Showing papers in "Waste and Biomass Valorization in 2019"
TL;DR: The selection of highly promising bacterial and/or fungal consortium has the ability to produce various extracellular enzymes including cellulase, hemicellulase, and lignases which can be used in CBP for efficient biological pretreatment of lignocellulosic biomass following production of biofuels and bioproducts.
Abstract: Increasing energy demands are not only exploiting the fossil resources but, also depleting natural environment. Biofuels from lignocellulosic biomass is a renewable, ecofriendly, sustainable and could be a promising alternative to fossil fuels. However, pretreatment is an essential step to disarray the layers of lignocellulose prior to enzymatic hydrolysis. Among various pretreatments of lignocellulose, the biological pretreatment using microorganisms such as bacteria and fungi are gaining popularity due to its financial and environmental benefits. Careful selection of the suitable microbial consortium for efficient pretreatment of biomass is a critical step. The co-culture of bacteria and/or fungi in consolidated bioprocessing (CBP) is highly beneficial in the breakdown of complex biopolymers due to their high enzyme activity. Our selection of highly promising bacterial and/or fungal consortium has the ability to produce various extracellular enzymes including cellulase, hemicellulase, and lignases. It can be used in CBP for efficient biological pretreatment of lignocellulosic biomass following production of biofuels and bioproducts.
TL;DR: In this paper, a review article highlights the availability of oil palm biomass in Malaysia, the chemical compositions, as well as a brief description of current technologies for converting palm biomass into value added products.
Abstract: Oil palm industry is the largest contributor of biomass in Malaysia. Oil palm biomass are constantly generated in large quantities annually with a small fraction being converted into value added product while a large percentage are left underutilized. Several researchers have reported the various technologies available for the conversion of oil palm biomass into useful bio-products, including bio-fuel, biogas, bio-fertilizers, bio-composite and briquettes. In general, these technologies are either underutilized or inadequate for full conversion of these abundantly available biomass, hence, there is an urgent need for upgrading of such technologies. This review article highlights the availability of oil palm biomass in Malaysia, the chemical compositions, as well as a brief description of current technologies for converting oil palm biomass into value added products. The review also outlines a summary of the various products obtained from oil palm biomass. Steps to achieve maximum utilization of biomass from oil palm industry are also proposed.
TL;DR: In this paper, a geographic information system based methodology was developed to investigate the spatial distribution of municipal solid waste (MSW) and to identify the optimal location for new potential waste-to-energy in Europe.
Abstract: This paper provides an overview of waste generation and treatment operations in the European Union (EU) and other European countries and an analysis of the possibilities for the use of municipal solid waste (MSW) for energy production. A geographic information system based methodology was developed to investigate the spatial distribution of MSW and to identify the optimal location for new potential waste-to-energy in Europe. In 2016, there were 512 plants in Europe, with 251 combined heat and power plants, 161 electricity-only and 94 heat-only plants, which provide a total incineration capacity of 93 million tonnes. The suitability analysis showed that there is a potential to implement around 248 new waste to energy plants in the EU and 330 in all Europe, with a total capacity of 37 and 50 million tonnes, respectively. This represents an additional primary energy production of 260 PJ (6.2 Mtoe) in the EU, in comparison to 406 PJ (9.7 Mtoe) already produced in 2015, and about 352 PJ (8.4 Mtoe) in all European countries considered in this analysis.
TL;DR: In this article, the Back to Earth Alternative (BEA) and circular economy concepts are introduced into the digestate management process taking into consideration the initial quality of the digestates and the techniques and processes necessary to meet the specific regulatory and quality requirements for the utilization of this waste stream for different applications.
Abstract: The anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) and food waste achieves both environmental and economic benefits. This bio-process, well-known for producing biogas, is used extensively for industrial applications all over the world. Despite the use of AD across the world, the overall sustainability of this process as a source of an alternate fuel (i.e., biomethane) is intrinsically linked to the successful management of one of its major byproducts, the digestate. In order for the digestate to be classified as a “product” rather than a “waste” and to achieve regulatory compliance, this liquid stream needs to undergo biological or physicochemical treatments. The most common treatment for digestate is the use as a soil amendment. Nutrients surplus, variable agricultural seasonal requirements, escalating transportation cost, and market acceptance (e.g., risk for food safety) represents the major obstacle for the use of digestate for agricultural applications. Therefore, it is necessary to study alternative approaches for digestate management and utilization options. One alternative concept is the Back to Earth Alternative (BEA) whose aim is to bring appropriately treated residues back to their non-mobile state, as they were extracted from the earth to be used as raw materials, which would achieve actual closing of the materials cycles. Similarly, the same concept can be introduced into the digestate management process, with the goal of reducing resource costs and mitigate potential impacts on climate change, by employing a more holistic circular economy model instead of linear economy model commonly referred to as “take-make-dispose”. The overarching aim of this study is to introduce the BEA and circular economy concepts into the digestate management process taking into consideration the initial quality of the digestate and the techniques and processes necessary to meet the specific regulatory and quality requirements for the utilization of this waste stream for different applications. Cost benefit analysis and environmental impact were also evaluated for each BEA.
