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

Clean Technologies and Environmental Policy - A process of ethanol production from wheat straw in Iran was simulated using SuperPro Designer. Wheat is the main cereal crop in Iran. Khuzestan...     

Pb(II) and Cd(II) removal from aqueous solutions by olive cake

The removal of heavy metals from wastewater using olive cake as an adsorbent was investigated. The effect of the contact time, pH, temperature, and concentration of adsorbate on adsorption performance of olive cake for Pb(II) and Cd(II) ions were examined by batch method. Adsorption of Pb(II) and Cd(II) in aqueous solution onto olive cake was studied in single component. After establishing the optimum conditions, elution of these ions from the adsorbent surface was also examined. The optimum sorption conditions were determined for two elements. Maximum desorption of the Pb(II) and Cd(II) ions were found to be 95.92 and 53.97% by 0.5M HNO(3) and 0.2M HCl, respectively. The morphological analysis of the olive cake was performed by the scanning electron microscopy (SEM).     

Techno-economic evaluation of PHB production from activated sludge

Activated sludge biomass enriched under suitable conditions is a promising source for poly-3-hydroxybutyrate (PHB) production, a biodegradable polymer. The techno-economic evaluation of PHB production using activated sludge biomass has been carried out. The PHB yield and plant capacity was found to significantly affect the PHB production cost. The PHB production cost for a plant processing (fermentation) capacity of 100 m³/day and 44% PHB yield is about US$ 11.8/kg, which reduces to US$ 5.38/kg for 1,000 m³/day plant capacity and 70% PHB yield. The cost of the carbon substrate was found to significantly affect the overall economics of PHB production.     

Hydrophilic olive cake extracts: characterization by physicochemical properties and Cu(II) complexation

Disposed olive cake generates hydrophilic components that can be mobilized in the aquatic environment. This paper deals with the characterization of such components, isolated by alkaline extraction. It is shown that these substances possess properties very much resembling humic acid, including a substantial inventory of proton exchanging groups. Extraction and purification of the hydrophilic components from the disposed olive cake was performed by the standard approach for isolation of humic acids from solid sources, i.e. alternating alkaline dissolution and acid flocculation, leaving the purified extract in the protonated form. The purified sample was characterized by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Fourier Transform Infra Red Spectroscopy (FTIR), UV-vis, Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and Asymmetrical Flow Field-Flow Fractionation (AFFFF). The complex formation properties were investigated by potentiometry using Cu(II) ion selective electrode under atmospheric conditions at I=0.1M NaClO(4) (aqueous solution) and pH 6. The formation constant for the CuHA complex is found to be logbeta=5.3+/-0.4 which is close to the corresponding value (logbeta=5.2+/-0.4) obtained from similar investigations with the commercially available Aldrich humic acid (this study) and corresponding published values for various humic acids. Both, structural properties and complex formation data show that the olive cake extract has considerable similarities with humic acids from different sources, pointing towards potential similarities in environmental behavior and impact.     

Techno-economic analysis of green hydrogen production from biogas autothermal reforming

The development and deployment of energy mix hydrogen production technologies, and the prospect of supplying “green” hydrogen to fuel-cell cars are expected to play significant roles in the near future. The sustainability of the process is a key enabler for a hydrogen-including economy. A techno-economic analysis of the BioRobur technology, which involves the green hydrogen production of 100 N m³ H₂/h (5.0 grade), has been performed in this study to provide a basis for comparison between the final cost of the hydrogen and the European target. Moreover, a technology for its eventual implementation has been addressed, in which the weakness and strengths have been identified by means of a SWOT analysis. The cost and supply analysis of this biogas-to-hydrogen production system, via autothermal reforming, indicates that municipal solid waste (MSW) is an important source of the low-cost supply of biogas-derived hydrogen. As far as the market potential is concerned, this analysis suggests that MSW can provide about 286,607 kg/day at 5 €/kg H₂ (delivery cost). Additionally, after 10 years of amortization, the final cost to produce 100 N m³/h of H₂ would be 2.5 €/kg, which is far lower than the European target for the cost of obtaining H₂ through biogas reforming, that is, 5 €/kg of H₂.     

