Sustainable Bioleaching of Rare Earth Elements from Industrial Waste Materials Using Agricultural Wastes
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Abstract The purpose of this study was to determine the copper (Cu) biosorption capacities of several agricultural wastes from aqueous solutions. Samples of agricultural wastes were tested unaltered and after hydrochloric acid (HCl) treatment. Additional parameters tested include sample dose, contact time, particle size, mixing temperature, and the concentrations and pH of the Cu solutions. Desorption studies were performed to determine if the removed Cu could be recovered. In addition, tests were conducted to determine if the agricultural waste samples (AWS) could be reused for additional Cu biosorption cycles. The results of this study demonstrate a wide range of Cu biosorption proficiencies ranging from 0% to 100% removal. The parameters that resulted in higher Cu removal include higher pH and lower Cu solution concentration. Desorption results showed a 58% to 86% Cu recovery rate. Three of the five reused AWS were effective at removing Cu during subsequent trials. Therefore, these AWS types can be reused for additional Cu biosorption cycles. Hence, it is possible that using those AWS for metal treatment could reduce hazardous waste disposal inefficiencies and costs by avoiding disposing of spent AWS following each Cu biosorption cycle.
Distillers’ grain (DG) is one of the lignocellulosic agricultural waste streams having a high potential for biofuel production, however it is causing health and environmental problems in Southwest region of China because of improper treatment before being used for landfill. In this work, we aimed to identify fungal strains that efficiently hydrolyze DG and explored the possibility to further improve the hydrolysis of DG and other agricultural wastes by co-culturing these fungi. The tested fungal strains included 11 strains that were isolated from DG (Maotai Town, Guizhou, China) and 19 strains that were selected from the CBS collection of Westerdijk Fungal Biodiversity Institute. Aspergillus niger CBS 110.42 and CBS 554.65 and Phanerochaete chrysosporium CBS 246.84 showed overall best cellulose and xylan degrading activity, whereas high laccase and peroxidase activities were detected for Oidiodendron echinulatum CBS 113.65 and Bjerkandera adusta CBS 143380, respectively. Furthermore, A. niger CBS 554.65 co-cultured with Trichoderma reesei CBS 383.78 and A. niger CBS 110.42 with P. chrysosporium CBS 246.84 showed the best improvement (up to 2- and 3-fold higher of β-glucosidase and β-xylosidase activities). These fungi and the combinations have strong potential to be further developed for local bioenergy production.
Consistent and reliable preprocessing, conveyance, and reactor in-feed systems, particularly for low-cost waste feedstocks, remains a major technical challenge for the emerging Bioeconomy. By identifying critical biomass attributes and connecting them to flow and conversion behavior, science-driven system designs can address these often-overlooked solids handling challenges. The Wonderful Company (TWC) is the world's largest almond and pistachio grower, generating 250,000 dry tons/year of waste material including hulls, shells, and wood (>5 million tons/year industry wide in the U.S.). This project seeks to turn this environmental and economic liability into a sustainable and profitable resource, targeting conversion via gasification to syngas for electricity and bio-char, by addressing related material handling and feeding challenges. Based on optimized preprocessing strategies, bulk material flow, and thermal conversion properties, an overall system design will be developed. The methodology will be tested with FCIC's benchmark loblolly pine residues, to demonstrate the robustness of the overall approach and provide insight and guidance for future systems. The project will culminate in extended field trials to demonstrate an improved continuous feeding system with a commercial biomass-to-electricity gasifier vendor, and an economic analysis demonstrating a reduction in electricity production costs by maximizing on-stream time while minimizing preprocessing and CapEx costs.
Bio-based thermal insulation materials are in high demand due to their availability, reproducibility, and carbon-sequestration nature. However, high flammability, moisture condensation, and high thermal conductivity of biogenic material are major concerns for sustainable building applications. In this study, we report the fire-retardant cellulose aerogel insulation nanocomposites derived from wheat straw and silica aerogel, in which sodium bicarbonate improves its fire retardancy. We combined blended straw fibers and hammermilled straw fibers to create a structural hierarchy composite. The blended straw, with its longer and thicker size, served as reinforcement, while the hammermilled straw fibers acted as filler. This hierarchical structure was further integrated with aerogel for applications in green buildings. The as-prepared materials show a low thermal conductivity of 24.1 mW/m.K, high flexural modulus of 736 MPa, hydrophobicity with a water contact angle of 110.42°, and excellent fire retardancy. Altogether, this work provides an effective method for the synthesis of fire-retardant biogenic thermal insulation materials and shows a promising way for next-generation bio-based insulation materials.
This Cooperative Research and Development Agreement (CRADA) is between the National Renewable Energy Laboratory (NREL), a world leader in biomass conversion research and Ecopetrol American Inc., Ecopetrol S.A.'s U.S. subsidiary. The research and development efforts described in the Joint Work Statement (JWS) will take advantage of the strengths of both parties. NREL will use its Integrated Biorefinery Facility and vast experience in the conversion of lignocellulosic feedstocks to fuel ethanol to develop processes for the conversion of Ecopetrol's feedstocks. Ecopetrol will establish the infrastructure in Columbia to commercialize the conversion process.