TL;DR: In this article, the authors used coin type CR2032 cells fabricated using the PKS ACs electrodes separated by fiber glass separator and electrolyte to measure the charge storage of physically and chemically activated carbon synthesized from oil palm kernel shell.
Abstract: Electrochemical charge storage of physically and chemically activated carbon synthesized from oil palm kernel shell (PKS) in three different aqueous electrolytes (1 M H2SO4, 1 M Na2SO4 and 6 M KOH) are presented. Coin type CR2032 cells fabricated using the PKS ACs electrodes separated by fiber glass separator and electrolyte are used as devices for measurements. Achievable operating potential for these devices varied as H2SO4 (1.0 V) < KOH (1.2 V) < Na2SO4 (2.0 V). The highest energy density was obtained in Na2SO4 electrolyte (7.4 Wh kg−1) at a power density of 300 W kg−1. The device stability cycle at low current density (0.5 A g−1) for 3500 times showed capacitance retention in range of 78–114% in all devices.
TL;DR: The potential of the marine microalgae as fertilizer in cultivation of maize was revealed, with increased growth performance at the early stage of growth and improved yield characteristics, in addition to increased seed germination.
Abstract: Fertilizers play a key role in yield if agriculture crops and their market value. Hence, large scale production of low cost, eco-friendly and broad spectrum fertilizers are mandatory. This study was to assess the effect of marine microalgal fertilizer on growth and yield of maize (Zea mays L.). The maize plants were raised in soil supplemented with two marine microalgae (Chlorella vulgaris and Spirulina platensis) along with cow dung manure for 75 days under green house condition. The marine microalgal treatment increased growth performance at the early stage of growth and improved yield characteristics, in addition to increased seed germination. Cow dung and two marine microalgae mixture treatment exhibited high growth and yield revealed the potential of the marine microalgae as fertilizer in cultivation of maize.
TL;DR: In this article, the effect and interaction of process parameters including reaction temperature, reaction time and particle size was optimized using central composite design of response surface methodology, and the optimized process parameters were found at temperature of 300°C, reaction times of 20min and the particle size of 3mm producing maximum 549% of biochar yield.
Abstract: Agricultural waste is considered as a burden all over the world due to its disposal issues In this research an effort is made to utilize agricultural residue for the production of cost effective and environmental friendly fuel The study also focused on investigation of role of best process conditions to get optimized biochar (OB) from the slow pyrolysis of novel biomass, waste pomegranate peel (WPP) The effect and interaction of process parameters including reaction temperature, reaction time and particle size was optimized using central composite design of response surface methodology The optimized process parameters were found at temperature of 300 °C, reaction time of 20 min and the particle size of 3 mm producing maximum 549% of biochar yield Furthermore, the WPP and OB were considered and compared for physical and chemical analyses including scanning electron microscope (SEM), Fourier transform infrared spectroscopy, thermo gravimetric analysis, and higher heating value (HHV), proximate and ultimate analysis Considerable modification in structure has been seen in the product which can be observed by SEM analysis In result of thermal processing through pyrolysis, HHV of OB was improved to 235 from 1461 MJ/kg of parent biomass
TL;DR: In this article, a pot experiment was conducted to compare the effects of compost from fish waste (FW) on the yield and macro and microelemental composition of ice lettuce (Lactuca sativa L.).
Abstract: The manuscript presents results of the evaluation of compost from fish waste (FW) as a fertilizer for agricultural use. A pot experiment was conducted to compare the effects of compost from FW on the yield and macro and microelemental composition of ice lettuce (Lactuca sativa L.). In addition, the phytotoxicity degree of the compost and compost effects on seed germination and primary root growth were determined with white mustard (Sinapis alba L.). Compost used in the study consisted of FW and pine bark. Results of the evaluation enable concluding that the compost from FW is non-phytotoxic, mature, stable, and suitable for use in agriculture. Its addition to soil caused an increase in fresh and dry matter yield of leaves of ice lettuce (L. sativa L.). Fertilization had a significant effect on increased contents of nitrogen, phosphorus, potassium, sodium, calcium, and magnesium in leaves of the test plant. The average accumulation of microelements in ice lettuce (L. sativa L.) grown in the soil fertilized with compost from FW followed the descending order Fe > Cu > Ni > Zn > Mn, respectively. Soil fertilization with compost from FW improved the K:(Mg + Ca), K:Mg and K:Ca ratios but, simultaneously, deteriorated the Ca:P ratio.
