Special Issue "Green Technologies: Bridging Conventional Practices and Industry 4.0"

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Green Processes".

Deadline for manuscript submissions: 31 March 2020.

Special Issue Editors

Prof. Dr. Dominic C. Y. Foo
E-Mail Website
Guest Editor
Department of Chemical and Environmental Engineering, University of Nottingham, Malaysia
Interests: process design and integration; waste minimization; carbon emission reduction
Special Issues and Collections in MDPI journals
Dr. Pau-Loke SHOW
E-Mail Website
Guest Editor
Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Malaysia
Interests: bioprocess engineering; extraction of bio products; synthesis of ionic liquid; fermentation and enzymes; biopolymer and microalgae
Special Issues and Collections in MDPI journals
Assoc. Prof. Dr. Suchithra Thangalazhy Gopakumar
E-Mail Website
Guest Editor
Department of Chemical and Environmental Engineering, University of Nottingham, Malaysia
Interests: biomass and biofuels; biomass pre-treatment; biomass thermochemical conversions; biofuel upgrading; extraction of bio-chemicals

Special Issue Information

Dear Colleagues,

Green technologies have been globally accepted as efficient and sustainable techniques for the utilization of natural resources. Currently, Industry 4.0, which is also called a “smart industry”, aims for the integration of cyber and physical systems to minimize waste and maximize productivity.  Therefore, green technologies can be identified as key components in Industry 4.0. The scope of this Special Issue is to address how conventional green technologies can be part of smart industries by minimizing waste, maximizing productivity, optimizing the supply chain, or by additive manufacturing (3D printing). This theme is focusing on the scope and challenges of integrating current environmental technologies in future industries.

This Special Issue, Green Technologies: Bridging Conventional Practices and Industry 4.0, aims to incorporate the advances in green technologies to cyber-based industries. Topics include, but are not limited to, the following:

  • Development of new disease-specific models to guide therapy;
  • 3D printing
  • Air pollution monitoring and control
  • Carbon emission reduction
  • Computational tools for environmental applications
  • Energy and environmental policy
  • Environmental monitoring, assessment and management
  • Industry 4.0
  • Process system engineering
  • Renewable energy
  • Solid/biomass waste treatment, management, and recycling
  • Waste minimisation
Prof. Dr. Dominic C. Y. Foo
Assoc. Prof. Dr. Show Pau Loke
Assoc. Prof. Dr.  Suchithra Thangalazhy Gopakumar
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Please note that for papers submitted after 30 June 2020 an APC of 1500 CHF applies. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • data analysis
  • environmental technologies
  • energy
  • modelling
  • process systems

Published Papers (15 papers)

