Pyrolysis kinetics and combustion characteristics of waste recovered fuels

Alternative fuels, such as biomass and refuse derived fuels tend to play an increasingly important role in the European energy industry. Co-firing fuels derived from non-hazardous waste streams have the potential of covering a significant part of the future demand on co-incineration capacities, which is expected to increase due to the implementation of the 2000/76 EC landfill Directive. However, their combustion behaviour has not yet been fully investigated, because of the difficulty to define representative fuel characteristics simulating accurately all the fuel fractions. In the present study, refuse derived fuel behaviour was investigated by thermogravimetry under pyrolysis and combustion conditions. A non-isothermal thermogravimetric analyser (TA Q600) operated at ambient pressure was used for both the pyrolysis and combustion experiments. The devolatilisation of the waste samples was investigated at a temperature range of 30-1000 °C with the constant heating rate of 20 °C/min and for particle sizes between 150 and 250 μm. Combustion tests were realized under the same heating conditions. The independent parallel, first order, reactions model was elaborated for the kinetic analysis of the pyrolysis results. The thermal degradation of the refuse derived fuel samples was modeled assuming four parallel reactions corresponding to the devolatilisation of cellulose, hemicellulose, lignin and plastics. Increased activation energies were calculated for the plastics fraction. Lignin presented the lowest contribution in the pyrolysis of the samples. Slightly increased combustion reactivities were found for the waste fuel samples compared to lignite. It is concluded that waste recovered fuels can be used in existing combustion facilities either alone or in combination with coal and future investigations should focus on the operational behaviour of large-scale facilities when exploiting these waste species.     

Combined use of waste materials—recovery of chitin from shrimp shells by lactic acid fermentation supplemented with date juice waste or glucose

BACKGROUND: Chitin, a source of chitosan, was extracted from the teguments of white shrimp Parapenaeus longirostris, by means of Lactobacillus helveticus growing on date juice waste or glucose for comparison. A fermentor containing 10% (w/v) of shrimp shells was inoculated with a suspension of L. helveticus strain milano (10% v/v). RESULTS: For an initial pH of 8.5–9.0 and a temperature of 30 °C, maximum deproteinization and demineralization were 76 and 53%, achieved for 80 and 300 g L^?1 glucose, respectively. The level of demineralization increased to 60% for an increase in in temperature from 30 to 35 °C. The use of date juice, as an alternative to the use of a primary carbon source such as glucose, led at best to 44% demineralization, for 208 g L^?1 of total sugar at 35 °C, and 91% deproteinization, for 80 g L^?1 total sugar content at 30 °C. CONCLUSION: Demineralization was not improved by the use of date juice, most likely due to its calcium content, which, during acidification, prevents the diffusion of calcium from the shells to the surrounding medium. Contrarily, the proteolytic activity of LAB appeared to be improved by the mineral content of date juice, leading to almost complete deproteinization of shrimp shells. Copyright © 2008 Society of Chemical Industry     

Extraction of proteins from shrimp processing waste

Up to 70% of the theoretical protein content of shrimp waste was recovered by a boiling water extraction method. Digestion time, volume and concentration of calcium hydroxide were varied to optimise the yield of dry matter recovered on processing the shrimp waste. Amino acid analysis was carried out to characterise the protein content of the dry matter.     

Production of high‐quality chitin and chitosan from preconditioned shrimp shells

Chitin and chitosan with improved characteristics were produced from shrimp shell waste preconditioned by limited decay or by treatment with 0.016 mol L^?1 benzoic acid. Preconditioned shrimp shells were transparent, had a clean surface and were susceptible to demineralization and deproteinization using 0.68 mol L^?1 HCl and 0.62 mol L^?1 NaOH, respectively. The ash and protein residues in the final chitosan were about 0.2% and 0.4%, respectively, the viscosity was up to 7000 cps, and the solubility and transparency nearly 100%. In comparison with treatment at ambient temperature (30 °C) without preconditioning, the chemical consumption, the duration of the treatment, ash and protein residues was reduced to 75–25%, whereas viscosity and absence of insolubles improved by a factor of 2–3. Copyright © 2006 Society of Chemical Industry     

Improved chitin production by pretreatment of shrimp shells

Pretreatment of shrimp shells was investigated in order to lower the costs and to improve the sustainability of chitin production. Physical pretreatment comprising drying, grinding and sieving is attractive for the recovery of 50% of shrimp protein as a dry powder. Pretreatment of shells by shearing in acidified water results in the removal of up to 60% of the protein and a reduction of their mineral content without a decrease in the chitin yield. Both pretreatment procedures will lead to cleaner technology for chitin production, to a considerably lower need for chemicals, to useful protein by‐products, and to less‐contaminated industrial effluent. Copyright © 2004 Society of Chemical Industry     

Energy protein intake during nutritional recovery and nutritional status achieved

