Pile Temperature Research Articles

Composting of Pineapple Residues and Food Waste: A Pilot-Scale Study

Spraying herbicide, followed by burning, is a common practice for clearing pineapple residues (leaves and stems) and preparing subsequent cultivation crops in the Mekong Delta, Vietnam. This is an unsustainable agricultural practice that causes environmental pollution. In this study, pilot-scale pineapple residue composting was studied at Tan Phuoc district, Tien Giang province. Approximately 5.5 t of pineapple leaves and stems were mixed with 10 wt% food waste and 0.1 % v/w effective microorganisms. Chopped pineapple residues and food waste were distributed in layers in sequence and sprayed with the microorganism solution. Composting was carried out in a pyramid-shaped pile with a bottom diameter of approximately 5 m and a height of about 1.5 m. The composting temperatures were monitored daily using a digital thermometer. The composting mixture was withdrawn, mixed thoroughly and then re-distributed to the composting pile every 3 d. Composting was performed after 45 d when the composting pile temperature almost reached ambient temperature. The compost product was subjected to pH and mesophilic/thermophilic microorganism cell density measurements. Phytotoxicity tests were carried out, and other important parameters such as organic content, useful/harmful microorganisms and heavy metals were determined. Mesophilic and thermophilic microorganism densities were approximately 2 x 108 and 3.8 x 107 CFU/g. The compost pH was 7.3, and the organic matter content reached 32.3 wt%. Heavy metals and harmful microorganisms, such as E. coli and Salmonella, were also within Vietnamese standards. Root length and number of roots were 372.8 % and 22.6 % higher than controls; stem length and diameter were 137.5 mm and 15.1 mm, and were not significantly different from controls (p

Transfering heat performance for controlling the spontaneous combustion in coalfield of heat pipe

A heat pipe coal pile experiment platform was established to test the performance of the heat pipe in the heat transfer of the coal pile. Experiments were carried out to measure and analyze the continuous cooling characteristics and cooling rate of the internal heat dissipation of coal piles of different heights under different temperature heat sources. The results show that when the heat source temperature is higher, there is a greater cooling rate inside the coal pile. The closer it is to the heat source, the more obvious the heat dissipation inside the coal pile will be affected by the heat pipe and heat source. This experiment verifies the feasibility of the heat pipe to automatically and continuously transfers the internal heat of the coal pile under the action of the difference between the outside temperature and the internal temperature of the coal pile, to achieve the purpose of preventing spontaneous combustion of the coal pile.

Research on grain storage temperature prediction model based on improved long short-term memory

Stored-grain temperature is the most important factor in grain storage. According to the measured data, the temperature in the grain pile can be effectively predicted, which can find problems in advance, reduce grain loss and increase grain quality. Long Short-Term memory (LSTM) can perform better in longer sequences than ordinary RNN. This paper is applied to the analysis of big data of grain storage and the early warning of grain storage temperature. In this paper, the selected LSTM is optimized and the early warning model of grain situation is established, and the analysis steps of the early warning model are given. In order to verify the availability of the improved LSTM network structure, RNN and three variants were used to predict the grain temperature under the same conditions, the prediction effect of the improved CLSTM is better.

Algunos parámetros biológicos en la evaluación de la estabilidad y la madurez de dos compost

Composting represents an alternative for the use of organic waste by transforming it into an organic amendment that improves the structure and fertility of soils. As it is a microbiological process, the objective was to analyze some biological parameters in the evaluation of the stability and maturity of two compost. Two compost was made with waste generated at the Simón Bolívar University one obtained from organic waste generated in the dining room and the other from plant remains from the pruning of the gardens. The parameters evaluated were temperature and microbial count, expressed as colony-forming units per gram of compost for yeast, and for aerobic and anaerobic bacteria (in turn classifying the bacteria by the Gram staining method), as well as the germination index determined by the phytotoxicity test. The results obtained allowed us to conclude that: the temperature of the compost pile is a good indicator of the evolution of the composting process, as it is closely associated with biological activity indicating the stages of the process, in the compost analyzed, the counting of microorganisms allowed to evaluate them as stable, the bacterial classification by Gram staining, represented a good indicator of the successions that occur in the composting process and was useful to help the classification of the bacteria present; the phytotoxicity test corroborated the degree of maturity and stability of the studied compost.