TL;DR: In this paper, the authors review literature studies on the co-pyrogasification of plastics and biomass by considering various aspects including the process principle, reactors, influence of feedstock characteristics and operating parameters on the products, as well as the synergies observed during the thermoconversion of polypropylene and biomass mixtures with some reference to coal mixtures when necessary.
Abstract: Over the past few decades, the sharp rise in post-consumer plastic and biomass waste has resulted in an ever growing challenge to treat such waste sustainably. Co-pyrogasification of plastics and biomass mixtures, as opposed to separately converting these waste streams, offers several advantages including an improvement in syngas quality and composition (H2/CO ratio) in relation to the desired application, and an easier reactor feeding of plastics. Furthermore, many studies have shown that co-pyrogasification promotes the conversion of waste to gas rather than char and tar. However, in order to achieve the desired product distribution or syngas composition, operating parameters such as the reactor temperature, equivalence ratio (air or oxygen), steam/fuel ratio and catalyst, have to be optimized. Thus, this paper aims to review literature studies on the co-pyrogasification of plastics and biomass by considering various aspects including the process principle, reactors, influence of feedstock characteristics and operating parameters on the products, as well as the synergies observed during the thermoconversion of plastics and biomass mixtures with some reference to coal mixtures when necessary.
TL;DR: In this article, the authors reviewed the development of intensified pretreatment technologies with their current status and advancements and discussed several key processes and recommendations for cost-effective and eco-friendly pretreatment.
Abstract: Sustainable and renewable resources are inevitable factors for biofuel production to meet the energy and transportation fuel demand of a nation. The urge in meeting the energy demand can be achieved by intensified research on agricultural and waste biomass utilization. In recent days, advanced agricultural practice throughout the world generates surplus biomass residues and this can be utilized through aggressive pretreatment technology for bioethanol production. Bioethanol production from food crops was having some ethical issues on cost and availability of potential sources. It has been anticipated that the lignocellulosic biomass to bioethanol transformation process contains several challenges and bottlenecks. Selection of an appropriate of pretreatment technology for individual lignocellulosic biomass decides the economic feasibility of biofuel production process. Scientists from different countries were working on the development of biofuel production in sustainable manner, but the technology abides only at a demonstration level due to lack of process intensification. Recent advancements in processing and conversion of biomass dealt with integration of conventional pretreatment principles to vanquish the bottleneck issues faced in development of sustainable biofuel production technology. This paper reviews the development of intensified pretreatment technologies with their current status and advancements. Several key processes and recommendations for cost-effective and eco-friendly pretreatment technologies were also discussed in details.
TL;DR: In this article, the authors aimed at modeling and optimizing the production of fatty acid methyl esters from esterified palm kernel oil using two heterogeneous biowaste catalysts namely calcined banana peel ash (CBPA) and calcined cocoa pod husk ash (CCPHA).
Abstract: This study aimed at modeling and optimizing the production of fatty acid methyl esters from esterified palm kernel oil using two heterogeneous biowaste catalysts namely calcined banana peel ash (CBPA) and calcined cocoa pod husk ash (CCPHA). The central composite design of response surface methodology (RSM) was employed for investigating the individual and interactive effects of the process input variables (methanol/oil ratio, catalyst weight and reaction time) on the palm kernel oil methyl esters (PKOME) yield. The same optimal conditions (methanol/oil ratio 0.8 v/v, catalyst weight 4 wt% and reaction time 65 min) were predicted by RSM for the transesterification reaction catalyzed by CBPA and CCPHA at constant temperature of 65 °C. The observed PKOME yields under the optimal condition using the two catalysts were 99.5 and 99.3 wt% for CBPA and CCPHA, respectively. The developed quadratic models were appraised using different statistical indicators such as coefficient of determination (R2) and average absolute deviation (AAD). R2 of 0.9064 and 0.8245 and AAD of 0.5526 and 0.6901 computed for CBPA and CCPHA-catalyzed transesterification reactions, respectively, showed both models gave good predictions. In both cases, methanol/oil ratio was the most significant factor on the PKOME yield. The PKOME produced using the two catalysts satisfied both the ASTM D6751 and EN 14214 standard specifications. Both banana fruit peel and cocoa pod husk could adequately serve as low-cost feedstock for PKOME synthesis.
TL;DR: In this paper, the authors used citrus peels (lemon, mandarin, orange and grapefruit) for the production of bacterial cellulose (BC) and found that the FTIR spectra of the BCs produced in citrus peel hydrolysates were similar to BC produced in commercially available nutrients.