Thirty years ago malnourished Chilean children were recovered by CONIN; they were fed ad libitum and this may have favoured the appearance of overweight-obesity (SP/OB). The objective of this study was to evaluate the relationship between energy-calorie intake during nutritional recovery and the appearance of overweight-obesity (SP/OB). The design was a retrospective, analytical study of the universe formed by the 168 clinical records found, of children below 2 years of age, recovered by CONIN between 1977 and 1982. Nutritional status was assessed using the Sempé criteria (applied in the period evaluated) and those of WHO, (currently in use), on admission, after 4 month treatment and on discharge. By Sempé criteria, malnutrition on admission was classified 25% severe, 63% moderate and 12% mild; instead, using WHO standards these figures were 14.9%, 29.2% y 38.1%, respectively; the remaining children were well nourished. On discharge, there was no SP/OB by W/A (Sempé), but by W/H (WHO) 6% and 13.8% were SP/OB after 3 months and on discharge, respectively. Food intake, administered ad libitum, reached a mean of 148 kcals/ kg/d and 4 g prot/kg/d. SP/OB children had greater daily weight gain (30.3 vs 19.2 g/d) than the non-obese children and greater daily weight gain than the mean for age and sex (19.7 vs 8.2 g/dia). The prescribed feeding reached values considered high by currently used criteria; actual intake, administered ad-libitum, was significantly lower and was associated with 13.8% of children with overweight-obesity at the time of discharge.     

亚临界流体萃取法回收废弃虾蟹壳中虾青素

考察了以废弃虾蟹壳为原料,亚临界流体萃取法提取虾青素的工艺。通过单因素及正交实验优化了提取条件,提取工艺为:以二氯甲烷为溶剂,100℃,9.31~11.72 MPa,静态提取时间15 min,循环2次,提取率为0.037 3%。与传统的有机溶剂浸提法提取结果比较表明,亚临界流体萃取的提取率高出33.2%,且耗时减少82.8%。     

废电池回收锌生产硫酸锌工艺的研究

研究从废电池中回收锌生产硫酸锌的工艺，该工艺成功解决了废电池对环境的污染问题，为锌盐行业拓宽了资源渠道。从废电池中回收锌生产硫酸锌工艺简单，投资少，经济效益显著，仅原料锌一项每吨产品即可降低原料成本470元。产品符合国家标准。     

Green ceramic pigment based on chromium recovered from a plating waste

The development of pigments with new formulas, departing from lower-cost raw materials, is driven by market growth and competitiveness required by the ceramic sector. In this work, the application of a residue from a metallurgical plant, containing a high amount of chromium (III) in ceramics glazes was studied. Cr₂O₃ was successfully separated from chrome plating waste resulting in a suitable synthesize ceramic pigment, based on this chromophore. A washing treatment was applied to the residue followed by a calcination at 1000 °C prior to the usage as pigment. The adequate purity of Cr₂O₃ recovered from waste was confirmed by analytical techniques (XRF, XRD, DTA-TG, FTIR and SEM-EDX). The glasses, containing 5 wt% of recovered Cr₂O₃, were carried out using frits and transparent micronized glass for mono- and double firing processes. The materials were characterized by XRD and FTIR, and by the colorimetric parameters CIELab. The resulting glazes containing the waste are within the range of typical pigments based on Cr₂O₃ in silicate and aluminate glazes for single firing, showing dark green hues in comparison with the previous data obtained from commercial grade Cr(III) oxide. However the presence of small amounts of the other chromophores in the waste modifies the tonality, affecting the purity of the chroma by increasing darkness. The leaching tests performed on the glazes suggest that Cr(III) is stable in this ceramic matrix. This results show that glazing is a suitable process for the Solidification/Stabilization of this waste.     

Separation of chitin from shrimp shells enabled by transition metal salt aqueous solution and ionic liquid

Chitin is a widely used important industrial polymer mainly from shrimp shells, but its commercial preparation is under the great challenge of serious pollution due to the requirement of HCl and Na OH.Herein, we demonstrated that high purity chitin can be obtained from waste shrimp shells(WSSs) by cascade separation with transition metal salt aqueous solution and ionic liquid(IL). Firstly, calcium carbonate of WSSs was effectively removed in the metal salt aqueous solution driven by the ion exch...     

利用壳聚糖的生产废弃液制备双乙酸钠

工业上用甲壳素生产壳聚糖会产生高浓度强碱性废液,传统工业方法是将其处理后排放,这样既浪费资源又污染环境。本文利用该废液制备防腐剂——双乙酸钠（SDA）,从废液脱色、浓缩、投入乙酸的量、反应温度、反应时间、干燥温度与时间等制备条件进行了研究,确定了最佳制备工艺。所得产品中含40.38%乙酸和58.42%乙酸钠,水含量小于2%,质量符合FAO/WHO标准。     

从废干电池中回收锌锰及电镀再利用

采用硫酸和亚硫酸的体积比为10∶1的混合水溶液对废干电池进行浸酸处理,得到硫酸锌和硫酸锰的混合水溶液,并将该液作为主要原料配制电镀溶液进行锌锰合金电镀实验。镀液组成及工艺条件为23.4g/LZn2 ,19.2g/LMn2 ,252.8g/LNa3C6H5O7·2H2O,1g/L聚乙二醇(6000),1.5g/L硫脲,50mg/LNa2S2O3,pH4~5,温度20~30°C,阴极电流密度1~6A/dm2。获得了含锰4.07%~15.8%的锌锰合金镀层,该镀层表面平整,结晶组织细致,结合力好。     

