Research Paper
Energy and Renewable Energies
Davood Mohammadzamani; Mahdi Jafari; Mohammad Rasooli
Abstract
Introduction The yield of methane production in the anaerobic digestion processes of municipal organic solid waste alone is low. Adding animal waste or other additives to municipal solid waste as feed for anaerobic digestion system not only increases the relative composition of methane, but also increases ...
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Introduction The yield of methane production in the anaerobic digestion processes of municipal organic solid waste alone is low. Adding animal waste or other additives to municipal solid waste as feed for anaerobic digestion system not only increases the relative composition of methane, but also increases the rate of biogas production (Rivas-García, 2020). Carbon and nitrogen are essential elements for the growth and reproduction of aerobic microorganisms. The balanced ratio for C/N in the process is between 20-30. Simultaneous digestion is used to balance the C/N ratio (Yousefi & Bahri. 2021). This process has many advantages, including the synergistic effect of microorganisms, increasing the stability of the process, increasing the efficiency of biogas, increasing the recycling of nutrients and reducing odor.Materials and Methods This research was carried out with the aim of increasing the rate of biogas production, reducing the feed retention time in the digester and increasing the amount of biogas production, by investigating the effect of co-digestion of urban solid organic waste with cow excrement using anaerobic digestion method. For this purpose, 52 samples of mixed urban waste (during the year 1400, once a week and one sample each time) were prepared from the waste transfer station of Qazvin city, and in order to investigate the effect of animal manure on the studied variables, from a cattle farm located in 50 kg of fresh manure was collected in the region. After preparing the samples, a laboratory bioreactor was used to perform the experiments. The biogas production process was carried out in two stages. In the first stage, urban waste materials were used, and in the second stage, a combination of urban waste materials and animal manure was used.Results and Discussion The ratio of carbon to nitrogen (C/N) in the primary feed and residual materials was obtained in the first and second stages. In this way, this ratio was estimated as 19.39 and 27.64 for the primary feed and the remaining materials in the first stage and 18.60 and 28.23 respectively for the second stage.In this study, the amount of ash decreased during the process, which indicated the participation of this substance in improving the activity of microorganisms. In both stages of the experiments, the organic matter of the primary feed decreased during the digestion process, which indicates the decomposition of these materials during the process. Also, the conversion percentage of dry material from primary feed to secondary material in stage 1 and 2 was 8.2% and 10.5%, respectively, which shows that in the second stage, in which the combination of animal manure was used, the percentage of conversion The dry matter is more and the process has progressed towards the production of biogas.The changes in the pressure of biogas inside the tank in the experiment related to stage 1 reached its maximum value (0.19 bar/kg) within 23 days after the start of the process, and then stabilized at 0.14 bar/kg of solid material in the last seven days. Is. Since the criterion for the completion of the digestion process was pressure stabilization in seven consecutive days, therefore, after 38 days, the first stage process was completed and the biogas and residual (secondary) materials were discharged. The maximum biogas pressure in the second stage test was 0.28 bar/kg of solid material, which was achieved on the 15th day, and finally, after 26 days, the pressure reached 0.16 and stabilized at this pressure for seven days. Therefore, the digestion process in the second stage lasted for 32 days. Therefore, it can be seen that by using animal manure in the primary feed and keeping other variables constant, the retention time has decreased by 6 days compared to the first stage.The maximum amount of biogas produced in stage 1 was equal to 6.27 liters/kg of solid matter and in stage 2 it was equal to 10.3 liters/kg of solid matter. As can be seen, by using animal manure in combination with urban organic waste, the volume of biogas production has increased under the same conditions. Taking into account the cumulative amount of biogas production, it was found that in stage 1 and 2, 140.89 and 230 liters/kg of solid biogas were produced during the digestion period, respectively. Therefore, the efficiency of biogas production has increased by 38%. Although the total amount of biogas produced in both stages of the experiments compared to the theoretical values obtained in this study (at the rate of 370 liters/kg of solid matter) and also reported by other researchers (Salehoun, et.al, 2020 and Kozminesky , 1995) has been less.Conclusion According to the results of this study, it was found that in the second stage compared to the first stage, the role of the two elements carbon and nitrogen in the biogas production process became more effective and one should expect more biogas production in the process, because the increase in the conversion of organic matter and nitrogen is The more effective decomposition of these materials by microorganisms has been achieved by adding animal manure to the primary feed.According to the results obtained from this study, it can be concluded that in the process of biogas production, the combination of animal manure with urban organic waste, in addition to reducing the retention time, can help to increase the efficiency of biogas production, which in this study A 38% increase in biogas production was observed in the case of using a combination of animal manure with urban organic waste compared to using only urban organic waste. Although the role of other variables such as temperature, type and amount of stirring, type of initial preparation of materials in terms of size, humidity, pH, addition of yeast and bacteria, degree of impurity and toxicity of materials, ratio of carbon to nitrogen, type and size of reactor and other examined the variables.