Thermo-Mechanical Performance of a Phase Change Energy Pile in Saturated Sand

To reduce the thermal response and improve the heat storage capacity of energy piles, a phase change (PC) energy pile was proposed. This innovative PC pile is made of concrete containing macro-encapsulated PCM hollow steel balls (HSB) as coarse aggregates. A numerical model was developed to simulate the thermo-mechanical behaviors of the PC pile under thermal cycles and sustained loading. The computational model is a three-dimensional model that is symmetrical for the two horizontal directions in geometry. Heat transfer process follows conservation laws of energy. The numerical model was validated by the experiments conducted on the PC pile and the results show that the model can reproduce the major thermo-mechanical effects. Then, the model was used to compare the performance between the ordinary concrete pile and the PC pile in saturated sand under the same experimental conditions, where the piles were considered to be thermo-elastic in nature and the sand was considered as a Mohr–Coulomb elastic-plastic material. The thermo-mechanical response of the PC pile under different thermal loads was analyzed. The results show that at the end of heating, the temperature, strain, and displacement of the PC pile were lower than those of the ordinary pile. As the thermal loading increased, the range of temperature change in the soil around the PC pile increased, as well as the strain and displacement of the pile. The residual strain and plastic displacement after the temperature cycles also increased with the increase of thermal loading. Therefore, when designing phase change energy piles, full consideration should be given to the matching of thermal loads and PC temperature, so as to balance the heat transfer rate of the pile and the thermal response.

Effects of storage on dry matter, energy content and amount of extractives in Norway spruce bark

Wood bark is one of the major feedstocks in bioenergy and bioeconomy scenarios in Finland. Currently it is used mainly for producing heat and power, which make buffer storage essential due to seasonal variations in the demand for energy. The storage of bark is associated with problems like the occurrence of self-heating, biomass losses, and the reduction of its quality as fuel. Extraction of valuable extractives from the bark before burning is an interesting option when aiming to increase the value of this side-stream. However, the content of extractives starts to decrease immediately after tree felling and this degradation continues during storage.This study examined changes in fuel quality and extractive amounts during the storage of Norway spruce (Picea abies) bark from sawmills. The moisture content of the bark decreased five percent during the storage period of eight weeks. The temperature in the storage pile rose within one week to over 50° and there was evidence of appreciable initial biological activity within the bark. The dry matter losses of spruce bark were on average six % per month.The content of acetone-soluble extractives decreased significantly, being 66.2% of the original amount after eight weeks’ storage. The most significant changes in extractive content occurred within the two first weeks of storage when 30% of the extractives were lost. This means that in order to utilize these valuable compounds, the material should be sent for further processing as soon as possible after debarking.

Changes in microbial populations during co-composting of dewatered sewage sludge with pruning wastes in windrow piles

Abstract. Nafez AH, Nikaeen M, Hassanzadeh A, Kadkhodaei S. 2020. Changes in microbial populations during co-composting of dewatered sewage sludge with pruning wastes in windrow piles. Biodiversitas 21: 4648-4655. The aim of this paper was to study the composting of sewage sludge (SS) and pruning waste as bulking agent with regard to abiotic factors and succession of functional microbial groups. To prepare the composting piles bulking agent and SS in volumetric ratios of 1:1 (TW1), 2:1(TW2), and 3:1(TW3) were used, and a pile of raw sludge was used as control. Samples for investigation were obtained from the composting piles at time intervals of 5-7 d. The temperature of the control pile and TW1 was just 37°C and did not reach the thermophilic phase. The number of thermophilic bacteria increased to 14 log CFU gDW-1 in the thermophilic phase. The salmonella was lost on the 47th and 19th days of the composting process, for TW2 and TW3, respectively. There was a significant correlation between mesophilic fungi with mesophilic bacteria (r=0.942, P<0.001). The majority of the microbial populations inspected revealed their maximum numbers towards the end of the thermophilic phase, with decreasing tendencies afterward. The number of evaluated microorganisms was controlled by differences in physicochemical parameters at different composting phases. The results revealed that the scheduling of the thermophilic period, as well as the microbial community and environmental situations, affects the microbial structure andTW2 had the best quality compared to other piles in achieving the best thermophilic phase and elimination of pathogenic microorganisms.

