Characterizing the waste generated from different agro-industrial segments enables the strategic management of residues, with the goal of maximizing recovery within the premises of a circular economy. This research aimed to determine the coefficient of waste generated in broiler chick hatcheries as well as to characterize the waste, taking into account the points of culling and the ages of the laying hens. Furthermore, the waste was used in composting with sheep manure (SM) at increasing inclusion rates (0:100, 10:90, 20:80, 30:70, 40:60, and 50:50). On average, 0.16 kg (DM) of hatchery waste is generated per kg of broiler chicks born. At the hatchery, at least 79% of the total disposal occurs at the hatcher stage. This value is impacted by chicken age (P < 0.05), with birds of a late laying age generating waste with higher contents of carbon (C), volatile solids (VS), ether extract (EE), and nitrogen (N). Culling during egg reception and the manual transfer process account for only 1.8% of the total waste generated on average and thus contribute little to the composition of the overall residues. However, the mechanical transfer process may represent up to 19.0% of the total waste generated by hens of an intermediate laying age. According to the average of all the composting stages, the maximum reduction in solids and C from the hatchery waste was reached when the waste accounted for 50% of the windrow composition. Such conditions resulted in organic fertilizer with the highest N content (2.8%), equivalent to 40.0% more than that in the treatment with no added hatchery waste. The compost resulting from 50% hatchery waste inclusion also had the highest humic acid to fulvic acid (HA:FA) ratio and the highest calcium content due to the higher proportion of eggshells. These findings lead to the recommendation for the inclusion of hatchery waste in composting with SM at a 50% rate by mass. (C) 2020 Elsevier Ltd. All rights reserved.
Separation and recovery of high-purity Si powder from kerf-loss Si slurry waste is a critical challenge for the photovoltaic industry. A green surfactant poly (propylene glycol) bis (2-aminopropyl ether) (PEA) was employed as a collector to facilitate the separation of Si and SiC from kerf-loss Si waste during flotation process. Single flotation tests of Si and SiC were conducted using 5 x 10(-6) mol/L PEA, respectively. The separation efficiencies of Si and SiC in conjunction with PEA adsorption mechanism were investigated. It was found that the maximum recoveries rate of SiC and Si were 90.59% (pH 9.00) and 80.93% (pH 1.96), respectively. Furthermore, the maximum Si grade was determined as 92.31% at pH 8.95 for the sinking part of the mixture generating excellent floatability and selectivity. Zeta potential measurements, FT-IR spectra, and XPS analyses demonstrated that PEA was present on the surface of Si and SiC through electrostatic and hydrogen-bond interactions. The adsorption mechanism was explained based on the results. This research provides an efficient and environmentally friendly route for the separation and recovery of high purity silicon from kerf-loss Si waste. (C) 2020 Elsevier Ltd. All rights reserved.
In this study, the effects of different biochar catalysts on the quality of bio-oil derived from the co-pyrolysis of sewage sludge (SS) and rice husk (RH) are explored. Catalysts include SS biochar (SWC), RH biochar (RHC), mixed SS and RH biochar (SRC), and RH ash (RHA). The quality of bio-oil was evaluated based on the results of gas chromatography-mass spectrometry (GC-MS; including the contents of hydrocarbons and N-species), oxygen content, higher heating value, and pH. The GC-MS analysis results illustrated that N-species content in the bio-oil reduced with the addition of the biochar catalyst, while the hydrocarbons content increased from 15.51% for co-pyrolysis to 38.74-61.84% for different biochar catalysts at a catalytic temperature of 650 degrees C. RHC exhibited the best catalytic effect in terms of decreasing the content of N-species by 58.79% and increasing the content of hydrocarbons by nearly four times compared to co-pyrolysis. The higher heating value of bio-oil raised from 25.75 to 34.67 MJ/kg, while oxygen content decreased from 31.1 to 8.81 wt%, and the pH increased from 4.06 to 5.48. Moreover, the catalytic mechanism of catalytic co-pyrolysis over RHC, including the hydrocarbon generation pathway and nitrogen removal, is also discussed here. High specific surface area of RHC provides sufficient active sites (e.g. O-containing and N-containing functional groups) for the catalytic reaction of pyrolytic intermediates. (C) 2020 Elsevier Ltd. All rights reserved.