Research Paper
Land Evaluation and Suitability
foziyeh kohani; Hamid Reza Matinfar; Mahmod Rostamtnia; Alireza Amirian-Chakan
Abstract
Introduction Assessing land suitability and determining its production potential to manage soil and land resources is one of the best sustainable agricultural policies. Barley is the second most cultivated crop in Iran after wheat. However, all soils in Iran are equally suitable for barley production. ...
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Introduction Assessing land suitability and determining its production potential to manage soil and land resources is one of the best sustainable agricultural policies. Barley is the second most cultivated crop in Iran after wheat. However, all soils in Iran are equally suitable for barley production. This study was conducted with the aim of evaluating the suitability of land for barley cultivation using a spatial model integrated with Geographical Information System (GIS).Materials and Methods The suitability of the land for barley cultivation is affected by various factors including (percentage of sand, percentage of silt, percentage of clay, percentage of saturated moisture, structure, percentage of surface gravel, water retention capacity, organic matter, nitrogen, phosphorus, potassium, EC, CEC, SAR, CaCO3 and pH) that were identified in the study area. In order to evaluate the suitability of land for the production of barley crops, Cumulative Quality Index (IQI) and Numerical Quality Index (NQI) were used with two series of data sets including: Total Data Set (TDS) and Minimum Data Set (MDS) and the results of this The indices were compared with two indices, storie and square root.Results and Discussion 17 measured parameters were used as the total data set (TDS) and 5 parameters (sand percentage, clay percentage, silt percentage, saturated moisture and pH) were used as the minimum data set (MDS). Also, the results showed that using the data set The minimum (MDS) provides a closer estimate to the storied and square-root methods compared to using the total data set (TDS), thus even considering a limited number of effective soil properties with respect to spending less time and money on quality assessment. Soil and agricultural management can provide better results.Conclusion By calculating various indices and comparing them with the more common storie and square root methods, it becomes possible to survey and monitor land using new techniques. This helps validate the accuracy of the index performance. With the square root and storie techniques, the value of each parameter is categorised based on sources and conducted studies, and the requirements of the barley plant. Each parameter receives a specific grade. Considering the assigned grades and comparing them with the estimated values from the ground experiments, it is possible to identify which areas of land are more or less suitable for the intended purpose. Satellite images combined with ground observation data provide valuable information for land evaluation. The results showed that most of the units in the storie model and the square root were placed in the medium suitability class (S2) for barley production. Comparing the correlation between land suitability assessment methods and measuring soil quality indices method showed that there is the highest correlation between the NQIMDS method and the square root. In general, it can be said that the soil quality index can provide better results with minimum data set and less time and cost for soil quality assessment and agricultural management. The soil maps produced for agricultural suitability analysis in this research can serve as an effective aid in decision-making processes. Subsequent research should concentrate on employing new predictive tools to enhance forecasting abilities. Most studies have used fundamental GIS techniques for resource allocation. GIS is a potent tool for spatial analysis in resource allocation. Since land resources are decreasing rapidly, land use planning should be accomplished efficiently to recognize new areas for crop production. The use of advanced simulation software assists in the reduction of redundancy within other processes while simultaneously increasing their accuracy. Consequently, researchers must concentrate on carrying out studies concerning new and developed GIS software. Unmanned aerial vehicles (UAVs) could enhance accessibility, and therefore improve the effectiveness of resource allocation (Yu et al., 2014). Modelling techniques can be employed to evaluate the practical impact of resources.The results of this research can be useful in managerial decisions. In future studies, the use of new predictive tools should be considered. As land resources are rapidly decreasing, effective land use planning should be considered to identify new crop production areas. The use of advanced simulation software helps to eliminate the redundancy of other processes and increase accuracy (82, 93). Therefore, researchers should focus on conducting studies related to new and improved GIS software. Unmanned aerial vehicles (UAVs) may increase access to increase the effectiveness of resource allocation (103). Modeling techniques can be used to assess the practical impact of resources.