Bacterial and Fungal Community Dynamics and Shaping Factors During Agricultural Waste Composting with Zeolite and Biochar Addition

Bacterial and fungal communities play significant roles in waste biodegradation and nutrient reservation during composting. Biochar and zeolite were widely reported to directly or indirectly promote microbial growth. Therefore, the effects of zeolite and biochar on the abundance and structure of bacterial and fungal communities and their shaping factors during the composting of agricultural waste were studied. Four treatments were carried out as follows: Run A as the control without any addition, Run B with zeolite (5%), Run C with biochar (5%), and Run D with zeolite (5%) and biochar (5%), respectively. The bacterial and fungal community structures were detected by high-throughput sequencing. Redundancy analysis was used for determining the relationship between community structure and physico-chemical parameters. The results indicated that the addition of biochar and zeolite changed the physico-chemical parameters (e.g., pile temperature, pH, total organic matter, ammonium, nitrate, and water-soluble carbon) during the composting process. Zeolite and biochar significantly changed the structure and diversity of bacterial and fungal populations. Moreover, the bacterial community rather than the fungal community was sensitive to the biochar and zeolite addition during the composting process. Community phylogenetic characteristics showed that Nocardiopsaceae, Bacillaceae, Leuconostocaceae, Phyllobacteriaceae, and Xanthomonadaceae were the predominant bacterial species at the family-level. Chaetomiaceae and Trichocomaceae were the two most dominant fungal species. The pH, total organic matter, and nitrate were the most important factors affecting the bacterial and fungal population changes during the composting process.

Impacts of pile temperature on antibiotic resistance, metal resistance and microbial community during swine manure composting

The impact of pile temperature on the fate of antibiotic resistance genes (ARGs), metal resistance genes (MRGs) and mobile genetic elements (MGEs) during aerobic composting was not fully explored. Here, three composting piles were tested with different maximum temperature control. A total of 211 ARGs, 9 MRGs and 44 MGEs were observed. After 42 days, the numbers and the total abundances of detected genes were generally decreased (3.8%–50.0% and 25.4%–66.0%, respectively) in three treatments, except for the total abundance of MRGs (increased by 82.2%–500.5%). Higher pile temperature substantially stimulated the attenuation of gene diversity, but had no significant impact on promoting the decline in total abundances. For certain gene subtypes, higher temperature remarkably promoted their removal or suppressed their rebounding during maturation phase. The erm(F), sul1 and floR were potential indicators of ARGs during composting. The MGEs IS26, int1, intl2, IncP_oriT and IncQ_oriT acted as crucial hubs for ARGs and MRGs. Genera Acinetobacter, Pseudomonas, Corynebacterium_1 and Proteiniphilum were major potential hosts for multiple genes. The ARG, MRG and MGE profiles were mainly driven by the joint effect of environmental factors and microbial community.

Composting and vermicomposting residues of açaí and babassu for sustainable agriculture in Amazon

Agroindustrial wastes in southeastern Amazon are abundant and there are policies encouraging proper disposal for such wastes for sustainable agriculture. In this study we compared the chemical parameters of composts resulting from composting and vermicomposting sheep manure added to agroindustrial wastes as a bulking agent. Piles of compost were created using sheep manure, fruit waste, and a bulking agent. The treatments consisted of compost piles of: Tc - sheep manure and fruit pulp; Ta - sheep manure, fruit pulp and triturated açaí seeds; Ts - sheep manure, fruit pulp and sawdust, and Tb - sheep manure, fruit pulp and babassu coconut residue. After 50 days, a fraction of the compost from each pile was transferred to vermireactors to compare processes. At the end of the experiment, samples were taken in triplicate from all treatments in both composting and vermicomposting units for chemical analysis. The assessed variables were daily temperature of compost piles and vermireators, C/N ratio, Volatile solids (VS), total kjeldahl nitrogen (TKN), total phosphorus (TP), total potassium (TK), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), copper (Cu), zinc (Zn), manganese (Mn), boron (Bo). Sawdust-based and babassu-based compost, from composting process, has the lower time for stabilization (about 40 days), pH closer to neutral and more efficient in reducing the C:N ratio than vermicomposts. Vermicomposting process increased the concentration of almost all nutrients in treatments, except for babassu-based compost.