A true biorefinery for processing lignocellulosic biomass should achieve maximum utilization of all major constituents (cellulose, hemicellulose, & lignin) within the feedstock. In this work a combined pretreatment process of dilute acid (DA) and N-methyl morpholine N-oxide (NMMO) is described that allows for both fractionation and subsequent complete hydrolysis of the feedstocks (corn stover and sugarcane bagasse). During this multi-step processing, the dilute acid pretreatment solubilizes the majority (>90%) of the hemicellulosic fraction, while the NMMO treatment yields a cellulosic fraction that is completely digestible within 48 hours at low enzyme loadings. With both the cellulosic and hemicellulosic fractions being converted into separate, dissolved sugar fractions, the remaining portion is nearly pure lignin. When used independently, DA and NMMO pretreatments are only able to achieve ~80% and ~45% cellulosic conversion, respectively. Mass balance calculations along with experimental results are used to illustrate the feasibility of separation and recycling of NMMO.
A key challenge facing most bioprocessing operations is that multiple unit operations are required, thereby resulting in complex, energy-intensive, and expensive processes. Further, biomass transportation costs drive the need for smaller, distributed processing plants. To incorporate the smaller scales desirable for biomass, novel processes must be developed with reduced capital costs. With over 20 years of experience in the development and commercialization of microchannel reactor technology, Oregon State University will partner with Pacific Northwest National Laboratory to demonstrate a microchannel reactor with lower capital costs for an alcohol-to-jet (ATJ) process technology that is currently being commercialized by LanzaTech. Ethanol can be produced from biomass feedstocks such as LanzaTech’s proprietary biochemical process using carbon from a number of possible feedstocks; syngas generated from biomass resources (e.g., MSW, organic industrial waste, agriculture waste) or reformed biogas, or from other biomass feedstocks such as corn kernel fiber. Ethanol then undergoes catalytic dehydration to form ethylene followed by a two-step oligomerization, hydrogenation, and fractionation to control the hydrocarbon product slate to the jet-range. Successful process development aided by a market pull for low carbon aviation fuel has spurred scale-up and commercial demonstration. However, Sustainable Aviation Fuel is a very price sensitive market and improved economics through process intensification will make the current ATJ process even more attractive. Recent efforts at PNNL have culminated in the development of a new catalyst technology for the conversion of ethanol to n-butene-rich olefins. A greater than 90% conversion, total olefin selectivity of 80-90% (n-butene selectivity ~60%), and good stability over a 100 hour test duration has been demonstrated at the bench scale. Producing butene-rich olefins directly from ethanol with high yield is new and impactful because the higher olefins can be selectively oligomerized to distillate-range hydrocarbons, thus eliminating one process step from the current ATJ process. Further, coupling the severely endothermic ethanol dehydration with exothermic C-C bond formation results in more energy efficient processing. Additional intensification and energy savings will stem from incorporating this new ethanol to n-butene catalyst technology within the ATJ process implemented using a microchannel reactor platform. Due to recent advances in microchannel manufacturing methods and associated cost reductions we believe the time is right to adapt this technology toward new commercial bioconversion applications.
Highlights: • Technical specifications for agricultural plastic wastes (APWs) recycling proposed. • Specifications are the base for best economical and environmental APW valorisation. • Analysis of APW reveals inherent characteristics and constraints of APW streams. • Thorough survey on mechanical recycling processes and industry as it applies to APW. • Specifications for APW recycling tested, adjusted and verified through pilot trials. - Abstract: Technical specifications appropriate for the recycling of agricultural plastic wastes (APWs), widely accepted by the recycling industry were developed. The specifications establish quality standards to be met by the agricultural plastics producers, users and the agricultural plastic waste management chain. They constitute the base for the best economical and environmental valorisation of the APW. The analysis of the APW streams conducted across Europe in the framework of the European project “LabelAgriWaste” revealed the inherent characteristics of the APW streams and the inherent constraints (technical or economical) of the APW. The APW stream properties related to its recycling potential and measured during pilot trials are presented and a subsequent universally accepted simplified and expanded list of APW recycling technical specifications is proposed and justified. The list includes two sets of specifications, applied to two different quality categories of recyclable APW: one for pellet production process (“Quality I”) and another one for plastic profile production process (“Quality II”). Parameters that are taken into consideration in the specifications include the APW physical characteristics, contamination, composition and degradation. The proposed specifications are focused on polyethylene based APW that represents the vast majority of the APW stream. However, the specifications can be adjusted to cover also APW of different materials (e.g. PP or PVC) that are found in very small quantities in protected cultivations in Europe. The adoption of the proposed specifications could transform this waste stream into a labelled commodity traded freely in the market and will constitute the base for the best economical and environmental valorisation of the APW.