Research Paper
Soil Biology, Biochemistry and Biotechnology
Farzaneh Dehdari; Mehdi Mehrabi koushki; Hamid Alvanipour; Jamshid Hayati
Abstract
Introduction: Soil contamination by crude oil is common in oilfield in different processes including extraction, transfer and refining of crude oil and its products. Bioremediation is an interesting strategy to remediation of soils polluted with crude oils and its derivatives. This method is based on ...
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Introduction: Soil contamination by crude oil is common in oilfield in different processes including extraction, transfer and refining of crude oil and its products. Bioremediation is an interesting strategy to remediation of soils polluted with crude oils and its derivatives. This method is based on the employed of organisms to neutralize oils in the environment. During bioremediation process, microorganisms degrade and transform persistent crude oil hydrocarbons into simple and less persistent molecules. It is very important to identify the microorganisms that can utilize and degrade these pollutants. Generally, fungi play an essential role in the biodegrading and remediation of soils polluted with hydrocarbons. Therefore, the present study was carried out to evaluate the tolerance of the fungal isolates obtained from the oil-contaminated soil to crude oil in Maroon oilfield.Materials and Methods Twenty-three fungal isolates belonging to 12 genera were used to investigate their toleration to crude oil. The fungi had been isolated in December 2016 from soil samples contaminated with crude oils from four sites in the maroon oilfield of Ahwaz. The fungal isolates were obtained from the fungal collection of the department of plant protection of shahid chamran university of Ahvaz. The fungi had been identified based on phylogenetic analysis and morphological characteristics. The tolerance of these fungi to crude oil was studied by growing them on PDA medium containing 30, 40, and 50% concentrations of crude oil and through Radial growth measurements. The tolerance to crude oil was calculated based on growth inhibition percentage of fungal isolates. The research was conducted in a factorial completely randomized design for analysis of the growth-inhibitory percentages.Three replications were performed for each control (PDA-Tween culture medium without crude oil) and treatment. Mean data comparisons were performed based on Duncan's multi-range method at 1% significance level (P<0.01), using SAS 9.1 software.Results and Discussion: All isolates grew in the culture medium containing different concentrations of crude oil. The results of variance analysis showed significant difference between the main effects of isolates and different levels of crude oil, as well as their interaction effects on growth inhibition (P< 0.01). The growth inhibition means of three concentrations of 50, 40, and 30% was 33.6, 26.1, and 21.4, respectively, which indicated the direct relationship between the concentration level and the growth inhibition percentage. Naturally crude oil is a heterogeneous mixture that composed of hydrocarbons compounds, sulfur and other heavy elements, therefore an increase in its concentration leads to an addition in its toxicity. Comparisons of the mean of growth inhibition in different isolates in response to crude oil concentrations demonstrated that Aspergillus sp. SCUA-Deh-3 with 65.1 inhibition growth and placed in the group a had the lowest growth ability and highest sensitivity to oil and statistically significant difference exists between this isolate and all fungi (P< 0.01). M. circinelloides SCUA-34 and Cladosporium puyae SCUA-m5f4 ranked next with 45.1 and 41.8 inhibition of growth respectively and were placed in group b. Alternaria destruens SCUA-Deh-1 and Aspergillus sp.SCUA with 5.05 and 6.5 inhibitions and placed in group M had the lowest sensitivity and inhibition and had significant difference with all other fungi (P> 0.01). Also, the growth rate of both used Alternaria isolates enhanced by increasing oil concentration in media. The growth inhibition means were equal only in two isolates, Penicillium chrysogenum SCUA-Deh-12 and Aspergillus sp. SCUA-m1f8r2, in two concentrations of 30 and 40 % (4.6 and 19.6, respectively). Also, Aspergillus sp. SCUA-m3f10 had equal means percent inhibition of growth in two concentrations of 40 and 50 (28.5). Furthermore, in the isolates of Aspergillus sp. SCUA-Deh-3 initially stimulated growth at 40% concentration and then the growth inhibition percentage increased at concentration of 50%.Conclusion: These results showed that Alternaria destruens SCUA-Deh-1 and Aspergillus sp. SCUA-m1f7r2 have more growth potential than other fungi at presence of crude oil in growth medium. Also, the growth inhibition of Alternaria decreased by increasing of crude oil concentration. In other words, these two isolates were considered the most tolerant isolates to crude oil. So it seems; these native isolates are among the best fungi for bioremediation of oil-contaminated soils. However, regarding the biological degradation of petroleum materials, it seems necessary to mention that physicochemical properties and bioavailability of hydrocarbon pollutants play an important roles in their bioremediation.
