mohammadali ebrahimi-nik

In the quest for improved anaerobic digestion (AD) efficiency and stability, iron-based additives and drinking water treatment sludge (DWTS) have emerged as promising components. This study explores the kinetics of methane production during AD of dairy manure under various concentrations of iron shavings (IS) and Fe3O4 (10, 20, and 30 mg/L) and DWTS (6, 12, and 18 mg/L). The experimental data were employed to assess the suitability of the Michaelis-Menten model as a non-linear regression (NLR) equation for evaluating the kinetics of dairy manure AD with these additives. The results demonstrate that the Michaelis-Menten model exhibits sufficient predictive capability for estimating cumulative methane production during the digestion process. The model was then utilized to compare the average cumulative methane production across the investigated treatments using the least significant difference (LSD) method, as well as to calculate the quantity of methane production at 25%, 50%, 75%, and 90% of the final methane yield. Notably, the findings revealed a significant difference (P > 0.05) in biomethane production among the different levels of DWTS, IS, and Fe3O4. Additionally, treatments containing varying levels of DWTS exhibited significantly shorter time durations to achieve 25% and 50% of their maximum methane yield compared to treatments containing Fe3O4. The most pronounced changes in these parameters were observed between distinct levels of IS.

This study investigates the production of flooring from oriented strand board (OSB) made with urban and garden tree pruning waste, with the aim of reducing urban management costs and creating stable income. Two types of directional chipboard flooring were produced: "B," using 45% garden tree pruning and 55% urban tree pruning, and "T," using 100% garden tree pruning and urea formaldehyde resin. The study varied the percentage of resin in two levels (10% and 12%) and the percentage of cake moisture in two levels (12% and 14%). Several tests were conducted based on international flooring standards, including surface wettability, free fall impact resistance, surface hardness, concentrated loading, and abrasion resistance. The results showed that OSB type T flooring had less moisture absorption and shrinkage in the surface wettability test, while T-type OSB flooring had better surface hardness, wear resistance, and resistance to force in the concentrated load test at point 2 compared to other types. The study concludes that producing flooring with 100% garden tree pruning chips, 12% urea formaldehyde resin, and 14% cake moisture can yield the best results. Based on the results, it is possible to use all four types of finished flooring in humid climates and high-traffic environments such as industrial buildings, companies, and residences. It is suggested that the biodegraded pruning of trees be used in the production of other engineered boards to preserve forests as the source of oxygen and habitat for animal species.

Increasing in consumption of fossil fuels and their price and environmental impacts, have led to a growing need and interest in replacement of these fuels with new and renewable energy sources. Anaerobic digestion is one of the attractive methods to produce biogas from organic matter.Wet state and solid state arethe categories of anaerobic digestion. Some benefits of solid-state anaerobic digestion (SS-AD) include the need for smaller reactor capacity requirements, less energy used for heating, and easier handling.In this study, SS-AD of organic fraction of municipal solid waste (OFMSW) was examined. The study was done in the laboratory scale of (1-liter volume), mesophiliccondition (37°C), and 20% solid content. Characterization of OFMSW indicated good potential of these materials to produce biogas through SS-AD (69.37% of total solids, 76.2% of volatile solids, and a C/N ratio of 38.28%). According to the results of SS-AD, a total of 372 ml biogas/g of volatile solids was obtained under normal laboratory conditions, of which 230 ml (61.82%) was methane. Also, a reduction of 64.7% was obtained for volatile solids, which is one of the parameters of the experiment productivity.

Nowadays, due to the conventional methods of landfilling, the environmental concerns about generated leachate are becoming a global problem. Physical-chemical process is considered a potential and cost-effective solution for the treatment of municipal landfill leachate. Since jar-test are time-consuming experiments for obtaining the appropriate concentration of coagulants, the aim of this research was the treatment of landfill leachate using response surface methodology as a substitute for conventional methods in coagulation–flocculation process.

