Environmental Engineering Science最新文献

Efficient separation of oil droplets from oil/water emulsions is necessary for many energy and food industrial processes and for industrial wastewater treatment. Membrane microfiltration has been explored to address this issue because it is simple to operate and low in cost. However, filtration of oil droplets with a size around or less than 1 μm is still a major challenge. Furthermore, the fabrication process for polymeric membranes often uses hazardous organic solvents and petroleum-derived and nonbiodegradable raw materials, which pose additional environmental health and safety risk. In this study, we examined the use of chitosan-based membranes to efficiently remove oil droplets with an average diameter of ∼1 μm. The membranes were fabricated based on the rapid dissolution of chitosan in an alkaline/urea solvent system at a low temperature, thus avoiding the use of any toxic organic solvent. The chitosan membranes were further modified by dopamine and tannic acid (TA). The as-prepared membrane was characterized in terms of surface morphology, pore size distribution, and mechanical strength. The membrane performance was evaluated on a custom-designed crossflow filtration system. The results showed that the modified chitosan membrane with dopamine and TA had a water flux of 230.9 LMH at 1bar transmembrane pressure and oil droplet rejection of 99%. This water flux represented an increase of more than 10 times when compared with the original chitosan membrane without modification. The study also demonstrated excellent antifouling properties of the modified membrane that could achieve near 100% water flux recovery.

Social equity has been a concept of interest for many years, gaining increased focus from energy and environmental communities. The equitable development, collection, and reporting of sociodemographic data (e.g., data related to socioeconomic status, race, and ethnicity) are needed to help meet several of the United Nations Sustainable Development Goals (i.e., Affordable and Clean Energy; Reduce Inequalities; Peace, Justice and Strong Institutions; and Partnerships for the Goals). Yet, there has not been a consolidation of relevant concepts and application framing in energy and environmental life cycle assessment and decision-making practices. Our study aims to help fill this gap by consolidating existing knowledge on relevant equity applications, providing examples of sociodemographic data needs, and presenting a path toward a more holistic equity administration. In this critique, we present a framework for integrating equity in energy and environmental research and practitioner settings, which we call systemic equity. Systemic equity requires the simultaneous and effective administration of resources (i.e., distributive equity), policies (i.e., procedural equity), and addressing the cultural needs of the systematically marginalized (i.e., recognitional equity). To help provide common language and shared understanding for when equity is ineffectively administered, we present ostensible equity (i.e., when resource and policy needs are met, but cultural needs are inadequately met), aspirational equity (i.e., when policy and cultural needs are met, but resources are inadequate), and exploitational equity (i.e., when resource and cultural needs are met, but policies are inadequate). We close by establishing an adaptive 10-step process for developing standard sociodemographic data practices. The systemic equity framework and 10-step process are translatable to other practitioner and research communities. Nonetheless, energy and environmental scientists, in collaboration with transdisciplinary stakeholders, should administer this framework and process urgently.

Coal mine drainage (CMD) impairs tens of thousands of kilometers of U.S. waterways each year, in part with the leaching of low concentrations of rare earth elements (REEs). REEs are essential for modern technologies, yet economically viable natural deposits are geospatially limited, thus engendering geopolitical concerns, and their mining is energy intense and environmentally destructive. This work summarizes laboratory-scale experimental results of a trap-extract-precipitate (TEP) process and uses the mass and energy balances to estimate the economic costs and environmental impacts of the TEP. The TEP process uses the alkalinity and filtering capacity of stabilized flue gas desulfurization (sFGD) material or water treatment plant (WTP) sludge to remediate CMD waters and extract REEs. Passive treatment systems that use WTP sludge are cheaper than those that use sFGD material ($89,300/year or $86/gT-REE vs. $89,800/year or $278/gT-REE) and have improved environmental performance across all indicators from two different impact assessment methods. These differences are largely attributable to the larger neutralizing capacity of WTP sludge in the treatment application.

