J.Env.Sci. Tech., Autumn 2006, No.30


Nitrate removal from drinking water by ion exchange and reverse osmosis

 

Ali Torabian

Faculty of Environment, Tehran University

Amir Hesam Hasani*

Mehrnoosh Samak Abedi*

*Faculty of Environment, Science and Research Branch, Islamic Azad University

 

Key words: nitrate, drinking water, ion exchange, reverse osmosis

 

Abstract

Nitrate is one of the major components which is known as a chemical pollutant indicator in water and can be removed by physico-chemical and biological methods.

In this study, ion exchange and reverse osmosis processes were studied for nitrate removal.

The reverse osmosis system used in this research contained a TFC membrane with the capacity of 300 l/day, a pressure tank, and micro filters measuring 1 and 5 micrometers.

Synthetic nitrate solutions with concentrations of 25, 50, 100, 200 mg/l were injected into the system at a fixed amount of TSD.

The ion exchange column was made of plexy glass with a volumetric rate of 15 BV/hr.  

Nitrate with concentrations of 25, 50, 100 mg/l and different amounts of TDS (400, 700, 1000 milligrams per liter) were injected into the column.

The study lasted for 8 months and the following results were obtained:

 

-- An increase in nitrate concentration causes a decrease in efficiency from 93.5 to            82.5 percent for the reverse osmosis and from 99.7 to 95 percent for the ion exchange.

-- An increase in TDS has a negative effect on efficiency so that the removal efficiency changes from 99.7 to 83 percent in the ion exchange.

--An increase in the other anions like sulfate causes a decrease in efficiency in the ion exchange system.

--The regeneration solution has an effect on the operation of the ion exchange system. The best removal efficiency is about 99.7 percent, observed at a TDS of 400 when resin is regenerated by sodium hydroxide.

--The highest removal efficiency belongs to the nitrate concentration of 25 milligrams per liter and a TDS of 400 milligrams per liter in both methods: 99.8 percent for the ion exchange and 93.5 percent for the reverse osmosis systems.






J.Env.Sci. Tech., Autumn 2006, No.30


Identification of parameters influencing hexavalent chromium mist measurement using Taguchi experimental design

 

Aram Tirgar*

Farideh Golbabaei *

Keramat Nourijelyani**

Masood Salehi**

Seyed Jamaleddin Shahtaheri*

* Department of Occupational Health, School of Public Health and Institute of Public Health Research, Tehran University of Medical Sciences.

** Department of Epidemiology and Biostatistics, School of Public Health and Institute of Public Health Research, Tehran University of Medical Sciences.

 

 

Key words: hexavalent chromium mist, mist, electroplating, Taguchi experimental design

 

Abstract

Hexavalent chromium, Cr+6, has been classified as a human respiratory carcinogen. Many workers in different industrial fields, mainly chromium electroplating, are exposed to this chemical. So, there has been a considerable interest among industrial hygienists in assessing Cr+6 concentrations accurately.  Since Cr+6 is relatively unstable and is likely to decrease during sampling and sample storage and analysis, it is necessary to determine the effective factors which influence Cr+6 mist sampling. Therefore, this study was carried out in order to determine the major parameters influencing Cr+6 mist sampling method, using Taguchi experimental design. A chromium electroplating bath was used to produce homogeneous mist and a total of 24 Cr+6 mist samples were collected using the U.S. National Institute for Occupational Safety and Health method 7600.  The results revealed that Cr+6 concentration was higher: (1) for sampling by closed-face filter cassettes than for sampling by open-face filter cassettes (P <0.05); (2) for samples collected at 35 cm above the electroplating solution surface than for samples collected at 50 cm (P <0.001); (3) for sampling duration of 30 minutes than for sampling duration of 180 minutes (P <0.001); and, (4) for samples extracted immediately after sampling than for samples with delayed extraction (24 hours after sampling) (P <0.001).Taguchi test results showed that the optimal conditions for Cr+6 measurement were as follows: sampling at a height of 35 cm, sampling duration of 30 min, immediate sample extraction, and sampling with closed-face filter cassettes. Under these conditions, the highest Cr+6 concentrations would be collected and the highest degree of confidence could be obtained.






J.Env.Sci. Tech., Autumn 2006, No.30


Calculation of external costs of road transportation on social environment (with an emphasis on road accidents)

 

Fatemeh Zahed

Transportation Research Institute, Ministry of Roads and Transportation, IR_BEH@YAHOO.COM

Abdolreza Rezaee Arjroody

Transportation Research Institute, Ministry of Roads and Transportation, REZAEEAR@YAHOO.COM

 

Key words: road accident, external cost, DALY, V.S.L.

 

Abstract

Accident costs are either internal or external. The external costs include the value of human life and the negative economic impacts of disabilities and mental injuries. In this paper, the external costs of death and disability in Iran were estimated for the years 1378-1379 based on the existing statistics on road accidents.