Adding a recyclable amendment to facilitate sewage sludge biodrying and reduce costs

Finding an economical amendment, available in a steady supply, is needed to support the biodrying industrialization. This research developed a recyclable biodrying amendment (RBA) to condition the biodrying of sewage sludge. The pilot-scale treatment (TR), which included the addition of equivalent weights of RBA and sawdust as amendments, resulted in a higher pile temperature and longer thermophilic phase compared to the control (TC), which used only sawdust as an amendment. The final moisture content levels were below 50% with both TR and TC. The heat use efficiency for water evaporation was 72.2% and 73.0% in TR and TC, respectively. The activity of α-amylase and cellulose 1,4-β-cellobiosidase increased during the thermophilic phase, while the activity of endo-1,4-β-glucanase and endo-1,4-β-xylanase decreased during the thermophilic phase with both TR and TC. The fourier-transform infrared spectra indicated that adding the RBA resulted in good biodegradability of the lipids, proteins, and polysaccharides. The humic acid to fulvic acid ratio in TR and TC increased from 0.33 (TR) and 0.35 (TC) on day 0–0.46 (TR) and 0.45 (TC) on day 21, indicating the humification process. The RBA recovery rate was 95.6% and can be reused. These findings highlight that adding RBA showed satisfactory biodrying performance, reduced the amendment cost, and the biodrying product could be incinerated without energy deficit.

Inoculation of cattle manure with microbial agents increases efficiency and promotes maturity in composting.

In this study, fresh cattle manure was mixed with rice straw at a ratio of 10:1 in fresh weight and then composted in a self-built, aerated static composting box, whose dimension was 1m × 0.8m × 0.8m with a volume of approximately 0.6m3. To deal with the inconvenient and time-consuming problem of multiple stage inoculation, a single, one-time inoculation agent containing diverse microorganisms that are active at both the initial heating and thermophilic phases was developed. A total of 12 from 42 strains isolated from the none-inoculated Experiment 1 composting system were selected as microorganismal agents in Experiment 2 according to their species, prevalence and cultural temperature. 200mL of each microorganism enrichment broth was mixed to the inoculation group at the beginning of composting. A total of 2400mL of sterilize distilled water was added to the control group. The parameters of temperature, moisture, pH, C/N ratio, organic matter degradation, and germination index were investigated for both inoculation and control composting groups. Results showed that inoculation did not significantly shorten composting time. However, the pile temperature was increased with the maximum temperatures of 64.6°C and 60.3°C for the inoculation and control groups, respectively. The degradation of organic matter was accelerated (P < 0.05), and significantly higher GI value (P < 0.05) indicated that the maturity was promoted by the inoculation microorganism. This suggests that the final composting product would provide value as alternative source of nutrients for plants. Conclusively, we suggested a multiple microorganism inoculation method to increase the efficiency and promote maturity in cattle manure composting.

Experimental Study on Heat Extraction from Coal Pile by Heat Pipe

Coal spontaneous combustion is one of the major disasters in coal storage and coal transportation. Consequently, coal fire prevention and control technology is one of great significance to the safe operation of coal mines. Heat pipe is a passive heat transfer device by phase change method. Thermal energy can be transported from the underground to the surface continuously by the heat pipe effect, so that it is expected to diffuse concentrated heat and reduce the temperature of the coal pile, which is effective for preventing coal spontaneous combustion. The experiment removing thermal energy from the underground coal is carried out in order to identify the feasibility of the heat pipe heat extraction heat from the coal dump. The results out of the present experimental conditions were shown that the application of heat pipes are contributing to extinguishing coal fire as well as for energy recovery utilization purpose.