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Research

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Open AccessFeature PaperArticle
Hygro-Thermo-Mechanical Responses of Balsa Wood Core Sandwich Composite Beam Exposed to Fire
Processes 2020, 8(1), 103; https://doi.org/10.3390/pr8010103 - 13 Jan 2020
Abstract
In this study, the hygro–thermo–mechanical responses of balsa core sandwich structured composite was investigated by using experimental, analytical and numerical results. These investigations were performed on two types of specimen conditions: dry and moisture saturation sandwich composite specimens that are composed of E-glass/polyester [...] Read more.
In this study, the hygro–thermo–mechanical responses of balsa core sandwich structured composite was investigated by using experimental, analytical and numerical results. These investigations were performed on two types of specimen conditions: dry and moisture saturation sandwich composite specimens that are composed of E-glass/polyester skins bonded to a balsa core. The wet specimens were immersed in distilled water at 40 °C until saturated with water. The both dry and wet sandwich composite specimens were heated by fire. The mass loss kinetic and the mechanical properties were investigated by using a cone calorimeter following the ISO 5660 standard and three-point bending mechanical test device. Experimental data show that the permeability and fire resistance of the sandwich structure are controlled by two composite skins. Obtained results allow us to understand the Hygro–Thermo–Mechanical Responses of the sandwich structured composite under application conditions. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessArticle
Multivariate Analysis and Machine Learning for Ripeness Classification of Cape Gooseberry Fruits
Processes 2019, 7(12), 928; https://doi.org/10.3390/pr7120928 - 05 Dec 2019
Abstract
This paper explores five multivariate techniques for information fusion on sorting the visual ripeness of Cape gooseberry fruits (principal component analysis, linear discriminant analysis, independent component analysis, eigenvector centrality feature selection, and multi-cluster feature selection.) These techniques are applied to the concatenated channels [...] Read more.
This paper explores five multivariate techniques for information fusion on sorting the visual ripeness of Cape gooseberry fruits (principal component analysis, linear discriminant analysis, independent component analysis, eigenvector centrality feature selection, and multi-cluster feature selection.) These techniques are applied to the concatenated channels corresponding to red, green, and blue (RGB), hue, saturation, value (HSV), and lightness, red/green value, and blue/yellow value (L*a*b) color spaces (9 features in total). Machine learning techniques have been reported for sorting the Cape gooseberry fruits’ ripeness. Classifiers such as neural networks, support vector machines, and nearest neighbors discriminate on fruit samples using different color spaces. Despite the color spaces being equivalent up to a transformation, a few classifiers enable better performances due to differences in the pixel distribution of samples. Experimental results show that selection and combination of color channels allow classifiers to reach similar levels of accuracy; however, combination methods still require higher computational complexity. The highest level of accuracy was obtained using the seven-dimensional principal component analysis feature space. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessFeature PaperArticle
Recovery of Protein from Dairy Milk Waste Product Using Alcohol-Salt Liquid Biphasic Flotation
Processes 2019, 7(12), 875; https://doi.org/10.3390/pr7120875 - 21 Nov 2019
Abstract
Expired dairy products are often disposed of due to the potential health hazard they pose to living organisms. Lack of methods to recover valuable components from them are also a reason for manufactures to dispose of the expired dairy products. Milk encompasses several [...] Read more.