In order to quantify the accident impacts on health, DALY (Disability Adjusted Life Year) indicator was employed. This indicator is used to measure the state of population health (with regard to cost-effectiveness) and is the only quantitative indicator for the calculation of the external costs of death, disease, and disability, and indicates the number of years lost as a result of premature mortality, relative disability, and the like. Then, the monetary value of each DALY was determined. Finally, the external costs of road accidents for Iran were calculated and compared with the country’s Gross National Product (GDP).






J.Env.Sci. Tech., Autumn 2006, No.30


Detergent removal from car manufacturing

industrial wastewater and its standardization

 

Amir Hossein Javid*

Sayyed Ahmad Mirbagheri

Faculty of Civil Engineering, K.N.T.University

Mehran Pourtalari*

*Faculty of Energy and Environment, Science and Research Branch, Islamic Azad University

 

Key words: industrial wastewater, detergent, surfactant, car manufacturing industries.

 

Abstract

Car manufacturing industries are considered as one of the most important environmental pollutants and this is mainly due to the high concentration of detergents in their wastewater. Because of their components, detergents have different effects on the environment such as causing Eutrophication, being harmful to the aquatics, reducing mobility among fishes, and inhibiting enzyme reactions. Therefore, the removal of these compounds from the car manufacturing wastewater is very important. It is to be mentioned that all these industries try to have a more efficient industrial wastewater treatment plant at lower costs.

This study aimed at finding the best method for detergent removal by determining the effect of such processes as flocculation and coagulation, detergent oxidation using Fenton method, and reverse osmosis.

The above-mentioned methods were used for the wastewater of an Iranian car manufacturing company (Iran-Khodro) and the results of pilot experiments and laboratory analyses show that the reverse osmosis, as a physical method, can remove detergents with 95% efficiency. The results also show that the removal efficiency of Poly Aluminum Chloride (PAC)   in coagulation and flocculation process was 84% in pH=6 and 45 mg/l dosage.






J.Env.Sci. Tech., Autumn 2006, No.30


The capability of Anodonta cygnea (Unionidae)

in the biological treatment of urban wastewater

(an open system approach)

 

Arash Javanshir

Faculty of Natural Resources, Tehran University

Mojgan Jandaghi

Faculty of Energy and Environment, Science and Research Branch, Islamic Azad University

 

Key words: wastewater treatment, filtration rate, Anodonta cygnea, phosphate and nitrate, Chlorella sp., Scenedesmus sp. Algae

 

 

Abstract

Agricultural and industrial sewages affect the quality of water everywhere and the dissolved phosphate and nitrate in such wastewaters create many environmental problems.

This study aims at reducing the dissolved components of wastewater using biological methods instead of the chemical ones. The swan mussel (Anodonta cygnea) is one of the most famous fresh water suspension feeders and seems to be an active agent for the removal of suspended particles and bacteria from water resources.

To see whether A. cygnea is capable of reducing the nitrate and phosphate dissolved in urban wastewater, a number of them were placed in an open system at 19 - 20º C. Their filtration rate (ml. min-1. g -1 (Ash Free Dry Weight (AFDW)) and the retention rate of the dissolved phosphate and nitrate salts were measured. The volume of the water passed through the gills was calculated with the help of dixenic culture of Chlorella sp. and Scenedesmus sp. The algae developed in Guillard and Rhyter media and were used when their concentration reached about 400. 103 cells. ml-1.

The results show that when fresh algae increase in number to meet their vital needs, they are capable of removing a considerable amount of the dissolved materials.  The dissolved nitrate tended to decrease from 204.17 mg.L-1 to 140.42 mg.L-1, and the filtration rate was about 10.01 ml.min-1.g-1 Ash Free Dry Weight (AFDW) during 20 minutes in the open system.

Moreover, it turned out that there was a positive correlation between the weight and the specific filtration rates of mussels. While weight increased from 2.02 gr to 2.14 gr (AFDW), specific processed water also increased from 5.87 ml.min-1.g-1 AFDW to 10.01 ml.min-1.g-1 AFDW (p< 0.003). Furthermore, the results showed that an increase in the pollutants’ concentration resulted in an increase in the specific filtration rate by mussels. When nitrate increased artificially (by adding nitrate salts) from 84.53 mg.L-1 to 204.17 mg.L-1 in the inputs of the two experiments, the specific filtration rate increased from 5.87 ml.min-1.g-1 AFDW to 10.01 ml.min-1.g-1 AFDW and the nitrate concentration observed in the outputs from 66.97 mg.l-1 to 140.42 mg.l-1 (p<0.001). In the case of phosphate salts, their concentration decreased from 60.49 mg.L-1 to 40.35 mg.L-1 and the filtration rate was 10.83 ml.min-1.g-1 AFDW during 20 minutes. Meanwhile, the specific filtration rate increased from 3.84 ml.min-1.g-1 AFDW to 10.83 ml.min-1.g-1 AFDW (p<0.037) when body weight increased from 2.02 to 2.14 gr. The results also showed that when dissolved phosphate increased artificially (by adding Phosphate salts) from 20.74 mg.L-1 to 60.49 mg.L-1 in the inputs of the two experiments, specific filtration rates increased from 3.84 ml.min-1.g-1 AFDW to 10.83 ml.min-1.g-1 AFDW and the phosphate concentration observed in the outputs were 17.81 mg.l-1 and 40.35 mg.l-1 (p<0.014). Based on the obtained results, Anodonta cygnea can be considered as a natural purifying agent in the treatment of urban wastewaters. The results of this study can practically be used in other experiments.