Research Paper
Plant Nutrition, Soil Fertility and Fertilizers
Ali Amiri Gelwardi; Mohammad Ali Bahmanyar; Bahi Jalili
Abstract
Introduction: The environmental effects caused by the use of chemical fertilizers, including water and soil pollution, are a threat to the health of the environment. Researchers are trying to reduce the harmful effects of using chemical fertilizers and applying as much mineral resources as possible in ...
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Introduction: The environmental effects caused by the use of chemical fertilizers, including water and soil pollution, are a threat to the health of the environment. Researchers are trying to reduce the harmful effects of using chemical fertilizers and applying as much mineral resources as possible in the soil to meet the nutritional needs of plants. The use of natural amendments such as zeolite, pumice and bentonite play an important role in reducing the loss of nutrients and increasing the fertilizer use efficiency. These amendments, having a special physical and chemical structure, play an important role to increase the absorption of water and nutrients. As a result, this research was conducted with the aim of determining the effect of zeolite, pumice and bentonite application on the seed yield, yield components and concentration of macro elements such as nitrogen, phosphorus and potassium of soybean seeds and leaves in two soils with different characteristics.Materials and methods: This experiment was conducted as a split plot in three replicates and in 84 pots in the research greenhouse of Sari Agricultural Sciences and Natural Resources University in 2021. In this experiment, the main factors include two types of soil texture (silty clay and sandy loam) and the secondary factors in fourteen levels include the control, PK chemical fertilizer treatment according to the soil test, zeolite, pumice and bentonite, each at 2 levels of 0.5 and 1% without fertilizer, 0.5% zeolite, pumice and bentonite with 75% PK fertilizer, 1% zeolite, pumice and bentonite with 50% PK fertilizer were considered. each of the treatments was mixed with 10 kg of soil to the pots. After applying the treatment, three germinated soybean seeds were planted in each pot. In all stages of growth irrigation, weeding, pest and disease control were done. After harvesting, seed yield, the thousand seed weight, pod number and concentrations of nutritional elements such as nitrogen, phosphorus and potassium were measured in seeds and leaves. The data obtained from the experiment were statistically analyzed using Statistic software. The comparison of the means was also done using the LSD test method at the 5% level.Result and discussion: The results showed that the effect of the type of soil on seed yield, the thousand seed weight and concentration of phosphorus in seeds and also on the concentration of nitrogen, phosphorus and potassium in leaves was significant. In addition, the effect of the amendment treatments on all studied traits was significant except leaf potassium. While the interaction effect of soil type (texture) and treatments was significant on seed yield, leaf nitrogen, seed phosphorus and seed potassium. the highest amount of seed yield of 67/02 gram per pot was observed in silty clay soil and in 0/5 % zeolite with 75% PK fertilizer and the lowest amount of seed yield of 43.73 gram per pot was obtained in sandy loam soil and 1 % pumice with 50% PK fertilizer. Also the maximum amount of thousand seed weight and number of pods in per pot were observed in the 1% zeolite treatment and the lowest in the 1% bentonite with 50% fertilizer treatment. Bentonite 1% treatment, increased seed nitrogen by 11% compared to control. The mean comparison results showed that in silty clay soil, the highest percent of leaf nitrogen of as 7.79 percent in 1% zeolite with 50% PK fertilizer was measured and in sandy loam soil, the highest percent of leaf nitrogen of 6.86 percent was measured in 0.5% zeolite with 50% PK fertilizer. the highest percent of seed phosphorus and seed potassium was obtained in silty clay soil and 1% bentonite and sandy loam soil and 0/5 % zeolite with 75% PK fertilizer treatments respectively. The lowest amount of seed phosphorus and potassium were measured in sandy loam soil and 0/5 % pumice treatments.Conclusion: among the amendments studied in this research, zeolite and bentonite had the greatest effect on the studied traits. The positive effect of different levels of zeolite alone and with PK fertilizer was observed on seed yield, thousand seed weight, number of pods in per pot, leaf nitrogen and seed potassium. The general results of the present research showed that the use of 1% zeolite, improved the growth of the plants and increased the yield components. Also the use of zeolite with PK fertilizer for increasing the seed yield was recommended.
Research Paper
Soil Physics, Erosion and Conservation
lida piri moghadam; farhad khormali; hamed rezaei; Farshad Kiani
Abstract
Introduction: loess are a special type of silty soil with a porous structure and poor cohesion, and often contain silt with minor amounts of clay to fine sand . These characteristics make loess among the problematic soils in terms of engineering geology. problematic soils are observed in different parts ...