Highlights: Black-Right-Pointing-Pointer Definition of parameters characterising agricultural plastic waste (APW) quality. Black-Right-Pointing-Pointer Analysis of samples to determine APW quality for recycling or energy recovery. Black-Right-Pointing-Pointer Majority of APW samples from various countries have very good quality for recycling. Black-Right-Pointing-Pointer Upper limit of 50% w/w soil contamination in APW acceptable for energy recovery. Black-Right-Pointing-Pointer Chlorine and heavy metals content in APW below the lowest limit for energy recovery. - Abstract: A holistic environmentally sound waste management scheme that transforms agricultural plastic waste (APW) streams into labelled guaranteed quality commodities freely traded in open market has been developed by the European research project LabelAgriWaste. The APW quality is defined by the APW material requirements, translated to technical specifications, for recycling or energy recovery. The present work investigates the characteristics of the APW quality and the key factors affecting it from the introduction of the virgin product to the market to the APW stream reaching the disposer. Samples of APW from different countries were traced from their application to the field through their storage phase and transportation to the final destination. The test results showed that the majority of APW retained their mechanical properties after their use preserving a 'very good quality' for recycling in terms of degradation. The degree of soil contamination concerning the APW recycling and energy recovery potential fluctuates depending on the agricultural plastic category and application. The chlorine and heavy metal content of the tested APW materials was much lower than the maximum acceptable limits for their potential use in cement industries.
Bacterial cellulose (BC), which is a hemicellulose- and lignin-free type of cellulose with unique properties, was produced by Komagataeibacter medellinensis, a new acid-resistant bacterial strain, using not suitable human consumption and sub-valorized food supply chain waste (FSCW) and agricultural by-products, namely, rotten banana, rotten mango and cheese whey. The BC was analyzed using Fourier transform infrared (ATR-FTIR) , tensile test, atomic absorption spectroscopy and thermogravimetric analysis. The properties of the BC obtained from each culture medium used were different, ranging from a material with high resistance and stiffness (280.6 MPa, 9.4 GPa) to a material with low resistance and less stiffness (17.7 MPa, 0.8 GPa). These properties provide considerable opportunities for obtaining different materials with multiple applications, such as composite reinforcements, wound dressings and edible films. The highest production of BC was achieved with rotten banana medium, and this BC also had the highest tensile properties. Meanwhile, the BC produced from cheese whey medium had the highest maximum rate of degradation temperature at 368 °C. This research demonstrated that FSCW and agrowaste by-products are advantageous alternative feedstocks in terms of economics and environmental concerns for producing BC with multiple properties and fields of application.
This research evaluated a rotary kiln gasification system utilizing agricultural wastes to generate syn gas. The goal of the project was to develop an efficient methodology for harnessing energy from agricultural waste. Objectives included: installation and cold testing of the gasification system; hot testing the gasification system with two agricultural wastes; development of an operations plan, including a data procurement and analysis plan; development of a predictive model and validation of the model; developing process improvement recommendations; and construction of two deployment pathway models (e.g., institutional and farm).
This research evaluated a rotary kiln gasification system utilizing agricultural wastes to generate syn gas. The goal of the project was to develop an efficient methodology for harnessing energy from agricultural waste. Objectives included: installation and cold testing of the gasification system; hot testing the gasification system with two agricultural wastes; development of an operations plan, including a data procurement and analysis plan; development of a predictive model and validation of the model; developing process improvement recommendations; and construction of two deployment pathway models (e.g., institutional and farm).
This research evaluated a rotary kiln gasification system utilizing agricultural wastes to generate syn gas. The goal of the project was to develop an efficient methodology for harnessing energy from agricultural waste. Objectives included: installation and cold testing of the gasification system; hot testing the gasification system with two agricultural wastes; development of an operations plan, including a data procurement and analysis plan; development of a predictive model and validation of the model; developing process improvement recommendations; and construction of two deployment pathway models (e.g., institutional and farm).
This research evaluated a rotary kiln gasification system utilizing agricultural wastes to generate syn gas. The goal of the project was to develop an efficient methodology for harnessing energy from agricultural waste. Objectives included: installation and cold testing of the gasification system; hot testing the gasification system with two agricultural wastes; development of an operations plan, including a data procurement and analysis plan; development of a predictive model and validation of the model; developing process improvement recommendations; and construction of two deployment pathway models (e.g., institutional and farm).
This research evaluated a rotary kiln gasification system utilizing agricultural wastes to generate syn gas. The goal of the project was to develop an efficient methodology for harnessing energy from agricultural waste. Objectives included: installation and cold testing of the gasification system; hot testing the gasification system with two agricultural wastes; development of an operations plan, including a data procurement and analysis plan; development of a predictive model and validation of the model; developing process improvement recommendations; and construction of two deployment pathway models (e.g., institutional and farm).
The present invention is directed to a method for providing an agricultural waste product having amorphous silica, carbon, and impurities; extracting from the agricultural waste product an amount of the impurities; changing the ratio of carbon to silica; and reducing the silica to a high purity silicon (e.g., to photovoltaic silicon).