Juliana Q. Albarelli

Energetic and economic evaluation of waste glycerol cogeneration in Brazil

Glycerol is an important by-product of biodiesel production. It is used in many industrial segments, but the increasing production of this chemical has become an issue of concern. Many studies have been done to give new applicability to this product; a promising field is the usage of glycerol for energy production. Therefore, this study evaluates the technical and economic feasibility of a new and potential proposal at the national level, the generation of electricity and heat, through a cogeneration system using glycerol. The results demonstrate the viability of this proposal, since the payback on capital invested obtained was approximately 4 years, with the possibility of reduction to 3 years when installed in regions with low infrastructure.

Economic Analysis of an Integrated Annatto Seeds-Sugarcane Biorefinery Using Supercritical CO2 Extraction as a First Step

Recently, supercritical fluid extraction (SFE) has been indicated to be utilized as part of a biorefinery, rather than as a stand-alone technology, since besides extracting added value compounds selectively it has been shown to have a positive effect on the downstream processing of biomass. To this extent, this work evaluates economically the encouraging experimental results regarding the use of SFE during annatto seeds valorization. Additionally, other features were discussed such as the benefits of enhancing the bioactive compounds concentration through physical processes and of integrating the proposed annatto seeds biorefinery to a hypothetical sugarcane biorefinery, which produces its essential inputs, e.g., CO2, ethanol, heat and electricity. For this, first, different configurations were modeled and simulated using the commercial simulator Aspen Plus® to determine the mass and energy balances. Next, each configuration was economically assessed using MATLAB. SFE proved to be decisive to the economic feasibility of the proposed annatto seeds-sugarcane biorefinery concept. SFE pretreatment associated with sequential fine particles separation process enabled higher bixin-rich extract production using low-pressure solvent extraction method employing ethanol, meanwhile tocotrienols-rich extract is obtained as a first product. Nevertheless, the economic evaluation showed that increasing tocotrienols-rich extract production has a more pronounced positive impact on the economic viability of the concept.

Evaluation of Glass Beads Coated with Chitosan for the Adsorption of Copper(II) Ions from Aqueous Solution

Chitosan, a natural polymer obtained from the de-acetylation of chitin, has been extensively studied in adsorption applications because its amino and hydroxyl groups can act as chelation sites. However, this material is rarely used as an adsorbent, mainly because of mechanical strength limitations. A possible means of making its use viable is the immobilization of chitosan onto solid matrices using particle-coating techniques. Studies have shown that the use of immobilized chitosan not only improves the mechanical strength of the adsorbent, but also enhances its mass-transfer properties. In this context, the present study has investigated the adsorption application of chitosan coated onto glass beads in batch and dynamic systems for the removal of copper ions from aqueous solution. The adsorption equilibrium properties were measured at different temperatures (25, 40, 50 and 60 oC) and the Langmuir, Freundlich and Langmuir–Freundlich models were used to fit the equilibrium data. Kinetic studies showed that adsorption equilibrium was attained after 10 h. The pseudo-first-order and pseudo-second-order kinetic models in both linear and non-linear forms together with the intra-particle diffusion model were used to fit the adsorption kinetics data. The best fit was obtained with the pseudo-second-order kinetic model, thereby suggesting that the limiting factor to mass transfer was chemical adsorption. The results indicate that chitosan immobilized onto glass beads demonstrate a good adsorption performance, with similar or even better results relative to other chitosan-based materials. Dynamic adsorption studies using the coated beads in a fixed bed system demonstrated the viability of their use for wastewater treatment.

A New Proposal of Cellulosic Ethanol to Boost Sugarcane Biorefineries: Techno-Economic Evaluation

Commercial simulator Aspen Plus was used to simulate a biorefinery producing ethanol from sugarcane juice and second generation ethanol production using bagasse fine fraction composed of parenchyma cells (P-fraction). Liquid hot water and steam explosion pretreatment technologies were evaluated. The processes were thermal and water integrated and compared to a biorefinery producing ethanol from juice and sugarcane bagasse. The results indicated that after thermal and water integration, the evaluated processes were self-sufficient in energy demand, being able to sell the surplus electricity to the grid, and presented water intake inside the environmental limit for Sao Paulo State, Brazil. The processes that evaluated the use of the bagasse fine fraction presented higher economic results compared with the use of the entire bagasse. Even though, due to the high enzyme costs, the payback calculated for the biorefineries were higher than 8 years for all cases that considered second generation ethanol and the net present value for the investment was negative. The reduction on the enzyme load, in a way that the conversion rates could be maintained, is the limiting factor to make second generation ethanol competitive with the most immediate uses of bagasse: fuel for the cogeneration system to surplus electricity production.