Expired dairy products are often disposed of due to the potential health hazard they pose to living organisms. Lack of methods to recover valuable components from them are also a reason for manufactures to dispose of the expired dairy products. Milk encompasses several different components with their own functional properties that can be applied in production of food and non-food technical products. This study aims to investigate the novel approach of using liquid biphasic flotation (LBF) method for protein extraction from expired milk products and obtaining the optimal operating conditions for protein extraction. The optimized conditions were found at 80% concentration ethanol as top phase, 150 g/L dipotassium hydrogen phosphate along with 10% (w/v) milk as bottom phase, and a flotation time of 7.5 min. The protein recovery yield and separation efficiency after optimization were 94.97% and 86.289%, respectively. The experiment has been scaled up by 40 times to ensure it can be commercialized, and the protein recovery yield and separation efficiency were found to be 78.92% and 85.62%, respectively. This novel approach gives a chance for expired milk products to be changed from waste to raw materials which is beneficial for the environment and the economy. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessFeature PaperArticle
Characterization and Modelling Studies of Activated Carbon Produced from Rubber-Seed Shell Using KOH for CO2 Adsorption
Processes 2019, 7(11), 855; https://doi.org/10.3390/pr7110855 - 14 Nov 2019
Abstract
Global warming due to the emission of carbon dioxide (CO2) has become a serious problem in recent times. Although diverse methods have been offered, adsorption using activated carbon (AC) from agriculture waste is regarded to be the most applicable one due [...] Read more.
Global warming due to the emission of carbon dioxide (CO2) has become a serious problem in recent times. Although diverse methods have been offered, adsorption using activated carbon (AC) from agriculture waste is regarded to be the most applicable one due to numerous advantages. In this paper, the preparation of AC from rubber-seed shell (RSS), an agriculture residue through chemical activation using potassium hydroxide (KOH), was investigated. The prepared AC was characterized by nitrogen adsorption–desorption isotherms measured in Micrometrices ASAP 2020 and FESEM. The optimal activation conditions were found at an impregnation ratio of 1:2 and carbonized at a temperature of 700 °C for 120 min. Sample A6 is found to yield the largest surface area of 1129.68 m2/g with a mesoporous pore diameter of 3.46 nm, respectively. Using the static volumetric technique evaluated at 25 °C and 1.25 bar, the maximum CO2 adsorption capacity is 43.509 cm3/g. The experimental data were analyzed using several isotherm and kinetic models. Owing to the closeness of regression coefficient (R2) to unity, the Freundlich isotherm and pseudo-second kinetic model provide the best fit to the experimental data suggesting that the RSS AC prepared is an attractive source for CO2 adsorption applications. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessFeature PaperArticle
Thermophysical Properties and CO2 Absorption of Ammonium-Based Protic Ionic Liquids Containing Acetate and Butyrate Anions
Processes 2019, 7(11), 820; https://doi.org/10.3390/pr7110820 - 05 Nov 2019
Abstract
Ionic liquids, which are classified as new solvents, have been identified to be potential solvents in the application of CO2 capture. In this work, six ammonium-based protic ionic liquids, containing ethanolammonium [EtOHA], tributylammonium [TBA], bis(2-ethylhexyl)ammonium [BEHA] cations, and acetate [AC] and butyrate [...] Read more.
Ionic liquids, which are classified as new solvents, have been identified to be potential solvents in the application of CO2 capture. In this work, six ammonium-based protic ionic liquids, containing ethanolammonium [EtOHA], tributylammonium [TBA], bis(2-ethylhexyl)ammonium [BEHA] cations, and acetate [AC] and butyrate [BA] anions, were synthesized and characterized. The thermophysical properties of the ammonium-based protic ionic liquids were measured. Density, ρ, and dynamic viscosity, η, were determined at temperatures between 293.15 K and 363.15 K. The density and viscosity values were correlated using empirical correlations and the thermal coefficient expansion, αp, and molecular volume, Vm, were estimated using density values. The thermal stability of the ammonium-based protic ionic liquids was investigated using thermogravimetric analyzer (TGA) at a heating rate of 10 °C·min‒1. The CO2 absorption of the ammonium-based ionic liquids were measured up to 20 bar at 298.15 K. From the experimental results, [BEHA][BA] had the highest affinity towards CO2 with the mol fraction of CO2 absorbed approaching 0.5 at 20 bar. Generally, ionic liquids with butyrate anions have better CO2 absorption than that of acetate anions while [BEHA] ionic liquids have higher affinity towards CO2 followed by [TBA] and [EtOHA] ionic liquids. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessFeature PaperArticle
