فهرست مطالب سید امید رستگار

Phosphorus is an essential element for all living organisms, and it cannot be replaced by any other element. Phosphorus has however a limited resource, and it is estimated that the extracted phosphorus resources (Apatite) will last for another 50 to 100 years. One of the most widely used technologies for recycling phosphorus is the precipitation of phosphorus from sewage sludge and leachate. Phosphorus Recovery as struvite (NH4MgPO4.6H2O) from sewage sludge has attracted special attention due to its potential for use as an ecological and slow release fertilizer. Struvite is a white, grain-like solid, odor-free and sludge–free ingredient, composed of magnesium, ammonium and phosphate at equal molar concentrations. Therefore, this study is designed to examine the effect of struvite replacement with triple superphosphate fertilizer on some physiological parameters and phosphorus availability in wheat plants in calcareous soils deficient in phosphorus.

Methods and Materials:

Soil with phosphorus deficiency was collected from 0-30 cm depth under arable lands of Hajjiabad-e Seyyedeh located in Ghorveh township, Kurdistan Province, Iran. The soil was air-dried and ground to pass through a 2-mm sieve, followed by laboratory analysis to determine its physico-chemical properties. The struvite used in the research was obtained by optimizing the three main factors of sulfuric acid concentration, solid-to-liquid ratio, and time for the leaching process, and the three key factors of Mg:P ratio, N:P ratio and pH for the precipitation process by Response Surface Methodology. To achieve the aim of this study a factorial experiment was carried based on completely randomized design with 4 replications. The factors included the application of different proportions of struvite replaced with triple superphosphate (S0:P100, S25:P75, S50:P50, S75:P25 and S100:P0) and 4 levels of phosphorus (0, 50, 100 and 150 kg TSP ha-1) and a total of 54 pots. The application rate for struvite was calculated based on total phosphorus (P2O5). Then 10 wheat seeds were planted in each pot at 2-cm depth which after plant emerging and greening, declined to 4 plants in each pot. The pots were randomly moved twice a week during the growth period to eliminate environmental effects. Irrigation and weeding operations were applied by hand. Plants were harvested 60 days after planting (beginning of flowering), washed with distilled water and dried with tissue paper. The samples were air-dried and then oven dried at 70˚C to a constant weight in a forced air-driven oven. Phosphorus concentrations in plant extracts were measured by the molybdenum vanadate or yellow method and chlorophyll content (a, b and ab) and carotenoids using the Arnon method. The statistical results of the data were analyzed using SAS software and LSD test (at 5% level) was used for comparing the mean values.

Based on the obtained results, all the investigated treatments and their interactions were significant at p<0.01. However, the interaction effect of fresh weight shoots and height was significant at p<0.05. The comparison of the average data showed that the highest amount of fresh weight shoots (7.79 g pot-1), dry weight shoots (1.130 g pot-1) and height (29.66 cm) was obtained from the application of S75:P25 150 kgTSP ha-1. By use of struvite instead of triple superphosphate fertilizer, the phosphorus concentration and uptake of wheat increased at all three fertilizer levels, so that the highest phosphorus concentration (0.174%) was obtained from S75:P25 150 kg TSP ha-1. However, there was no statistically significant difference for S100:P0 (0.169%) treatment. The highest amount of phosphorus uptake in wheat with an average of 0.197 g pot-1 was obtained from the S75:P25 treatment (150 kg TSP ha-1), compared to the treatment of 100% struvite (S100:P0) and 100% triple superphosphate fertilizer (S0:P100) with the averages of 0.158 and 0.109 g pot-1, respectively, showing 19.79 and 44.67 percent increase. Also, the results showed that the treatment of 150 kg TSP ha-1 100% struvite (S100:P0) compared to 100% triple superphosphate fertilizer (S0:P100) increased the amounts of chlorophyll a, b, ab and carotenoids by 7.78, 3.82, 6.44 and 6.84 percent, respectively.

Despite struvite's low solubility, it is a highly soluble phosphorus fertilizer for plants . However, the reasons for this apparent contradiction and also the specific mechanisms of struvite dissolution are still unclear. Hence, further accurate measurements at different pH and EC conditions with different physical and chemical properties of soil studying phosphorus fractionation in soil will help to better understand the use of struvite. Therefore, it is recommended to optimize the timing and application rate of struvite in relation to the demand for different agricultural and garden crops.

