Drying kinetic analysis of municipal solid waste using modified page model and pattern search method

This work studied the drying kinetics of the organic fractions of municipal solid waste (MSW) samples with different initial moisture contents and presented a new method for determination of drying kinetic parameters. A series of drying experiments at different temperatures were performed by using a thermogravimetric technique. Based on the modified Page drying model and the general pattern search method, a new drying kinetic method was developed using multiple isothermal drying curves simultaneously. The new method fitted the experimental data more accurately than the traditional method. Drying kinetic behaviors under extrapolated conditions were also predicted and validated. The new method indicated that the drying activation energies for the samples with initial moisture contents of 31.1 and 17.2 % on wet basis were 25.97 and 24.73 kJ mol−1. These results are useful for drying process simulation and industrial dryer design. This new method can be also applied to determine the drying parameters of other materials with high reliability.

Influence of alkyl chain length on sulfated zirconia catalysed batch and continuous esterification of carboxylic acids by light alcohols

The impact of alkyl chain length on the esterification of C2–C16 organic acids with C1–C4 alcohols has been systematically investigated over bulk and SBA-15 supported sulfated zirconias (SZs). Rates of catalytic esterification for methanol with acetic acid are directly proportional to the sulfur content for both SZ and SZ/SBA-15, with the high dispersion of SZ achievable in conformal coatings over mesoporous SBA-15 confering significant rate-enhancements. Esterification over the most active 0.24 mmol gcat−1 bulk SZ and 0.29 mmol gcat−1 SZ/SBA-15 materials was inversely proportional to the alkyl chain length of alcohol and acid reactants; being most sensitive to changes from methanol to ethanol and acetic to hexanoic acids respectively. Kinetic analyses reveal that these alkyl chain dependencies are in excellent accord with the Taft relationship for polar and steric effects in aliphatic systems and the enthalpy of alcohol adsorption, implicating a Langmuir–Hinshelwood mechanism. The first continuous production of methyl propionate over a SZ fixed-bed is also demonstrated.

In vivo and in vitro disappearance of energy and nutrients in novel carbohydrates and cereal grains by pigs

