Showing papers in "Clean Technologies and Environmental Policy in 2018"

An overview of biorefinery-derived platform chemicals from a cellulose and hemicellulose biorefinery

Abstract: Until recently, most of energy and industrially produced chemicals were derived from fossil fuel-based resources. This along with the continued depletion of finite fossil resources and their attributed adverse environmental impacts, alternatively sourced and more sustainable resources are being pursued as feedstock replacements. Thus, biomass has been identified as an alternate renewable and more sustainable resource as a means to reduce this sector's dependence on fossil fuel-based resources and to alleviate their environmental impacts. As such, lignocellulosic biomass has been further identified and demonstrated as an abundant renewable resource for the production of biofuels, platform chemicals, and their respective value-added products. This review article provides an overview of the techniques developed for the valorization of biomass in the production of platform chemicals within a biorefinery, and the status for commercialization.

The causal relationship between renewable energy consumption and economic growth: evidence from Europe

Abstract: The European Union Renewable Energy Directive sets an objective of increasing the renewable energy share of the used renewable energy in the EU by 2020. The objective of this study is to analyze and compare the short-run and long-run relationship between renewable energy consumption and economic growth in 12 European Union countries and to derive implications for renewable energy policy. To do so, we apply panel vector error correction model using the available annual data from 1990 to 2014 on 12 European Union countries. Moreover, Granger causality test is conducted to examine whether there exists any causal linkage between economic growth and renewable energy consumption. The findings indicate the presence of unidirectional causality running from economic growth to renewable energy consumption in the short run. However, in the long run, a bidirectional causal relationship between the variables in question exists.

An efficient conversion of waste feather keratin into ecofriendly bioplastic film

Abstract: Feathers biomass from poultry industry is considered as an important waste product, which creates serious environmental problems. In this study, keratin was extracted from waste chicken feathers using sodium sulfide as a reducing agent under optimized conditions. The extracted keratin particles were used to develop a bioploymeric film by adding microcrystalline cellulose as nano-additive agent. The calculated yield of 80.2% was obtained for keratin from feathers dry weight 25 g (w/w). The extracted keratin was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis, differential scanning calorimetry, wide-angle X-ray diffraction. The physiochemical characteristics of the feathers were compared with the keratin powder. The regenerated keratin particles preserved their chemical composition, thermal strength and stability after chemical extraction. The extracted keratin particles showed 10–20-µm spongy porous microparticles in SEM analysis. The keratin powder was used to synthesize a bioplastic film using glycerol (3.5%) and microcrystalline cellulose (0.2%) in NaOH for 48 h at 60 °C. The calculated thickness of bioplastic film was 1.12 × 10−4 mm with tensile strength of 3.62 ± 0.6 MPa. The Young’s modulus and break elongation for synthesized bioplastic film were 1.52 ± 0.34 MPa and 15.8 ± 2.2%, respectively. The feather and keratin showed maximum similarity index of 64.74% (l-alanyl, l-alanyl, l-alanine, p-nitroanilide) and 64.32% with d-pantethine, respectively, using OMNIC Specta software. Overall, the study presented a highly efficient method to convert the waste feather biomass into a bioplastic film which can be used in biopolymer, biomedical and pharmaceutical industries.

Coagulation–flocculation process with metal salts, synthetic polymers and biopolymers for the removal of trace metals (Cu, Pb, Ni, Zn) from municipal wastewater

Abstract: To ensure compliance with regulatory standards, it is important to examine the potential of treatment technologies to enhance trace metal removal from wastewater This study investigated the effectiveness of coagulation–flocculation at removing trace metals from humus effluent with ferric chloride (FeCl3), the synthetic polymer polyethyleneimine (PEI) and the biopolymers chitosan and floculan Effluent samples were collected from a trickling filter treatment works operating in the UK and contained 21 ± 4 μg/L Cu, 08 ± 01 μg/L Pb, 4 ± 1 μg/L Ni and 43 ± 9 μg/L Zn The influence of coagulant dosage and the velocity and time of the slow mixing stage were studied via a series of jar tests Chitosan and PEI had a moderate effect on the removal of trace metals (≤ 35%) FeCl3 removed 48% Cu, 56% Pb and 41% Zn at the optimised dose of 010 mg/L At the optimised dose of 025 mg/L, floculan removed 77% Cu, 68% Pb and 42% Zn The dominant mechanism for particle removal by FeCl3 was enmeshment in the precipitates (ie sweep flocculation), whereas, for floculan, inter-particle bridging was the dominant removal mechanism Overall, FeCl3 and floculan were found to be most effective at removing trace metals from wastewater

Novel mesoporous Fe3O4/SiO2/CTAB–SiO2 as an effective adsorbent for the removal of amoxicillin and tetracycline from water

