RESUMEN
Background: this research studied the feasibility of a simple method for extracting gold from central processing units [CPUs] of computer circuit boards without solvent
Methods: ceramic and composite CPUs of computer circuit boards were used. Gold was extracted using a hydrometallurgical method in six stages: grinding of CPUs, leaching in nitric acid, leaching in aqua regia, removing the excess nitric acid, extracting the gold, washing and purifying the gold deposits. Measurements of extracted precious metals were carried out by inductively coupled plasma [ICP]
Results: the results indicated that mean concentrations of gold in the first and second stages of leaching were 0.138 and 31.16 mg/L, respectively. Following the washing stage, the concentration of gold in the final deposit was 25 mg/L. The purity rate of the final deposit was 83.9%, and the final gold recovery yielded 82.3%
Conclusion: the results of this study indicated there is a potential for extracting a high percentage of precious metals from e-wastes without solvent
RESUMEN
Background: Entry of untreated wastewater of wool scouring factories has been associated with many environmental hazards because of high rate of pollution. Presently effective treatment methods and reducing the costs of operation and maintenance from treatment units have always been under the attention of this industry owners. The aim of this survey is to present a suitable method for the treatment of wool scouring
Methods: In this study, chemical coagulant is used for wastewater treatment [aluminum sulfate, ferric chloride, poly aluminum chloride and lime]. And then these materials with "ozone" as a strong oxidative in reduction of the amount of Chemical Oxygen Demand [COD] in wastewater effluent has been surveyed
Results: The results of this work showed that only ferric chloride and aluminum sulfate among the above chemical coagulant had a high efficiency in the turbidity removal. Productivity of turbidity removal using ferric chloride with the pH of 4 to 5 was 99%, and turbidity was reduced from 166 Nephelometric Turbidity Units [NTU] to 1.5 NTU, and productivity of turbidity removal using aluminum sulfate within the pH 4.5 to 5 was 99.33% that reduced turbidity from 166 to 1.1 NTU. Results of ozonation with 5 g/hour and the oxygen flow of 2.5 litter per min with the pH assess of 15, 30, 45, 60, 90, 120, and 150 min to wastewater from chemical treatment with ferric chloride showed that the rate of COD was reduced from 24700 mg/L to 2940 mg/L. In ozonation to wastewater of chemical treatment with aluminum sulfate within the above rang of time, the rate of COD was reduced from 22500 mg/l to 4800 mg/l
Conclusion: We can be hopeful that in near future, getting the cheap technology of ozone production in industrial scale, one can use this technology for the propose of removal of pollutants having removal preferable by help of advanced treatment approaches
RESUMEN
Background: Infected with intestinal parasites is one of the most important health and economical problems, which could have different effects, such as diarrheal diseases or death associated. The purpose of this study was to determine the level of prevalence of Cryptosporidium and Giardia parasites in the vegetable marketed in Ilam city
Methods: This study was performed on 280 samples of fresh vegetables and lettuce in Ilam. The samples were taken at the level of 500 grams from the places where vegetables and lettuce are sold. Micro liters of each sample was placed on the slide using automatic micropipette, and Logel and Zyl-Nelson stainings were performed in order to identify Cryptosporidium and Giardia
Results: From 200 samples, 54 samples were contaminated to Cryptosporidium oocyte and 13 samples to Giardia cysts. From 80 lettuce samples also 32 samples were contaminated to Cryptosporidium oocyte, and 6 samples contaminated to Giardia cysts. The results showed that the overall infection was 37%. Infection with Giardia cysts was 6.8% and infection with Cryptosporidium oocyte was 30.7%, and Cryptosporidium infection rates in vegetables and lettuce were different. This difference was statistically significant [P<0.05]
Conclusion: As a result of this research it is determined that the prevalence of Giardia and Cryptosporidium in Ilam vegetables is significantly higher, and the contamination of lettuce is far greater. Therefore, authorities should be more attentive to the field of education and the control of parasitic diseases
RESUMEN
Background: Successful waste management programs are linked to internal factors, SW [strength and weakness points], and external factors, OT [opportunities and threats], and at the macro level are grounds for sustainable development. Studies may be related to David's study which presented a method to quantify strength, weakness, opportunity, threats [SWOT] analysis
Methods: In this study, designed to investigate recycling and managing dry residues in District 1, threat factors were studied and internal factors evaluation [IFE] and external factors evaluation [EFE] matrixes were scored. Tehran Municipality District 1 has 10 subdistricts and 26 neighborhoods. The dry residues from Municipality District 1 that currently weigh approximately 2678 tons per day
Results: Results showed that WO strategies for improving weaknesses and employing opportunities available in District 1 are ideal. After constructing the Quantitative Strategic Planning Matrix [QSPM], WO strategies were prioritized
Conclusion: The evaluation matrix of internal and external factors in the city of Tehran indicated that waste management has weak internal factors. Meanwhile, evaluation points of external factors showed that, in the current situation, SWOT could achieve good results. Waste management systems are involved with different multi-disciplinary factors; therefore, trends in the development of waste treatment technologies have been led by various social, economic, and environmental drivers in Tehran