In vivo and in vitro experiments were conducted to determine digestibility of GE and nutrients, as well as DE and ME of carbohydrates fed to growing pigs. The objective of Exp. 1 was to determine the DE and ME of 4 novel carbohydrates fed to pigs. The 4 novel carbohydrates were 2 sources of resistant starch (RS 60 and RS 70), soluble corn fiber (SCF), and pullulan. These carbohydrates were produced to increase total dietary fiber (TDF) intake by humans. Maltodextrin (MD) was used as a highly digestible control carbohydrate. The DE and ME for RS 60 (1,779 and 1,903 kcal/kg, respectively), RS 75(1,784 and 1,677 kcal/kg, respectively), and SCF (1,936 and 1,712 kcal/kg, respectively) were less (P < 0.05) than for MD (3,465 and 3,344 kcal/kg, respectively) and pullulan (2,755 and 2,766 kcal/kg, respectively), and pullulan contained less (P < 0.05) DE and ME than MD. However, there was no difference in the DE and ME for RS 60, RS 75, and SCF. The varying degrees of small intestinal digestibility and differences in fermentability among these novel carbohydrates may explain the differences in the DE and ME among carbohydrates. Therefore, the objectives of Exp. 2 were to determine the effect of these 4 novel carbohydrates and cellulose on apparent ileal (AID) and apparent total tract (ATTD) disappearance, and hindgut disappearance (HGD) of GE, TDF, and nutrients when added to diets fed to ileal-cannulated pigs. The second objective was to measure the endogenous flow of TDF to be able to calculate the standardized ileal disappearance (SID) and standardized total tract (STTD) disappearance of TDF in the 4 novel fibers fed to pigs. Results of the experiment indicated that the AID of GE and DM in diets containing cellulose or the novel fibers was less (P < 0.05) than of the maltodextrin diet, but the ATTD of GE and DM was not different among diets. The addition of RS 60, RS 75, and SCF did not affect the AID of acid hydrolysed ether extract (AEE), CP, or ash, but the addition of cellulose and pullulan reduced (P < 0.01) the AID of CP. The average ileal and total tract endogenous losses of TDF were calculated to be 25.25 and 42.87 g/kg DMI, respectively. The SID of TDF in diets containing RS 60, SCF, and pullulan were greater (P < 0.01) than the SID of TDF in the cellulose diet, but the STTD of the SCF diet was greater (P < 0.05) than for the cellulose and pullulan diets. Results of this experiment indicate that the presence of TDF reduces small intestinal disappearance of total carbohydrates and energy which may reduce the DE and ME of diets and ingredients. Therefore, the objective of Exp. 3 was to determine the DE and ME in yellow dent corn, Nutridense corn, dehulled barley, dehulled oats, polished rice, rye, sorghum, and wheat fed to growing pigs and to determine the AID and ATTD of GE, OM, CP, AEE, starch, total carbohydrates, and TDF in these cereal grains fed to pigs. Results indicated that the AID of GE, OM, and total carbohydrates was greater (P < 0.001) in rice than in all other cereal grains. The AID of starch was also greater (P < 0.001) in rice than in yellow dent corn, dehulled barley, rye, and wheat. The ATTD of GE was greater (P < 0.001) in rice than in yellow dent corn, rye, sorghum, and wheat. With a few exceptions, the AID and ATTD of GE and nutrients in Nutridense corn was not different from the values for dehulled oats. Likewise, with a few exceptions, the AID, ATTD, and HGD of GE, OM, total carbohydrates, and TDF in yellow corn, sorghum, and wheat were not different from each other. The AID of GE and AEE in dehulled barley was greater (P < 0.001) than in rye. The ATTD of GE and most nutrients was greater (P < 0.001) in dehulled barley than in rye. Dehulled oats had the greatest (P < 0.001) ME (kcal/kg DM) whereas rye had the least ME (kcal/kg DM) among the cereal grains. Results of the experiment indicate that the presence of TDF and RS may reduce small intestinal digestibility of starch in cereal grains resulting in reduced DE and ME in these grains. Digestibility experiments involving animals are time consuming and expensive. Therefore, the objective of Exp. 4 was to correlate DM and OM digestibility obtained from 3 in vitro procedures with ATTD of GE and with the concentration of DE in 50 corn samples that were fed to growing pigs. The second objective was to develop a regression model that can predict the ATTD of GE or the concentration of DE in corn. The third objective was to evaluate the suitability of using the DaisyII incubator as an alternative to the traditional water bath when determining in vitro DM and OM digestibility. Results indicated that corn samples incubated with Viscozyme for 48 h in the DaisyII incubator improved (P < 0.001) the ability of the procedure to detect small differences in the ATTD of GE or to detect small differences in the concentration of DE in corn. Likewise, compared with using cellulase or fecal inoculum, the variability in the ATTD of GE and the variability in the DE in corn was better (R2 = 0.56; P < 0.05 and R2 = 0.53; P < 0.06, respectively) explained if Viscozyme was used than if cellulase or fecal inoculum was used. A validated regression model that predicted the DE in corn was developed using Viscozyme and with the corn samples incubated in the DaisyII incubator for a 48 h. In conclusion, this present work used the pig as a model for human gastrointestinal function and evaluates carbohydrates from 2 different nutritional perspectives – humans and animals. The addition of novel carbohydrates reduced the digestibility of energy in the diets without necessarily reducing the digestibility of other nutrients. Thus, supplementation of novel carbohydrates in the diets may be beneficial for the management of diabetes. Aside from diabetic management, cereal grains such as rye and sorghum, may also help in BW management because of there low caloric value, but for undernourished individuals, dehulled oats, dehulled barley, and rice are the ideal grains. From an animal nutrition standpoint, high concentration of dietary fiber is undesirable because it reduces feed efficiency. Therefore, the inclusion of feed ingredients that have a high concentration of dietary fiber is often limited in animal diets. Although in vivo determination is ideal, in vitro procedures are useful tools to determine caloric value of food and feed ingredients.