Physical and Thermal Studies of Carbon-Enriched Silicon Oxycarbide Synthesized from Floating Plants
Processes 2019, 7(11), 794; https://doi.org/10.3390/pr7110794 - 02 Nov 2019
Abstract
In the present study, amorphous mesoporous silicon oxycarbide materials (SiOC) were successfully synthesized via a low-cost facile method by using potassium hydroxide activation, high temperature carbonization, and acid treatment. The precursors were obtained from floating plants (floating moss, water cabbage, and water caltrops). [...] Read more.
In the present study, amorphous mesoporous silicon oxycarbide materials (SiOC) were successfully synthesized via a low-cost facile method by using potassium hydroxide activation, high temperature carbonization, and acid treatment. The precursors were obtained from floating plants (floating moss, water cabbage, and water caltrops). X-ray diffraction (XRD) results confirmed the amorphous Si–O–C structure and Raman spectra revealed the graphitized carbon phase. Floating moss sample resulted in a rather rough surface with irregular patches and water caltrops sample resulted in a highly porous network structure. The rough surface of the floating moss sample with greater particle size is caused by the high carbon/oxygen ratio (1: 0.29) and low amount of hydroxyl group compared to the other two samples. The pore volumes of these floating moss, water cabbage, and water caltrops samples were 0.4, 0.49, and 0.63 cm3 g−1, respectively, resulting in thermal conductivities of 6.55, 2.46, and 1.14 Wm−1 K−1, respectively. Floating plants, or more specifically, floating moss, are thus a potential material for SiOC production. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessFeature PaperArticle
Conversion Technologies: Evaluation of Economic Performance and Environmental Impact Analysis for Municipal Solid Waste in Malaysia
Processes 2019, 7(10), 752; https://doi.org/10.3390/pr7100752 - 16 Oct 2019
Abstract
The generation of municipal solid waste (MSW) is increasing globally every year, including in Malaysia. Approaching the year 2020, Malaysia still has MSW disposal issues since most waste goes to landfills rather than being utilized as energy. Process network synthesis (PNS) is a [...] Read more.
The generation of municipal solid waste (MSW) is increasing globally every year, including in Malaysia. Approaching the year 2020, Malaysia still has MSW disposal issues since most waste goes to landfills rather than being utilized as energy. Process network synthesis (PNS) is a tool to optimize the conversion technologies of MSW. This study optimizes MSW conversion technologies using a PNS tool, the “process graph” (P-graph). The four highest compositions (i.e., food waste, agriculture waste, paper, and plastics) of MSW generated in Malaysia were optimized using a P-graph. Two types of conversion technologies were considered, biological conversion (anaerobic digestion) and thermal conversion (pyrolysis and incinerator), since limited data were available for use as optimization input. All these conversion technologies were compared with the standard method used: landfilling. One hundred feasible structure were generated using a P-graph. Two feasible structures were selected from nine, based on the maximum economic performance and minimal environmental impact. Feasible structure 9 was appointed as the design with the maximum economic performance (MYR 6.65 billion per annum) and feasible structure 7 as the design with the minimal environmental impact (89,600 m3/year of greenhouse gas emission). Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessArticle
Gaussian Process Methodology for Multi-Frequency Marine Controlled-Source Electromagnetic Profile Estimation in Isotropic Medium
Processes 2019, 7(10), 661; https://doi.org/10.3390/pr7100661 - 27 Sep 2019
Abstract
The marine controlled-source electromagnetic (CSEM) technique is an application of electromagnetic (EM) waves to image the electrical resistivity of the subsurface underneath the seabed. The modeling of marine CSEM is a crucial and time-consuming task due to the complexity of its mathematical equations. [...] Read more.
