Effect Of Initial Moisture Content Research Articles

Effect of initial moisture content, resulting from different ratios of vegetable waste to maize straw, on compost was mediated by composting temperatures and microbial communities at low temperatures

Owing to the huge amounts and perishable character of vegetable wastes, composting is one of the best options for recycling vegetable wastes post-harvest. The initial moisture content (MC) is critical for optimizing composting process, but the effect of high MC in undehydrated vegetable wastes on composting was rarely reported. For this, the plant-scale windrows were prepared by mixing cauliflower waste and maize straw at different ratios to control initial MC of 70 % (T1-70) and 80 % (T2-80), respectively, and composted in winter. As composting progressed, substantial organic matter degradation, progressive humification, decreases in electrical conductivity and increases of pH and germination index (GI) were observed in both treatments. Nonetheless, T1-70 accelerated heating rate early during composting, prolonged high temperature period (>50 °C) by 30 d, thus increased the harmless level of composting, and significantly improved the humification of end-products compared to T2-80. Results also revealed that T1-70 activated more indigenous microbes and enhanced microbial interactions early during composting, with the fungi enriched in T1-70 playing an important role in accelerating the composting process. Remarkably, the difference in composting temperatures, humification degree, and microbial communities between the two treatments was most significant during the maturation phase. In this phase, MWH_CFBk5, Planktosalinus, Pseudopedobacter, and Luteimonas enriched in T1-70 were positively correlated with humification indices. It is suggested that the effect of initial MC, resulting from different ratios of vegetable waste to maize straw, on their composting was mediated by the composting temperature and microbial communities at low temperatures.

Airborne power ultrasound for paper drying: an experimental study

A novel approach for paper drying using airborne ultrasound technology is presented. A unique experimental setup is developed, and a systematic study is conducted using 23 factorial design of experiments and Analysis of Variance. Three controlling factors are considered in the experiments including the initial moisture content, basis weight and refining condition. The outcome of the experiments is compared to a previous work on direct-contact ultrasonic drying of paper. The results confirm that similar to direct-contact, for airborne ultrasonic drying, the basis weight/thickness of the sample is the most important factor in ultrasonic drying and it is followed by the effect of initial moisture content. Using linear regression model, a correlation for predicting the total time of ultrasonic drying is provided. Quality of the dried samples is evaluated, and the permeability measurements confirmed the effect of pore characteristics on ultrasonic drying. The analysis for energy consumption reveals that airborne ultrasonic drying is more efficient at higher moisture contents.

Long-term performance assessment of post-tensioned timber connections under different climates

Timber structures are sensitive to the changes in climatic condition as wood absorbs or desorbs moisture from the ambient environment. The varying climatic condition can induce time-dependent deformation of timber that further leads to long-term variation of structural performance. Such issue needs to be carefully considered during the design process especially for structures in outdoor environment and uncontrolled indoor environment. This study assesses the long-term prestressing force loss of post-tensioned timber connections under different climatic conditions. First, the climatic conditions in ten Chinese and Canadian cities were identified. The statistics and yearly variations of relative humidity and temperature were analyzed and compared. Subsequently, a validated numerical model was used to predict the long-term variation of moisture content over 50 years in the ten cities. The effects of initial moisture content and member sizes were discussed. Finally, four long-term performance (prestressing force loss) levels were proposed based on the maximum lifetime prestressing force loss percentage. Various post-tensioned timber connections accounting for different climatic conditions, initial moisture content, member sizes and connection details were simulated and assessed by determining the long-term performance level. The results in this study demonstrated that climatic condition significantly affected the long-term performance level of post-tensioned timber connections. Furthermore, the percentage of extensive prestressing force loss during the long-term service was closely correlated with the initial moisture content, member sizes and connection details.

Effectiveness of combined catalytic infrared radiation and holding time for decontamination Aspergillus niger on dried shiitake mushrooms (Lentinus edodes) with different moisture contents

This paper investigated the effect of catalytic infrared radiation (CIR) only and CIR coupled with holding time (CIRH) on decontamination of damp-returning dried shiitake mushrooms contaminated with Aspergillus niger (A. niger). The effect of initial moisture content (IMC) of the samples on CIR/CIRH operation layout was also investigated. Analysis of surface color, observations of electron microscopy and evaluation of quality (retention rate of total sugar, crude protein and total phenolics) directly manifested that CIRH treatment had the outstanding potential to maintain the original appearance and microstructure compared to CIR (p < 0.05). Meanwhile, the envisaged model (Log-Linear + tail) achieved expected results for the inactivation of A. niger with R2 = 0.9790–0.9977, which can well predict the changes in A. niger of dried shiitake mushrooms with different IMCs in the holding process. Therefore, the present work could pave the way for future production of good quality dried shiitake mushrooms using CIRH.