Abstract: The current study was carried out to investigate the efficiency of using magnetic mesoporous of cetyltrimethylammonium bromide-functionalized silica-coated magnetite for removing amoxicillin (AMX) and tetracycline (TC) from tap water, river water, and medical wastewater as real samples. The properties of the synthesized adsorbent were characterized through transmission electron microscopy (TEM), scanning electron microscopy, X-ray diffraction spectrometry, Fourier transform infrared spectroscopy, vibrating sample magnetometry, pHpzc, and also Brunauer, Emmett, and Teller (BET) methods. The BET surface area and the average diameter of mesoporous Fe3O4/SiO2/CTAB–SiO2 in accordance with TEM were 157.8 m2 g−1 and around 55 nm, respectively. In batch tests, the adsorption parameters, including the initial concentration, contact time, pH of solution, ionic strength, and adsorbent dose, were analysed. The experimental adsorption data were modelled using different classical and recently developed models. According to the results, the maximum adsorption capacities of AMX and TC on mesoporous Fe3O4/SiO2/CTAB–SiO2 were found to be 362.66 and 220.70 mg g−1, respectively. Also, the results indicated that AMX and TC loaded on the adsorbent could be easily desorbed with 0.1 mol L−1 HNO3+ acetonitrile (1:1, v/v) and the adsorbent showed good reusability for the adsorption of the drugs studied.

Optimization of biodiesel production from waste cooking oil by magnesium oxide nanocatalyst synthesized using coprecipitation method

Abstract: Nanostructured magnesium oxide (MgO) catalysts were prepared by the coprecipitation method and employed for the transesterification of waste cooking oil using methanol. The X-ray diffraction analysis showed that nanostructured MgO phase was formed at calcination temperature of 500 °C. The mean crystallite size of MgO nanoparticles is 7.86 nm. Fourier-transformed infrared spectroscopy studies confirmed the formation of MgO phase with the characteristic vibrational mode of Mg–O. UV–Vis diffuse reflectance spectroscopy reveals that the energy band gap is around 5.84 eV. The presence of magnesium and oxygen elements was determined from energy-dispersive X-ray analysis. The effect of various parameters such as catalyst loading, methanol-to-oil molar ratio, reaction temperature, reaction time and reusability was investigated. A maximum biodiesel yield of 93.3% was achieved with 2 wt% of MgO nanocatalyst (MO5 sample), methanol/oil molar ratio of 24:1, reaction temperature about 65 °C and reaction time 1 h. The nanocatalyst (MgO) was reused at least for 5 times and thereafter resulted in a decrease in the biodiesel yield. The kinetic study of the transesterification reaction followed pseudo-first-order rate kinetics. The composition of fatty acid methyl ester was determined using gas chromatography–mass spectroscopy.

A novel integrated decision-making approach for the evaluation and selection of renewable energy technologies

Abstract: The decision-making in energy sector involves finding a set of energy sources and conversion devices to meet the energy demands in an optimal way. Making an energy planning decision involves the balancing of diverse ecological, social, technical and economic aspects across space and time. Usually, technical and environmental aspects are represented in the form of multiple criteria and indicators that are often expressed as conflicting objectives. In order to attain higher efficiency in the implementation of renewable energy (RE) systems, the developers and investors have to deploy multi-criteria decision-making techniques. In this paper, a novel hybrid Decision Making Trial and Evaluation Laboratory and analytic network process (DEMATEL-ANP) model is proposed in order to stress the importance of the evaluation criteria when selecting alternative REs and the causal relationships between the criteria. Finally, complex proportional assessment and weighted aggregated sum product assessment methods are used to assess the performances of the REs with respect to different evaluating criteria. An illustrative example from Costs assessment of sustainable energy systems (CASES) project, financed by European Commission Framework 6 programme (EU FM 6) for EU member states is presented in order to demonstrate the application feasibility of the proposed model for the comparative assessment and ranking of RE technologies. Sensitivity analysis, result validation and critical outcomes are provided as well to offer guidelines for the policy makers in the selection of the best alternative RE with the maximum effectiveness.