In this study, the application of bio-acid leaching method based on the use of lemon juice to extract copper and zinc metals from mobile printed circuit boards has been investigated. Three important factors were investigated include lemon juice concentration, Solid / Liquid (S/L) ratio, and hydrogen peroxide (H2O2) concentration. Response surface methodology (RSM) was used to optimize the effective factors. The results showed that for particles with a size of 150 to 180 μm at a constant temperature of 20 ° C and time 4 h under optimal conditions including 1.41% (w/v) S/L ratio, 12.2% (v/v) H2O2 and 74% (v/v) lemon juice, copper and zinc recovery efficiencies are 89% and 73%, respectively. Moreover, the artificial neural network was used to predict the extraction of copper and zinc metals as a function of the studied factors. To validate the model, laboratory results were considered as evaluation data. The results of neural network modeling showed high accuracy to predict the target variable. The values of MRE, MSE, and R2 were 9.485, 15.254, and 0.9356% for the copper extraction model and 1.854%, 1.094, and 0.9963% for the zinc extraction model, respectively.

In this study, the modeling of vanadium, nickel and copper bioleaching from fuel oil ash ash using artificial neural networks was investigated. In the obtained models, the extraction percentage of metals was investigated as a function of factors such as initial pH (from 1-2.5), initial Fe2+ concentration (from 0 – 9 g/l), initial bacterial inoculation (from 1 – 10%) and process time (from 0-15 day). Three neural network models were presented to estimate the extraction percentage of metals. The propagation error method and Levenberg–Marquardt algorithm were used for training. Furthermore, trial and error method was used to determine the optimal number of neurons. One quarter of the data were used to evaluate the model and were not used for training process. The Mean Relative Errors (MRE) were obtained 5.35%, 3.07% and 2.82% for V, Ni and Cu, respectively. Also the higher 0.99 of R2 indicates the validity of the obtained models.

Ash produced by fuel-oil combustion in power plants contains nickel as one of the valuable metals. Ni recovery from the ash is very important in both economic and environmental aspects. In this study, leaching with assisted ultrasonic (sonoleaching) is used to extract Ni from the fuel oil ash. Response Surface Methodology (RSM) was used to optimize the effective factors including solid/liquid ratio (S/L ratio), sulfuric acid concentration and ultrasound power. Moreover, the kinetics of process was investigated using a modified shrinking core model to better understand the mechanism of the leaching reaction. Finally, the model predictions indicated that the diffusion step controls the overall dissolution kinetic. Also, the thermodynamic parameters of the process were investigated, and according to the obtained results, activated energy was 9.57 kJ.mol-1, and diffusion control the process.

Electrocoagulation process is one of the most effective treatment methods at among of the oxidation processes due to its unique properties such as simple design and extensive application for treating of industrial wastewater. To promote this process, different ways have been proposed. In this study, the electrocoagulation process was incremented by the placement of steel wool and platinum electrodes and its potential was evaluated by decolorization of crystal violet (CV) from aqueous solution.

the colored solution was prepared from CV powder by its dissolution in distillated water. Spectrophotometric method (600 nm) was used to determine the color content. Electrocoagulation experiments were conducted in a 1000 mL backer and at a batch method. To evaluate the kinetic studies, first and second order models were used. Toxicity tests were also performed using coliform bacteria to ensure the reduction of crystal violet toxicity.

The results showed that the process could remove the colored solution with a high percentage rate about 99.63% under optimal conditions (pH 9, time of 60 minutes, applied current 0.4 amperes and color concentration about 200 mg/L). The microbial toxicity test also indicated that the treated wastewater in this method can be reused or discharged in the environment.

Based on the results, the electrocoagulation with steel wool-platinum electrode arrangement can be effectively used in the treatment of color containing industrial wastewater.

Fractured carbonate reservoirs have low oil recovery efficiency due to wettability and tightness of rock matrix. One of the most applicable methods for enhanced oil recovery of carbonate reservoirs is to use smart water flooding. In addition using surfactants which have been obtained from Cedar leaf extract as a rich and cheap source leads enhanced oil recovery by improving the wettability properties. In this research, the effect of Ca2, Mg2 and SO42- concentrations in the smart water and also Cedar leaves extract concentration as a biosurfactant on wettability of carbonate rocks have been investigated. The analysis which is including contact angle measurments and cre flooding eperiments have been examined. Results showed the effect of Mg2 and Ca2 concentrations from 0.01 mol/L to 1 mol/L, SO42- concentration from 0.007 mol/L to 1 mol/L and biosurfactant concentration from 0.05 %(w/v) to 0.3 %(w/v) changes the carbonate wettability to water-wet, and oil recovery has increased from 35% to 57%. The contact angle has changed from 161 degrees to 41 degrees investigated in the 0.3 % (w/v) of biosurfactant concentration, which reflects the effect of the solution on the wettability of carbonate rocks.