Biohydrogen production from agroindustrial wastes via Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564)

The anaerobic production of biohydrogen from different pretreated agroindustrial wastes, including rice bran (RB), de-oiled RB (DRB), sago starch (SS), and palm oil mill effluent (POME) via Clostridium saccharoperbutylacetonicum N1-4 was investigated in a batch culture system at 30 °C and a pH of 6.2. A yield of 7627, 6995, and 6,363 mL H₂/L was obtained from H₂SO₄ (1 %)-treated DRB (10 %), enzymatically hydrolyzed DRB (10 %) and HCl (1 %)-treated DRB (10 %), respectively; however, untreated DRB (10 %) was able to produce only 3,286 mL H₂/L. A strategic treatment of RB (10 %) with HCl (1 %) followed by enzymatic hydrolysis could produce 3,172 mL H₂/L. An enzymatically hydrolyzed mixture of each POME and SS (5 %) produced 3,474 mL H₂/L, and a remarkable enhancement of H₂ production (7,020 mL H₂/L) was achieved when the same mixture was subjected to XAD-4 resin treatment. In contrast, the enzymatically hydrolyzed SS (5 %) could produce only 4,628 mL H₂/L. Conclusively, it can be stated that agricultural wastes have a potential as substrates for biohydrogen production and that pretreatment with C. saccharoperbutylacetonicum N1-4 can contribute positively to enhancing the production.     

Utilization of microwave and ultrasound pretreatments in the production of bioethanol from corn

Bioethanol production by simultaneous saccharification and fermentation (SSF) of corn meal by Saccharomyces cerevisiae var. ellipsoideus yeast in a batch system with prior ultrasound or microwave treatment was studied. The optimal duration of the pretreatments and the SSF process kinetics were assessed and determined. Also, the effect of ultrasound and microwave pretreatments on ethanol yield and productivity was investigated. An optimal duration of 5 min was determined for both pretreatments. Ultrasonic and microwave pretreatments effectively increased the glucose concentration obtained after liquefaction by 6.82 and 8.48%, respectively, compared to untreated control sample. Also, both pretreatments improved ethanol yield and productivity during the SSF process. Ultrasound and microwave pretreatments increased the maximum ethanol concentration produced in the SSF process by 11.15 and 13.40% (compared to the control sample), respectively. The application of microwave pretreatment resulted in higher glucose release during liquefaction and consequently in higher ethanol concentration, compared to ultrasound pretreatment. A maximum ethanol concentration of 9.91% (w/w) and percentage of theoretical ethanol yield of 92.27% were achieved after 44 h of the SSF process of corn meal with prior microwave treatment.     

TG-DTA, DRIFT and NMR characterisation of humic-like fractions from olive wastes and amended soil

The purpose of the present study is to investigate, by means of thermogravimetric analysis (TG) and differential thermal analysis (DTA), diffuse reflectance infrared Fourier transform (DRIFT) and 2D nuclear magnetic resonance (NMR) spectroscopies, the structural features of the humic-like fraction (HLF) from olive pulp (OP), its effluents originated from the fermentation processes for hydrogen (EH2) and methane production (ECH4) and humic acid (HA) from soil amended with each of these materials. A considerable structural modification emerged between the HLF, in particular from the ECH4 effluent, which was characterised by a high content of polyphenolic and polypeptidic substances. The short-term amendment trial with OP and EH2 indicated that no chemical or structural changes in soil HA appeared. In contrast, the amendment with ECH4 substantially influenced the chemical and structural composition of soil HA. The structural interpretation performed by 2D NMR indicated the presence of aliphatic and aromatic protons while the sugar-like content and O-CH3 groups decreased with respect to the soil control HA. It emerges from this study that olive wastes contain stabilised humic-like material that may be recycled as an amendment in areas where olive trees are cultivated.     

Integrating life cycle assessment (LCA) with boundary line analysis (BLA) to reduce agro-environmental risk of crop production: a case study of soybean production in Northern Iran

Clean Technologies and Environmental Policy - Increasing the yield of oilseeds is considered an important plan and strategy in different countries such as Iran. With limited available arable land,...     