Precipitation of calcium carbonate (i.e., scaling) can occur in both traditional tank (electric and gas) and "green" tankless hot water systems that have implications for public health, water and energy sustainability, infrastructure damage, and consumer esthetics. There are many scale reduction devices and technologies that aim to reduce or eliminate such problems, and several standardized methods have been proposed to research their performance with scientific rigor. All of the existing approaches were inherently nonreproducible or could not quantify important aspects of scale deposition, including quantity, location, and deposit durability. Here we develop and vet a Standardized Scaling Test Protocol that overcomes many of these deficiencies, using a laboratory-scale model premise plumbing system and a synthesized synthetic scaling water that could be reproduced in any laboratory. This approach produced 25.1 g of calcium carbonate scaling (95% confidence interval of 20.3-29.8 g, n = 3) in ∼5 days. Illustrative scale reduction for a range of representative technologies, including cation exchange, electrochemical deionization, magnetism, electric field generator, media-induced precipitation, phosphate sacrificial media, and citric acid sacrificial media, ranged from 0% to 100% using the standardized protocol. The general approach was also applied to suitable local natural water with high scaling potential, and similar capabilities were observed.

Oxygation (O) is a water-saving and energy-saving irrigation method that can also influence the absorption of cadmium (Cd) by rice, but the related mechanism is still unclear. In this study, the relationship between O method and Fe-Mn plaque formation was tested through pot experiments. The Fe-Mn plaque content and Cd concentration were measured during different rice growth periods, and the fitted models based on their correlation were established. The results show that, Fe-Mn plaque formation was the most significant factor affecting Cd accumulation in rice under O conditions. The content of rice root Fe-Mn plaque was higher after the application of O during the filling and maturity stages of rice growth, and Fe-Mn plaque inhibited Cd accumulation in the rice roots and grains and reduced the translocation factors (TFs) from the rice dithionite-citrate-bicarbonate extract (DCB) to the roots (TF_DCB-R) and from the roots to the straw (TF_Straw-G). O may influence the Fe-Mn plaque formation on the root surface to impede Cd absorption by rice. This research provides theoretical support for the Cd absorption under O conditions.

Chromium (Cr) (VI) is a toxic, mutagenic, and carcinogenic water pollutant. The standard ion chromatography (IC) method for quantification of Cr (VI) in water samples is Environmental Protection Agency Method 218.7, which requires postcolumn derivatization with 1,5-diphenylcarbazide and UV-Vis spectroscopy detection. Method 218.7 is Cr (VI) specific; thus, it does not allow detection of co-occurring natural and anthropogenic anions in environmental media. In this study, we developed an isocratic IC method with suppressed conductivity detection, a Metrohm Metrosep A Supp 7 column, and sodium carbonate/acetonitrile as mobile phase for simultaneous quantification of Cr (VI), ${ClO}_4^{-}$ , As (V) as arsenate, Se (VI) as selenate, and the common anions F^-, Cl^-, ${NO}_2^{-}$ , ${NO}_3^{-}$ , and ${SO}_4^{2-}$ . The determination coefficient for every analyte was >0.99 and the method showed good accuracy in quantification. Cr (VI), As (V), Se (VI), and ${ClO}_4^{-}$ limit of detection and limit of quantification were 0.1-0.6 μg/L and 0.5-2.1 μg/L, respectively. Recovery of Cr (VI) in various aqueous samples (tap water, surface water, groundwater, and wastewater) was between 97.2% and 102.8%. Overall, most analytes showed acceptable recovery (80-120%) in the environmental samples tested. The IC method was applied to track Cr (VI) and other anion concentrations in laboratory batch microcosms experiments with soil, surface water, and anaerobic medium. The IC method developed in this study should prove useful to environmental practitioners, academic and research organizations, and industries for monitoring low concentrations of multiple anions in environmental media, helping to decrease the sample requirement, time, and cost of analysis.