Recycling of glass in synthesis of MCM-48 mesoporous silica as catalyst support for Ni 2 O 3 photocatalyst for Congo red dye removal

Abstract: Glass was successfully recycled in the synthesis of mesoporous silica MCM-48 which was used as catalyst support for nickel oxide photocatalyst. The resulted products were evaluated using X-ray diffraction, scanning electron microscope and UV–Vis spectrophotometer. The precipitated nickel oxide is of Ni2O3 form and loading of it onto MCM-48 resulted in a reduction in the band gap energy from about 3.66 eV to about 2.4 eV. The role of MCM-48 as catalyst support for Ni2O3 in enhancing the adsorption capacity and photocatalytic properties of nickel oxide was evaluated through series of equilibrium studies and photocatalytic degradation of Congo red dye under visible light. Using of glass-based MCM-48 as catalyst support for Ni2O3 showed enhancing the adsorption capacity by 31.3 and 14.8% higher than the adsorption capacity of Ni2O3 and MCM-48, respectively. Also, the photocatalytic degradation percentage increased by about 67.3% relative to the Ni2O3 degradation percentage. The nature of MCM-48/Ni2O3 adsorption mechanism is chemisorption and occurs in multilayer form throughout the heterogeneous surface of the composite. The using of MCM-48 as support for Ni2O3 photocatalyst enhanced the adsorption capacity through increasing the total surface area. The loading process resulted in fixing of the Ni2O3 particles throughout the porous structure which producing more exposed active photocatalyst sites and active adsorption sites for the incident photons as well as preventing the nickel oxide particles from agglomeration. Based on the obtained results, supporting of Ni2O3 particles onto MCM-48 is promising active centers for the degradation of Congo red dye molecules.

Biochar production from microalgae cultivation through pyrolysis as a sustainable carbon sequestration and biorefinery approach

Abstract: Microalgae cultivation and biomass to biochar conversion is a potential approach for global carbon sequestration in microalgal biorefinery. Excessive atmospheric carbon dioxide (CO2) is utilized in microalgal biomass cultivation for biochar production. In the current study, microalgal biomass productivity was determined using different CO2 concentrations for biochar production, and the physicochemical properties of microalgal biochar were characterized to determine its potential applications for carbon sequestration and biorefinery. The indigenous microalga Chlorella vulgaris FSP-E was cultivated in photobioreactors under controlled environment with different CO2 gas concentrations as the sole carbon source. Microalgal biomass pyrolysis was performed thereafter in a fixed-bed reactor to produce biochar and other coproducts. C. vulgaris FSP-E showed a maximum biomass productivity of 0.87 g L−1 day−1. A biochar yield of 26.9% was obtained from pyrolysis under an optimum temperature of 500 °C at a heating rate of 10 °C min−1. C. vulgaris FSP-E biochar showed an alkaline pH value of 8.1 with H/C and O/C atomic ratios beneficial for carbon sequestration and soil application. The potential use of microalgal biochar as an alternative coal was also demonstrated by the increased heating value of 23.42 MJ kg−1. C. vulgaris FSP-E biochar exhibited a surface morphology, thereby suggesting its applicability as a bio-adsorbent. The cultivation of microalgae C. vulgaris FSP-E and the production of its respective biochar is a potential approach as clean technology for carbon sequestration and microalgal biorefinery toward a sustainable environment.

Optimization of solid waste management in rural villages of developing countries

Abstract: Optimum municipal solid waste (MSW) management system is an essential aspect to be considered. Optimal MSW management system could incur high cost of investment related to its construction, operation, and maintenance. The optimal configurations of the technologies within the system are of high importance, especially in developing countries due to the limitation on financial support. There are still limited studies on the integration of the possible configurations of the selected MSW management, which are centralized, clustered, and decentralized, in addition to location planning. A cost optimization model with the consideration of location planning is developed to identify the optimal configuration of the MSW management system with technologies considered such as landfilling, composting, refuse derived fuel, and reuse and recycling. The configuration considered in the study includes a centralized system, where all waste is gathered in a specific location and treated. The second configuration is the clustered system, where zones are identified, and waste treatment center is built in each zone. Finally, the decentralized, where smaller treatment centers are built at each village. The case study took place at the Desoq District, Kafr El Sheikh, Egypt. It is inhabited with a population of about 0.5 M capita. Fifteen scenarios are generated to account for the different combination of system configurations and the type of waste treatment and disposal unit. A mixed integer linear programming (MILP) model is developed to perform the optimization. The results showed that increasing in the type and degree of treatment increases the net profit. This means that the incorporation of sorting, recycling, composting and RDF production leads to higher profit compared to landfilling only. The centralized systems turned out to attain more net profit than decentralized and clustered systems. The optimum scenario with maximum net profit value was the centralized system with sorting, composting, waste to energy facilities, and one landfill with a net profit of 3.864 USD/t/d. The optimal location for such centralized system is identified to be located beside Desoq wastewater treatment plant and between Desoq and Sanhour cities. The same model can be applied to other rural areas in developing countries.