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Introduction: loess are a special type of silty soil with a porous structure and poor cohesion, and often contain silt with minor amounts of clay to fine sand . These characteristics make loess among the problematic soils in terms of engineering geology. problematic soils are observed in different parts of the world including Australia, Brazil, New Zealand, the United States and many areas of Iran. Some fine-grained soils are structurally unstable, that is, they are easily dispersed and are highly erodible. Hence, presence of such soils in engineering and Agricultural projects can cause great damage and financial loss. One of the most important influencing factors in the vulnerability of loess soils is the dispersion phenomenon. Dispersion or colloidal erosion is a physical-chemical process that often occurs in fine-grained soils containing clay particles. In general, dispersion phenomena occur when the shear stress induced by the flow exceeds the friction among particles, causing surface abrasion. Erosion can extend itself along a drying crack, settlement, hydraulic fracture, or other high permeability channels in a soil mass. Dispersive loess soil easily and quickly separates and disperses from each other in water with low salt concentration without any special mechanical stimulation. Climate and physicochemical characteristics are two important factors in soil dispersive. which affect the degree of soil dispersive. Climate affects soil development by influencing physicochemical characteristics. On the other hand, soil texture, clay content, porosity and Bulk density, pH and solubility of salts in soil are closely related to dispersive. Although, extensive researches carried out to determine the dispersion potential of the soils, affecting factors on dispersion phenomenon and validation of the soil dispersion tests, no comprehensive studies have been performed on The effect of climatic characteristics loess soils in golestan province. Therefore, the aim of this research is to investigate the effect of climate and physicochemical characteristics on soil dispersive.Materials and Methods: This research was focused on loess soils of Golestan province. seven pedons were selected, sampled and described in different parts of the province. Climatic data was prepared and physicochemical and dispersive analyzes were performed on soil samples. The values of pH, electrical conductivity, equivalent calcium carbonate, cation exchange capacity and bulk density were measured. In order to study the degree of divergence, Sherrard's chemical test and pinhole test were performed.Results and Discussion By investigating the amount of rainfall in different regions of the province, it was found that the loess soils of Golestan province are not in the same climatic conditions. The results showed that the climatic and physicochemical characteristics of the soils in interaction with each other had a significant effect on the evolution of the soil and the reduction of divergence in the studied soils. The highest amount of precipitation was in Ramyan and Minodasht region And these two regions had greater depth of soil and heavier texture than other pedons. The results of the pinhole test show these soils with intermadiate dispersion potential. While the results of the chemical test for most of the samples are non dispersive. According to the results obtained from the pinhole test, Minodasht and Sufian pedons with rainfall of 815.8 and 608.9 mm were completely non-divergent, and Hoten pedon with Aridic moisture regime and rainfall of 189.7 mm had the highest dispersion potential. In total, 30% of the horizons showed moderate dispersion. which were mostly in the Aridic moisture regime. The chemical test in this research also confirmed the presence of a small amount of sodium ion in the saturated soil extract, and only three horizons had the potential of chemical divergence based on the SAR level. From the results, it can be analyzed that the soil dispersion in this research is due to the physical nature of soil particles.Conclusion: The review of climatic data and the results of physico-chemical tests showed the existence of direct coordination between the climatic and physico-chemical properties of the soil. So that with the increase of rainfall, the soil formation process increased. This means that in soils with xeric regime and high rainfall, the percentage of clay, organic matter, porosity and water retention in the soil has increased. As a result, the dispersion potential in these soils has decreased. Keywords: Loess soils, Dispersive soil, Physicochemical dispersion, Pinhole test.
Research Paper
Energy and Renewable Energies
Abbas Shekofte del; Abbas Asakereh; Mohsen Soleymani; Seyed Mohammad Safieddin Ardebili
Abstract
Introduction: Anaerobic digestion, in addition to producing biogas, can minimize the environmental problems of animal manure and produce high-quality fertilizer. Finding suitable places for the construction of anaerobic digestion reactors is essential for the sustainable development of these types of ...