Abstract: Cellulose is the most common polymer in the world, formed by β-1,4 linked glucopyranose units. In this study, citrus peels (lemon, mandarin, orange and grapefruit) were used for the production of bacterial cellulose (BC). The peels were hydrolyzed with dilute acid and hydrolysates were used for BC production. The production of BC was carried out at 28–32 °C for 21 days under static conditions with Komagataeibacter hansenii GA2016. BC yields were found to be between 2.06 and 3.92%. It was found that the FTIR spectra of the BCs produced in citrus peel hydrolysates were similar to BC produced in the commercially available nutrients. The result of this study showed that all the BCs produced from citrus peels were characterized to have high water holding capacity, thin fiber diameter, high the thermal stability and high crystallinity.
TL;DR: In this paper, a review of the utilization of wastewater for micro-gal cultivation is discussed with particular attention to the feasibility of utilizing POME as microalgal growth medium, and the concept of using stepwise strategies to obtain high value added product is proposed.
Abstract: South East Asia dominates the production of palm oil worldwide. During the traditional wet processing, palm oil mill effluent (POME) wastewater is generated which poses serious environmental problems. Wastewater treatment using microalgae was initiated recently because of the advantages to lower nutrient content efficiently while the biomass can be utilized as bulk biomass or value added product. In the present review the utilization of wastewater for microalgal cultivation is discussed with particular attention to the feasibility of utilizing POME as microalgal growth medium. Whereas much recent research was focused on the production of bulk biomass, the potential for the production of value-added compounds has not often been addressed. Various strategies of obtaining high-value products are discussed. These include cultivation systems, algal species selection as well as and their growth strategies (autotrophic, heterotrophic, mixotrophic). In addition, potential problems associated with microalgal cultivation on POME will be evaluated. Finally, the concept of using stepwise strategies to obtain high value added product will be proposed.
TL;DR: This review aims to demonstrate the main concepts regarding bioproducts and microalgae, the relevant data about the sectors of application, and the main challenges and perspectives associated with these subjects by using bibliometric mapping.
Abstract: Microalgae have received considerable attention due to several applications in which they can be used, such as bioremediation and the production of high-value products. Microalgal biomass is known for its richness and variety of bioproducts such as lipids, carbohydrates, proteins, pigments and antioxidants. They can be used for several purposes, for example, in the production of biofuels, food nutrition (human and animal), pharmacology and cosmetology. However, despite the importance of these applications, there are still certain difficulties to produce microalgae bioproducts in large-scale. The high general cost of microalgal production is one of the major disadvantages, since cultivation, extraction and biorefining steps are necessary. Unfortunately, these processes are frequently not compensated by the final product sales price. The identification of the target compounds present in biomass as well as the costs involved in these steps are necessary to promote microalgal development for agricultural, commercial and industrial applications. To focus on the main aspects related to the bioproducts present in biomass, this review aims to demonstrate the main concepts regarding bioproducts and microalgae, the relevant data about the sectors of application, and the main challenges and perspectives associated with these subjects by using bibliometric mapping.
TL;DR: A pattern of increasing acidity with decreasing extraction duration was observed, suggesting preferential extraction of free fatty acids (FFA), with the fatty acid profile of the oil found to be similar to lipids commonly utilized for biofuel production.
Abstract: Spent coffee grounds (SCG) are a potentially valuable source of lipids for sustainable production of biofuels. However, there are several feedstock properties and solvent extraction parameters that can impact on the oil yield and quality, potentially reducing the possible environmental benefits of deriving oils from this waste stream. This study presents results of laboratory and pilot plant scale experimental investigations into lipid recovery from spent coffee, determining the effects of solvent extraction variables including duration, SCG-to-solvent ratio and SCG residual moisture. SCG samples from both the industrial production of instant coffee and retail coffee shops were characterized in terms of moisture content, particle size distribution and oil content to identify the impact of these variables on the efficiency of lipid recovery by solvent extraction. The dry weight oil content of the instant SCG samples ranged from 24.2 to 30.4% w/w, while the retail SCG samples contained considerably lower amounts of lipids with their oil content ranging between 13.4 and 14.8% w/w. The highest oil yields were found at an extraction duration of 8 h, while a moisture content of ~2% w/w led to increased yields relative to completely dry samples. A pattern of increasing acidity with decreasing extraction duration was observed, suggesting preferential extraction of free fatty acids (FFA), with the fatty acid (FA) profile of the oil found to be similar to lipids commonly utilized for biofuel production.
TL;DR: In this article, the authors reviewed the new achievements of odor abatement technologies (adsorption, chemical scrubbing, biofiltration, biotrickling, bioscrubbing, activated sludge diffusion) in wastewater treatment plants (WWTPs) and then identified a new aspect for the future studies.