Methodology for Minimising the Utility Consumption of a 2g Ethanol Process

The production of ethanol from lignocellulosic biomass has gained increased interest in recent years, notably in the context of valorising agricultural by-products and providing fuels from renewable sources In order to increase their competitiveness, the energy demand of such processes needs to be minimised. This issue procures two benefits : (1) reduce utility consumption and (2) increase cogeneration possibility. In the present article we investigate this problem for a study process: ethanol production from sugarcane bagasse by enzymatic hydrolysis and glucose fermentation. We therefore apply a rigorous optimisation methodology in which we control certain design parameters in order to maximize the net production of utility. As a result, we obtain a design for our process which (1) eliminates the need for an external hot utility, (2) minimizes the need for the cold utility and (3) maximises the cogeneration possibility.As a conclusion, the proposed methodology provides a strong tool for minimising the utility consumption for a 2G ethanol plant. Considering its key components, it can further be applied in the context of a multi-objective problem.

Environmental, Energetic and Economic Evaluation of Implementing a Supercritical Fluid-Based Nanocellulose Production Process in a Sugarcane Biorefinery

Nanocellulose, which is a disintegration product of plant cellulose, has recently come to public attention because of its great mechanical properties combined with renewability and biodegradability. From an environmental point-of-view, nanocellulose has shown potential for applications in drinking water filtration, catalytic degradation of organic pollutants, etc. Nanocellulose prepared from renewable and biodegradable lignocellulosic materials is only considered green and environment-friendly when its obtaining method is also environmentally friendly. Thus, this procedure should be done by means of an eco-friendly multistep procedure. Towards this direction in this study, nanocelulose production that uses supercritical fluid-based processes for cellulose separation, e.g. supercritical CO2 explosion or organosolv assisted by CO2, were compared with conventional steam explosion and organosolv processes in terms of environmental, energetic and economic aspects using commercial simulator Aspen Plus. In addition, the implementation of nanocelulose production as part of an ethanol production process from lignocellulosic materials was also investigated. The results showed that the production of nanocellulose from the lignocellulosic residue of the ethanol production through enzymatic hydrolysis is very promising. On the other hand, this more economically attractive process design was when explosion-based methods (i.g. SO2-catalized steam explosion and supercritical CO2 explosion) were used during cellulose separation step. It was determined that over 95% of the energy needs for cellulose disintegration during nanocellulose production process come from heating requirements. However, it was also found that this latter step can be self sufficient in terms of energy usage when the undisintegrated cellulose is used as fuel into an energy generation system. It was estimated that a combined heat and power boiler can produce a heat surplus of 365 kWh, which can be redirected to the lignocellulosic biomass fractionation, enzymatic hydrolysis and/or ethanol production processes, thus reducing the overall energy requirement. In terms of environmental aspects, three environmental indicators were examined. The CO2 emissions per kg of nanocellulose produced was found to be acceptable as it is, but the chemicals/water usage should be re-examined, as their requirements were deemed higher than the desirable.

Energy Consumption Versus Antioxidant Activity of Pressurized Fluid Extracts from Pfaffia glomerata Roots

Conventional extraction techniques have been applied to obtain antioxidant extracts from Pfaffia glomerata roots, most of the times, using polar extracting solvents. Even if these techniques are able to provide extracts with antioxidant activities, more environmentally friendly techniques are nowadays preferred. Among them, supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) with green solvents have been widely applied to natural bioactive compounds extraction. The limitation of the use of pure supercritical CO2 for obtaining antioxidant extracts from Pfaffia glomerata roots was already demonstrated. When high amounts of modifier are added, the formation of a gas-expanded liquid is observed. This extracting solvent combines the advantages of the solvation properties of typical liquids and the transport properties of supercritical fluids, being an intermediate process between SFE and PLE, which can be called as pressurized fluid extraction (PFE). In this work, PFE of Brazilian ginseng (Pfaffia glomerata) roots were performed in order to obtain antioxidant extracts with potential applications in the pharmaceutical and food areas. Several CO2+ethanol mixtures (90:10 %, 50:50 % and 0:100 %, w/w) as extracting fluid were assayed. The effects of other two process parameters including pressure (10-20 MPa) and temperature (323-363 K) on the extraction yield, antioxidant activity and energy consumption per unit of manufactured product were investigated. PFE process was simulated using the SuperPro Designer simulation platform. The use of 10 % (w/w) of ethanol produced extracts with the highest antioxidant activity. On the other hand, higher temperature and ethanol percentage resulted in higher extraction yield and lower energy consumption per unit of manufactured product, while pressure did not affect any response variables. Copyright