Process Intensification Strategies Research Articles

Process intensification strategies for enhanced holocellulose solubilization: Beneficiation of pineapple peel waste for cleaner butanol production

Biorefinery sector has become a serious dispute for cleaner and sustainable development in recent years. In the present study, pretreatment of pineapple peel waste was carried out in high pressure reactor using various pretreatment-enhancers. The type and concentration effect of each enhancer on hemicellulose solubilization was systematically investigated. The binary acid (phenol + sulfuric acid) at 180 °C was found to be superior amongst other studied enhancers, giving 81.17% (w/v) hemicellulose solubilization in liquid-fraction under optimized conditions. Solid residue thus obtained was subjected to enzymatic hydrolysis that resulted into 24.50% (w/v) cellulose breakdown. Treated solid residue was further characterized by scanning electron microscopy and fourier transform infrared spectroscopy to elucidate structural changes. The pooled fractions (acid treated and enzymatically hydrolyzed) were fermented using Clostridium acetobutylicum NRRL B 527 which resulted in butanol production of 5.18 g/L with yield of 0.13 g butanol/g sugar consumed. Therefore, pretreatment of pineapple peel waste evaluated in this study can be considered as milestone in utilization of low cost feedstock, for bioenergy production.

Biochemical Production with Purified Cell-Free Systems

Bioprocesses offer a powerful set of opportunities for current chemical process innovation. Such conversions provide opportunities to employ process intensification strategies and the right characteristics to scale down and harness the power of modular process design, but strain engineering and the use of microbial systems for industrial biochemicals production remain unpredictable and expensive. Purified cell-free technologies, in which complex enzyme reaction cascades are used to catalyze bioconversions of interest, can be designed to mitigate these limitations. Such systems allow predictive kinetic modeling and full control of reaction conductions, enabling a dramatically increased design-built-test cycle iteration rate. When sufficiently robust engineered enzymes are used, opportunities to leverage harsh reaction conditions, long-term recycling strategies, and hybridization with chemical catalysis can be used to dramatically improve the value proposition of biochemicals production. Further research is required to realize the potential of these approaches and to address the current platform-limiting challenges around cofactor cost and reuse.

On‐the‐fly Catalyst Accretion and Screening in Chemoselective Flow Hydrogenation

AbstractHerein, it is reported an on‐the‐fly accretion/reaction protocol to evaluate the structure‐performance relationship in the chemoselective flow citral hydrogenation over Ni‐based catalysts. Based on the methodology one was able to determine Ni nanoparticles ideal average size (ca. 9 nm), in a rapid and facile manner. The methodology offers a simple workflow, cost‐effective and adaptable strategy for process intensification and optimization.

Modeling, simulation and intensification of hydroprocessing of micro-algae oil to produce renewable aviation fuel

Micro-algae are photosynthetic organisms, which represent a promissory renewable raw material for biofuels production, since they can be cultivated in non-fertile lands, avoiding the competition with food crops for land use. From micro-algae, oil can be obtained oil that can be converted to biodiesel, green diesel and biojet fuel. In particular, the renewable aviation fuel is one of the less explored biofuels; nevertheless, for the aviation sector, this is the best alternative to reduce CO2 emissions, allowing its sustainable development. In order to produce hydrocarbons in the boiling point range of jet fuel, we need to transform the micro-algae oil. A number of research projects report the use of micro-algae oil for the production of biojet fuel through the hydrotreating process. However, the application of process intensification strategies for the hydroprocessing of micro-algae oil has not been reported. Therefore, in this work we propose the modeling, simulation and intensification of the hydrotreating process to produce biojet fuel, considering micro-algae oil as raw material. The hydroprocessing of micro-algae oil is modeled in Aspen Plus processes simulator, based on data from an experimental study recently reported. The produced renewable hydrocarbons are purified through conventional and intensified distillation sequences; thereby, conventional and intensified hydrotreating processes are defined and evaluated in terms of total annual costs, CO2 emissions and biojet fuel price. Simulation results show that the implementation of intensification strategies leads to the production of biojet fuel with reduced carbon dioxide emissions, 34% less, and a competitive price per liter, 78% cheaper than fossil jet fuel price.

