Rodriguez, Carolina
    Water pollution by heavy metals has significant effects on aquatic ecosystems. Copper is one of the heavy metals that can cause environmental pollution and toxic effects in natural waters. This encourages the development of better technological alternatives for the removal of this pollutant. This work explores the application of ZnO nanoparticles (ZnO-NPs) for the removal of Cu(II) ions from acidic waters. ZnO NPs were characterized and adsorption experiments were performed under different acidic pHs to evaluate the removal of Cu(II) ions with ZnO NPs. The ZnO NPs were chemically stable under acidic conditions. The adsorption capacity of ZnO NPs for Cu(II) was up to 47.5 and 40.2 mg.g(-1) at pH 4.8 and pH 4.0, respectively. The results revealed that qmax (47.5 mg.g(-1)) and maximum removal efficiency of Cu(II) (98.4%) are achieved at pH = 4.8. In addition, the surface roughness of ZnO NPs decreases approximately 70% after adsorption of Cu(II) at pH 4. The Cu(II) adsorption behavior was more adequately explained by Temkin isotherm model. Additionally, adsorption kinetics were efficiently explained with the pseudo-second-order kinetic model. These results show that ZnO NPs can be an efficient alternative for the removal of Cu(II) from acidic waters and the adsorption process was more efficient under pH = 4.8. This study provides new information about the potential application of ZnO NPs as an effective adsorbent for the remediation and treatment of acidic waters contaminated with Cu(II).
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    Life cycle assessment of greywater treatment systems for water-reuse management in rural areas
    (2021) Rodriguez, Carolina; Sanchez, Rafael; Rebolledo, Natalia; Schneider, Nicolas; Serrano, Jennyfer; Leiva, Eduardo
    Water scarcity is a major concern worldwide. Population growth, as well as the intensive use of water resources for industrial and agricultural activities, among others, have caused water stress in various regions of the world. Rural areas are usually more affected due to water scarcity and a lack of sanitary infrastructure. The current practices associated with urban water management have been considered inefficient to respond to these problems. In recent years, the reuse of greywater has emerged as a promising and sustainable alternative. Several pilot greywater treatment systems have been implemented in rural areas of different countries, however, studies about the environmental impacts of these decentralized systems under different scenarios are lacking. In this work, the life cycle assessment of greywater treatment systems considering several scenarios was studied. Our results showed that the decrease in environmental impacts due to the saving of drinking water is more evident when the water supply is carried out through cistern trucks. This occurs because the environmental impact of land transport of water is extremely high and represents over 89% of the global warming indicator [kg CO2 eq] and 96% ozone depletion [kg CFC-11 eq] contributions of the system. Greywater treatment systems with backwashing and solar panels as a source of energy have lower environmental impacts, reducing CO2 and CFC emissions by 50% for the maintenance phase and by 85% (CO2) and 47% (CFC) for the operation phase. Furthermore, the acquisition of solar panels was economically feasible, with a payback of 19.7 years. This analysis showed the environmental feasibility of small-scale greywater treatment
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    Light or Dark Greywater for Water Reuse? Economic Assessment of On-Site Greywater Treatment Systems in Rural Areas
    (2021) Leiva, Eduardo; Rodriguez, Carolina; Sanchez, Rafael; Serrano, Jennyfer
    Water scarcity is causing a great impact on the population. Rural areas are most affected by often lacking a stable water supply, being more susceptible to the impact of drought events, and with greater risk of contamination due to the lack of appropriate water treatment systems. Decentralized greywater treatment systems for water reuse in rural areas can be a powerful alternative to alleviate these impacts. However, the economic feasibility of these systems must be thoroughly evaluated. This study reports an economic analysis carried out on the viability of greywater reuse considering scenarios with light greywater or dark greywater to be treated. For this, data obtained from the assembly and monitoring of greywater treatment systems located in the north-central zone of Chile, supplemented with data obtained from the literature were used. The results showed that both scenarios are not economically viable, since the investment and operating costs are not amortized by the savings in water. In both evaluated cases (public schools), the economic indicators were less negative when treating light greywater compared with the sum of light greywater and dark greywater as the inlet water to be treated. The investment and operating costs restrict the implementation of these water reuse systems, since in the evaluation period (20 years) a return on the initial investment is not achieved. Even so, our results suggest that the best alternative to reuse greywater in small-scale decentralized systems is to treat light greywater, but it is necessary to consider a state subsidy that not only supports capital costs but also reduces operating and maintenance costs. These findings support the idea that the type of water to be treated is a factor to consider in the implementation of decentralized greywater treatment systems for the reuse of water in rural areas and can help decision-making on the design and configuration of these systems.