Effect of the optimum and residual moisture content on the strength characteristics of unsaturated sands

Soil exists mainly in unsaturated conditions. Therefore, accurate prediction of the soil shear strength for unsaturated conditions also becomes equally important for the geotechnical design of earth structures. This study primarily investigates the effect of the moisture content of unsaturated soil on its shear strength. The strength characteristics of silica sands with different grain sizes were studied using the modified triaxial apparatus and analytical methods. For this purpose, four series of triaxial compression tests on silica sands were performed by varying the moisture content of the test sample at compaction and shearing as optimum or residual moisture content. The test results showed that the test sample sheared at optimum and residual moisture content exhibited higher shear strength when the sample was initially compacted at residual and optimum moisture content, respectively. The moisture content at compaction and the soil grain size considerably influence the shear strength of unsaturated sandy soils. Furthermore, the analytical method used in this study for unsaturated soil shear strength prediction does not account for the effect of initial moisture content in predicting unsaturated soil shear strength.

Synergistic Effects of Initial Moisture Content and Particle Size on Drying Rate and Heat Production during Bio-Drying of Sludge after Electro-Dewatering

Electro-dewatered sludge (EDS) can be bio-dried alone, instead of adding bulking agents. The initial moisture content (IMC) and particle size of the electro-dewatered sludge affect the efficiency and energy consumption during the bio-drying process. This study aimed to investigate the synergistic effects of sludge IMC and particle size on the drying rate and heat production of bio-drying with EDS. Experiments were conducted with two different IMC sludge and two different sludge particle sizes. Results showed that the highest moisture removal rate was 43.18% in treatment T4, which had materials with a smaller particle size (<3 mm) and lower IMC (38.69%). And bio-drying of T4 had the highest biological heat production (7413.14 kJ, i.e., 741.31 kJ/kg sludge), and the lowest bio-drying index (the ratio of water loss to volatile solid loss) was 7.10 among the four treatments. Five thin-layer drying kinetic models and a nonlinear regression method were analyzed to estimate the bio-drying kinetic parameters. The Midilli et al. model had a better fitting result, and the highest R2 value was 0.9929 during bio-drying of EDS. The new coefficients k (0.1465) and n (1.0898) were obtained. Through the heat balance, the heat used for evaporation was 40–57% of the total energy consumption (5873–9140 kJ). According to the PCA, the particle size had a great influence on the bio-drying process. Also, the particle size positively correlated with temperature, moisture ratio, and drying rate.

Experimental study of paper drying with direct-contact ultrasound mechanism

A systematic-study is conducted using an innovative technology for paper drying by applying ultrasound mechanism. The advantages include greater energy efficiency, lower drying time and temperature, improvement of the product quality, and it is considered a green technology. The effects of initial moisture content, thickness, and refining condition are studied for different types of pulps (hardwood and softwood) using 23 factorial design of experiments. Analysis of Variance show that in the range of the studied parameters, thickness has the maximum effect on ultrasonic drying time followed by the initial moisture content. In addition, using a linear regression model, a relationships for the total time of drying is provided. The results confirmed that ultrasonic drying is more efficient at higher moisture content and higher thickness of the sample. These results are related to the structural characteristic of the samples such as porosity, pore distribution, and surface roughness.

Effect of steam curing on pasting and textural properties, starch structure and the quality of a local aromatic rice variety

Steam curing is a process that is used to improve the quality of freshly harvested rice in the shortest time. The purpose of this study was to evaluate the effects of initial moisture content (IMC) and steaming time on the marketability of rice. The results indicate positive and more impressive effects of prolonged steaming (30 min) on head rice percentage (HRP), grain hardness, and elongation in the sample with IMC of 20% (w.b) compared with the sample with IMC of 17% (w.b). The results also showed a decreased peak (PV) and breakdown (BD) viscosity in both IMC. The highest decrease was observed in the samples that were steamed for 30 min. The results of scanning electron microscopy (SEM) revealed that the steaming of paddy for 30 min could not create a completely smooth surface in the grain. These observations indicate the inadequacy and uneven distribution of moisture for complete gelatinization even in grains with higher IMC. Practical applications Steam curing at atmospheric pressure is an applicable and effective method to reduce losses during milling process even for short time due to the structural changes. For high quality aromatic rice, short time steaming has positive effect on cooking quality with no significant changes in aroma. In order to produce good quality and marketable product by this method, it is necessary to process paddy with minimal or no chalky kernels.