Emergence and fate of siloxanes in waste streams: Release mechanisms, partitioning and persistence in three environmental compartments

Siloxanes are widely used in personal care and industrial products due to their low surface tension, thermal stability, antimicrobial and hydrophobic properties, among other characteristics. Volatile methyl siloxanes (VMS) have been detected both in landfill gas and biogas from anaerobic digesters at wastewater treatment plants. As a result, they are released to gas phase during waste decomposition and wastewater treatment. During transformation processes of digester or landfill gas to energy, siloxanes are converted to silicon oxides, leaving abrasive deposits on engine components. These deposits cause increased maintenance costs and in some cases complete engine overhauls become necessary. ^ The objectives of this study were to compare the VMS types and levels present in biogas generated in the anaerobic digesters and landfills and evaluate the energetics of siloxane transformations under anaerobic conditions. Siloxane emissions, resulting from disposal of silicone-based materials, are expected to increase by 29% within the next 10 years. Estimated concentrations and the risk factors of exposure to siloxanes were evaluated based on the initial concentrations, partitioning characteristics and persistence. It was determined that D4 has the highest risk factor associated to bioaccumulation in liquid and solid phase, whereas D5 was highest in gas phase. Additionally, as siloxanes are combusted, the particle size range causes them to be potentially hazardous to human health. When inhaled, they may affix onto the alveoli of the lungs and may lead to development of silicosis. Siloxane-based COD-loading was evaluated and determined to be an insignificant factor concerning COD limits in wastewater. ^ Removal of siloxane compounds is recommended prior to land application of biosolids or combustion of biogas. A comparison of estimated costs was made between maintenance practices for removal of siloxane deposits and installation/operation of fixed-bed carbon absorption systems. In the majority of cases, the installation of fixed-bed adsorption systems would not be a feasible option for the sole purpose of siloxane removal. However they may be utilized to remove additional compounds simultaneously.^

Resistance to Meloidogyne incognita, Meloidogyne javanica and Pratylenchus brachyurus in sunflower cultivars adapted to the tropical region of Brazil.

The continuous soybean-maize crop succession in the tropical region of Brazil has led to significant increases in the population size of root-knot (Meloidogyne incognita and M. javanica ) and root-lesion nematodes (Pratylenchus brachyurus), which make soils unsuitable for soybean cropping. A greenhouse study was conducted to identify sunflower genotypes adapted to the tropical region of Brazil and that are resistant to M. incognita, M. javanica and/or P. brachyurus . Two experiments for each nematode were conducted in a completely randomized design with six replicates. Gall index was calculated from visual scores (0?5) of gall intensity on roots for the root-knot nematode. Initial and final population density and reproduction factor were also measured for each nematode. Sunflower genotypes varied in resistance to the nematodes. Sunflower hybrids BRS 321 and BRS 323 were resistant to M. javanica and P. brachyurus and exhibited low gall index for M. incognita . The cultivars are good alternatives to using in the succession of soybean in nematode-infested areas of the tropical regions of Brazil. No sunflower genotype was identified as resistant to M. incognita and thus sunflower cropping is not indicated in areas infested with this nematode.

Chemical looping reforming from methane to syngas: investigation on CeO2 oxygen carrier lifetime and optimal process times

Emissions of CO2 are constantly growing since the beginning of industrial era. Interruption of the production of major emitters sectors (energy and agriculture) is not a viable way and reducing all the emission through carbon capture and storage (CCS) is not economically viable and little publicly accepted, therefore, it becomes fundamentals to take actions like retrofitting already developed infrastructure employing cleanest resources, modify the actual processes limiting the emissions, and reduce the emissions already present through direct air capture. The present thesis will deeply discuss the aspects mentioned in regard to syngas and hydrogen production since they have a central role in the market of energy and chemicals. Among the strategies discussed, greater emphasis is given to the application of looping technologies and to direct air capture processes, as they have been the main point of this work. Particularly, chemical looping methane reforming to syngas was studied with Aspen Plus thermodynamic simulations, thermogravimetric analysis characterization (TGA) and testing in a fixed bed reactor. The process was studied cyclically exploiting the redox properties of a Ce-based oxide oxygen carrier synthetized with a simple forming procedure. The two steps of the looping cycles were studied isothermally at 900 °C and 950° C with a mixture of 10 %CH4 in N2 and of 3% O2 in N2, for carrier reduction and oxidation, respectively. During the stay abroad, in collaboration with the EHT of Zurich, a CO2 capture process in presence of amine solid sorbents was investigated, studying the difference in the performance achievable with the use of contactors of different geometry. The process was studied at two concentrations (382 ppm CO2 in N2 and 5.62% CO2 in N2) and at different flow rates, to understand the dynamics of the adsorption process and to define the mass transfer limiting step.