Biomass ash-based mineral admixture prepared from municipal sewage sludge and its application in cement composites

Abstract: Biomass as the biodegradable fraction of both agricultural products and industrial and municipal waste is currently a versatile energy resource. It can be stored and converted in practically any form of energy carrier and also into biochemicals and biomaterials from which, once they have been used, the energy content can be recovered to generate electricity, heat, or transport fuels. Moreover, the residues of its incineration can often be reused as pozzolanic additions to cement which can be considered as an environmentally friendly way of their disposal. In this paper, municipal sewage sludge with the organic carbon content of 27% was used for the preparation of biomass ash that should potentially find use as environmentally friendly mineral admixture to construction binders. Based on physical and chemical characterization of the raw material that showed a suitable chemical and phase composition, organic matter in a significant amount, and no thermal decomposition processes above 700 °C, biomass ash was produced. The biomass ash was obtained by incineration of sewage sludge at 700 °C, and mechanical activation contained 52% of amorphous phase which correlates with its good pozzolanic activity. The concentration of heavy metals, soluble chlorides, nitrates, and sulfates in biomass ash is found well below the standard permissible values. The composites prepared with a biomass ash dosage of 10, 20, and 30 wt% of Portland cement exhibited good functional properties. The increase in porosity up to 6% and decrease in compressive strength up to 3% were satisfactory. The results of leaching tests showed that composites with biomass ash contain only trace amounts of chlorides, nitrates, and sulfates. Apparently, the chlorides contained in biomass ash (0.7 mg/g) were immobilized in the cement matrix because the amounts of leached chlorides (0.04 wt%) were the same for all composites and well below the permissible limit for concrete. As revealed by the X-ray diffraction and thermogravimetric analyses, a significant decrease in portlandite content with increasing biomass ash content confirmed the pozzolanic reaction in biomass ash containing composite mixes. The environmental assessment showed a significant decrease in both carbon dioxide production and energy consumption with the increasing biomass ash content. For the composite with 30% biomass ash dosage, it was 21% of CO2 and 11% of energy, as compared with the reference mix. The combination of good functional and environmental parameters of the analyzed composites makes good prerequisites for their application in construction industry. Taylor-made mineral admixture on biomass ash basis can find a broad use as eco-efficient admixture to cement- and lime-based binders.

Techno-economic assessment of bioethanol production from wheat straw: a case study of Iran

Abstract: A process of ethanol production from wheat straw in Iran was simulated using SuperPro Designer. Wheat is the main cereal crop in Iran. Khuzestan Province was selected as a potential location for the construction of plant. A method was developed to estimate the plant capacity. The base plant size in Khuzestan was estimated to be 316 t day−1. The effect of plant size, logistics of residue collection, wheat yield, and agreements with local farmers on the profitability was calculated, and the minimum selling price was determined for different scenarios. In addition, the sensitivity analysis and economic risk assessment were conducted. The operating cost was mainly sensitive to the wheat straw and enzyme costs. The Monte Carlo simulation results showed that the risk of the base case biorefinery is fairly acceptable at moderate to high selling prices, and increasing the plant size could lessen the risk at lower ethanol selling prices.

Waste to energy: the effects of Pseudomonas sp. on Chlorella sorokiniana biomass and lipid productions in palm oil mill effluent

Abstract: Microalgae are recognised as promising feedstock for biofuel production. The feasibility in commercial scale microalgae cultivation could be enhanced by incorporating palm oil mill effluent (POME) as culture medium, for greater biomass growth and lipid production, together with POME bioremediation. The polluting POME is generated massively in Malaysia. POME contains high concentrations of carbon and nutrients, thus it is suitable to be applied for microalgae cultivation. The approach on waste to energy should be advanced. We studied the effects of applying Pseudomonas sp. on Chlorella sorokiniana CY-1 cultivation in POME. Pseudomonas sp. was found effective in POME decolourisation prior to C. sorokiniana CY-1 cultivation. Yet, microalgae biomass and lipid productions were higher in the non-decolourised POME. Pseudomonas sp. was as well-being co-cultivated with C. sorokiniana CY-1 in ratios of microalgae versus bacteria of 1:1; 2:1 and 1:2. Biomass of 2.04 g L−1 and biomass productivity of 185.71 mg L−1 d−1 were attained in ratio of 1:1. Interestingly, the lipid content exhibited was excellent (16.04%), and about twofold higher than other ratios and the control (without bacteria). Fatty acids compositions were dominated by C16:0 (32.49%), C18:1 (24.06%) and C18:2 (20.28%), which were desirable fatty acids for biodiesel production. Effective POME bioremediation achieved with chemical oxygen demand, total nitrogen and total phosphorus removal of 53.7, 55.6 and 77.3%, respectively. Co-cultivation of microalgae and bacteria can be applied in the POME treatment plant. This allows satisfactory biomass and excellent lipid yields for biofuel production, as well as effective wastewater bioremediation.