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Introduction: Anaerobic digestion, in addition to producing biogas, can minimize the environmental problems of animal manure and produce high-quality fertilizer. Finding suitable places for the construction of anaerobic digestion reactors is essential for the sustainable development of these types of power plants. Locating the biogas production site is a complex process with different and sometimes contradictory criteria including environmental, economic and technical criteria from which the location-related factors play the main role. The integration of geographic information systems (GIS) with multi-criteria decision making (MCDM) provides a powerful tool that can be useful in locating biogas power plants.Materials and Methods: In this study, spatial and non-spatial data were integrated with geographic information system in order to determine the optimal places for installing anaerobic digesters of livestock and poultry waste in the southeast of Khuzestan province. Data related to the type and number of livestock and poultry were collected separately from the Ministry of Agriculture. The location of livestock farms and chicken farms was determined using the GPS system. Livestock and poultry raised in the traditional way in the villages were not taking into account due to the problems of collecting manure and lack of economic justification. In order to determine the evaluation criteria and score them, similar studies, rules and guidelines, as well as the Delphi technique were used. 14 sub-criteria were evaluated in three main environmental, social-safety and topographical groups. Land suitability layers for the construction of anaerobic digestion reactors were prepared from the perspective of all sub-criteria in the GIS environment. In order to simplify calculations and easier weighting of criteria and sub-criteria to obtain the final result, some layers of criteria were combined. In this way, 14 layers were combined and overlapped until 7 layers of final criteria were formed. Since the spatial potential layer of biogas production is the main criterion and has the main effect on the suitability of land for the construction of a power plant, and on the other hand, it has no essential relationship with other criteria, it was valued separately. Roads and residential areas were also valued separately due to the greater importance of lower transport costs, accessibility, reducing transport time and losses, as well as environmental, health and safety impacts. The overall layer of surface water was obtained by multiplying the four layers of land suitability considering the sea, river, wetland and flood prone areas. Sensitive areas including forest, agriculture and protected areas were also considered in an exclusive layer. The other two layers were the combination layer of slope, height and fault, and the combination of railway lines and high voltage power lines. These layers were weighted using pairwise comparisons and hierarchical analysis method. The final layer of land suitability for the construction of anaerobic digesters and power plant was created by overlapping all the criteria layers based on the obtained weight.Results and Discussion: The findings showed that anaerobic digestion of livestock and poultry wastes in the region has a potential to produce 7.25 million m3/year of biogas. Cow and chicken excrement have the largest share with 51.32 and 29.34 percent, respectively. The restriction layer showed that 73.28% of the area is unusable due to one or more restrictions. The results also showed that "regional biogas production potential" and "access to roads and energy consumption centers" are respectively the most effective factors in determining the appropriate location for the power plant. Finally, using spatial analysis in ArcGIS environment, the studied area was classified into five suitability levels: "unsuitable", "weak", "moderate", "suitable" and "very suitable". Based on this, 73.28% of the studied area was completely unsuitable and only 1.68% of the studied area was very suitable for the construction of a power plant. But in almost all the studied areas, there was enough land with suitable or very suitable conditions to build a biogas plant.Conclusion: In the studied area, lands with suitable conditions for the construction of a power plant from animal waste using anaerobic digestion technology were identified. There is a suitable distribution of "suitable" or "very suitable" levels in the study area for the construction of a biogas power plant. The findings of this study can be a guide for those in charge to make a decision for the construction of a power plant.
Research Paper
Energy and Renewable Energies
Mahmoud Karimi; Reza Mohammadigol; roohollah rahimi
Abstract
Introduction: Biodiesel is viewed as a promising alternative to fossil fuels due to its favorable chemical properties and environmental benefits. Research has shifted towards producing biodiesel from non-edible oils and waste cooking oils to avoid food scarcity issues. The high cost of production is ...