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    Nitrogen Removal by an Anaerobic Iron-Dependent Ammonium Oxidation (Feammox) Enrichment: Potential for Wastewater Treatment
    (2021) Rodriguez, Carolina; Cisternas, Jaime; Serrano, Jennyfer; Leiva, Eduardo
    Nitrogen pollution in water is a growing concern. Anthropogenic activities have increased the amount of nitrogen released into watercourses, which harms human health and the environment, and causes serious problems, such as eutrophication. Feammox is a recently discovered biological pathway associated with the nitrogen cycle that has gained scientific interest. This process couples anaerobic ammonium oxidation with iron reduction. This work presents a study on the Feammox mechanism from the enrichment of an activated sludge obtained from a sewage treatment plant. The enrichment was carried out at neutral pH to study the N-2 pathway, that is, the Feammox process with the oxidation of ammonium (NH4+) directly to N-2. In addition, different sources of iron were studied: iron chloride (FeCl3); ferrihydrite; and goethite. The characterization of the sludge showed the genes associated with ammonia monooxygenase, nitrate and nitrite reductases processes, along with relevant microbial species. The enrichment, carried out for 42 days and monitored every 14 days, showed that FeCl3 as a source of Fe was more effective for the coupled process of oxidation of NH4+ and the reduction of Fe(III) to Fe(II). At the end of the enrichment period, a removal of 31% and 32.2% of NH4+, and an increase in Fe(II) concentration by 52.4 and 63.9 times regarding the initial value were achieved in aerobic and anaerobic sludge, respectively. This study provides information on the potential of Feammox in the removal of N from wastewater, and the oxidation/reduction yields in the initial enrichment phase.
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    Overexpression of p73 as a Tissue Marker for High-Risk Gastritis
    (AMER ASSOC CANCER RESEARCH, 2010) Carrasco, Gonzalo; Diaz, Jose; Valbuena, Jose R.; Ibanez, Paulina; Rodriguez, Paz; Araya, Gabriela; Rodriguez, Carolina; Torres, Javiera; Duarte, Ignacio; Aravena, Edmundo; Mena, Fernando; Barrientos, Carlos; Corvalan, Alejandro H.
    Purpose: Histologic assessment of high-risk gastritis for the development of gastric cancer is not well defined. The identification of tissue markers together with the integration of histologic features will be required for this assessment.
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    Performance and treatment assessment of a pilot-scale decentralized greywater reuse system in rural schools of north-central Chile
    (2022) Rodriguez, Carolina; Carrasco, Fernanda; Sanchez, Rafael; Rebolledo, Natalia; Schneider, Nicolas; Serrano, Jennyfer; Leiva, Eduardo
    The problem of water scarcity in the world has gained great relevance in recent decades. One of the fields of study that has been developed as an ecological alternative to combat the water demand is the reuse of greywater. Greywater corresponds to domestic wastewater that excludes water from the toilet. These waters have the potential to be reused after simple treatments for non-potable uses. In the last decade, Chile has gone through the most intense mega-drought in its history. One of the most affected regions is the Coquimbo Region, located in the north-central zone, with a semi-arid climate and extensive agricultural activity. This paper presents the first results of pilot greywater treatment systems installed in rural public schools in the Coquimbo Region. In the first instance, different sorbent materials such as sand, zeolite, acid-activated carbon (AAC), base-activated carbon (BAC) and heat-activated carbon (HAC) were studied for the removal of organic matter and turbidity. It was found that the adsorbent materials based on carbon were more efficient for the removal of organic matter, registering maximum mean sorption capacities of 107.7 mg/g, 77.5 mg/g and 78.5 mg/g, for AAC, BAC and HAC, respectively. On the one hand, the treatment columns composed HAC, zeolite and sand, were very effective for removing turbidity, reaching removal percentages over 90%. On the other hand, pilot treatment systems were efficient in reaching the water quality levels required by Chilean legislation for the use of irrigation of recreational areas and services, and in some cases for the use of ornamental irrigation. The advantage of these systems is their simplicity and low installation cost. These systems have allowed savings of between 840 and 26,000 L per month, depending on the size of the school, which has allowed the watering of gardens.
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    Removal of Mn(II) from Acidic Wastewaters Using Graphene Oxide-ZnO Nanocomposites
    (2021) Leiva, Eduardo; Tapia, Camila; Rodriguez, Carolina
    Pollution due to acidic and metal-enriched waters affects the quality of surface and groundwater resources, limiting their uses for various purposes. Particularly, manganese pollution has attracted attention due to its impact on human health and its negative effects on ecosystems. Applications of nanomaterials such as graphene oxide (GO) have emerged as potential candidates for removing complex contaminants. In this study, we present the preliminary results of the removal of Mn(II) ions from acidic waters by using GO functionalized with zinc oxide nanoparticles (ZnO). Batch adsorption experiments were performed under two different acidity conditions (pH1 = 5.0 and pH2 = 4.0), in order to evaluate the impact of acid pH on the adsorption capacity. We observed that the adsorption of Mn(II) was independent of the pH(PZC) value of the nanoadsorbents. The qmax with GO/ZnO nanocomposites was 5.6 mg/g (34.1% removal) at pH = 5.0, while with more acidic conditions (pH = 4.0) it reached 12.6 mg/g (61.2% removal). In turn, the results show that GO/ZnO nanocomposites were more efficient to remove Mn(II) compared with non-functionalized GO under the pH2 condition (pH2 = 4.0). Both Langmuir and Freundlich models fit well with the adsorption process, suggesting that both mechanisms are involved in the removal of Mn(II) with GO and GO/ZnO nanocomposites. Furthermore, adsorption isotherms were efficiently modeled with the pseudo-second-order kinetic model. These results indicate that the removal of Mn(II) by GO/ZnO is strongly influenced by the pH of the solution, and the decoration with ZnO significantly increases the adsorption capacity of Mn(II) ions. These findings can provide valuable information for optimizing the design and configuration of wastewater treatment technologies based on GO nanomaterials for the removal of Mn(II) from natural and industrial waters.