Comparative life cycle assessment of lithium-ion batteries with lithium metal, silicon nanowire, and graphite anodes

Abstract: Lithium metal and silicon nanowires, with higher specific capacity than graphite, are the most promising alternative advanced anode materials for use in next-generation batteries. By comparing three batteries designed, respectively, with a lithium metal anode, a silicon nanowire anode, and a graphite anode, the authors strive to analyse the life cycle of different negative electrodes with different specific capacities and compare their cradle-to-gate environmental impacts. This paper finds that a higher specific capacity of the negative material causes lower environmental impact of the same battery. The battery with a lithium metal anode has a lower environmental impact than the battery with a graphite anode. Surprisingly, although the silicon nanowire anode has a higher specific energy than graphite, the production of a battery with silicon nanowires causes a higher environmental impact than the production of a battery with graphite. In fact, the high specific energy of silicon nanowires can decrease the environmental impact of a battery with silicon nanowires, but silicon nanowire preparation causes extremely high emissions. Therefore, batteries with lithium metal anodes are the most environmentally friendly lithium-ion batteries. Batteries with lithium metal anodes could be the next generation of environmentally friendly batteries for electric vehicles.

Water vortex hydropower technology: a state-of-the-art review of developmental trends

Abstract: With the explosive growth of global energy demand coupled with effects of climate change, there is a significant shift towards green energy generation in recent years. Of the various renewable energy resources available, micro-hydro-power and pico-hydro-power remain very popular in both developed and developing countries. Since 2006, significant growth has spurted in the use of artificial free-surface vortices to generate low and ultra-low-head hydropower following the development of the so-called gravitational water vortex hydropower plant. The technology works on the principle of harnessing hydroelectric power from the high angular velocity experienced in the core of a whirlpool generated in a vortex chamber. In this article, a state-of-the-art review is undertaken on the vortex hydropower technology including a historical review of the technology, the underlying hydraulic principles of such devices, overview of research and technologies that have been deployed to date together with an evaluation of their performance and key findings. Currently, there are 19–22 known live vortex hydropower technologies operating internationally with key academic and commercial research activity in Europe and Asia. The average efficiency from these sites was found to be in the region of 53% which is lower than conventional propeller turbines but higher than waterwheel systems. It was found that the vortex plant, due to its ability to sustain relatively high efficiencies at low heads and small to medium flow rates, addresses a gap in the current turbine application chart. Its key advantage lies in the high-power densities produced compared with conventional technologies. The system also demonstrates potential to be able to function as a fish passage; however, stronger validation is required to prove this for a range of turbine systems. Finally, the authors propose a number of areas that should be investigated that should provide immediate improvements to the turbine in terms of performance.

Optimization of biofuels production via a water–energy–food nexus framework

Abstract: Biofuels have emerged as an attractive renewable alternative to satisfy the global energy demands. The large-scale production of biofuels requires the installation of biorefining systems that involve strategic decisions for the logistics and operation in the production of biofuels such as location, feedstock type(s), production capacities and interactions with the surrounding environment. This work proposes an optimization framework for the design of a biorefining system while accounting for the interactions with the surrounding watershed using a material flow analysis technique through the design of an efficient supply chain for the production and distribution of feedstocks, grains and biofuels considering the water and land requirements. The proposed model deals with the uncertainty involved in the project (e.g., prices of feedstocks and products, biofuel demands and precipitation in the watershed). A mixed-integer linear programming model is proposed to simultaneously consider the economic and environmental objectives. A case study located in Mexico is solved for a set of scenarios with the purpose of illustrating the capabilities of the proposed optimization approach. The results show strong trade-offs between the considered objectives and the impact of uncertainties.

Fire-resistant geopolymer bricks synthesized from high-calcium fly ash with outdoor heat exposure

Abstract: This research proposed an alternative utilization of high-calcium fly ash to produce geopolymer bricks for fire-resistant applications. Outdoor heat exposure (OHE) was applied to cure geopolymer mortar. The temperature was up to 40 °C. Geopolymer brick was created with a 30-day compressive strength of 47 MPa via OHE curing for 3 days. The brick experienced a low weight loss after the firing test, which indicated its fire-resistant property. For the flame test, the maximum temperature on the opposite side of the brick from the flame was lower than 380 °C, with no observable cracks, complying with the fire-test requirement. Therefore, high-calcium fly ash geopolymer cured with OHE is suitable for use as a fire-resistant material. In addition, outdoor heat exposure is a promising renewable means to cure geopolymer.