Silver nanoparticles (AgNPs) are the most widely used engineered nanomaterials in consumer products, primarily due to their antimicrobial properties. This widespread usage has resulted in concerns regarding potential adverse environmental impacts and increased probability of human exposure. As the number of AgNP consumer products grows, the likelihood of interactions with other household materials increases. AgNP products have the potential to interact with household cleaning products in laundry, dishwashers, or during general use of all-purpose surface cleaners. This study has investigated the interaction between surfactant-based surface cleaning products and AgNPs of different sizes and with different capping agents. One AgNP consumer product, two laboratory-synthesized AgNPs, and ionic silver were selected for interaction with one cationic, one anionic, and one nonionic surfactant product to simulate AgNP transformations during consumer product usage before disposal and subsequent environmental release. Changes in size, morphology, and chemical composition were detected during a 60 min exposure to surfactant-based surface cleaning products using ultraviolet-visible (UV/Vis) spectroscopy, transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX), and dynamic light scattering (DLS). Generally, once AgNP suspensions were exposed to surfactant-based surface cleaning products, all the particles showed an initial aggregation, likely due to disruption of their capping agents. Over the 60 min exposure, cleaning agent-1 (cationic) showed more significant particle aggregates than cleaning agent-2 (anionic) and cleaning agent-3 (nonionic). In addition, UV/Vis, TEM-EDX, and DLS confirmed formation of incidental AgNPs from interaction of ionic silver with all surfactant types.

A growing world population with increasing levels of food consumption will lead to more dairy and swine production and increasing amount of manure that requires treatment. Discharge of excessive nutrients and carbon in untreated animal manure can lead to greenhouse gas emissions and eutrophication concerns, and treatment efforts can be expensive for small scale farmers in marginalized communities. The overall goal of this study was to determine the environmental and economic sustainability of four animal manure management scenarios in Costa Rica: (1) no treatment, (2) biodigesters, (3) biodigesters and struvite precipitation, and (4) biodigesters, struvite precipitation, and lagoons. Life cycle assessment was used to assess the carbon footprint and eutrophication potential, whereas life cycle cost analysis was used to evaluate the equivalent uniform annual worth over the construction and operation and maintenance life stages. Recovery of biogas as a cooking fuel and recovery of nutrients from the struvite reactor reduced the carbon footprint, leading to carbon offsets of up to 2,500 kg CO₂ eq/year. Offsets were primarily due to avoiding methane emissions during energy recovery. Eutrophication potential decreased as resource recovery processes were integrated, primarily due to improved removal of phosphorus in effluent waters. Resource recovery efforts led to equivalent uniform annual benefits of $825 to $1,056/year, which could provide a helpful revenue source for lower-income farmers. This research can provide clarity on how small-scale farmers in marginalized settings can utilize resource recovery technologies to better manage animal manure, while improving economic and environmental sustainability outcomes.

El Tiple is one of many marginalized Afrodescendant communities confined within a green desert located in the southwest region of Colombia. This green desert is most widely known as the second-largest sugarcane monoculture field in the Americas. Herein, we describe a transdisciplinary and participatory effort to understand agroindustrial expansion in the region through the lens of the El Tiple community. Using qualitative and quantitative methodologies, we characterized the socioenvironmental context of El Tiple in terms of ethnography, autoethnography, social cartography, and ethnobotany. We implemented a participatory approach to codevelop a technology-assisted strategy for strengthening the community's small-scale farming activities. Our contextual analysis results show systemic food dispossession, which arises from several factors, including dramatic land transformation, rapid depletion and contamination of natural assets, and biodiversity loss. All these factors are associated with the presence of bordering sugarcane plantations. In collaboration with community members, we designed, constructed, and analyzed a greenhouse hydroponic cultivation system as an actionable means to gradually restore local production of food and medicinal plants for the community. Our transdisciplinary and participatory approach demonstrates how academics can partner with vulnerable communities in the coproduction of knowledge and solutions to pressing social needs.

Ethical reasoning is an important ability for engineers working with marginalized communities in global contexts. However, the ethical awareness and development that are critical for this work may not be included in traditional engineering education. This article presents faculty perspectives on the ethical and societal issues (ESI) that should be taught and the pedagogies that are used to prepare students for development engineering. Among 60 survey respondents who taught courses focused on global and/or development (GD) issues, the ESI topics that were particularly congruent included poverty, sustainability, social justice, and engineering decisions under uncertainty. Faculty interviews highlighted that GD should foreground the human side of engineering, respectful partnerships with communities grounded in an asset perspective, and considerations of historical elements. Discussions, case studies, design, and reflection are impactful pedagogies that can complement learning through service to achieve ESI educational goals.