Multi-trait and random regression mature weight heritability and breeding value estimates in Nelore cattle

Mature weight breeding values were estimated using a multi-trait animal model (MM) and a random regression animal model (RRM). Data consisted of 82 064 weight records from 8 145 animals, recorded from birth to eight years of age. Weights at standard ages were considered in the MM. All models included contemporary groups as fixed effects, and age of dam (linear and quadratic effects) and animal age as covariates. In the RRM, mean trends were modelled through a cubic regression on orthogonal polynomials of animal age and genetic maternal and direct and maternal permanent environmental effects were also included as random. Legendre polynomials of orders 4, 3, 6 and 3 were used for animal and maternal genetic and permanent environmental effects, respectively, considering five classes of residual variances. Mature weight (five years) direct heritability estimates were 0.35 (MM) and 0.38 (RRM). Rank correlation between sires' breeding values estimated by MM and RRM was 0.82. However, selecting the top 2% (12) or 10% (62) of the young sires based on the MM predicted breeding values, respectively 71% and 80% of the same sires would be selected if RRM estimates were used instead. The RRM modelled the changes in the (co) variances with age adequately and larger breeding value accuracies can be expected using this model.

Pentachlorophenol (PCP) dechlorination in horizontal-flow anaerobic immobilized biomass (HAIB) reactors

This study verifies the potential applicability of horizontal-flow anaerobic immobilized biomass (HAIB) reactors to pentachlorophenol (PCP) dechlorination. Two bench-scale HAIB reactors (R1 and R2) were filled with cubic polyurethane foam matrices containing immobilized anaerobic sludge. The reactors were then continuously fed with synthetic wastewater consisting of PCP, glucose, acetic acid, and formic acid as co-substrates for PCP anaerobic degradation. Before being immobilized in polyurethane foam matrices, the biomass was exposed to wastewater containing PCP in reactors fed at a semi-continuous rate of 2.0 mu g PCP g(-1) VS. The applied PCP loading rate was increased from 0.05 to 2.59 mg PCP l(-1) day(-1) for RI, and from 0.06 to 4.15 mg PCP l(-1) day(-1) for R2. The organic loading rates (OLR) were 1.1 and 1.7 kg COD m(-3) day(-1) at hydraulic retention times (HRT) of 24 h for R1 and 18 In for R2. Under such conditions, chemical oxygen demand (COD) removal efficiencies of up to 98% were achieved in the HAIB reactors. Both reactors exhibited the ability to remove 97% of the loaded PCP. Dichlorophenol (DCP) was the primary chlorophenol detected in the effluent. The adsorption of PCP and metabolites formed during PCP degradation in the packed bed was negligible for PCP removal efficiency. (C) 2009 Elsevier Ltd. All rights reserved.

Dynamics of sulfidogenesis associated to methanogenesis in horizontal-flow anaerobic immobilized biomass reactor

Two bench-scale horizontal anaerobic fixed bed reactors were tested to remove both sulfate and organic matter from wastewater. First, the reactors (R1 and R2) were supplied with synthetic wastewater containing sulfate and a solution of ethanol and volatile fatty acids. Subsequently, RI and R2 were fed with only ethanol or acetate, respectively. The substitution to ethanol in R1 increased the sulfate reduction efficiency from 83% to nearly 100% for a chemical oxygen demand to sulfate (COD/sulfate) ratio of 3.0. In contrast, in R2, the switch in carbon source to acetate strongly decreased sulfidogenesis and the maximum sulfate reduction achieved was 47%. Process stability in long-term experiments and high removal efficiencies of both organic matter and sulfate were achieved with ethanol as the sole carbon source. The results allow concluding that syntrophism instead of competition between the sulfate reducing bacteria and acetoclastic methanogenic archaeal populations prevailed in the reactor. (C) 2009 Elsevier Ltd. All rights reserved.