Abstract: The ever increasing public complaints arising from wastewater treatment plants (WWTPs) grow since sewerage treatment has been associated with nauseous odorous on account of the anaerobic decomposition process and emission. Various physical/chemical and/or biological methods were used for abating odours worldwide. Thus, an updated comprehensive review for the WWTP odor abatement technologies is urgently required. This study reviews the new achievements of odor abatement technologies (adsorption, chemical scrubbing, biofiltration, biotrickling, bioscrubbing, activated sludge diffusion) in WWTPs and then identifies a new aspect for the future studies. Overall, hybrid technologies (physical/chemical + biotechnologies) attract increasing attention since their highly reliable removal efficiency for various odorants, however, the high costs for investment and O&M (operation & maintenance) of the adsorption part and the complexity and variability of odorants are still the major challenging for wide engineering application and technological innovation. Thus, developing the cost-effective, environmentally friendly odor control technologies, like using the alum sludge (waterworks residue) based adsorbents/media, in terms of using “waste” for waste treatment, could be a highly promising prospect.
TL;DR: In this article, the authors used cellulase and pectinase to hydrolyze orange peel in order to increase the amount of fermentable sugars, which is a low-cost feedstock for bacterial cellulose (BC) production.
Abstract: Oranges (Citrus sinensis) are the world’s most processed fruit. The waste from processing is rich in soluble sugars, cellulose, hemicelluloses and pectin and therefore has potential as feedstock for bacterial cellulose (BC) production. In this study, cellulase and pectinase were used to hydrolyze orange peel in order to increase the amount of fermentable sugars. Response surface methodology was used to evaluate the effects of reaction parameters, and 80.99 g/L reducing sugar was obtained with cellulase of 1589.41 U/g, pectinase of 31.75 U/g and a reaction time of 5.28 h. Besides, the orange peel fluid and orange peel hydrolysate were used as the culture media for Gluconacetobacter xylinus during BC production. The orange peel media have no significant inhibiting effect on the fermentation activity of G. xylinus for BC production. As an acetic acid buffer was used or nitrogen source was added to the orange peel media, BC production was 4.2–6.32 times higher than that in traditional Hestrin and Schramm (HS) medium. The SEM and IR spectra showed that the BC produced was not much different than that produced in HS medium. These results demonstrate that orange peel not only can be used as a low cost feedstock to produce BC, but it also provides a solution to the waste disposal problem of the orange juice industry.
TL;DR: In this article, the authors investigated the influence of chicken feather peptone (CFP) for citric acid production in Aspergillus niger and found that CFP increased the production of the acid.
Abstract: Citric acid is a commercially important organic acid with a wide range of applications. To reduce the cost of producing citric acid, sugar beet molasses and chicken feather peptone (CFP) were used as the sole carbon and nitrogen sources, respectively for submerged citric acid biosynthesis using Aspergillus niger. To improve the citric acid production, the parental isolate of A. niger MO-25 was improved by mutation using ethidium bromide. Citric acid production using molasses was significantly affected by CFP concentrations (1–6 g/L). The maximum citric acid concentration was determined at 4 g/L CFP and 168 h. When CFP compared to commercial peptones (casein and bacto), the highest citric acid production was obtained with CFP. Furthermore, the addition of KH2PO4 (0.15 g/L) enhanced citric acid production (68.8 g/L). These results suggested that sugar beet molasses supplemented with CFP as organic nitrogen and mineral salt sources could be utilized for the economical and efficient production of citric acid. This is the first study to investigate the influence of CFP for citric acid production.
TL;DR: In this article, the influence of Pulsed Electric Fields (PEF) of different intensities (3-9kV/cm and 0-300μs) on the extraction of total phenols from lemon peel residues by pressing was investigated.
Abstract: In this contribution, the influence of Pulsed Electric Fields (PEF) of different intensities (3–9 kV/cm and 0–300 μs) on the extraction of Total Phenols from lemon peel residues by pressing was investigated. According to the cellular disintegration index, the optimum treatment time for the increase in permeability was determined as 30 pulses of 30 μs. It was determined that the effect of PEF was independent of lemon residue size. The effectiveness of pressing-assisted extraction was evaluated by measuring the Total Phenol Content (TPC), the real antioxidant capacity and the concentrations of the main lemon polyphenols, the flavonones hesperidin and eriocitrin. The variables studied in the extraction were time, pressure applied and intensity of the electric fields. This study concludes that electric field intensity of 7 kV/cm increased the efficiency of polyphenol extraction by 300%, giving maximum values of 84 mg of hesperidin in 100 g FW and 176 mg of eriocitrin in 100 g FW. Thus, it was concluded that PEF provides a new methodology to improve polyphenol extraction with a non-thermal, environment-friendly technology, and this represents a method for increasing economic benefits of industrial processes.
TL;DR: In this article, a green synthesis of spherical silver nanoparticles (AgNPs) by using sapota fruit pomace was carried out using UV-Visible spectroscopy.