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Introduction: Biodiesel is viewed as a promising alternative to fossil fuels due to its favorable chemical properties and environmental benefits. Research has shifted towards producing biodiesel from non-edible oils and waste cooking oils to avoid food scarcity issues. The high cost of production is a major challenge, with raw materials accounting for 75% of the total cost. Sustainability depends on low-cost feedstocks like waste cooking oil. Exergy analysis is a useful tool for optimizing biodiesel production by reducing energy and resource consumption and increasing production yield. The study focuses on the exergy flow of transesterification of waste cooking canola oil, with parameters like methanol:oil ratio, catalyst concentration, and temperature being evaluated.Materials and Methods: Waste cooking oil (WCO) was used in the present study, with physicochemical properties including density, viscosity, free fatty acid content, and acid value measured. Biodiesel production using a two-step catalyzed method was carried out, with the first step being esterification to remove high water and FFA content in the waste cooking oil. The second step involved transesterification using different methanol:oil ratios, catalyst concentrations, and reaction temperatures. The FAME content of the samples was analyzed using gas chromatography and an equation was provided to calculate the FAME content of the biodiesel samples. In the process of transesterification of WCO, four balance equations were used to analyze exergy. Mass, energy, and entropy input and output must be balanced, with a portion of exergy input being destroyed. The mass exergy component is divided into physical, chemical, potential, and kinetic exergy. The overall exergy of a mixture of substances was calculated by considering physical and chemical exergy. Mixing in the transesterification process is irreversible, with potential work being wasted. Exergy transfer by heat flow and workflow was calculated using specific equations. An exergy conversion coefficient was used to estimate the chemical exergy content of fuels. Dead state conditions were considered for calculating exergy efficiency in the transesterification process.Results and Discussion: The GC analysis of transesterification conversion products from a standard sample showed that the main components in WCO-derived biodiesel were methyl salicylate, methyl palmitate, methyl stearate, methyl oleate, methyl linoleate, and methyl oleate. The efficiency of the transesterification process under specific conditions was determined to be 90.23% with an exergy efficiency of 91.73%. Exergy analysis revealed that the exergy embodied in biodiesel was higher than that in WCO, but a portion of WCO's exergy was consumed in the production of biodiesel. The study also highlighted ways to reduce energy loss and material waste in the transesterification process, emphasizing the importance of recycling and reusing waste materials to improve overall resource efficiency. The experiment variables of methanol:oil molar ratio, KOH concentration, and reaction temperature were investigated in the transesterification process for biodiesel production. A higher methanol:oil molar ratio of 6:1 was recommended for maximum yield when using pure oil with low FFA and water content. Increasing the ratio from 4:1 to 8:1 resulted in higher biodiesel yield and exergy efficiency. However, further increasing the ratio to 12:1 led to decreased efficiency. The KOH concentration and reaction temperature also had significant impacts on biodiesel yield and exergy efficiency. Higher catalyst concentration and reaction temperature increased exergy destruction, while a temperature increase from 45℃ to 55℃ improved efficiency and yield. The study suggested that careful optimization of these variables is essential for maximizing biodiesel production and minimizing exergy losses.Conclusions: Exergy analysis is a valuable tool for assessing the environmental impacts of products, processes, or activities by quantifying energy and material usage and waste generation within a comprehensive framework. It also allows for estimating the resource requirements for processes such as transesterification in the production of renewable resources like biodiesel. In this study, the exergy flow in the transesterification of waste cooking oil was evaluated, with a focus on the impact of variables such as methanol:oil ratio, potassium hydroxide concentration, and reaction temperature on biodiesel yield, exergy efficiency, and exergy destruction. Experimental data was collected and used for exergy calculations, revealing that maximum biodiesel yield and exergy efficiency were achieved at specific conditions. Excess methanol or potassium hydroxide led to decreased efficiency and increased exergy loss in the process. Lower temperatures also resulted in higher exergy loss due to reduced conversion efficiency. Understanding the effects of these variables can help improve exergy efficiency and economic performance in commercial biodiesel production. Exergy analysis can also be used to evaluate environmental performance and aid in the development of environmental policies and resource management strategies.
Research Paper
Soil Chemistry and Pollution
Nima Davodi; Mostafa Chorom; Nematollah Jaafarzadeh Haghighi fard
Abstract
Introduction: Today, the production of plastic in the world is more than 400 million tons per year. This massive volume of plastic, in the form of various products from kitchen appliances to industrial and agricultural products, is growing rapidly. According to the statistics presented in 2020, about ...
