Journal of Environmental Studies
Year:2010 | Volume:36 | Issue:53|Papers Count:17

Limitations on freshwater resources have caused researchers and water resources managers to focus an increasing attention over the past few decades on water quality protection. Surface water quality management in such resources as rivers, seas, lakes, and estuaries is of a greater importance than other water resources and a greater number of studies have been conducted on them as they are more accessible and, therefore, more directly exposed to a variety of contaminants and pollutants. Application of appropriate and efficient mathematical models for river water quality simulation is essential for the formulation of comprehensive guidelines used in evaluating measures that are employed for river pollution control and management. The non-linear equations dominating pollutant transfer phenomena in rivers, the complexity of their simultaneous solution, and the multiplicity of kinetic constants and coefficients have made it difficult, or at times impossible, to use physically-based models and methods for this purpose. Therefore, most of these models can only be applied to simplified cases or to situations where the models are strictly calibrated and validated, with no adequate accuracy when applied to unrestricted conditions. The uncertainties in water quality problems have made fuzzy inference systems, especially as combined with adaptive neural networks, to be used as a novel approach. The main objective of the present study is to exploit the capabilities of the adaptive neuro-fuzzy inference system (ANFIS) for river quality predictions with emphasis on DO and BOD. In the case study carried out on the Zayandehroud River, BOD predictions were obtained by the proposed system with a correlation coefficient of 0.953 in the calibration stage and 0.931 in the validation stage and DO predictions were obtained with a correlation coefficient of 0.921 in the calibration stage and 0.904 in the validation stage. Comparison of the results provided by the adaptive neuro-fuzzy inference system and the measured values reveals the high accuracy level of the proposed model.

In the recent years, sediments are used for the assessment of pollution. Since sediments have been in contact for a long time with over lying water, therefore they have been able to absorb pollution on to their surface. In the present investigation, the surficial sediments of Siahrud River have been analyzed. Grab samples were taken from ten samplings sites. The samples were immediately sealed and stored at 4°c until their arrival at the laboratory. Grain size fraction less than 63mm was chosen for chemical analysis. The total metal content was determined by digesting the samples with a mixture of HNO3 & HClO4. The chemical partitioning of metals was determined by means of the sequential extraction scheme proposed by the European Union's Standards, Measurements and Testing Program (SM and T, formerly BCR).This scheme consists of three successive extractions that make it possible to determine the association of the metals in three phases: acid-soluble, reducible and oxidizable. The most resistant bonds were digested by hot 50% HCl (phase 4). Furthermore, a fourth fifth phase, within lattice was determined as the difference between the total metal content and the sum of the contents in the four previous phases. The analysis of metals in the solutions was carried out by an inductively coupled plasma mass spectrometer (ICPAES). The accuracy of the analytical procedures for total metal determinations was checked using CRM 320 (sediment reference material). Replicate analysis of this CRM showed good accuracy, with recovery rates for metals between 97 and 101%. A standard reference material (CRM-601) was used to verify the accuracy of the sequential extraction method. Similarities between the behavior and origin of the metals studied were established by cluster analysis using the weighted pair group method. The loose, sulphide and organic bonds of metals with various sedimentary phases has been assessed by chemical partitioning technique.

As the largest lake, the Caspian Sea is one of the most important lakes in the world from ecological, political and natural resources points of view. The Caspian Sea is increasingly being under environmental threats and pressures because of residential, industrial and agricultural areas, oil exploitation and production activities within and in the vicinity of long coastlines of this lake. Studying the bottom sediments as the final sink of the fated pollutants has been of interest to evaluate the overall quality of the aquatic environments. Much attention has been paid to the study of the water and sediment quality and ecology of the Caspian Sea. In the present study, heavy metals and petroleum hydrocarbon contents in surface sediment samples of a large area from east to central coasts of southern Caspian sea (from Miankaleh bay in Golestan province to Ramsar coasts in Mazandaran province, Iran) are studied.

This study intends to monitor and evaluate the THMs concentration in the 6 different water districts in the city of Tehran as well as one district outside the city water district but inside the city limits. THMs are the main disinfectant by products (DBP) of chlorination, which are suspected to be human carcinogens. Formation of Trihalomethanes (THM) in drinking water depends mostly on raw water qualities such as pH, temperature, treatment process, residence time of water in the distribution system, as well as the bromine, chlorine and naturally occurring organic matter (NOM) concentrations. Because of the low cost of chlorine and convenience of application, chlorination is the most widely used disinfection process for drinking water….