The marine controlled-source electromagnetic (CSEM) technique is an application of electromagnetic (EM) waves to image the electrical resistivity of the subsurface underneath the seabed. The modeling of marine CSEM is a crucial and time-consuming task due to the complexity of its mathematical equations. Hence, high computational cost is incurred to solve the linear systems, especially for high-dimensional models. Addressing these problems, we propose Gaussian process (GP) calibrated with computer experiment outputs to estimate multi-frequency marine CSEM profiles at various hydrocarbon depths. This methodology utilizes prior information to provide beneficial EM profiles with uncertainty quantification in terms of variance (95% confidence interval). In this paper, prior marine CSEM information was generated through Computer Simulation Technology (CST) software at various observed hydrocarbon depths (250–2750 m with an increment of 250 m each) and different transmission frequencies (0.125, 0.25, and 0.5 Hz). A two-dimensional (2D) forward GP model was developed for every frequency by utilizing the marine CSEM information. From the results, the uncertainty measurement showed that the estimates were close to the mean. For model validation, the calculated root mean square error (RMSE) and coefficient of variation (CV) proved in good agreement between the computer output and the estimated EM profile at unobserved hydrocarbon depths. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessArticle
The Performance and Exhaust Emissions of a Diesel Engine Fuelled with Calophyllum inophyllum—Palm Biodiesel
Processes 2019, 7(9), 597; https://doi.org/10.3390/pr7090597 - 05 Sep 2019
Cited by 3
Abstract
Nowadays, increased interest among the scientific community to explore the Calophyllum inophyllum as alternative fuels for diesel engines is observed. This research is about using mixed Calophyllum inophyllum-palm oil biodiesel production and evaluation that biodiesel in a diesel engine. The Calophyllum inophyllum [...] Read more.
Nowadays, increased interest among the scientific community to explore the Calophyllum inophyllum as alternative fuels for diesel engines is observed. This research is about using mixed Calophyllum inophyllum-palm oil biodiesel production and evaluation that biodiesel in a diesel engine. The Calophyllum inophyllum–palm oil methyl ester (CPME) is processed using the following procedure: (1) the crude Calophyllum inophyllum and palm oils are mixed at the same ratio of 50:50 volume %, (2) degumming, (3) acid-catalysed esterification, (4) purification, and (5) alkaline-catalysed transesterification. The results are indeed encouraging which satisfy the international standards, CPME shows the high heating value (37.9 MJ/kg) but lower kinematic viscosity (4.50 mm2/s) due to change the fatty acid methyl ester (FAME) composition compared to Calophyllum inophyllum methyl ester (CIME). The average results show that the blended fuels have higher Brake Specific Fuel Consumption (BSFC) and NOx emissions, lower Brake Thermal Efficiency (BTE), along with CO and HC emissions than diesel fuel over the entire range of speeds. Among the blends, CPME5 offered better performance compared to other fuels. It can be recommended that the CPME blend has great potential as an alternative fuel because of its excellent characteristics, better performance, and less harmful emission than CIME blends. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessFeature PaperArticle
A Sugarcane-Bagasse-Based Adsorbent Employed for Mitigating Eutrophication Threats and Producing Biodiesel Simultaneously
Processes 2019, 7(9), 572; https://doi.org/10.3390/pr7090572 - 28 Aug 2019
Abstract
Eutrophication is an inevitable phenomenon, and it has recently become an unabated threat. As a positive, the thriving microalgal biomass in eutrophic water is conventionally perceived to be loaded with myriad valuable biochemical compounds. Therefore, a sugarcane-bagasse-based adsorbent was proposed in this study [...] Read more.