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Introduction: Today, the production of plastic in the world is more than 400 million tons per year. This massive volume of plastic, in the form of various products from kitchen appliances to industrial and agricultural products, is growing rapidly. According to the statistics presented in 2020, about 9% of the plastics produced in the world are recycled. Therefore, most plastics remain persistent in the soil or in the seas as plastic waste. Microplastics (MPs) particles less than 5 mm in diameter originate from the breakdown of larger plastic debris such as plastic bags, bottles, and packaging materials. MPs, as an emerging contaminant, have gained worldwide attention. Unfortunately, current recycling methods have failed to provide a comprehensive solution to plastic waste disposal. However, in the past decade, most research on the effects of MPs pollution has focused on marine ecosystems, while very limited research has focused on terrestrial ecosystems. Soil ecosystems, especially agricultural lands, are known as the main reservoir of MPs but the effects of MPs on soil ecosystems remain largely unknown. Soil acts as a significant reservoir for MPs and can have substantial impacts on soil quality and fertility. Upon entering soil, MPs can potentially threaten soil health. MPs can interact with soil particles and organic matter and affect soil structure, nutrient cycling, and microbial communities. Studies have shown that MPs can alter soil microbial communities, potentially leading to changes in ecosystem functioning. MPs in the soil act as a means of absorbing and transporting pollutants. They transport agricultural chemicals, heavy metals and pathogens deep into the soil. The impact of MPs on soil organisms and ecosystems is not yet fully understood, and more research is needed to assess the extent of the problem and its potential consequences. They can negatively impact soil function and fertility by disrupting the physical, chemical, and biological properties of soil. A deeper understanding of how MPs enter, distribute, and accumulate in soils, as well as their impacts on various soil functions, is essential for developing effective strategies to manage and mitigate MPs soil pollution. Therefore, the purpose of this research was to determine the distribution of MPs in the deep soil and to identify the structure of MPs and the extent of their effects on some chemical and biological properties in Ahvaz urban waste landfill.Materials and Methods: To investigate the impact of MPs on some chemical and biological properties of soils in a municipal landfill, a factorial experiment was conducted in a randomized complete block design. The experiment consisted of 18 experimental soil units with three replications. Soil samples were collected from three depths (0-10, 10-20, and 20-30 cm) from each of five municipal landfills using a hand auger. Additionally, soil samples from the same depths were collected from a control area without any waste landfill. Chemical and biological characteristics of soils, including soil salinity, soil acidity, soil organic matter, soluble cations and anions, total nitrogen, available phosphorus, soil lime content, microbial respiration, soil microbial biomass, extraction and identification of MPs based on standard laboratory methods were measured. Identification of MPs using FTIR analysis was considered as a crucial step in this study. The experimental design consisted of two factors: landfill area (landfill vs. control) and soil depth (three levels). The experimental design was done in a factorial form in a randomized complete block. Comparison of average data was also done using Tokay’s 5% probability level test, data results were statistically analyzed with SAS software and graphs were drawn in Excel.Results and desiccation: The findings of the present study revealed a significant positive correlation between landfill areas and the control area. This indicates that landfill activities have a substantial impact on the concentration of MPs in their surrounding environment. In the soils near the municipal landfills, extremely high levels of MPs were encountered, with up to 4300 MPs pieces per kilogram of soil. This level of MPs contamination indicates severe soil pollution in these areas. Further analysis of the identified MPs revealed that two polymers, polyethylene (PE) and polypropylene (PP), accounted for a major portion of this contamination. Specifically, 71.81% of the MPs studied were PE, 17.15% were PP, 3.11% were polystyrene (PS), and 8.21% were polyvinyl chloride (PVC). This suggests that plastic materials, particularly plastic bags, bottles, and other items made of PE and PP, play a significant role in MPs soil pollution. In addition to physical effects, MPs can also have detrimental consequences for the biological and chemical properties of soil. The results showed that there is an inverse relationship between soil pH and the number of MPs, which means that as the number of MPs increases, the pH level decreases. But this relationship is not the same in all regions and at all depths. An increase or decrease in soil pH is probably due to the release of alkaline or acidic components from MPs. Soil salinity in areas one to five is higher than the control area. In some areas, at the same time as the number of MPs decreases with increasing depth, soil salinity increases and in others it decreases. The amount of soil organic matter in the areas with MPs pollution was significantly higher than the control area. The results showed that the presence of MPs in the soil is associated with a significant increase in the amount of total nitrogen in the soil. The reason for this increase can be related to the effects of MPs on microbial activity and biochemical processes in the soil. The average microbial respiration in the control area is 261 mg C-CO2/Kg soil, which is 38% lower than the average microbial respiration in areas contaminated with MPs. The average microbial biomass in the control area was 73.7 mg C/Kg soil, which is 51% less than the contaminated areas. A significant increase in microbial biomass in soils contaminated with MPs indicates an increase in the population of microbes, which can be due to the efforts of microbes to decompose MPs. This study demonstrated that MPs , as a major source of pollution in municipal landfills, can lead to significant changes in the chemical and biological characteristics of soils. These changes can negatively impact soil fertility, biodiversity, and the health of soil organisms. MPs might sorb (adhere) to nutrients and organic matter, altering their availability to plants and soil microbes. Additionally, the breakdown of MPs could release chemicals that indirectly affect soil chemistry.Conclusion: The effects of MPs on soil chemical properties resulted in significant increases in pH, EC, calcium and magnesium, soil organic matter, phosphorus, and total nitrogen. Soil organic matter, phosphorus, total nitrogen, and salinity increased by 3.4, 2.2, 7.2, and 2 times, respectively. The presence of MPs increased microbial respiration and microbial biomass in the surface soil, but at lower depths, decreased due to excessive salinity. Overall, this study demonstrates that MPs can have substantial effects on soil chemical and biological properties.