Nowadays, with population growth in urban areas, providing safe water and health are considered as the basic needs of human, alongside the various pollutants due to urban activities, agriculture and industrial areas on adjacent ranges into urban water resources around the environment is such that study necessary to prevent the pollution of water resources and identification of pollution sources shows. The aim of this paper to identify research sources of water pollutants Sabzevar range of water supply in the city is using the data available.Sabzevar city with more than thousand years old and with a population of about 220 thousand people point to as the second city after Mashhad City in North East of Iran, today in the field of providing good quality drinking water with pollution problems that the groundwater resources of the serious issues is. Level range studied for this purpose, which is equal to 210.75 square kilometers Sabzevar drinking water sources (including 24 deep wells), the plain reservoir Sabzevar in the north, northwest and the West at intervals between 5 to 65 kilometer supply is .Therefore, the range affecting water resources include Sabzevar Northern Plains reservoir Sabzevar (code 4735) limit the salty river (Kal Shur) Sabzevar (main drainage plain) is. Drinking water of Sabzevar from underground water supply of plain Sabzevar affected various human activities (urban, agricultural and industrial) various pollutants into drinking water confine is Sabzevar. Recognizing the importance of these resources and also the amount of pollutants injected urban water infections, this study is trying to line with the comprehensive plan Sabzevar water pollution, water with good quality required for this area and reduce potential pollution of water resources must be examined.

It is necessary to care the quantity and quality of the water resources especially in arid and semi-arid regions. Shahrekord plain where it has a 551 Km2 total area, groundwater is discharging almost 255 MCM annually and uses for drinking and agriculture. The main objective of this study was classification of groundwater quality and comparison with the drinking water standard limits in Shahrekord aquifer. Some of the chemical properties such as Cation, Anion, Electrical Conductivity (EC), Total Hardness (TH) and Total Dissolved Solids (TDS) were measured in four times (Spring and Autumn  2004 and 2005). The results show that the some of the chemical concentration in North-Western part (NWP) of the aquifer including Ca, Mg, SO4, HCO3, Cl and Na was lower than Southern part (SP). Bicarbonate in the Anions and Calcium in the Cations has the maximum values; however they are lower than the standard limits. Water type was assigned as Calcium Bicarbonate in terms of available ions combination in Shahrekord aquifer. The TH in the wells varies from 150 to 300 (mg/lit /CaCo3). The water quality is classified in hard water category base on TH. The result shows that there wasn’t considerable difference in TH and TDS values on spring and autumn seasons. The maximum nitrate concentration is about of 37 mg\lit in agricultural landuse of northern sites. Result shows that Total Hardness (TH) and Total Dissolved Solids (TDS) in southern parts and Nitrate concentration in northern parts have maximum values concentration. This subject shows that the source of these water quality parameters is difference together. Azotic fertilizer seepage of agricultural lands increase Nitrate contamination and urban wastewater had most effect to provide the chemical concentration and Total Dissolved Solids.

The activated sludge process is the most used biological wastewater treatment method in the world. Sludge bulking is one of the most common problems relateing to activated sludge wastewater treatment, and this fact causes poor settling in secondary sedimentation tank. Sludge volume index(SVI) and the zone settling velocity(ZSV) are parameters to quantify the settleability of activated sludge . Assessment of influence of walnut shell as an agricultural waste, powdered activated carbon as a common adsorbent and clay as a mineral on the activated sludge settling properties was the principal aim of this research. Second phase of Shahinshahr Wastewater Treatment Plant was selected for wastewater sampling and conducting experiments of this research. SVI tests were done in a 1-Lit graduated cylinders and settling column used for determining of ZSV was with 200 cm height and 20 cm diameter. Average values of SVI for control sample was 823 mL/g, optimum dosages of walnut shell, clay and powdered activated carbon reduced SVI to 100 mL/g (88 percent decrease). Average values of ZSV for control sample was 1.222 m/h, different additives increased ZSV of control sample to 2-3 times. This increase in ZSV is important because hydraulic surface overflow rate(SOR) is also increased without loss of their efficiencies. Sludge return with these additives caused an improvement in sludge settleability. Jar tests revealed that these additives mainly act as ballasting agents rather than as flocculants and this mechanism is responsible for decreasing SVI. Walnut shell and clay, the same as activated carbon, improved the sludge settleability. Activated carbon is an expensive adsorbent and using this material is costly, while walnut shell and clay are cheep and natural. Therefore, walnut shell and clay can be used as alternatives of activated carbon.