Reducing sugars production from sugarcane bagasse wastes by hydrolysis in sub-critical water

Biomass is an important renewable and sustainable source of energy. The rational utilization of biomass wastes is important not only for the prevention of environmental issues, but also for the effective utilization of natural resources. Reducing sugar, as a biomass energy precursor, can be further transformed to fuel alcohol in a fermentation process. Sub-critical water is an environmentally friendly solvent and attractive reaction medium. This study deals with the production of reducing sugar from sugarcane bagasse by hydrolysis in sub-critical water and the hydrolysis kinetics of sugarcane bagasse. Kinetics was conducted in a temperature range of 200–240°C using a 200-ml stainless steel batch reactor. A simplified kinetic model based on a parallel and consecutive reaction was proposed. The differential equations resulting from the model were fit to experimental data to obtain kinetic rate constants. The activation energy and the pre-exponential factor were determined. A good agreement between the simplified model and the experimental data was obtained. The experimental results show that the best hydrolysis technology involves a reaction temperature of 240°C, and a reaction time of 120 s. Under these conditions, the reducing sugar yield reaches 61.5%.     

Design of experiments in environmental chemistry studies: example of the extraction of triazines from soil after olive cake amendment

The disposal of natural, composted and vermicomposted olive cake for modifying the fate of triazine herbicides with different physicochemical properties (terbuthylazine, cyanazine, simazine and prometryn) has been tested. Experimental design (surface response methodology plus desirability function) to multicriteria optimization was carried out to evaluate both dose and type of amendment to retain the cited analytes and to develop two simple and low cost analytical methods for extracting triazines from soil. From a methodological point of view, classical and D-optimal designs were employed depending on the problem. Thus, the best combination of soil amount and solvent ratio, the most important parameters affecting triazine extraction from soil, was looked for by means of Central Composite Designs. Under the optimized conditions, the range of triazines recovery was 75-85% for shaking extraction and 87-107% for ultrasonic extraction. Regarding the amendment assay, D-optimal design was selected to keep the reliability of the estimations. Natural olive cake added to the soil at a high dose (8%) reduced herbicide recovery to ca. 50-60% for terbuthylazine, prometryn and simazine, while cyanazine recovery was negligible. Design of experiment provides an efficient working strategy to explore those conditions which ensure the optimum or target value of several responses evaluated simultaneously.     

Adsorption of copper from aqueous solution on Brassica cumpestris (mustard oil cake)

The adsorption behavior of various heavy metals on mustard oil cake (MOC) was studied. The maximum adsorption of Cu(II) was observed followed by Zn(II), Cr(VI), Mn(II), Cd(II), Ni(II) and Pb(II). The adsorption of Cu(II) was found to be dependent on initial concentration of solution, pH, adsorbent dose, temperature and contact time. The adsorption followed pseudo-first-order and second-order kinetics but pseudo-second-order kinetic model was better obeyed since experimental data agreed well with theoretical data. Thermodynamic parameters were also evaluated. The adsorption process was found to be endothermic and spontaneous in nature. Attempts were also made to desorb Cu(II) from the adsorbent and regeneration of the spent adsorbent. The breakthrough and exhaustive capacities were found to be 5 and 10 mg g(-1), respectively.     

Chemical recycling of plastic wastes made from polyethylene (LDPE and HDPE) and polypropylene (PP)

The recycling of either model polymers or waste products based on low-density polyethylene (LDPE), high-density polyethylene (HDPE) or polypropylene (PP) is examined using the dissolution/reprecipitation method, as well as pyrolysis. In the first technique, different solvents/non-solvents were examined at different weight percent amounts and temperatures using as raw material both model polymers and commercial products (packaging film, bags, pipes, food-retail outlets). The recovery of polymer in every case was greater than 90%. FT-IR spectra and tensile mechanical properties of the samples before and after recycling were measured. Furthermore, catalytic pyrolysis was carried out in a laboratory fixed bed reactor with an FCC catalyst using again model polymers and waste products as raw materials. Analysis of the derived gases and oils showed that pyrolysis gave a mainly aliphatic composition consisting of a series of hydrocarbons (alkanes and alkenes), with a great potential to be recycled back into the petrochemical industry as a feedstock for the production of new plastics or refined fuels.     