Experiments were performed in a six-cell jar-test with effective volume of 500 mL. The ability of Ferric chloride hexahydrate to response to four parameters including COD, TSS, alkalinity and turbidity was investigated. To evaluate the model and optimization of coagulant concentration and pH, central composite design and response surface methodology were used due to the highest removal efficiency. Physical and chemical analyses were performed based on standard methods for the examination of water and wastewater.

The results showed that the quadratic model was achived for the three responses (COD, TSS and alkalinity) and the Reduced Quadratic model was obtained for Turbidity under the optimum conditions for the concentration of 10.23g/L at pH 8.85. Verification experiments, under optimum conditions in removal of COD, TSS, turbidity and alkalinity resulted 66.79%, 88.61%, 97.53% and 67.89%, respectively. Statistical studies (ANOVA table, the amounts of R2 and P-value) showed that the models were suitable for providing experimental data and in all models, the R2 value was greater than 0.99. P-value values also showed that the effects of quadratic model and reduced quadratic model were significant in ferric choloride dosage and coagulation pH. These experimental results were consistent with those predicted by the model.

According to the obtained results by response surface methodology, coagulation–flocculation process can be used as the effective process to remove leachate inhibitors.

Fuel supply for cooking among Iranian nomads have always been problematic job. The use of wood as a source of energy is very common in nomads. Traditional method of firing releases a huge amount of smoke, which may lead to respiratory problems in women. Moreover, collection of wood corresponds to destroy of natural resources. The aim of this study is to assess the feasibility of using ship dung (as the most available biomass in nomadic life), as a cleaner cooking fuel in an improved biogas stove. In this research a micro gasifier biomass cook stove as an improved biomass cook stove was evaluated based on Emission & Performance Test Protocol. Sheep dung pellets of 38 mm length and 13.6 mm diameter was used as biofuel. In addition to measurement of descriptive characteristics, the heating value of fuel was estimated based on elemental analyzing results and the models presented in previous researches. Emission of Carbon monoxide was monitored throughout the test. No smoke was observed during the stove operation. The thermal power of the stove was measured to be 3.4 kW. With the efficiency of 28 percent, 3 L of water got to boiling point in 16 min consuming 440 g of pellet. The average amount of emitted CO was recorded to be acceptable range. The results of micro gasifier biomass cook stove evaluation with sheep dung pellet as fuel showed that, this devise has a good technical and emission performance with this fuel and it can be used for nomad’s household. Further on field research is needed to adjust the stove size and design to the common life style of nomads.

The purpose of this study is to estimate the bio-oil from the pyrolysis process of waste products in terms of moisture, constant carbon, volatile matter and ash. The results of 41 different studies were used to modeling. We use the neural network model as a policy tool in the evaluation and prediction bio-oil from the pyrolysis process of waste products. Statistical method was used to determine the optimal values of the neural network parameters. The results of comparisons between two Multi- Layer Perceptron (MLP) and Radial Basis Function (RBF) neural networks showed that the RBF has a high ability to estimate the bio-oil. The value of correlation coefficient between experimental and predicted bio-oil by RBF was equal to 0.99. The neural network evaluation results showed that it can be used as a tool to estimate the production of bio-oil and it has been used in bio-oil production management decisions.

Due to the increasing consumption of fossil fuels in the world as well as their increasing cost and environmental impacts, the great need and interest to replace them with renewable energy resources has increased. Anaerobic digestion is a biochemical process that is able to convert almost all kinds of multi-dimensional biodegradable organic matters under anaerobic conditions to biogas. According to water content, anaerobic digestion methods are classified as wet and solid state. The solid-state anaerobic digestion has been claimed to be advantageous over liquid AD for a number of reasons including smaller reactor volume, lower energy requirements for heating and minimal material handling. In this paper, biogas production from solid state anaerobic digestion of municipal sewage sludge was studied. A series of single-stage batch mesophilic (37 ± 1oC) anaerobic digestions were performed at a total solids concentration of 20% in 1 liter reactor volume. The evaluation of municipal sewage sludge characteristics showed that this substrate has a good potential for solid state anaerobic digestion (Total solids, volatile solids and C/N ratio were obtained 25.7%, 50.7% and 11.7, respectively). The biogas yield was achieved 362 ml/g VS, which methane content of biogas was 213 ml (58.8%). The volatile solids reduction, a significant parameter to measure productivity of anaerobic digestion, was obtained to be 63.7%.