Abstract: Green synthesis of spherical silver nanoparticles (AgNPs) by using sapota fruit pomace was carried out in the present study. The extraction procedure for sapota pomace and reaction conditions were simple and convenient to handle and straightforwardly optimized using UV–Visible spectroscopy. The generated AgNPs were characterized using Fourier-transform infrared spectroscopy (FTIR). The morphology and crystalline phase of the AgNPs were determined from X-ray diffraction (XRD) spectroscopy and transmission electron microscopy (TEM). The spherical AgNPs synthesized after reduction with sapota pomace extract were biphasic in nature and displayed a particle size of 8–16 nm with moderate stability (Zeta potential of − 13.41). AgNPs synthesized with sapota pomace extract showed good antibacterial properties against Gram-positive as well as Gram-negative microorganisms, comparable to reported literature. The results of this study promote a productive utilization of fruit waste for the synthesis of nanoparticles.
TL;DR: In this paper, the authors aim to maximize the phenolic compounds extraction from sunflower seed cake by using a second order polynomial model to optimize the extraction factors, including ultrasound amplitude and temperature.
Abstract: Sunflower seed cake is a by-product of the sunflower oil industry which is a valuable source of protein for animal feed. The presence of phenolic compounds significantly affects the sunflower proteins quality to animal feeding, decreasing its commercial value. Seeking to valorize this by-product, by improving the nutritive potential of the sunflower cake and getting an extract rich in antioxidants, the present study aims to maximize the phenolic compounds extraction from sunflower seed cake. The following parameters were evaluated: temperature (20–70 °C), ethanol concentration (0–85%) and ultrasound amplitude (0–80 µm). Response surface methodology was employed to optimize the extraction factors and a second order polynomial model provided a satisfactory fit to the experimental data. The response variables analyzed were the total phenolic compounds and the chlorogenic acid concentrations, which ranged between 751 and 1851 mg gallic acid equivalent (GAE)/100 g and 609–1635 mg CGA/100 g of sunflower seed cake in dry basis, respectively. The temperature and ethanol concentration showed the highest effect on the TPC extraction from sunflower cake. The ultrasound-assisted extraction effect was observed only in the first minute of extraction, having no influence at longer times.
TL;DR: In this article, the physicochemical composition and valorization of papaya peel and seeds are discussed. And the authors show that PP is a valuable source of bioactive compounds, which can be converted into many value-added products.
Abstract: Papaya is a popular fruit consumed worldwide and well-known for its food and nutritional values. It is used in food industries for the production of jams, jellies, etc. As a result, these industries generate huge amounts of papaya peel (PP) and seeds as by-products, which are typically considered a waste, and thus discarded. However, our current investigation indicates that PP is a valuable source of bioactive compounds, which can be converted into many value-added products. In this article, we review the physicochemical composition and valorization of PP. PP can be utilized to obtain many value-added products by fermentation (e.g., biofuels, adsorbents, dietary fibers, biomedicine, biomaterials). The biorefinery approach for PP will definitely increase the value of this waste by producing an array of value-added products and achieving zero waste generation.
TL;DR: In this article, the performance, emission and combustion characteristics of diesel engine are investigated with the supply of fresh air-fuel mixture for conventional diesel and waste cooking oil methyl ester as fuels and in the second phase the fresh air fuel mixture is blended with 30% exhaust gas.
Abstract: The present research work deals with the application of 30% exhaust gas recirculation (EGR) in a direct injection compression ignition engine fuelled with 100% waste cooking oil methyl ester and conventional diesel. In the first phase of this research work, the performance, emission and combustion characteristics of diesel engine are investigated with the supply of fresh air–fuel mixture for conventional diesel and waste cooking oil methyl ester as fuels and in the second phase the fresh air–fuel mixture is blended with 30% exhaust gas. The study reveals that the 30% EGR addition decreased the brake thermal efficiency by 8 and 18% for conventional diesel and 100% waste cooking oil methyl ester as fuels. Nitrogen oxides emission is reduced to a great extent by 47.5% for diesel fuel and 58.9% for biodiesel fuel at full load condition. Further, the 30% EGR has substantially increased the carbon monoxide and unburnt hydrocarbon emissions for both the fuels at maximum brake mean effective pressure. In addition similar pattern of in-cylinder gas pressure, heat release rate, cumulative heat rate have been observed for fresh air fuel mixture and 30% EGR under various loading conditions.
TL;DR: In this article, microwave assisted extraction (MAE), high hydrostatic pressure (HHP) and ultrasonic-assisted extraction (UAE) were used as novel processes for sour cherry pomace extraction.