Sustainable production of renewable aviation fuel through intensification strategies

In the transportation industry, aviation is one of the most dynamic sectors. The forecast indicates that aviation will grow at 4.8% until 2036, which implies that fuel requirements will double along with CO2 emissions. Therefore, the sustainable development of aviation sector faces great challenges and relies on a four-pillar strategy, which includes increasing engine efficiency, optimization of flight trajectories, and alternative fuels. Renewable jet fuel, also known as biojet fuel, consists of hydrocarbons in the range of boiling point of fossil jet fuel, C8-C16, obtained from the biomass processing. There are different pathways to produce biojet fuel, being the hydroprocessing of triglyceride feedstock one of the most reliable and advanced. The hydrotreating process consists of three main steps: hydrodeoxygenation, cracking and isomerizing, and finally purification; also, it allows obtaining biojet fuel with the required properties from different renewable oils. Nevertheless, it has several opportunity areas to decrease energy consumption and environmental impact.Therefore, in this work an analysis of hydrotreating processes to produce biojet fuel is presented in terms of energy consumption, total annual costs, and CO2 emissions. Different renewable raw materials of high productive potential in Mexico are considered; along with the implementation of process intensification strategies for the separation train. Results show that the use of thermally coupled distillation sequences allows designing sustainable processes for the production of biojet fuel economically competitive with fossil jet fuel.

A novel process intensification strategy for second-generation ethanol production from sugarcane bagasse in fluidized bed reactor

Due to forthcoming scarcity of fossil fuels and serious environmental concerns, concerted efforts are required to develop the intensified and robust ethanol production from renewable sources. Currently, lignocellulosic materials are among the main available renewable carbon source in the world. Within this context, we present a novel proposal of intensification of the process for second generation (2G) ethanol production from sugarcane bagasse (SCB) employing fluidized bed reactor. Successive steps of SCB i.e. alkaline pre-treatment, saccharification and fermentation to ethanol were carried out in a same column reactor without opening it during the entire process. In the alkaline pretreatment process, a 22 full factorial design of experiments was designed and executed to evaluate the effect of NaOH concentration (from 0.1 to 0.5 M) and time (from 1 to 4 h) on the enzymatic digestibility of pretreated biomass. Enzymatic hydrolysis yielded glucose and xylose of around 87% and 43%, were achieved, respectively, in saccharification step, when used alkaline pre-treated biomass conducted in process by using variables in high level. Thus, Simultaneous saccharification and co-fermentation (SSCF) were performed by using the wild xylose and glucose fermenting yeast Scheffersomyces shehatae UFMG-HM 52.2, verifying ethanol yield and productivity of 0.34 g/g and 0.18 g L/h, respectively. Results showed the potential of using fluidized bed reactor for ethanol production under different process conditions, reducing equipments and process costs with mass transference.

Membrane Engineering for Green Process Engineering

Abstract Green process engineering, which is based on the principles of the process intensification strategy, can provide an important contribution toward achieving industrial sustainable development. Green process engineering refers to innovative equipment and process methods that are expected to bring about substantial improvements in chemical and any other manufacturing and processing aspects. It includes decreasing production costs, equipment size, energy consumption, and waste generation, and improving remote control, information fluxes, and process flexibility. Membrane-based technology assists in the pursuit of these principles, and the potential of membrane operations has been widely recognized in the last few years. This work starts by presenting an overview of the membrane operations that are utilized in water treatment and in the production of energy and raw materials. Next, it describes the potential advantages of innovative membrane-based integrated systems. A case study on an integrated membrane system (IMS) for seawater desalination coupled with raw materials production is presented. The aim of this work is to show how membrane systems can contribute to the realization of the goals of zero liquid discharge (ZLD), total raw materials utilization, and low energy consumption.