Specific methanogenic activity in an anaerobic-aerobic reactor applied to the treatment of domestic residual water

The specific methanogenic activity (SMA) test is an important tool for the monitoring of anaerobic digestion. This paper presents the behavior of the methanogenic archaea of an anaerobic sludge under different conditions of oxygenation in a fixed-bed anaerobic-aerobic reactor treating domestic sewage. The reactor was operated in a continuous manner under different liquid recycle ratios from aerobic to anaerobic zones in order to remove carbon and nitrogen. The application of the SMA test was adapted from several authors and the measurement of the accumulated methane in the reactor was carried out by means of gas chromatography. Methanogenic organisms were not inhibited by the presence of oxygen. In contrast, the values of CH, production rate by sludge exposed to oxygen were greater than those obtained for strictly anaerobic sludge.

Topology Optimized Design, Microfabrication and Characterization of Electro-Thermally Driven Microgripper

This article presents a systematic and logical study of the topology optimized design, microfabrication, and static/dynamic performance characterization of an electro-thermo-mechanical microgripper. The microgripper is designed using a topology optimization algorithm based on a spatial filtering technique and considering different penalization coefficients for different material properties during the optimization cycle. The microgripper design has a symmetric monolithic 2D structure which consists of a complex combination of rigid links integrating both the actuating and gripping mechanisms. The numerical simulation is performed by studying the effects of convective heat transfer, thermal boundary conditions at the fixed anchors, and microgripper performance considering temperature-dependent and independent material properties. The microgripper is fabricated from a 25 mm thick nickel foil using laser microfabrication technology and its static/dynamic performance is experimentally evaluated. The static and dynamic electro-mechanical characteristics are analyzed as step response functions with respect to tweezing/actuating displacements, applied current/power, and actual electric resistance. A microgripper prototype having overall dimensions of 1mm (L) X 2.5mm (W) is able to deliver the maximum tweezing and actuating displacements of 25.5 mm and 33.2 mm along X and Y axes, respectively, under an applied power of 2.32 W. Experimental performance is compared with finite element modeling simulation results.

Regeneration of Activated Carbon by (Photo)-Fenton Oxidation

This work aims to study the adsorption of phenol on activated carbons (ACs) and the consecutive in situ regeneration of carbon by Fenton oxidation. Two different operations have been carried Out: (1) a batch procedure in order to investigate the influence of Fe(2+) and H(2)O(2) concentrations; (2) continuous fixed bed adsorption, followed by a batch circulation of the Fenton`s reagent through the saturated AC bed. to examine the efficiency of the real process. Two different activated carbons have been also studied: a both micro- and mesoporous AC (L27) and an only microporous One (S23). In the batch reactor the best conditions found for pollutant mineralization in the homogeneous Fenton system are not the best For AC regeneration: a continuous reduction of adsorption capacity of L27 is observed after 3 oxidations, due to the decrease of both AC weight and surface area. Higher concentration of Fe(2+) and lower concentration of H(2)O(2) (2 times the stoichiometry) lead to a 50% recovery of the initial adsorption capacity during at least four consecutive cycles for L27, while about 20% or less for S23. In the consecutive continuous adsorption/batch Fenton oxidation process, the regeneration efficiency reaches 30-40% for L27 after two cycles whatever the feed concentration and less than 10% for S23. A photo-Fenton test performed on L27 shows almost complete mineralization (contrary to ""dark"" Fenton) and further improves recovery of AC adsorption capacity although not complete (56% after two cycles).