Biological treatment of oil and gas produced water: a review and meta-analysis

Abstract: Biological treatment is effective but infrequently used for oil and gas produced water. To date, physical–chemical treatment methods have been favored due to the smaller space requirements and operational simplicity. Changing regulatory requirements and increased interest in recycling and beneficial reuse have led to increased interest in biological treatment. To elucidate its potential role, we reviewed and summarized 59 studies on the biological treatment of produced water. Oilfield produced water was predominantly studied (> 50%). More studies using real produced water were from China than from any other country (37%). Real produced water was used in most studies (73%). Studies were predominantly bench-scale experiments (69%). Fixed-film reactors were most prevalent (27%). Water quality of produced waters treated was variable; median total dissolved solids (TDS) was 28,000 mg L−1 and median chemical oxygen demand (COD) was 1125 mg L−1. Inhibition by salinity was variable according to the treatment system and study design, but efficacy generally decreased when TDS was above 50,000 mg L−1. For studies treating real samples, average COD removal was 73% when TDS was less than 50,000 mg L−1, and 54% when TDS was greater than 50,000 mg L−1. Key issues were microbial acclimation, toxicity, biological fouling, and mineral scaling. Finding an inoculum was not problematic as microorganisms capable of degrading hydrocarbons were isolated from various environments. Treatment performance was better where synthetic produced water was used in lieu of real samples. Biological treatment is promising for producing effluents suitable for reuse, particularly where it functions as part of a larger treatment train.

Techno-economic analysis of organosolv pretreatment process from lignocellulosic biomass

Abstract: Lignocellulosic ethanol is a promising alternative to replace liquid fossil fuels for the transportation sector in the near future. Organosolv pretreatment has been tested as a method for separating lignin from the biomass and commercializing it as a biopolymer. Based on published laboratory scale data, we propose a feasible process flowsheet for organosolv pretreatment. Simulation of the pretreatment process provided mass and energy balances for a techno-economic analysis, and the values were compared with the most prevalent and mature pretreatment method: diluted acid. Organosolv pretreatment required more energy, 578.1 versus 213.8 MW for diluted acid pretreatment, but resulted in a higher ethanol concentration after the biomass fermentation, 11.1% compared to 5.4%. Total annual costs (TACs) calculations showed advantages for diluted acid pretreatment, but future improvements explored in the sensitivity analysis turned into possible savings of 42.8% in the minimum ethanol selling price for organosolv pretreatment.

Agave bagasse biorefinery: processing and perspectives

Abstract: Agave bagasse (AB) is the main solid waste generated by the tequila industry in Mexico, which is an environmental concern due to its considerable volume of production (377,000 Ton in 2016). AB is a lignocellulosic biomass that has been considered as a potential feedstock for different industrial uses in the framework of lignocellulosic biorefinery concept. The lignocellulosic biomass is a complex structure constituted by cellulose, hemicellulose and lignin. Therefore, for a complete waste revalorization, different processing steps would be required. In this work, the scientific advances toward the AB biorefinery composed by three sequential stages: pretreatment, treatment and biofuels production were reviewed. Moreover, the by-products of the process could also be recovered and used for the synthesis of value-added products. This integrative approach of AB in the conceptualized biorefinery generates positive impacts on environment as well as on local and regional economies.

Integrating bioelectrochemical systems for sustainable wastewater treatment

Abstract: Current wastewater treatment processes such as activated sludge process and other aeration technologies are resource-consuming and are unsustainable. Novel and integrated processes are crucial to the development of sustainable wastewater treatment systems. In this context, anaerobic treatment technologies provide numerous opportunities for minimization of energy and resource consumption and maximization of beneficial products. Further, integration of anaerobic digestion augmented by co-digestion, fermentation, dark fermentation or photo-fermentation and other bioelectrochemical systems may result in resource-efficient waste management and environmental protection. This mini-review discusses various possibilities and highlights recent developments of integrated aerobic and anaerobic technologies with bioelectrochemical systems for sustainable wastewater treatment.

Improved design for textile production process based on life cycle assessment

Abstract: The textile industry has a high environmental impact, discharging significant amounts of industrial water, consuming high levels of energy, and emitting vast amounts of air pollutants. To meet the requirement of sustainable manufacturing, we built a system-oriented improved design framework based on life cycle assessment (LCA) for an existing polyester–cotton production system to reduce the environmental impacts of the production process. LCA was used to identify candidates for best available technology (BAT) development. The effect of the BATs on environmental, economic, and product performance was evaluated. LCA identified that polyester–cotton production exerted the greatest environmental impacts on marine aquatic ecotoxicity potential, global warming potential, and abiotic depletion. The printing and dyeing stages of the production process were the most damaging to the environment. Six BATs were proposed and all were feasible with clear economic and environmental benefits, as the resource depletion, ecological influence, and human health values were reduced by 50.13, 50.08, and 7.65%, respectively, compared with the existing process. In addition, the quality of the products, such as color fastness and color shade, was greatly improved. We suggest that future studies should also take into consideration the distribution and use stage using accurate and representative original data, to further improve the sustainability of the production process. Human health, fertilizer leakage, land use, and pesticides should also be taken into account within the life cycle of textiles.

