JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY
Year:2005 | Volume:- | Issue:26|Papers Count:12

The characteristic and treatment of wastewater in tin and galvanized plating industries were investigated in this study. This study showed that such wastewater contains heavy metals like chromium, iron, and tin having concentrations of 1176.47, 130, and 11 mg/L, respectively. The results also indicated that by adding sodium bisulfate and a coagulant aid such as ferric chloride and lime, coagulation and flocculation is the effective method for the treatment of the Wastewater. The results indicated that:  Sodium bisulfate with the optimum concentrations of 50 and 3120 mg/L can remove about 99% of chromium from chromic acid and sodium dichromate wastewater. Ferric chloride with the optimum concentration of 5 mg/L can remove 90.86%, 98.28%, and 99.73% of the heavy metals such as chromium, iron, and tin from this wastewater. Lime with an optimum concentration of 2.5 mg/L can reduce the ferric chloride to 3 mg/L, and can remove 97.11% of the heavy metals such as iron, chromium, and tin from the wastewater.The results also show that ferric chloride with the highest effectiveness for the removal of heavy metals and the lowest sludge production is the best coagulant for this wastewater and that lime together with ferric chloride is very effective in the removal of heavy metals.

All over the world, the soluble gases accompanying oil extraction, which contain highly toxic compounds, are flared under certain conditions in order to reduce toxicity. The present study, while performing an analysis of the condition of the flares of Ahwaz oil wells, tries to propose managerial solutions. To this end, the human, natural, and physical environments influenced by flares have been investigated in Ahwaz. Both theoretical and field research methods (searching the Internet, interviews with environmentalists and experts in the National Iranian Oil Company, personal observations, etc.) have been employed. Some of the results are related to the emission impacts of the flares and their location relevant to Ahwaz. Others shed light on the effects of the flares on the economy of the country, and the health and hygiene of the citizens of Ahwaz. Still others demonstrate the impact of the flares on the animals, plants, soil, and water of the area. The distribution of air pollutants (NOx, H2S, CO, and CO2) .from these flares has been investigated. The emergence of lung and respiratory diseases, and billions of Rials of economic loss, are among the consequences. Managerial suggestions have been put forward, considering both the presence and the absence of flaring at the oil wells.

The study of light propagation in seawater has improved in recent years. Among the newest methods is Laser Remote Sensing that gives us data from different sea layers in a fraction of a second with no disturbance in the environment. In order to study the laser propagation in seawater, a series of experiments were performed by the second harmonic of Nd: YAG laser in the solid-state laser laboratory at the Atomic Energy Organization of Iran. Using a mirror on the bed of a channel, we measured the reflected pulses by an energy-meter in different types of water (distilled water, drinking water, and a sample of water from the Oman Sea (60', 30" E and25', 14" N) from a depth of 6 meters in Chabahar Bay). Diagrams show that propagation of the laser light in water is nonlinear in different depths and intensities, and that it penetrates to a certain depth in constant intensity. As expected, higher radiant intensities had higher reflected intensity but a lower attenuation coefficient except in some points (contrary to the Beer's law). The attenuation coefficient is bigger for the sample of the Oman Sea than the distilled water (in constant radiant intensity and angle) of which one of the reasons can be the dissolved material, determined by their salinity. So we can get information about the different types of water at different depths doing in situ experiments in a short time.

Computer simulation of flow patterns due to wind effect and prediction of the formation of currents and circulations in natural and artificial lakes can be useful in the environmental research studies. In the present study, a two-dimensional flow solver is developed for modeling wind-induced lake flows. In this model, hydraulics parameters such as depth and horizontal velocity components are computed by solving the depth average equations of continuity and motion on three-dimensional bed surfaces. The equations are converted into discrete form using cell vertex finite volume method for triangular unstructured mesh. In order to stabilize the explicit procedure of solution, artificial viscosity terms are used. In this study, a new technique is used for wet and dry modeling in the shores of solving domain. The accuracy of the results is evaluated by comparing the results of the present model with other results available, for wind-induced flow in a circular basin. Finally, the flow circulations due to wind stresses on water sw1ace of Chitgar artificial lake, which is being designed in the west of Tehran, are predicted by the application of the developed model.

Tehran is one of the most polluted cities in the world and is a good candidate for the evaluation of the effects of pollution caused by vehicles on the radial growth of Pine (Pinus eldarica) trees. Trees have been cored at three sites: Azadi Square, the most polluted site, and two others spots: Chitgar Park and Sorkhehesar Park, our control sites. The concentrations of the heavy metals (Pb, Mn, Ba, Cu, Zn) in the tree rings determined by ICP showed no significant difference between the rings when grouped in 5-yr intervals, but their concentrations at the Azadi site were significantly higher than those at the control sites. The comparison of the pine trees of the same age at the three sites indicates that radial growth of pines at Azadi Square has been reduced over the past 10 years.A comparison between this research and similar studies indicates that tree rings in dry regions such as Tehran with calcareous soil are not as good bio-monitors as the trees in wet regions with acidic soil.