Combined treatment approaches based on ultrasound for removal of triazophos from wastewater

Pesticides have been the major contributors to the growth of agricultural productivity, but the wide spread use in the fields and discharge from the manufacturing industries have also contributed to environmental concerns. In the present work, degradation of triazophos (O,O-diethyl-O-(1-phenyl-1H-1,2,4-triazol-3-yl) phosphorothioate) as a model pollutant has been investigated using high volume continuous ultrasonic flow cell for the first time. Effect of power dissipation and initial pH on the extent of triazophos degradation using acoustic cavitation has been investigated initially. Under the optimized set of operating power dissipation and pH, effect of addition of hydrogen peroxide (ratio of C12H16N3O3PS (Triazophos):H2O2 over the range of 1:1–1:5), ozone (over the flow rate of 100–400mg/h) and Fenton’s reagent (C12H16N3O3PS:FeSO4:H2O2 ratio over the range of 1:1:1–1:4:4) has been investigated as possible process intensification strategy. Combined operation of US with H2O2 and Ozone resulted in 48.6% and 54.6% triazophos degradation respectively whereas combination of US and Fenton’s reagent resulted in maximum degradation as 92.2% and also resulted in maximum COD removal as 88.5%. The study also focused on identification of intermediate products formed during the degradation as well as establishing the kinetic rate constants and the synergistic index for different approaches. The study has established that cavitation can be effectively used for triazophos degradation with significant intensification benefits based on the use of combination approach.

Membrane Operations for Process Intensification in Desalination

Process intensification strategy (PIS) is emerging as an interesting guideline to revolutionize process industry in terms of improved efficiency and sustainability. Membrane engineering has appeared as a strong candidate to implement PIS. The most significant progress has been observed in desalination where substantial reduction in overall energy demand, environmental footprint, and process hazards has already been accomplished. Recent developments in membrane engineering are shaping the desalination industry into raw materials and energy production where fresh water will be produced as a byproduct. The present study discusses the current and perspective role of membrane engineering in achieving the objectives of PIS in the field of desalination.

Process intensification on the separation of benzene and thiophene by extractive distillation

The separation of benzene and trace thiophene by extractive distillation was intensified in two aspects, that is, selection of a suitable entrainer and improvement of the process. The mixture of dimethylformamide (DMF) and an ionic liquid (IL) was chosen as the entrainer. Vapor–liquid equilibrium (VLE) experiments using pure DMF and a mixed entrainer were conducted, and UNIFAC model for ILs was extended to the benzene‐thiophene‐DMF‐IL system. The results demonstrated that volatilization loss of DMF in the vapor phase was significantly reduced by adding IL. Moreover, an improved process with only four columns using a mixed entrainer was proposed. The results indicated that the improved process is more promising for decreasing energy consumption and equipment investment compared with the conventional six‐column process. The total heat duties of reboilers and condensers was decreased by 6.47% and 6.41%, respectively. The process intensification strategy may be directly extended to separate trace components of other systems. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4470–4480, 2015

Process development and intensification for enhanced production of Bacillus lipopeptides

The growing interest in Bacillus lipopeptides for high-value applications has driven process design, development and optimization for enhanced lipopeptide production. Traditional optimization approaches have been directed towards improving the overall titres by modification of media components and environmental parameters, almost exclusively in submerged cultures. Carbon and nitrogen sources, trace elements and oxygen availability have all been demonstrated to exhibit significant influences on lipopeptide yield, productivity and selectivity. This insight into process-linked kinetics, especially selectivity, has led to the introduction of novel process intensification and integration strategies which further promote process efficiency, and which include foam fractionation, inverse fluidization, rotating disc contacting and microfiltration with recycle. These strategies have not only transformed the production capabilities, but have also successfully integrated upstream production with downstream purification through cell retention and in situ product removal. This review analyses and critically discusses the impact of process conditions and process optimization strategies for improving lipopeptide production kinetics, specifically highlighting the emerging trend of process intensification and integration strategies and further, proposes a heuristic route to enhance lipopeptide production.

Liquid backmixing in an inclined rotating tubular fixed bed reactor – Augmenting liquid residence time via flow regime adjustment

The liquid residence time and the backmixing in an inclined rotating tubular fixed bed reactor operated with gas–liquid co-current downflow are studied experimentally. This novel reactor concept is introduced to extent the process intensification strategies of chemical multiphase reactors. The intermittent catalyst immersion due to rotation induces a continuous refreshment of the liquid at the catalyst surface and enhances the access of the gas phase to the catalyst in the drained section of the fixed bed. Depending on inclination angle and rotational velocity, different flow regimes are observed. In particular, the flow regimes with stratified gas–liquid flow can be utilized to enhance the performance of the reactor for heterogeneous catalytic reactions.The backmixing study is based on the method of the imperfect tracer pulse and the propagation of the tracer is measured by low-intrusive wire-mesh sensors. Compared to conventional trickle bed reactors, liquid residence time and axial dispersion are increased by the inclination and rotation. The effects of reactor inclination angle and rotational velocity as well as of particle size and liquid superficial velocity on the liquid backmixing in the inclined rotating tubular fixed bed reactor are shown in detail.