Eutrophication is an inevitable phenomenon, and it has recently become an unabated threat. As a positive, the thriving microalgal biomass in eutrophic water is conventionally perceived to be loaded with myriad valuable biochemical compounds. Therefore, a sugarcane-bagasse-based adsorbent was proposed in this study to harvest the microalgal biomass for producing biodiesel. By activating the sugarcane-bagasse-based adsorbent with 1.5 M of H2SO4, a highest adsorption capacity of 108.9 ± 0.3 mg/g was attained. This was fundamentally due to the surface potential of the 1.5 M H2SO4 acid-modified sugarcane-bagasse-based adsorbent possessing the lowest surface positivity value as calculated from its point of zero charge. The adsorption capacity was then improved to 192.9 ± 0.1 mg/g by stepwise optimizing the adsorbent size to 6.7–8.0 mm, adsorption medium pH to 2–4, and adsorbent dosage to 0.4 g per 100 mL of adsorption medium. This resulted in 91.5% microalgae removal efficiency. Excellent-quality biodiesel was also obtained as reflected by the fatty acid methyl ester (FAME) profile, showing the dominant species of C16–C18 encompassing 71% of the overall FAMEs. The sustainability of harvesting microalgal biomass via an adsorption-enhanced flocculation processes was also evidenced by the potentiality to reuse the spent acid-modified adsorbent. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessFeature PaperArticle
Thermal Analysis of Nigerian Oil Palm Biomass with Sachet-Water Plastic Wastes for Sustainable Production of Biofuel
Processes 2019, 7(7), 475; https://doi.org/10.3390/pr7070475 - 23 Jul 2019
Cited by 3
Abstract
Nigeria, being the world’s largest importer of diesel-powered gen-sets, is expected to invest in bio-fuels in the future. Hence, it is important to examine the thermal properties and synergy of wastes for potential downstream resource utilization. In this study, thermal conversion as a [...] Read more.
Nigeria, being the world’s largest importer of diesel-powered gen-sets, is expected to invest in bio-fuels in the future. Hence, it is important to examine the thermal properties and synergy of wastes for potential downstream resource utilization. In this study, thermal conversion as a route to reduce the exploding volume of wastes from sachet-water plastic (SWP) and oil palm empty fruit bunch (OPEFB) biomass was studied. Thermogravimetric (TGA) and subsequent differential scanning calorimeter (DSC) was used for the analysis. The effect of heating rate at 20 °C min−1 causes the increase of activation energy of the decomposition in the first-stage across all the blends (0.96 and 16.29 kJ mol−1). A similar phenomenon was seen when the heating rate was increased from 10 to 20 °C min−1 in the second-stage of decomposition. Overall, based on this study on the synergistic effects during the process, it can be deduced that co-pyrolysis can be an effective waste for energy platform. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessArticle
Fabrication of Green Superhydrophobic/Superoleophilic Wood Flour for Efficient Oil Separation from Water
Processes 2019, 7(7), 414; https://doi.org/10.3390/pr7070414 - 02 Jul 2019
Abstract
The removal of oil from waste water is gaining increasing attention. In this study, a novel synthesis method of green superhydrophobic/superoleophilic wood flour is proposed using the deposition of nano–zinc oxide (nZnO) aggregated on the fiber surface and the subsequent hydrophobic modification of [...] Read more.
The removal of oil from waste water is gaining increasing attention. In this study, a novel synthesis method of green superhydrophobic/superoleophilic wood flour is proposed using the deposition of nano–zinc oxide (nZnO) aggregated on the fiber surface and the subsequent hydrophobic modification of octadecanoic acid. The as-prepared wood flour displayed great superhydrophobicity and synchronous superoleophilicity properties with the water contact angle (WCA) of 156° and oil contact angle (OCA) of 0° for diesel oil. Furthermore, the as-prepared wood flour possessed an excellent stability, probably due to the strong adhesion of nZnO, which aggregates to the fiber surface of wood flour with the action of glutinous polystyrene. The maximum adsorption capacity of as-prepared wood flour was 20.81 g/g for engine oil, which showed that the as-prepared wood flour is a potential candidate as an efficient oil adsorbent in the field of water-oil separation. Moreover, it has good chemical steadiness and environmental durability. Taken together, all the information acquired from this research could be valuable in evaluating the potential of as-prepared wood flour as a competitive and sustainable oil-water separation material. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Review