The operation of fixed activated sludge system for treatment of wastewater containing heavy metal compounds (chromium, lead and nickel), by using of fixed activated sludge (FAS) system is studied in this research. A Plexiglas tank consisted of three sections including a downward-flow aerated reactor, an upward-flow aerated reactor and a gravity sediment unit, fed with the synthetic wastewater. The results showed that COD removal efficiency in the FAS is about 96% and the acclimation time for microorganisms is short. While chromium, lead and nickel removal efficiency in the fixed activated sludge at concentration of 1 mg/lit is 84%, 75% and 80%, respectively, by increasing concentration of them to 5 mg/lit, the removal percentage increased to 90%,84% and 87%, respectively. When concentration of chromium, lead and nickel increased to 10 mg/lit, the removal efficiency became 85%, 95% and 92%, respectively. Concentration of heavy metals (chromium, lead and nickel) at 50 mg/lit; caused the removal efficiency of 86%, 96% and 95.1%, respectively….

Contaminated lands around oil fields, especially soils contaminated by Polyaromatic hydrocarbons (PARs) are the common problem in these areas. PAHs such as Phenanthrene, Naphthalene, Benzo- a- pyrene are the major pollutant in the fields around petroleum refineries and arise largely as a result of coal and oil burning and other refineries activities. This causes an actual or potential threat to the environment and human, so removing them from polluted soil and water is necessary. In this regard, biological methods include II phytoremediation" as a new approach, are effective and economical. The aim of Phytoremediation in contaminated lands is using the ability of plants to uptake, accumulate, degrade and removing toxic substances. This is a promising technology for the clean-up of petroleum contaminated soils, especially in the tropical area where climatic conditions favor plant growth and microbial activity and therefore the frnancialresources can be limited. Grass species are excellent candidates for Phytoremediation due to their extensive fibrous root system, which allow for more interaction between the rhizosphere microbial community and the contaminant. The present study was conducted to investigate the role of a warm season grasstype, Sorghum vulgare Pers. Sudananse, in Phenanthrene, a major pollutant in soils around oil and gas fields, removal. The experiment was done in a green house scale with climatic conditions similar to mentioned region, in 16 weeks growth period…

According to importance of environmental resource in natural ecosystem preservation and human life, restriction of destruction is necessary. Miankaleh wetland in Mazandaran province is settlement of animal and herbaceous rare species and due to migration of birds therefore, this research will discuss determination of preservation value in Miankaleh international wetland and measure of individual’s willingness to pay (WTP) for Preservation benefits based on contingent valuation (CV) and questionnaire dichotomous choice. For measure of individual’s WTP was used Logit model and its estimation parameters are based on methods of maximum likelihood. Results show that 68.3% individuals have willing to pay for preservation value form the Miankaleh wetland. The mean of WTP for Preservation annual value of this wetland is RLs 6878.6 per household. The Preservation annual value was estimated 20.9 million RLs/ha for this wetland. Most important of effective variables are bid quantity, individual income, sex, education and jobs for preserve of this wetland. By using this results can be selected suitable price policy for preservation of Miankaleh.

According to importance of Environmental resource in preservation of natural ecosystems and human life, restriction on destruction is necessary. Miankaleh wetland in Mazandaran province is the settlement of animal and herbaceous rare species. This research will discuss determination of preservation value in Miankaleh international wetland and measure of individual's willingness to pay (WTP) for Preservation benefits based on contingent valuation (CV) and questionnaire dichotomous choice. For measuring the individual's WTP, Logit model was used. The estimation parameters are based on methods of maximum likelihood. Results show that 68.3% individuals have willing to pay for preservation of the Miankaleh wetland. According to the results, by increasing one unit in Bid, probability of acceptance is decreased equal to 0.924 percentages for preservation of Miankale Wetland. The annual mean of WTP for Preservation of this wetland is US $ 0.74 per household and US $ 2271.74 per hectare. Most important effective variables are bid quantity, individual income, sex, education and jobs for preservation of this wetland. It can be concluded that by application of the results of this study, a suitable price policy can be taken for preservation of Miankaleh…

In this paper different alternatives for hospital waste disposal in Karaj are compared with respect to practicability. The objective of this study is to conduct a survey of present practices (e.g. available procedures, techniques, and methods of handling and disposing of hospital waste), and determine the generation rate of hospital wastes. The study was performed in city of Karaj. Karaj is one of the largest cities in the country. There are 11 hospitals in Karaj (8 governmental hospitals and 3 private hospitals) with a total of 1443 active beds. All the hospitals selected for surveying….

In the present research, combination of Indexing system Method with Analytical Hierarchy Process has been applied to assess the environmental risks of gas pipe lines. By this process, classification and qualification of the numerous types of environmental risks would be accessible. Sum Index and Leak Impact Index indicate risk probability and effect severity, respectively. In this regard, total environmental risk is calculated based on multiplication of total risk probability in effect severity. Analytical hierarchy process is applied to evaluate the factors because of differences existed in the total effective level of these factors. For this purpose, Tasooj- Salmas gas transfer pipe line, 24 inch in size and 42 km in length was selected to study the environmental risks. By using geographical information system, investigated risks have been classified throughout the pipe line route….