Process Intensification for greenhouse gas separation from biogas: More efficient process schemes based on membrane-integrated systems

The separation of biogas leads to not only recovery and sequestration of CO2, but also to much greater purification and recovery of value-added CH4 able to be used, for example, to directly feed pipelines for domestic or small plants. In this work, an alternative approach for a preliminary design of separation process based on the use of polymeric membranes is proposed. Two different types of polymeric membranes were taken into account, Hyflon AD60 and Matrimid 5218, the first showing a higher permeability with respect to other membranes but a quite low selectivity (12.9), the second exhibiting a higher selectivity with respect to other membranes (41 and 100) even though a lower permeability. Four possible operation schemes using two different types of membranes in multistage configuration system are analysed as functions of the main design parameters, i.e., pressure ratio and permeation number. The achieved results are compared with certain targets and are also discussed in terms of process metrics, according to the Process Intensification Strategy. This latter analysis, coupled with a conventional one, provides an alternative point of view over the evaluation of the plant performance taking into account not only the final characteristics of the streams but also process efficiency, exploitation of raw material and energy, and the footprint occupied by the installation.

Development of an efficient process intensification strategy for enhancing Pfu DNA polymerase production in recombinant Escherichia coli.

An efficient induction strategy that consisted of multiple additions of small doses of isopropyl-β-D-thiogalactopyranoside (IPTG) in the early cell growth phase was developed for enhancing Pfu DNA polymerase production in Escherichia coli. In comparison to the most commonly used method of a single induction of 1 mM IPTG, the promising induction strategy resulted in an increase in the Pfu activity of 13.5% in shake flasks, while simultaneously decreasing the dose of IPTG by nearly half. An analysis of the intracellular IPTG concentrations indicated that the cells need to maintain an optimum intracellular IPTG concentration after 6 h for efficient Pfu DNA polymerase production. A significant increase in the Pfu DNA polymerase activity of 31.5% under the controlled dissolved oxygen concentration of 30% in a 5 L fermentor was achieved using the multiple IPTG induction strategy in comparison with the single IPTG induction. The induction strategy using multiple inputs of IPTG also avoided over accumulation of IPTG and reduced the cost of Pfu DNA polymerase production.

Internal mass transfer enhancement in flow-through catalytic membranes

Flow-through membrane reactors represent a strategy for process intensification, which benefits from the convective flow that is established due to a transmembrane pressure gradient. The interesting consequence from using these materials is the improved utilization of the catalyst dispersed in the membrane. We propose a theoretical analysis which quantifies the effectiveness factor (η) and the degree of conversion. More importantly, the regime of operation which maximizes the enhancement from convective effects is identified. It corresponds to conditions of not only high internal Peclet number (P), but also of comparable Thiele modulus (ϕ2). We find that these two parameters are related by a simple analytically derived expression: ϕ2≃1.26P. When this relationship holds, an upper limit to the enhancement in the effectiveness factor that can be observed is proportional to P. This result also provides an answer to the effectiveness–conversion trade-off in ‘dead-end’ operation, when both objectives are important. The analytical solutions enable the complete description of the system in Peclet–Thiele diagrams, where the different reaction-transport regimes are identified. Moreover, issues that become particularly relevant in membrane reactors are discussed: curvature, flow direction and the ratio between the concentration distributions at both surfaces. The simplified design rules obtained bridge the gap between materials synthesis (with permeability and thickness as tunable properties) and process design (enhancement of the internal transport and productivity).