Jump to: Research

Open AccessFeature PaperReview
Liquid Biphasic System: A Recent Bioseparation Technology
Processes 2020, 8(2), 149; https://doi.org/10.3390/pr8020149 (registering DOI) - 23 Jan 2020
Abstract
A well-known bioseparation technique namely liquid biphasic system (LBS) has attracted many researchers’ interest for being an alternative bioseparation technology for various kinds of biomolecules. The present review begins with an in-depth discussion on the fundamental principle of LBS and this is followed [...] Read more.
A well-known bioseparation technique namely liquid biphasic system (LBS) has attracted many researchers’ interest for being an alternative bioseparation technology for various kinds of biomolecules. The present review begins with an in-depth discussion on the fundamental principle of LBS and this is followed by the discussion on further development of various phase-forming components in LBS. Additionally, the implementation of various advance technologies to the LBS that is beneficial towards the efficiency of LBS for the extraction, separation, and purification of biomolecules was discussed. The key parameters affecting the LBS were presented and evaluated. Moreover, future prospect and challenges were highlighted to be a useful guide for future development of LBS. The efforts presented in this review will provide an insight for future researches in liquid-liquid separation techniques. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessFeature PaperReview
Anaerobic Co-Digestion of Wastewater Sludge: A Review of Potential Co-Substrates and Operating Factors for Improved Methane Yield
Processes 2020, 8(1), 39; https://doi.org/10.3390/pr8010039 - 01 Jan 2020
Abstract
Anaerobic digestion has been widely employed in waste treatment for its ability to capture methane gas released as a product during the digestion. Certain wastes, however, cannot be easily digested due to their low nutrient level insufficient for anaerobic digestion, thus co-digestion is [...] Read more.
Anaerobic digestion has been widely employed in waste treatment for its ability to capture methane gas released as a product during the digestion. Certain wastes, however, cannot be easily digested due to their low nutrient level insufficient for anaerobic digestion, thus co-digestion is a viable option. Numerous studies have shown that using co-substrates in anaerobic digestion systems improve methane yields as positive synergisms are established in the digestion medium, and the supply of missing nutrients are introduced by the co-substrates. Nevertheless, large-scale implementation of co-digestion technology is limited by inherent process limitations and operational concerns. This review summarizes the results from numerous laboratory, pilot, and full-scale anaerobic co-digestion (ACD) studies of wastewater sludge with the co-substrates of organic fraction of municipal solid waste, food waste, crude glycerol, agricultural waste, and fat, oil and grease. The critical factors that influence the ACD operation are also discussed. The ultimate aim of this review is to identify the best potential co-substrate for wastewater sludge anaerobic co-digestion and provide a recommendation for future reference. By adding co-substrates, a gain ranging from 13 to 176% in the methane yield was accomplished compared to the mono-digestions. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Open AccessReview
Sustainable Waste-to-Energy Development in Malaysia: Appraisal of Environmental, Financial, and Public Issues Related with Energy Recovery from Municipal Solid Waste
Processes 2019, 7(10), 676; https://doi.org/10.3390/pr7100676 - 01 Oct 2019
Abstract
As Malaysia is a fast-developing country, its prospects of sustainable energy generation are at the center of debate. Malaysian municipal solid waste (MSW) is projected to have a 3-5% increase in annual generation rate at the same time an increase of 4-8% for [...] Read more.
As Malaysia is a fast-developing country, its prospects of sustainable energy generation are at the center of debate. Malaysian municipal solid waste (MSW) is projected to have a 3-5% increase in annual generation rate at the same time an increase of 4-8% for electricity demand. In Malaysia, most of the landfills are open dumpsite and 89% of the collected MSW end up in landfills. Furthermore, huge attention is being focused on converting MSW into energy due to the enormous amount of daily MSW being generated. Sanitary landfill to capture methane from waste landfill gas (LFG) and incineration in a combined heat and power plant (CHP) are common MSW-to-energy technologies in Malaysia. MSW in Malaysia contains 45% organic fraction thus landfill contributes as a potential LFG source. Waste-to-energy (WTE) technologies in treating MSW potentially provide an attractive economic investment since its feedstock (MSW) is collected almost for free. At present, there are considerable issues in WTE technologies although the technology employing MSW as feedstock are well established, for instance the fluctuation of MSW composition and the complexity in treatment facilities with its pollutant emissions. Thus, this study discusses various WTE technologies in Malaysia by considering the energy potentials from all existing incineration plants and landfill sites as an effective MSW management in Malaysia. Furthermore, to promote local innovation and technology development and to ensure successful long-term sustainable economic viability, social inclusiveness, and environmental sustainability in Malaysia, the four faculties of sustainable development namely technical, economic, environmental, and social issues affiliated with MSW-to-Energy technologies were compared and evaluated. Full article
(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

1. Author: Dr. Tawalbeh
Affilation: Texas A&M University

2. Author: Dr. Aydin Berenjian
Affilation:
University of Waikato

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