Model fuel desulfurization and denitrogenation using copper and cerium modified mesoporous material (MSU-S) through adsorption process

Abstract: The application of MSU-S, CeO2-MSU-S, and Cu2O-MSU-S in desulfurization and denitrogenation of model fuel containing benzothiophene (BT), dibenzothiophene (DBT), quinoline and carbazole were studied in batch and continuous process. The copper-modified MSU-S showed the highest capacity to adsorb sulfur and nitrogen compounds compared to other adsorbents. The adsorption selectivity of all adsorbents for nitrogen was slightly higher than for sulfur, indicating the selective adsorption of nitrogen over sulfur. The Langmuir model represented better equilibrium data fitting than Freundlich model for carbazole, DBT, and BT adsorption on MSU-S, CeO2-MSU-S, and Cu2O-MSU-S. It was found that quinoline adsorption data on MSU-S, CeO2-MSU-S, and Cu2O-MSU-S can be presented by Freundlich model very well. The kinetics of adsorption followed the pseudo-second-order model for all species over each adsorbent. According to the breakthrough curve order, the adsorptive selectivity for the adsorbates increased in the order of DBT < BT < carbazole < quinoline for MSU-S and CeO2-MSU-S, and BT < DBT < carbazole < quinoline for Cu2O-MSU-S.

Renewable energy transition: a market-driven solution for the energy and environmental concerns in Chile

Abstract: Chile is undergoing a remarkable energy matrix transition to renewable energy. Renewable energies are expanding extraordinarily fast, exceeding earlier predictions. As a result, the country is expected to meet its 2025 goal of generating 20% of its electricity from renewable energy sources quite before. Chile has become one of the first countries in the world with subsidy-free markets, where renewable projects compete directly with other conventional sources. Favorable market conditions and successful policy reforms were keys to fostering this renewable energy development. Although the country has achieved a substantial growth in renewable energy investment in a relatively short period of time, this optimism should be treated with caution. A successful transition requires a combination of a clear decision making, persistent and consistent government policies, and a clear commitment to tackling challenges to accommodate renewable energy in the power system. In this context, this paper analyses the Chilean renewable industry and the required government policies to succeed in this transition. For this purpose, we identify several critical factors that have attracted and that could attract investment to the renewable energy sector and propose key recommendations to effectively address the major challenges faced for the future development of the industry.

An optimization study of a palm oil-based regional bio-energy supply chain under carbon pricing and trading policies

Abstract: Biomass residues due to their low bulk density typically require frequent transportation from biomass plantations in rural areas to conversion bio-energy power plants. This issue contrasts with environmental protection strategies, especially when power plants are facing different carbon reduction policies that enforce them to emit less than a given specific carbon amount. Although several researchers have investigated bio-energy supply chains concerning environmental policies, the majority of studies have been devoted to strategic decisions over a single planning period. This paper presents a multi-period bio-energy supply chain under carbon pricing (carbon tax) and carbon trading (cap-and-trade) policies at the tactical planning level. A mixed-integer linear programming model was adopted to optimize the proposed regional oil-palm biomass-to-bio-energy supply chain planning model. The numerical results indicate that when carbon pricing is in place when carbon tax increases linearly, carbon emissions’ reductions have a nonlinear trend, whereas both cost increase and carbon emissions’ reductions have a relatively upward trend in the carbon trading scheme. This paper also presents the sensitivity analysis of the proposed model regarding cost, emissions’ generation and supply chain performance. Finally, the paper recommends several significant practical implications and policy-making insights for managers and policymakers.

Comparative LCA of technology improvement opportunities for a 1.5-MW wind turbine in the context of an onshore wind farm

Abstract: This paper presents life cycle assessment (LCA) results of design variations for a 1.5-MW wind turbine due to the potential for advances in technology to improve their performance. Five LCAs have been conducted for design variants of a 1.5-MW wind turbine. The objective is to evaluate potential environmental impacts per kilowatt hour of electricity generated for a 114-MW onshore wind farm. Results for the baseline turbine show that higher contributions to impacts were obtained in the categories of ozone depletion potential, marine aquatic eco-toxicity potential, human toxicity potential and terrestrial eco-toxicity potential compared to technology improvement opportunities (TIOs) 1–4. Compared to the baseline turbine, TIO 1 with advanced rotors and reduced tower mass showed increased impact contributions to abiotic depletion potential, acidification potential, eutrophication potential, global warming potential and photochemical ozone creation potential, and TIO 2 with a new tower concept involving improved tower height showed an increase in contributions to abiotic depletion potential, acidification potential and global warming potential. Additionally, lower contributions to all the environmental categories were observed for TIO 3 with drivetrain improvements using permanent magnet generators while increased contributions towards abiotic depletion potential and global warming potential were noted for TIO 4 which combines TIO 1, TIO 2 and TIO 3. A comparative LCA study of wind turbine design variations for a particular power rating has not been explored in the literature. This study presents new insight into the environmental implications related with projected wind turbine design advancements.