Influence of moisture content, temperature, and time on free fatty acid in stored crude palm oil

Consequent to the importance of crude palm oil (CPO) to global food processing industries, and the need for quality assurance of CPO. A kinetic model that describes changes of free fatty acid (FFA) in industrially stored CPO has been developed. CPO FFA is a well-known indicator of the deterioration of CPO. The effect of initial moisture content, storage temperature, and time on CPO FFA have been investigated in this work. Specifically, statistical multi-regression models for changes in FFA and moisture content (MC) were developed at P-value < 0.05 or 95% confidence interval fence. It was found that CPO FFA increases with an increase in moisture content, temperature, and time in their linear term and in respect to decreases in their quadratic term, and interaction between moisture content and temperature. The CPO MC was also found to decrease with an increase in temperature and time and increases in the quadratic term of temperature. Although while the model for CPO FFA, based on Fisher's F-test: {mathrm{F}}_{mathrm{model}}(6.80)<{mathrm{F}}_{95mathrm{%}}(19.30), showed no lack-of-fit; that of CPO MC showed lack-of-fit, {mathrm{F}}_{mathrm{model}}(13.67)nless {mathrm{F}}_{95mathrm{%}}(4.39). Furthermore, based on inference from the statistical model, their kinetic models were also developed. While the CPO FFA kinetic, found to be a half-order kinetic model and its other auxiliary models showed a very good fit (R2 {0.9933–0.8614} and RMSE {0.0020–3.6716}); that of CPO MC was a poorly fitted first-order kinetic model (R2 {0.9885–0.3935} and RMSE {0.0605–17.8501}).

Insight into Effects of Initial Moisture Content on the Heat-Up of Sewage Sludge Composting During Mesophilic Phase

The effects of initial moisture content (55%, 60% and 65%) on the heat-up of sewage sludge (SS) composting during the mesophilic phase were investigated. Monitoring results showed that low moisture content (55%) increased the heating rate, high initial moisture content (60% and 65%) significantly improved the activities of cellulase and peroxidase during the mesophilic phase. Furthermore, although high moisture content improved the diversity of bacteria during composting, there were no significant differences in the microbial structure during the process of succession. So, rather than inhibiting the activity of the bacterial population, the negative effect of high moisture content (60 and 65 per cent) on composting temperature heat up was attributable to the difficulty of heating produced by the specific heat capacity of water. The correlation index between initial moisture content and microorganisms was relatively low, while the temperature was the largest environmental factor affecting the bacterial community. This conclusion provided a hint to make an association between initial moisture content and composting temperature-rising stage.

Computational modeling of biosludge drying

Considerable increases in industrial and urban wastewater sludge generation in recent years require proper treatment, such as thermal drying, and disposal. The sludge drying is a complex process involving simultaneous and coupled heat and mass transfer, which can be modeled by taking into account mass and heat balances, and assuming that water diffuses according to kinetic laws. This research implemented a simulation model for biosludge drying processes to predict the temperature and moisture distribution inside the biosludge, using the COMSOL Multiphysics® simulation program v5.2. A parametric analysis was carried out to determine the effect of initial moisture content on biosludge final temperature and moisture reduction. The simulated temperature and moisture content were experimentally validated and good agreement was observed between the simulation and experimental results. This model is a useful tool to optimize the drying process and develop better strategies for the control of the system.

Influence of initial wood moisture on decay process by two brown-rot fungi

The biological decomposition of lignocellulosic materials caused by basidiomycetes plays an essential role in the carbon cycle. Brown rot fungi represent important agents in the biodegradation of wood products and standing coniferous trees in natural ecosystems. The initial moisture content of the wood is an important factor in the degradation process. In this work, the effects of initial moisture content of Eucalyptus grandis sapwood on decay by two brown rot fungi Gloeophyllum trabeum and Laetiporus sulphureus were studied over a 10-month period. The fungal activity was evaluated, through wood weight loss, moisture content, anatomical changes (scan electronic and fluorescence microscopy) and Fourier-transform infrared spectroscopy. Weight loss increased through the 10-month test for both fungi, Laetiporus sulphureus producing higher mass losses. Colonization of the wood by both fungi started below the fiber saturation range. It was observed that the initial moisture content of the wood influenced the rate of deterioration: the wet samples showed higher weight loss compared to the dry samples. Changes in the chemical composition and structure of cell walls were detected. The initial moisture content of the substrate affected the development of the fungi, slowing their growth.