Ultrasonic Intensification of Grape Stalk Convective Drying: Kinetic and Energy Efficiency

Grape stalk is a by-product of the winemaking process with a high antioxidant content. Drying is a necessary stage before antioxidant extraction, which may affect not only kinetic and energy efficiency but also product quality. Coupling non-thermal technologies, such as power ultrasound, to convective drying is considered a strategy for process intensification in order to prevent certain drawbacks of conventional technologies. In this work, the use of power ultrasound in the convective drying of grape stalk was tested in order to estimate its influence on kinetic and energy efficiency. For this purpose, convective drying kinetics of grape stalk were carried out with and without power ultrasound application (21.8 kHz, at two ultrasonic power levels: 45 and 90 W). In addition, the inlet and outlet air temperatures of the drying chamber were monitored. The drying process was modeled considering heat and mass transfer phenomena jointly with the total energy consumption and the energy efficiency of the system. Power ultrasound application involved a shortening of grape stalk drying time, which was dependent on the drying air temperature (40 and 60°C) and the ultrasonic power applied (45 and 90 W). The modeling showed the increase in diffusion and convective heat transport phenomena produced by ultrasound application, despite grape stalk being a low-porosity product and, therefore, only slightly sensitive to ultrasonic effects. In addition, it was also highlighted that ultrasound application increased the energy efficiency during the drying of grape stalk.

Mineralization and efficiency in the homogeneous Fenton Orange G oxidation

This study focuses on the homogeneous Fenton oxidation of the synthetic azo-dye Orange G as a model compound. The impact of initial TOC, hydrogen peroxide and catalyst concentrations and of temperature on mineralization and efficiency in the use of hydrogen peroxide is addressed. Dissolved oxygen concentration is monitored as an indication of the efficient use of H2O2 in the process. A two-stage lumped kinetic model is proposed to address the effect of initial TOC, catalyst and oxidant concentrations and temperature on total organic carbon consumption. Temperature increase and dosification of the oxidant are evaluated and compared as process intensification strategies.

Pulsed electric field (PEF) as an intensification pretreatment for greener solvent lipid extraction from microalgae

Microalgae, with their high lipid content, are a promising feedstock for renewable fuels. Traditionally, human and environmentally toxic solvents have been used to extract these lipids, diminishing the sustainability of this process. Herein, pulsed electric field technology was utilized as a process intensification strategy to enhance lipid extraction from Ankistrodesmus falcatus wet biomass using the green solvent, ethyl acetate. The extraction efficiency for ethyl acetate without PEF was lower (83-88%) than chloroform. In addition, the ethyl acetate exhibited a 2-h induction period, while the chloroform showed no time dependence. Utilizing PEF technology resulted in 90% of the cells being lysed and a significant enhancement in the rate of lipid recovery using ethyl acetate. The increase in lipid recovery was due to the presence of the electric field and not due to temperature effects. The PEF technology uses less energy than other PEF systems reported in the literature.

Membrane Materials for Addressing Energy and Environmental Challenges

Our modern society must solve various severe problems to maintain and increase our quality of life: from water stress to global warming, to fossil fuel depletion, to environmental pollution. The process intensification (PI) strategy is expected to contribute to overcoming many of these issues by facilitating the transition from a resource-intensive to a knowledge-intensive industrial system that will guarantee sustainable growth. Membrane operations, which respond efficiently to the requirements of the PI strategy, have the potential to replace conventional energy-intensive separation techniques, which will boost the efficiency and reduce the environmental impact of separations as well as conversion processes. This work critically reviews the current status and emerging applications of (integrated) membrane operations with a special focus on energy and environmental applications.

Process intensification strategies and membrane engineering

An important contribution to the realization of industrial sustainable development can be given by “green process engineering”. Based on the principles of the Process intensification strategy it can lead to the development and the re-design of new processes more compact and efficient that allow the better exploitation of raw materials, a lower energy consumption and a reduced plant volume. Membrane technology contributes to the pursuit of these principles and, in the last few years, the potentialities of membrane operations have been widely recognized. In this work, an overview of membrane application and their perspectives in the field of hydrogen production and distillation will be analysed considering membrane reactors and membrane distillation as case studies. The scope is to show how the redesign as membrane systems of traditional operations might contribute to the realization of the goals of process intensification and green chemistry by a new “green process engineering”.