Diagnostic errors and repetitive sequential classifications in on-line process control by attributes

The procedure of on-line process control by attributes, known as Taguchi`s on-line process control, consists of inspecting the mth item (a single item) at every m produced items and deciding, at each inspection, whether the fraction of conforming items was reduced or not. If the inspected item is nonconforming, the production is stopped for adjustment. As the inspection system can be subject to diagnosis errors, one develops a probabilistic model that classifies repeatedly the examined item until a conforming or b non-conforming classification is observed. The first event that occurs (a conforming classifications or b non-conforming classifications) determines the final classification of the examined item. Proprieties of an ergodic Markov chain were used to get the expression of average cost of the system of control, which can be optimized by three parameters: the sampling interval of the inspections (m); the number of repeated conforming classifications (a); and the number of repeated non-conforming classifications (b). The optimum design is compared with two alternative approaches: the first one consists of a simple preventive policy. The production system is adjusted at every n produced items (no inspection is performed). The second classifies the examined item repeatedly r (fixed) times and considers it conforming if most classification results are conforming. Results indicate that the current proposal performs better than the procedure that fixes the number of repeated classifications and classifies the examined item as conforming if most classifications were conforming. On the other hand, the preventive policy can be averagely the most economical alternative rather than those ones that require inspection depending on the degree of errors and costs. A numerical example illustrates the proposed procedure. (C) 2009 Elsevier B. V. All rights reserved.

Evaluation of carcass characteristics of Bos indicus and tropically adapted Bos taurus breeds selected for postweaning weight

Data from 9 studies were compiled to evaluate the effects of 20 yr of selection for postweaning weight (PWW) on carcass characteristics and meat quality in experimental herds of control Nellore (NeC) and selected Nellore (NeS), Caracu (CaS), Guzerah (GuS), and Gir (GiS) breeds. These studies were conducted with animals from a genetic selection program at the Experimental Station of Sertaozinho, Sao Paulo State, Brazil. After the performance test (168 d postweaning), bulls (n = 490) from the calf crops born between 1992 and 2000 were finished and slaughtered to evaluate carcass traits and meat quality. Treatments were different across studies. A meta-analysis was conducted with a random coefficients model in which herd was considered a fixed effect and treatments within year and year were considered as random effects. Either calculated maturity degree or initial BW was used interchangeably as the covariate, and least squares means were used in the multiple-comparison analysis. The CaS and NeS had heavier (P = 0.002) carcasses than the NeC and GiS; GuS were intermediate. The CaS had the longest carcass (P < 0.001) and heaviest spare ribs (P < 0.001), striploin (P < 0.001), and beef plate (P = 0.013). Although the body, carcass, and quarter weights of NeS were similar to those of CaS, NeS had more edible meat in the leg region than did CaS bulls. Selection for PWW increased rib-eye area in Nellore bulls. Selected Caracu had the lowest (most favorable) shear force values compared with the NeS (P = 0.003), NeC (P = 0.005), GuS (P = 0.003), and GiS (P = 0.008). Selection for PWW increased body, carcass, and meat retail weights in the Nellore without altering dressing percentage and body fat percentage.

Chlorophyll Degradation and Formation of Colorless Chlorophyll Derivatives during Soybean (Glycine max L. Merill) Seed Maturation

The natural chlorophyll degradation results in noncolored chlorophyll catabolites (NCCs), but there are controversies if these are the final products. The formation and degradation of NCCs during soybean seed (Glycine max L. Merrill) maturation and two drying temperatures were investigated. Soybean was harvested at six maturation stages. The effect of postharvest drying at 40 and 60 degrees C on the NCC formation was analyzed by high-performance liquid chromatography (HPLC), and results were expressed as areas under the curve. All samples contained fractions with an absorption maximum at 320 nm, typical for NCC. The amounts of NCC increased until 114 days after planting and were significantly lower in advanced maturation stages. These results indicate that the NCC in soybeans might not be the final products of chlorophyll degradation. Their reduction in advanced maturation stages may be due to further metabolization. Heating soybeans at 40 and 60 degrees C promoted unnatural chlorophyll degradation and impaired the formation of NCC.