Abstract: Sour cherry pomace derived from mashed cherries that maintains the color and beneficial properties of the cherries (Prunus cerasus L.). In this study, microwave-assisted extraction (MAE) (900 W for 30, 60 and 90 s.), high hydrostatic pressure (HHP) (400 and 500 MPa for 1, 5 and 10 min at 20 °C) and ultrasonic-assisted extraction (UAE) (for 5,10 and 15 min with a power of 100%) was used as novel processes. Total phenolic content (TPC), morphological changes, antioxidant activity (AA) and structural changes of cherry pomace were measured by the Folin–Ciocalteu assay, high performance liquid chromatography (HPLC), DPPH-scavenging activity, scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). According to the results, all novel technologies (MAE-HHP-UAE) increase PC and AA with respect to conventional solvent extraction method (50 °C and 30 min) (CSE). Among novel technologies, MAE (90 s) had highest TPC (275.31 ± 4.26 GAE/100 g FW) and also had highest antioxidant activity (89.9 ± 0.22%). The lowest TPC and AA values were 108.36 ± 3.99 mg gallic acid equivalent (GAE)/100 g fresh weight (FW) and 71.30 ± 1.21% in CSE, respectively. According to FTIR results, there are no significant structural changes in samples when different extraction techniques were applied. Individual phenolics were quantified by using HPLC for different extraction techniques.
TL;DR: In this paper, Aspergillus oryzae and Rhizopus oryzales were used to remove 80% of COD after 3 days for ED1 and ED2 streams.
Abstract: The process to obtain starch from wheat requires high amounts of water, consequently generating large amounts of wastewater with very high environmental loading. This wastewater is traditionally sent to treatment facilities. This paper introduces an alternative method, where the wastewater of a wheat-starch plant is treated by edible filamentous fungi (Aspergillus oryzae and Rhizopus oryzae) to obtain a protein-rich biomass to be used as e.g. animal feed. The wastewater was taken from the clarified liquid of the first and second decanter (ED1 and ED2, respectively) and from the solid-rich stream (SS), whose carbohydrate and nitrogen concentrations ranged between 15 and 90 and 1.25–1.40 g/L, respectively. A. oryzae showed better performance than R. oryzae, removing more than 80% of COD after 3 days for ED1 and ED2 streams. Additionally, 12 g/L of dry biomass with protein content close to 35% (w/w) was collected, demonstrating the potential of filamentous fungi to be used in wastewater valorization. High content of fermentable solids in the SS sample led to high production of ethanol (10.91 g/L), which can be recovered and contribute to the economics of the process.
TL;DR: In this article, the applicability of orange peel hydrochar as a soil amendment for improving the physical properties of a compacted, clay soil was investigated and the growth of maize on substrates composed of clay soil and hydrochar and determine any potential phytotoxic effects.
Abstract: The main objectives of this work were the following: (1) to investigate the applicability of orange peel hydrochar as a soil amendment for improving the physical properties of a compacted, clay soil and (2) to study the growth of maize on substrates composed of clay soil and hydrochar and determine any potential phytotoxic effects. The effect on soil’s bulk density (BD), aeration, water holding capacity (WHC), and hydraulic conductivity were examined with hydrochar additions of 5, 10 and 15% (w/w) and determined by conventional laboratory methods. Potential phytotoxic effects were determined through the Zucconi germination index on fresh, diluted and 4-week old undiluted hydrochar extracts. The effect of hydrochar on maize growth was studied in clay soil (as reference), clay soil with 5% (w/w) fresh hydrochar, clay soil with 5% (w/w) of 4-week-old hydrochar and clay soil with 5% (w/w) biochar (for comparison). At an application rate of 5% (w/w) hydrochar, the bulk density was reduced from 1.35 to 1.22 g/cm3, the air-filled porosity was increased from 33 to 37% and the saturated hydraulic conductivity from 0.96 to 1.01 cm/h. The water holding capacity remained practically unchanged, however it was considerably reduced at higher application rates. The seed germination test indicated strong phytotoxicity of the fresh, undiluted hydrochar extract, which was reduced when the extract was diluted or the hydrochar allowed to mature for 4 weeks. The pot tests indicated that hydrochar did not improve the yield of maize, probably due to the presence of phytotoxic substances. This study demonstrated a new valorization pathway for a significant agricultural waste. Additionally, it proved the applicability of orange peel hydrochar for improving the physical properties of clay soil. However, due to phytotoxic effects, further work is required before a field application is considered.
TL;DR: This study revealed that FPH produced by C. sediminis RCM-SSR-7 has the potential to be used as animal feed and organic fertilizer and exhibited radical scavenging activity with an IC50 value of 0.102 mg ml−1.
Abstract: Accumulation of feather waste is becoming a major issue in solid waste management. Towards discovery of keratinolytic bacteria, screening of bacterial strains from feather dumping sites in North East, India was performed and 26 keratinolytic bacterial strains were isolated. Out of these, one isolate RCM-SSR-7 was found to be most promising strain exhibiting feather degradation as well as antioxidant and indole-3-acetic acid production. The strain was identified as Chryseobacterium sediminis RCM-SSR-7. The strain could use chicken feather as sole carbon and nitrogen source for growth. Three parameters (feather concentration, pH and incubation time) were studied to optimize feather protein hydrolysate (FPH) preparation using response surface methodology (RSM). The optimum condition for FPH preparation was achieved at 5% (w/v) feather concentration, pH 7.5, 30 °C and 84 h incubation time upon optimization by RSM. FPH was found to be rich in essential amino acids and trace elements (phosphorous, potassium, calcium, and iron). FPH exhibited radical scavenging activity with an IC50 value of 0.102 mg ml−1. In vitro digestibility showed that FPH is 86% digestible with pepsin and trypsin treatment. This study revealed that FPH produced by C. sediminis RCM-SSR-7 has the potential to be used as animal feed and organic fertilizer.