Use of 3D printing for biofuel production: efficient catalyst for sustainable biodiesel production from wastes

This work deals with the sustainable biodiesel production from low-cost renewable feedstock (waste and non-edible oils) using a heterogeneous catalyst constituted by potassium loaded on an amorphous aluminum silicate naturally occurring as volcanic material (pumice). The main challenge to biodiesel production from low-quality oils (used oils and greases) is the high percentage of free fatty acids (FFAs) and water in the feedstock that causes undesirable side reactions. The catalytic materials studied were tested in the transesterification reaction when using low-quality oils containing a high proportion of free fatty acids (FFAs) and water. Results indicated that the amount of acid and basic sites on the catalytic surface increases upon increasing potassium loading in the catalyst, displaying better performance for biodiesel production. Indeed, the modification of the aluminum silicate substrate upon potassium incorporation results in a catalytic material containing both acidic and basic sites, which are responsible for both triglycerides transesterification and FFA esterification reactions. The studied catalyst not only showed good performance in the biodiesel production reaction but also good tolerance to FFA and water contained in the feedstock for biodiesel production. The catalytic material was microstructured by 3D printing in order to design a catalytic stirring system with high mechanical strength, efficient and reusable. The use of 3D printing in biofuel production is a novelty that brings good solutions for catalyst production.     

Production of a microfiltration membrane from acrylic fiber (AF) and low-density polyethylene (LDPE) shrink film wastes

Clean Technologies and Environmental Policy - The main purpose of this study is the production of a nanofiber membrane from industrial wastes by using the electrospinning technique and...     

Perspectives for the production of bioethanol from wood and straw in Austria: technical, economic, and ecological aspects

Bioethanol produced from lignocellulosic resources is a promising candidate for the replacement of fossil fuels. In this study, we aim to determine the perspectives to produce lignocellulosic ethanol in Austria. Technical, environmental and economic aspects are being considered. Thirteen biotechnological production concepts using the raw materials straw and softwood were established and simulated with the steady state flowsheeting software IPSEpro. Bioethanol production cost and greenhouse gas (GHG) emissions for each system were calculated based on mass and energy balances obtained from process simulation. The emission of GHGs along the entire bioethanol process chain (“from well to wheel”) are compared to two reference systems producing the same amounts of by-products. In all concepts, process heat and considerable amounts of the by-products electricity, heat, pellets, C5 molasses, or biomethane could be obtained from residual biomass. Compared to a reference system driven by fossil energy, GHG emissions can be reduced by up to 76%. The production cost of ethanol was found to between 0.66?€ and 0.94?€ per liter of gasoline equivalent. The type and amount of by-product influence technical, economic, and environmental performance significantly. Converting all straw and softwood available in Austria to ethanol would result in an annual production of 340?kt.     

Activated carbon from agave wastes (agave tequilana) for supercapacitors via potentiostatic floating test

To prepare an efficient supercapacitor, an activated carbon from agave wastes was prepared and their electrochemical performance was evaluated as a novel electrode for supercapacitor. The carbon was prepared by two thermal pyrolysis processes under nitrogen atmosphere. The first pyrolysis was achieved at 500 °C until the charring of the bagasse; in the second pyrolysis step, the char was impregnated with different mass ratios of KOH (1:2–1:4) and thermally treated at 800 or 900 °C, for 1 h under N₂ flow. The textural analysis showed that the activated carbon had a specific surface area of 1462 m² g^?1 and depicted a type I isotherm (IUPAC) characteristic of a microporous carbon. Raman spectroscopy and XRD measurements confirm that the activated carbon contains a small graphitization degree and a disordered structure. The electrochemical study of the symmetric carbon supercapacitor was carried out in 1 M Li₂SO₄ solution as the electrolyte. The electrochemical performance of the coin cell supercapacitor was evaluated under an accelerated aging floating test consisting of potentiostatic steps at different voltages (1.5, 1.6 and 1.8 V) for 10 h followed by galvanostatic charge/discharge sequences, and the overall procedure summarized a floating time up to 200 h. The highest capacitance was observed at a floating voltage of 1.5 V, with a large initial specific capacitance of 297 F g^?1.