Optimization of Red Pigment Production by Solid State Fermentation Using Oil Palm Frond

Extensive study available on Monascus in solid-state fermentation (SSF), however, optimization study of Monascus sp. cultivated in stirred drum bioreactor is insufficiently reported. In this study, the Box–Behnken design (BBD) was employed for the analysis of the simultaneous effect of initial moisture content, aeration rate and peptone concentration to the red pigments production of Monascus purpureus FTC 5357 by using oil palm frond (OPF) in 5 L stirred drum bioreactor. A three-parameters, three-level BBD was used for the optimization. Based on the ANOVA analysis performed, initial moisture content, aeration rate and peptone concentration contributed significantly to the red pigments production. The optimal fermentation conditions resulted were initial moisture content; 70 % w/w, aeration rate; 1.30 vvm and peptone concentration; 4.40 % w/w. Under these conditions, the red pigments production were obtained to be 18.59 Au/g.d. The red pigments produced through SSF using OPF as a substrate by Monascus purpureus FTC 5357 has a great potential to be utilized as a source of pigment for food in future.

Determining the Thermal Conductivity of Clay during the Freezing Process by Artificial Neural Network

Thermal conductivity is an important thermal parameter in engineering design in cold regions. By measuring the thermal conductivity of clay using a transient hot-wire method in the laboratory, the influential factors of the thermal conductivity of soils during the freezing process were analyzed, and a predictive model of thermal conductivity was developed with an artificial neural network (ANN) technology. The results show that the variation of thermal conductivity can be divided into three stages with decreasing temperature, positive temperature stage, transition stage, and negative temperature stage. The thermal conductivity increases sharply in the transition stage. The difference between the thermal conductivity at positive and negative temperature is small when the dry density of the soil specimens is larger than the critical dry density, while the difference is large if the dry density is less than the critical dry density. As the negative temperature decreases, the larger the moisture content of the soil specimens, the larger the increase of thermal conductivity. The effect of initial moisture content on thermal conductivity is more significant than that of dry density and temperature. The change tendency of the thermal conductivity calculated by the established ANN model is basically consistent with that of the laboratory-measured values, indicating that this model can be able to accurately predict the thermal conductivity of the soil specimens in the freezing process.

Effects of enzymatic treatment conditions on dietary fibre content of wheat bran and use of cellulase‐treated bran in cookie

SummaryA commercial cellulase preparation (Viscozyme Cassava C) was employed to process wheat bran to improve the ratio of insoluble to soluble dietary fibre. The effects of initial moisture content, enzyme dosage, and incubation time on the content of soluble and insoluble fibre during the enzymatic treatment were investigated. The appropriate conditions for the cellulase treatment were initial moisture content of 0.75 g water g−1 dry matter, enzyme dosage of 9 U g−1 dry matter and incubation time of 120 min under which the ratio of insoluble to soluble fibre of wheat bran was lowered by 42%. Untreated and cellulase‐treated wheat bran was incorporated into cookies at levels of 0%, 20%, 30%, 40% and 50%. Cookie with 50% cellulase‐treated bran showed 21% lower ratio of insoluble to soluble fibre as well as 14% lower hardness and 13% higher overall acceptability than sample with the same amount of untreated bran.

Effect of initial moisture content and sample storage duration on compost stability using the ORG0020 dynamic respiration test

Biological tests are widely used to assess composting process status and finished material stability. Although compost stability is known to be influenced by moisture content (MC) and storage duration, there is a lack of data supporting boundary limits for standardised testing. Using the ORG0020 dynamic respiration test we assessed the stability of materials from different commercial composting sites processing only green waste or mixed green and food waste. Samples were tested at three different MC following adjustment with the ‘fist’ test within the range 40–60%. The results showed manipulation of MC within this range could have significant impact on measured stability for some but not all samples. Two samples reported significantly higher activity when MC was manipulated from ~50% to ~60%. For storage duration, samples showed significant decrease in measured activity over several weeks of cold storage. However, there was no significant difference in stability for samples tested up to nine days from receipt. The results of this research will support decisions relating to the boundary limits for moisture content and storage time for the ORG0020 test. The results will also provide insight to the wider range of biological tests used to assess compost stability.