Garcia Cruz, Ariel;Mtz-Enriquez, Arturo, I;Diaz-Jimenez, Lourdes;Ramos-Gonzalez, Rodolfo;Ascacio Valdes, Juan Alberto;Castaneda Flores, Martha E.;Hernandez Martinez, Jose Luis;Ilyina, Anna
Citrus wax is a waste generated during the purification process of the citrus essential oil. A lot of citrus wax wastes are globally produced, despite this, its composition and properties are not well known. Here we present comprehensive results proving the chemical composition and the physical properties of citrus wax. Additionally, our study provides the basis for obtaining value-added products from citrus wax wastes. The qualitative/quantitative analysis revealed the presence of different compounds, which range from flavonoids, saponins, carbohydrates, unsaturated compounds, phenolic hydroxyls, and long-chain fatty acid esters. Given that citrus wax is a source of many bioactive compounds, they were preferably extracted with ethanol. The ethanolic extracts demonstrated the presence in citrus wax of different bioactives, such as 5-5'-dehydrodiferulic acid, 3,7-dimethylquercetin, 5,6-dihydroxy-7,8,3',4'-tetramethoxyfla vone, tangeretin, and limonene. After the extraction of bioactives from citrus wax, a washed waxy material with high content of long-chain fatty acid esters was obtained. It was shown that this washed wax can be used for the production of biodiesel. The transesterification reactions in acid media was the preferred process because higher content of fatty acid methyl esters (such as hexadecanoic acid methyl ester and 9,12-octadecadienoic acid (Z,Z)-, methyl ester) were obtained. Currently, citrus wax does not have any industrial application, here we shown that under the concept of waste biorefinery, the citrus wax wastes are useful sources for producing value-added products such as bioactive compounds and biodiesel. (C) 2019 Elsevier Ltd. All rights reserved.
Ghorbannezhad, Payam;Park, Sunkyu;Onwudili, Jude A.
Ex-situ co-pyrolysis of sugarcane bagasse pith and polyethylene terephthalate (PET) was investigated over zeolite-based catalysts using a tandem micro-reactor at an optimised temperature of 700 degrees C. A combination of zeolite (HZSM-5) and sodium carbonate/gamma-alumina served as effective catalysts for 18% more oxygen removal than HZSM-5 alone. The combined catalysts led to improved yields of aromatic (8.7%) and olefinic (6.9%) compounds. Carbon yields of 20.3% total aromatics, 18.3% BTXE (benzene, toluene, xylenes and ethylbenzene), 17% olefins, and 7% phenols were achieved under optimal conditions of 700 degrees C, a pith (biomass) to PET ratio of 4 and an HZSM-5 to sodium carbonate/gamma-alumina ratio of 5. The catalytic presence of sodium prevented coke formation, which has been a major cause of deactivation of zeolite catalysts during co-pyrolysis of biomass and plastics. This finding indicates that the catalyst combination as well as biomass/plastic mixtures used in this work can lead to both high yields of valuable aromatic chemicals and potentially, extended catalyst life time. (C) 2019 Elsevier Ltd. All rights reserved.
Single-step synthesis of porous carbon (PC) from biomass is a challenge via microwave heating, because biomass rarely absorbs the microwave energy. Herein, wheat-straw-derived char, as a good microwave absorber, was used to achieve rapidly single-step synthesis of PC from an agricultural waste (wheat straw). KOH was used to generate abundant micropores in the PCs. High heating rate caused by microwave heating combined with the pyrolysis gases resulted in the formation of meso-/macropores. A series of post-oxidation reactions between active sites in the PCs and oxygen in the air led to the doping of oxygen-containing chemical groups. Consequently, the obtained PC possessed a high specific surface area of 1905 m(2) g(-1), a balanced pore distribution with abundant micropores (0.62 cm(3) g(-1)), considerable content of meso-/macropores (0.53 cm(3) g(-1)), and an oxygen-enriched structure (oxygen content up to 21.6%). These characteristics not only contributed to the achievement of a high specific capacitance of 268.5 F g(-1) at 0.5 A g(-1) for the resultant supercapacitor, but also resulted in an excellent rate capability with a high capacitance retention of 81.2% at 10 A g(-1) in a gel electrolyte (polyvinyl alcohol/LiCl). This supercapacitor can extract a high energy density of 21.5 W h kg(-1) at 0.5 A g(-1) and a high power density of 7.2 kW kg(-1) at 10 A g(-1). (C) 2019 Elsevier Ltd. All rights reserved.