Annually, 32% of agricultural crops are attacked by pests and diseases in Islamic Republic of Iran. Therefore, crop protection occupies an important position in Iranian economic program. The annual use of pesticides in Iran is about 24,000 tons, of which the highest amounts are related to insecticides, herbicides and fungicides. In addition, pesticides are used at comparatively higher levels in Gilan province, whereas they are used at the lowest level in Sistan and Balouchestan province. With respect to the consumption level, it should to be noted that about 2,069,786 million dollars is spent on importing pesticides and raw materials into the country.The present survey includes all obsolete pesticides which are not currently in the list of national registered pesticides or cannot be used due to various reasons such as being damaged or decayed, having exceeded the expiry date, or being recommended not to be used by POPs and PlC conventions. To be able to assess the current situation, storage conditions, and the types and levels of existing obsolete pesticides, visits were made to the storage rooms and warehouses of organizations and companies, where obsolete pesticides are stored. The main organizations which store these pesticides in Iran are: 1. Agricultural Support and Service Company (ASSC), 2. Plant Protection Organization (PPO), 3. Rural Cooperative Organization (RCO), and 4. Cultivation and Industrial Units (CIUs).According to the latest information in 1382 (2003-2004), the existing levels of obsolete pesticides are 637 tons, about 396 tons of which are stored in ASSC warehouses. Also, because the largest ASSC warehouse is situated in Tehran province, the largest amount of obsolete pesticides is stored in this warehouse, which is about 308 tons.Due to the types of crops that can be cultivated, the amount of cultivated lands, and climatatic conditions, it was found that Gilan province had the highest and Kordestan province the lowest levels of obsolete pesticides.The statistical analysis of data has shown that there are no significant differences in the obsolete pesticide contents of the warehouses of the three organizations (ASSC, PPO and RCO, at a= 5% level) all over the country. Also, the amount of obsolete pesticides in the warehouses of the three organizations throughout the country is lower than the permitted levels compared to their annual usage of pesticides.

Millions of liters of wastewater are produced by textile industry daily. Each liter of such wastewater contains more than 20 g of dyes that cause environmental problems. One of the efficient methods for removing these dyes from wastewater is electrocoagulation. Basic yellow 2 is a dye that has many uses in textile industry and this study was performed to investigate the variables that influence the efficiency of decolonization of a solution containing a dye (Basic yellow 2) by electrocoagulation. Current density, time of electrolysis, inter-electrode distance, electrode surface, electrolyte concentration, and the initial concentration of the dye were the variables that most influenced color removal. A simple electrochemical cell was prepared with an anode and cathode; then the effect of each variable was studied separately using synthetic wastewater in a batch mode. The results showed that the color removal percent in the range of 20-100 ppm from the dye solution was more than 90% when current density, time of electrolysis, inter-electrode distance, electrode Showed, and electrolyte concentration were 211.6 A/m2, about 11 min, 4 cm, 37.5 cm2, and 10 g/l, respectively.

Diatoms are major constituents of algal flora in aquatic ecosystem. This study was conducted in the 140-km Jajrood Rriver from April 2004 through May 2005. Samples were taken on monthly intervals from six stations. Physical parameters such as DO and EC were measured in situ and chemical parameters such as BOD and COD were measured in the laboratory. Samples of Epilithic diatoms were taken using a core device DI 25 cm2 , of Epipelic diatoms using a core device DI 16 cm2 , and of Epiphytic diatoms by cutting small portions of Microspora and Cladophora. For better observation, cell walls and permanent mounts were prepared using Patricke and Reimer procedure. In this study, 92 species belonging to 21 genera of diatomses were identified. A wide diversity of species was observed in Cymbella, Diatoma, Navicula and Cocconeis.

The study of the international environmental legal principles and regulations indicate that these points are new scientific findings in the field of evolving and developing environmental regulations. To this date, some of the international principles and legal regulations have been fixed and approved of, and some others are being compiled. During the industrial revolution era, subjects such as flood, earthquake, famine, and plague were considered as continuous threats at an international level. But now, the international destruction of environment has been recognized as an offense to the common international law, and a large number of bilateral and multi-lateral agreements and conventions for the enforcement of the international principles and rules between governments have been foreseen and are executable. However, the lack of an effective international legal authority for dealing with the environmental crimes properly is quite obvious.