Apparatus development for contact mechanics of energy pile-soil interface

An Energy Pile-Soil Interface Characteristic Apparatus (EPSICA) was developed to investigate the contact mechanics of the pile-soil interface. In the center of the apparatus, there is an energy pile model, around which different soil can be filled to simulate pile in different subsoil. The soil can be saturated. By applying loads on the top of the soil, the different depths were simulated. The temperature of energy piles was controlled by the cycling fluid with a water bath. The Pt100 sensors were installed in the pile and soil to measure the temperature changes. The miniature earth pressure cells were installed on the pile surface to measure the normal stress of the pile-soil interface. The FBG quasi-distributed optical fiber technology was used to measure the hoop strain to evaluate the circumferential deformation of the pile model. Taking the sand foundation as an example, the mechanical behavior of pile-soil contact behavior during the heating and cooling cycle was studied based on the temperature of pile and soil, normal stress of pile-soil interface and hoop strain of pile. The developed apparatus provides a new method for the study of thermos-mechanical behavior of energy pile.

Analysis and prediction of grain temperature from air temperature to ensure the safety of grain storage

ABSTRACT Food security is an influential factor for the development and future of humanity. Stored grain temperature is a key physical variable for grain quality control and management in stored-grain ecosystem. In this study, a prediction model using Fourier series based on least-squares method is introduced to describe the average temperature movement of grain pile and the daily air temperature, naming hysteresis cycle model (HCM). Then the HCM based on the Fourier analysis is proposed that incorporating with the least-squares method, the Fourier series model is applied to forecast the grain pile temperature from the daily air temperature. The HCM is built by finding relationship called conversion coefficients between the air and grain pile temperature that is constructed on the basis of Fourier analysis, and the optimal order of the model is determined by Akaike information criteria. Our method can reflect the time lag of the grain pile temperature changes with the change of air temperature and requires only a single variable (i.e. air temperature). Experiments including model fitting, temperature prediction, and results comparison for a period of 425 days from a real-world granary, yield satisfied results agreeing well with actual observation values. As a result of model validation, the proposed method has the root mean square error (RMSE) values ranging from 1.6°C to 2.3°C with average RMSE of 1.9°C. In other words, the proposed model can predict grain pile temperature with a high accuracy once an acceptable relationship between air temperature and grain pile temperature has been constructed from previously temperature data. Result analysis indicates effectiveness and workability of the proposed model for stored grain temperature prediction.

A CNN-based temperature prediction approach for grain storage

Temperature prediction has a pivotal role in the grain storage phase. Accurate prediction results can optimise the effect of ventilation decisions and reduce the losses of stored grain. Most existing studies have only focused on layer temperature predictions whose predict particle size is very large. In contrast, this paper attempts to use convolutional neural network (CNN) to predict the point temperature of grain piles. The CNN-based approach uses multiple convolution kernels that share weights to capture the characteristics of grain temperature at different locations, which make full use of the temperature information around the target point. Experiments on real business data show that compared to other conventional algorithms, CNN has the best prediction effect on point temperature prediction problems.

Effect of waste compaction density on stabilization of aerobic bioreactor landfills.

Landfill stabilization contributes to the safe operation and maintenance of landfills. This study used a simulated aerobic bioreactor landfill to investigate the impact of different compaction densities on its stabilization to provide a basis for optimal parameter selection during landfill design. Samples of municipal solid waste were tested with compaction densities of 450, 500, 550, 600, and 650 kg/m3 during the experiment. The optimum compaction density was obtained by periodically monitoring the temperature of the waste pile, the water quality of leachate, and the composition of the waste. The impacts of waste compaction density on waste pile temperature and leachate were investigated and coupled with the analysis of waste composition to discuss the possible reaction mechanism. Results showed that the most complete waste degradation occurred at 550 kg/m3 compaction density, which was effective at accelerating stabilization of the simulated aerobic bioreactor landfill. Limitations of the experiment are given to lay foundations for further study.