TL;DR: Results suggest that SPO, an inexpensive waste material, can be used to produce PHA in large scale for commercialization purpose with reduced production cost.
Abstract: Sludge palm oil (SPO), a difficult-to-be-used solid byproduct of the palm oil milling industry, was evaluated as potential carbon source for poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] production using recombinant Cupriavidus necator Re2058/pCB113. The biosynthesis of polyhydroxyalkanoate (PHA) was conducted using single stage shake flask growth to study different parameters affecting the bacterial growth. Fed-batch fermentations were conducted using SPO to increase the PHA productivity and to reach high density culture which is deemed necessary for large scale production. Initial shake flask studies showed that SPO can be utilized by the bacteria for growth and PHA accumulation. However, the yield of SPO conversion into cell biomass and PHA was low due to the difficulty in using the solid oil in liquid medium. With the aid of surfactant and mixing strategy, SPO which consisted mainly of free fatty acids was successfully emulsified in the mineral medium and was used for cell growth and PHA accumulation whereby 10 g/L of SPO supplied as emulsion solution produced 9.7 g/L of CDW containing 74 wt% P(3HB-co-22 mol% 3HHx). The high yield of biomass obtained indicates that SPO is an excellent feedstock for this strain. Fed-batch fermentation was conducted to increase the yield and productivity whereby a biomass productivity of 1.9 g/L/h and PHA productivity of 1.1 g/L/h were achieved. These results suggest that SPO, an inexpensive waste material, can be used to produce PHA in large scale for commercialization purpose with reduced production cost.
TL;DR: In this article, a green valorization approach was used to extract lycopene from tomato processing waste using an eco-friendly solvent mixture containing ethyl lactate and ethyl acetate.
Abstract: Lycopene is a highly-prized antioxidant with associated health benefits and is abundant in natural sources. A green valorization approach was used to extract lycopene from tomato processing waste. Ultrasound-assisted extraction was applied to the tomato waste using an eco-friendly solvent mixture containing ethyl lactate and ethyl acetate for the extraction of lycopene. Extraction parameters were: X1 = extraction temperature (°C), X2 = proportion of ethyl acetate in solvent mixture (% v/v), X3 = solvent:sample ratio (mL/g), and X4 = extraction time (min). A Box–Behnken design was used to define experimental conditions, and response surface methodology was then conducted to determine the optimized conditions: X1 = 63.4 °C, X2 = 30% (v/v), X3 = 100 mL/g, and X4 = 20 min. The experimental optimized extraction yield of lycopene was 1334.8 µg/g (d.w.), in agreement with the predicted yield. At the same conditions without ultrasound, a yield of 1209.5 µg/g (d.w.) was obtained (9.4% lower). Ultrasound increases extraction yield, and tomato processing by-products are a viable alternative source of extractable lycopene. This represents a greener strategy for the extraction of lycopene in comparison to conventional methods using organic solvents, and shows a promising alternative use for a food processing waste.
TL;DR: In this article, the effect of introducing processed food waste and unprocessed food waste (UPFW) on composting of green waste was evaluated and an improved product quality was observed in treatment C compared to other treatments.
Abstract: Green waste (GW) represents a large fraction of municipal solid waste (MSW) and has increased significantly with the rapid development of urban green areas in some countries. Composting is an appropriate method for the treatment and recovery of these wastes. However, the high content of lignocellulosic substances in GW is known to slow down the decomposition process. This research evaluated the effect of introducing processed food waste (PFW) and unprocessed food waste (UPFW) on composting of GW, it monitored the process itself and assessed the end-product quality. A field-scale experiment was developed using three treatments: Treatment A (100%GW), Treatment B (40%UPFW + 60%GW) and Treatment C (50%GW + 30%UPFW + 20%PFW). Treatment C reached thermophilic temperatures in a shorter time than the other treatments and maintained those temperatures for longer periods. In addition, treatment C reached ambient temperatures during curing in a shorter time compared to treatments A and B. An improved product quality was observed in treatment C compared to other treatments. For example, products from treatment C had lower ash content, higher concentrations of TOC and PTotal and lower EC values compared to treatments A and B. The final fertility index of the end-product from treatment C was 4.8–5.0, which indicates that the product can be suitable for agricultural use.