Assessing frost heave susceptibility of gravelly soils based on multivariate adaptive regression splines model

Frost heave of railway roadbed leads to track geometry degradation during the cold season, seriously threatening the safety of high-speed trains. An accurate estimation of freezing-induced deformation in subgrade aggregates is thus critical to construction and maintenance of transportation infrastructure in seasonally frozen regions. This paper proposes a practical approach to assessing the frost heave susceptibility of gravelly soils under unidirectional freezing conditions. Typical frost heave tests are first performed on gravel columns in closed and open systems. The multivariate adaptive regression splines algorithm is subsequently applied to develop a predictive model for the normalized heave of a specimen. Experimental data of freezing tests were collected from this study and available literature to compile a dataset. A randomly selected subset is used for training, while the complement of the subset is intended for testing. Relative importance analysis and analysis of variance are finally performed to examine the general and coupling effects of initial moisture content, fines, relative compaction, and stress level on the frost heave susceptibility of compacted soil. Hopefully, the developed model and comprehensive analysis of coarse fills could assist railway agencies in understanding the appropriate characterization of frost heave and provide an evaluation guideline for optimized railway roadbed.

Effect of initial moisture content on physical properties of Orthosiphon stamineus ground powder during storage

Initial moisture content of ground powder is very important factor in maintaining the physical quality of the product during storage. This research was conducted to investigate the effect of initial moisture content of Orthosiphon stamineus ground powder on physical properties such as moisture content, water activity and colour properties during short term storage period. In this research, the experimental treatments were arranged in a completed randomized design (CRD) that consisted of two main factors which were initial moisture content (8, 13 and 20 %) and storage period (0, 2, 4, 6, 8 and 10 weeks). The changes of moisture content, water activity and colour properties were analyzed using moisture analyzer, water activity meter and chroma meter, respectively. From the results, it was revealed that the best initial moisture content to maintain the quality of O. stamineus ground powder was 13 %. At early of storage period, moisture content and water activity were slightly reduced and they started to stable at week 8 to 10. The consistency of moisture content and water activity is expected to last for the next 6 months under same storage condition. However, it could be observed that the colour of O. staminus ground powder was slightly affected during short term storage.

The drying temperature and the moisture content at harvest affect the apparent metabolisable energy of two maize varieties in broiler chickens

ABSTRACT 1. The grain drying process may affect the feeding value of maize but until now, no general consensus has been reached. This knowledge is essential to manage maize nutritional value in feed and ensure optimal growth performance of broiler chickens. 2. A total of 72 male Ross 308 were used in a complete randomised block design to assess the effect of initial moisture content (MC) at harvest (high or low MC after the appearance of the black layer) and drying temperature (54°C, 90°C or 125°C) on the apparent faecal digestibility and the AMEn value of two maize grain types (flint and flint-dent varieties). Moreover, the relationship between in vitro dry matter digestibility coefficient (IVDMD) and salt-soluble protein (SSP) content of dried maize grain with AMEn was assessed. 3. High drying temperature (125°C) significantly decreased the AMEn (by 0.41 MJ/kg) of the maize. Maize with high-moisture content at harvest had significantly higher AMEn than maize with low moisture content (0.38 MJ/kg) depending on the variety. Based on the combination of MC at harvest and drying temperature, an AMEn difference of about 0.65 MJ per kg of dry matter was measured during this experiment. The faecal digestibility of starch remained close to 98% with low variation between the treatments. The decrease in AMEn at high drying temperature was related to the decrease in non-starch organic matter retention (NSOMR). IVDMD and SSP content were not correlated with AMEn of dried maize (R2 < 0.1). 4. This study showed that using drying temperature below 90°C for maize grain harvested at high MC, just after the black layer development, can enhance its AMEn. The IVDMD and SSP content failed to predict the AMEn of the dried maize, but further research is required to validate the results of this study.

Effect of Initial Moisture Content on Unconfined Compressive Strength of Cemented-Fiber-Clay

Effect of Initial Moisture Content on Unconfined Compressive Strength of Cemented-Fiber-Clay