Hydrothermal synthesis of tellurium nanorods by using recovered tellurium from waste electronic devices

Tellurium (Te) nanostructures with controlled morphology have received the considerable attention in various applications owing to tunable optic, thermoelectric, photoelectronic, piezoelectric, and electrochemical properties. Herein, we introduce the cost-effective and eco-friendly synthesis of Te nanorods (Te NRs) from end of life electronic devices via hydrothermal methods. The Te NRs show the average diameter of 44.6?nm and a length of 358?nm in presence of polyvinylpyrrolidone, as a stabilizing agent. Moreover, the bismuth and intact p-type semiconductor (i.e., Bi_0.5Sb_1.5Te₃) are selectively recovered as intermediated products. The Te NRs exhibit the NO₂ gas sensing properties with concentration as low as 1?ppm at room temperature and fast response/recovery times of 1.59 and 2.10?s at 1?ppm, respectively. We believe that this powerful approach can be expanded to not only selective recovery of valuable materials but synthesis of various nanomaterials from waste electronic devices.     

高碳石墨生产中废酸制备聚合氯化铝铁的研究

研究了利用“碱熔-水洗-酸浸”法提纯石墨过程中含Fe”废酸制备聚合氯化铝铁(PAFC)的工艺条件,结果表明直接用回收酸制备高效混凝剂PAFC切实可行,所制备的PAFC具有适用范围宽,混凝效果优的特点。     

Influence of technological processing on various nutritional characteristics of sunflower protein isolates

The composition and nutritional value of sunflower meals and protein isolates were determined. One of the meals was an ordinary industrial one (HI) and the other (HL) was prepared at the laboratory from the same batch of sunflower seeds. The protein isolates were obtained from both meals (AHI and AHL, respectively) and from the original seeds (AS), by means of a process employing water extraction and precipitation at pH 4.3. Chemical analysis of both meals showed that their moisture, protein crude fiber and fat contents had no significant difference. Sulphur amino acids (g/16 g N) were higher in the isolates than in the flours. The HL flour, and the AHL and AS isolates had a higher proportion of available lysine (96.9%, 93.0%, and 92.4% respectively) than the HI flour and AHI isolate. This improvement of protein quality was attained by the employment of less drastic thermal treatments in their preparation, as compared with the treatments to which other materials were submitted.     

Thermal properties of poly(ethylene terephthalate) recovered from municipal solid waste by steam autoclaving

The steam autoclaving of municipal solid waste followed by size separation was shown to be a way to recover virtually 100% of recyclable poly(ethylene terephthalate) (PET); this is a yield not attainable by a typical material recovery facility. The polymer properties of the recovered PET, which had undergone various degrees of thermal processing, were evaluated by thermogravimetric analysis, differential scanning calorimetry, gel permeation chromatography, viscometry, and solid‐state NMR to assess the commercial viability of polymer reuse. The weight‐average molecular weight (M_w) decreased as a result of autoclaving from 61,700 g/mol for postconsumer poly(ethylene terephthalate) (pcPET) to 59,700 g/mol for autoclaved postconsumer poly(ethylene terephthalate) [(apcPET)]. M_w for the reclaimed poly(ethylene terephthalate) (rPET) was slightly lower, at 57,400 g/mol. The melting temperature increased with two heat cycles from 236°C for the heat‐crystallized virgin poly(ethylene terephthalate) (vPET) pellets to 248°C for apcPET and up to 253°C for rPET. Correspondingly, the cold crystallization temperature decreased with increased processing from 134°C for vPET to 120°C for apcPET. The intrinsic viscosity varied from 0.773 dL/g for the vPET to 0.709 dL/g for rPET. Extruded samples were created to assess the potential commercial applications of the recovered rPET samples. The M_w values of the extruded apcPET and rPET samples dropped to 37,000 and 34,000 g/mol, respectively, after extrusion (three heat cycles); this indicated that exposure to heat dictated that these materials would be better suited for downcycled products, such as fibers and injected‐molded products. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

Valorization of chitins extracted from North Morocco shrimps: Comparison of chitin reactivity and characteristics

Huge quantities of waste discharged by the gray and pink shrimp decortication units in the North of Morocco can be valorized by producing about 950 tons of pure chitin, which can be transformed into 700 tons of highly to totally deacetylated chitosan. During the preparation of chitin and chitosan from gray and pink shrimps, differences in reaction behavior were observed even though these are taxonomically close species. The presented results concern several chitinous sources, and they show that the progress in the N-deacetylation reactions of chitin would be linked to the crystallinity index of the starting chitin. Following the kinetic study of the polymer hydrolysis during N-deacetylation, the difference in the molecular weights of the chitosan samples obtained under identical reaction conditions was related to the differences between molecular weights of the native chitin, 478 000 g.mol⁻¹ for pink shrimp and 562 000 for gray shrimp. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47804.