In recent years, the management and disposal of municipal waste has become a global problem and the most important environmental concern. Landfill generates a large amount of leachate. Biologically process is considered a potential and cost-effective solution for the treatment of municipal landfill leachate. The aim of research was the biological treatment of landfill leachate using a two-stage anaerobic bioreactor in pilot scale.
Experiments were performed in two anaerobic completely stirred tank reactors (CSTR) with effective volumes of 10 and 30 L at a constant flow rate of 2 L/day and hydraulic retention times of 5 and 15 days under mesophilic conditions. After the start-up period, loading rate was increased from 0.07 to 2.65 kgCOD/m3.day. The effluent of the first anaerobic reactor was used as the influent of the second reactor. Physical and chemical analysis were performed based on standard methods for the examination of water and wastewater, USA.
The results of experiments showed that the most suitable loading is 2.05 kgCOD/m3.day, which COD removal efficiency of reactors one, two and the system (total two steps CSTR) were 80, 65.1 and 93 %. In the whole system, BOD removal efficiency was obtained 92%. However, the NH4-N and alkalinity in the two anaerobic reactors were increased to 39 and 14.9%. The maximum methane percentage of the first and second reactors were 76 and 80%.
Two-stage anaerobic process can be used as the effective process to improve degradability and remove the organic pollutants.

Agriculture is an occupation in which the workers are prone to health problems, particularly musculoskeletal disorders. This job is one of the most strenous and most dangerous work activities with approximately 40% of the engaged population living in the developing countries. Iran is the world's largest producer of saffron (about 94% of the world production). Labour has the highest impact on the production of this crop. In this research, a kind of trolley is introduced in order to reduce the mechanical damages on the body of labors during saffron harvesting, and then the results are compared with traditional harvesting methods. In the experiments, the force and strength percent capability of 20 workers as saffron harvesters is evaluated using the 3DSSPP software. Two methods of saffron harvesting namely the traditional method with two common postures (half sitting and bowing) and harvesting while sitting on the trolley are considered. The different postures for the traditional harvesting methods and harvesting with the trolley were simulated and imported to the software. It was found that the most harm on the farmers occurs in their knees with half sitting. Evaluation of harvesting saffron with trolley showed that it results in the exertion of the least damage to farmers. However, harvesting with trolley exserts the most pressure on the back. However, the pressure is very little compared to half sitting and bowing postures. Hence this simple device is recommended for harvesting saffron.

A thermodynamic equilibrium model was developed to predict the gasification process in a bench-scale fluidized bed gasifier. Potato shoot (leaves and stems) was used as the feedstock of the gasifier. The experiments were done in five different gasification zone temperatures (650, 700, 750, 800 and 850°C), with a feeding rate of 0.166 kg/hour, and two equivalence ratios (ER: 0.2 and 0.25). The produced gas was analyzed and the portion of each component was calculated from a thermodynamic equilibrium model. The data from the experiments were compared with those of the modeling in order to validate the model. For 650°C, the closest results of the model to experiment data were observed for CO2 at ER = 0.2, followed by CO at ER = 0.25 with errors of 7% and 21%, respectively. The least difference between the model data and the experimental data at 700°C was observed for N2 with the error of 26% and 22% for ER= 0.2 and 0.25, respectively. At 750°C, the predicted values conformed reasonably well to the experimental data for CO with error less than 7%. Regarding the least error, the most admissible results were seen at 800°C for N2 with ER= 0.25 with an error of 7%. In this case, the most acceptable results of the model were obtained for 850°C, in which the error in predicting the amount of CH4 at ER= 0.25 was 0. Owing to the applicability of potato shoot in the gasification process, it can play a great role in energy production.