This study investigates the feasibility of anaerobic digestion (AD) of press mud previously pretreated, using two methods: Liquid Hot Water (LHW) and Thermo-Alkaline (TA), from an economic, energetic and environmental point of view. Two scenarios, a sugar mill with and without distillery were studied, considering monodigestion and vinasse codigestion. The results have shown that the LHW and TA pretreatments are self-sufficient in terms of thermal requirements since they can recover heat from the biogas engine, but the maximum electric and thermal net energy (64 MWh d(-1) and 95 MWh d(-1), respectively) was obtained during co-digestion with vinasse. The results of the environmental Life Cycle Analysis (LCA) show that the alternatives improve the environmental profiles, in both scenarios. The endpoint impact category "Human health" had the highest contribution because of both: the burning of fossil fuel at refinery to supply the required electricity; and the production of Ca(OH)(2) when vinasse was fed. The AD of pretreated press mud by LHW in CSTR reactors was the most viable for the scenario of a sugar mill without distillery, while the alternative co-digestion with the vinasse of the press mud without pretreatment was the most viable for the scenario of a sugar mill with distillery. This research shows that both the environmental and energetic profiles and the profitability of methane production can improve when the pretreatment and co-digestion of these wastes from the sugar - alcohol production process are considered. (C) 2019 Elsevier Ltd. All rights reserved.
Hydrothermal conversion (HTC) of sewage sludge (SS) and its relevant model compounds such as cellulose, glucose, lignin and soybean protein (substitute for protein) was experimentally conducted at moderate reaction temperature of 260 degrees C for 60 min. The structural properties, carbon-containing groups, and microstructure of the char were characterised by several techniques. The results revealed that more benzene rings were formed by small clusters and the C-O bond on Aryl-alkyl ether decomposed on the surface particles during the HTC process. In addition, the catalyst Zeolite Socony Mobil-5 (ZSM-5, Si/Al: 300) showed an excellent performance on the high graphite degree of the char under moderate reaction temperature of 260 degrees C. In particular, cellulose has the most dramatic influence on the depolymerisation of C-(C,H). As evidenced with SEM, the size of the char derived from SS with ZSM-5 catalyst is 10-15 mu m, which is smaller than the char without catalyst. A mechanism for derivation of char from individual model compounds is proposed. The end products of lignin are composed of polyaromatic char, while the composition of the char derived from protein suggests that polymerisation may occur during hydrothermal reaction leading to formation of structures with N-containing compounds. (C) 2019 Elsevier Ltd. All rights reserved.
This work is focused on the preparation of an activated charcoal by carbonization of waste tire rubbers (WTRs) and its evaluation for shape-stabilization of dodecyl alcohol (DDA) as an organic phase change material (PCM) used for thermal energy storage (TES). In the composite, DDA had TES function as carbonized waste tire (CWT) acted as supporting and thermal conductive frameworks. CWT prevented leakage of melted DDA during phase change due to its good adsorption ability until the weight ratio of DDA reached 78%. The shape-stabilized composite PCM was characterized by FT-IR, XRD, SEM, DSC and TGA techniques. The DSC results revealed that the composite PCM had very appropriate melting point of 21.68 +/- 0.12 degrees C and considerable high latent heat capacity of 181.6 +/- 1.2 J/g for thermoregulation of buildings. Compared to DDA, thermal degradation temperature of the composite PCM was extended as about 50 degrees C. The 500-cycled composite PCM had still showed reliable TES properties. Additionally, thermal conductivity (0.431 +/- 0.010 W/m.K) of the composite PCM was measured as about 2.3 times higher than that of DDA. The heating and cooling periods of the composite PCM were reduced by 17.2 and 20.0%, respectively compared to that of DDA due to its enhanced thermal conductivity. All results suggested that the produced CWT as low-cost and environmental friendly supporting material can be evaluated for absorbing PCMs used for passive solar TES utilization in buildings. (C) 2019 Elsevier Ltd. All rights reserved.
In view of the recycling of PSU plastics has a good energy saving and environmental protection significance. This paper is concerned with the mechanical properties, and long-term durability of virgin and recycled polysulfone plastics (PSU) collected from wasted PSU nonwovens, the mechanical experiment of tensile test and Izod impact test are carried out to investigate the effect of cycle processing on the performance of PSU. The long-term durability of virgin and recycled PSU is studied base on time-temperature superposition by using a dynamic mechanical analysis (DMA). The thermal stability is evaluated by pyrolytic activation energy calculated by Iso-conversional kinetics method using a Thermogravimetric analysis (TGA). The results show that the recycled PSU exhibits the similar tensile property while lower impact strength than virgin PSU. The long-term durability and thermal stability of virgin PSU are better than recycled PSU and decreased with increasing the times of cycle processing, which is attributed to the mixing of impurities and degradation of the molecular structure in the recycling process. (C) 2018 Elsevier Ltd. All rights reserved.