Investigation of groundwater flow and saturated multi-layer soil on the ground temperature response of an energy pile through thermal response and recovery testing

Thermal response testing (TRT) and thermal recovery testing were conducted on a full-scale precast energy pile installed in saturated multi-layer soils to investigate the thermal response on the pile and soils. The thermal and physical properties of the soil were assessed through laboratory testing and compared to the estimated properties from the thermal response and thermal recovery tests through use of the finite cylinder source (FCS) method and the moving infinite line source (MILS) method. The MILS method was used to assess Darcy’s velocity through thermal recovery testing at 13 m depth within the pile, eliminating the influence of ambient temperature and potential heat input from the TRT Unit. The ground temperature response was monitored parallel and perpendicular to groundwater flow in three locations during heating input and subsequent recovery, while the pile temperature distribution was monitored within the embedded U-loops. The results showed that thermal conductivity estimates were consistently higher from TRT results when compared to laboratory results, and application of the MILS method recorded values greater than the FCS method, particularly in thermal recovery. The MILS was shown to accurately predict Darcy’s velocity through thermal recovery testing, recording a value within the range estimated through laboratory testing. Furthermore, the ground temperature response displayed significant influence of the various soil layers through a temperature curvature with depth developing over time.

Monitoring the spontaneous combustion of coal stack based on ZigBee and LabView

The spontaneous combustion of coal piles is a great threat to all coal storage sites. In order to avoid the occurrence of spontaneous combustion of coal piles and reduce economic losses and casualties, a set of system is designed to monitor the internal temperature of coal piles and predict the temperature value and combustible gas concentration. The system has the advantages of monitoring and warning, short-term prediction and low power consumption.

Changes in Microbial Population Numbers during Composting of Some Organic Wastes in Greenhouse

Aim: This study identified and enumerated microorganisms associated with the composting of some organic wastes using the plate count method&#x0D; Study Design: The wastes were allowed to decompose for 70 days in greenhouse using the modified windrow method of composting. Standard methods were employed to monitor temperature changes in compost piles as well as changes in bacterial and fungal populations.&#x0D; Place and Duration of Study: This study was carried out at in the Agricultural Research Centre of the Federal University of Technology, Owerri, Nigeria.&#x0D; Methodology: The organic wastes namely Poultry Litter (PL), Pig waste (PW), Cow dung (CD) and Source-Separated Municipal Solid Waste (MSW) were composted/co-composted using the windrow method as modified .Sixty kilograms (60) each of PW, PL, CD and MSW were introduced respectively into 100-litre(L) buckets that had previously been perforated at several points. In the co-composted piles, 30 kg of both samples were introduced into the same 100 L bucket that had previously been perforated and then mixed thoroughly. The organic wastes were allowed to decompose at room temperature at a corner of the greenhouse. and initial microbial populations as well as subsequent populations in the compost bins were studied using standard microbiological methods&#x0D; Results: Microbial populations increased concurrently with temperature during the first 3 – 4 weeks of composting except, however, for faecal coliforms and Salmonella. The highest temperature recorded was 60°C for cow dung (CD) compost pile though at maturity the temperature in all compost piles ranged between 27°C to 30°C. The bacterial colony forming units were higher than fungal colony forming units throughout the composting period for both mesopholic and themophilic microorganisms. The population of mesophilic organisms increased in the first 14 – 15 days; for cow dung, the initial total heterotrophic bacteria count (THBC) and total coliform count (TCC) were 2.4 x107 cfu/g and 5.0 x105 cfu/g respectively and increased to 2.5x108 cfu/g and 1.7x107 cfu/g for THBC and TCC, respectively, after the 14th day. Thermophilic bacteria dominated all the composting systems after the 21st day and lasted to the 35th day except for cow dung compost where thermophilic temperatures were still observed on the 45th day with a THBC of 6.3x106 cfu/g on the 49th day. Faecal coliforms and Salmonella were completely eliminated in all the compost systems after the 28th day with temperature values between 47°C – 60°C.&#x0D; Conclusion: Organic wastes when managed properly through the application of knowledge of composting can be transformed into beneficial materials for human and agricultural use.