Comparative life cycle assessment (LCA) of bio-modified binder and conventional asphalt binder

Abstract: This study is a life cycle assessment (LCA) of conventional asphalt binder versus bio-modified binder that is produced by mixing asphalt binder with bio-binder obtained from swine manure. Both processes were evaluated and compared in terms of their contribution to global warming, using a global warming potential index and energy consumption. This LCA study uses a cradle-to-gate approach for the binder and includes a comparison between the environmental impacts of swine manure in lagoons and the production of bio-binder. The results show the energy consumption and global warming potential improvements after using bio-binder as a sustainable additive.

Treatment of palm oil mill effluent (POME) by coagulation flocculation process using peanut–okra and wheat germ–okra

Abstract: Coagulation–flocculation has been proven as one of the effective processes in treating palm oil mill effluent (POME), which is a highly polluted wastewater generated from palm oil milling process. Two pairs of natural coagulant–flocculant were studied and evaluated: peanut–okra and wheat germ–okra. This research aims to optimize the operating parameters of the coagulation flocculation process in removing turbidity, total suspended solid and chemical oxygen demand (COD) from POME by using a central composite design in the Design Expert® software. Important parameters such as operating pH, coagulant and flocculant dosages were empirically determined using jar test experiment and optimized using response surface methodology module. Significant quadratic polynomial models were obtained via regression analyses (R2) for peanut–okra (0.9355, 0.9534 and 0.8586 for turbidity, total suspended solids and COD removal, respectively) and wheat germ–okra (0.9638, 0.9578 and 0.7691 for turbidity, total suspended solids and COD removal, respectively). The highest observed removal efficiencies of turbidity, total suspended solids and COD (92.5, 86.6 and 34.8%, respectively, for peanut–okra; 86.6, 87.5 and 43.6%, respectively, for wheat germ–okra) were obtained at optimum pH, coagulant and flocculant dosages (pH 11.6, 1000.1 mg/L and 135.5 mg/L, respectively, for peanut–okra; pH 12, 1170.5 mg/L and 100 mg/L, respectively, for wheat germ–okra). The coagulation flocculation performance of peanut–okra and wheat germ–okra were comparable to each other. Characterizations of the natural coagulant–flocculant, as well as the sludge produced, were performed using Fourier transform infrared, energy-dispersive X-ray spectroscopy and field emission scanning electron microscope. More than 98% of water was removed from POME sludge by using centrifuge and drying methods, indicating that a significant reduction in sludge volume was achieved.

How to assess sustainability of countries via inverse data envelopment analysis

Abstract: In this paper, two input-oriented and output-oriented inverse semi-oriented radial measures are presented. Such models are applied to determine resource allocation and investment strategies for assessing sustainability of countries. Our proposed models can deal with both positive and negative data. In our proposed inverse input-oriented data envelopment analysis (DEA) model, optimal inputs are suggested while outputs and efficiency score of decision-making unit (DMU) under evaluation are unchanged. Similarly, in our proposed inverse output-oriented DEA model, optimal outputs are proposed while inputs and efficiency score of DMU under evaluation are kept unchanged. For the first time, we propose two new inverse DEA models to handle resource allocation and investment analysis problems given sustainable development aspects in the presence of negative data. A case study is given for assessing sustainability of countries.

Biochemical methane potential of brewery by-products

Abstract: Beer production generates by-products with high energy potential, namely trub (Tr, dead yeast from the fermentation) and spent grain (SG, smashed barley grains). This work investigates the biochemical methane potential (BMP, volume of methane produced per volatile solids of substrate—L kg−1) of these by-products, performing batch anaerobic biodegradability assays. Single substrates were evaluated as well as a mixture of Tr:SG (1:9, weight), in order to simulate the relative proportion generated in breweries. Tr reached the highest BMP [(515 ± 4) L kg−1], still, considering the total amount of by-product available, the mixture of Tr:SG proved to be more rewarding in terms of volume of methane produced. The co-digestion of Tr:SG with crude glycerol (cGly), which was chosen as a co-substrate to promote a synergetic effect on their biodegradability, was assessed by adding different amounts of cGly, up to 33% (in weight). The assay with 10% of cGly achieved the highest methane production [(573 ± 9) L kg−1] and biodegradability [(94 ± 2) %], evidencing its potential for energy generation. The co-digestion of these by-products presented a potential electricity production of 206 kWh per cubic meter of beer produced, being capable of serving 80% of the brewer’s energy needs for heating.