J.Env.Sci. Tech., Autumn 2006, No.30



The concentration and sources of heavy metals

in the sediments of Shirud River

 

 

Marjaneh  Kharrat  Sadeghi

Qaemshahr  branch, Islamic Azad University

Abdolreza  Karbassi  

Faculty of Environment, University of Tehran

 

Key words :  pollution, heavy metals, chemical partitioning, Shirud River

 

Abstract

This study aims at determining the anthropogenic and lithogenic sources of heavy metal pollution in Shirud River. To this end, seven sediment samples were collected and analyzed for both bulk and partition studies. A three-step chemical partitioning was used to find the anthropogenic sources of metals. The data reveal that due to oil pollution, the concentrations of Ni and V increase in the estuary. The main source of oil pollution could be attributed to oil drilling activities that have taken place in the last few years in the Caspian Sea . The Geochemical Index is indicative of a medium- to high-level pollution in the area under study.






J.Env.Sci. Tech., Autumn 2006, No.30


Determination of recreational value of Anzali wetland

using the travel cost method

Somayyeh Saudi

Faculty of Energy and Environment, Science and Research Branch, Islamic Azad University

 Saudi_shahaby@hotmail.com

Abbas Esmaeeli

Tarbiat Modares University

 

Key words: Anzali wetland, evaluation, travel cost method

 

Abstract

Anzali wetland with an area of about 200 km is situated in the southern margin of the Caspian Sea and bordered by the cities of Anzali, Rasht, Somehsara, and Rezvanshahr. It is considered as one of the important attractions of Guilan Province.

This study is to determine the recreational value of Anzali wetland using the regional travel cost method so that the results can be used as an effective tool for the planning and management of development projects.

This method is based on estimating the relationship between the number of visitors to a resort and its distance from their dwelling places and the average of their travel costs.

To this end, assuming the wetland as the center, 6 semicircles with a fixed distance of 300 km from each other were drawn so that they would cover all over the country.  Then, using a map and the existing statistics, the area and the population of any of these regions were calculated. In the next step, the socio-economic data extracted from the questionnaires completed by the visitors were analyzed. Then, considering the available data, the diagram showing the relationship between the travel cost and the number of visitors to this resort was drawn. After that, the different entrance fees were added to the total access costs, the new ratio of the visitors was obtained, and the curve of demand for Anzali wetland was drawn. Finally, by estimating the area under the demand curve, the daily recreational value of Anzali wetland was calculated to be 124,504,000 Rls., which shows the high recreational value of this wetland. The data show that most of the visitors of Anzali Wetland are 30-39 years old and the majority of them are high-school graduates and university students. Moreover, as visitors’ income increases, they decrease in number.






J.Env.Sci. Tech., Autumn 2006, No.30


The effect of road and railway transportation on wildlife

 

Borhan Riazi *

Neamatollah Khorasani **

  Mahmood Karami **

Banafsheh Houshyardel *

*Faculty of Energy and Environment, Science and Research Branch, Islamic Azad   University

  **Faculty of Natural Resources, Tehran University

 

Key words: road, railway, wild life, impact

 

Abstract                                                                                                        Biological environment, especially the wildlife, has seriously been affected by road and railway construction projects. The studies done on natural ecosystems in recent decades introduce roads and railways as factors that threaten the wildlife through the destruction and fragmentation of their habitats and preparing the grounds for overhunting and pollution.                     

For the animals whose habitats are in roadsides, noise pollution causes disorders in their hearing so that they cannot do their biological activities well. Meanwhile, they suffer from air pollution which leads to respiratory problems and other biological disorders. If the mitigation measures suggested in this article are employed, these difficulties can be decreased. Generally, roads have more negative effects on the wildlife than the railways. The main problems of roads are: the salt that is used for deicing the road surfaces, increasing access to the natural ecosystems, and as a result, destruction of the environment and hunting of the animals, use of warm surfaces of the roads -- specially by reptiles -- and attraction of animals to the road by car lights at night.                                                                                                           






J.Env.Sci. Tech., Autumn 2006, No.30


Using the Convention on Environmental Impact Assessment in a Transboundary Context (ESPOO) to solve the Caspian Sea environmental problems

 

Parvin Farshchi*

Nazanin Roohshahbaz*

*Faculty of Energy and Environment, Science and Research Branch, Islamic Azad University

 

Key words: environmental problems with a tranboundary nature, environmental impact assessment, ESPOO Convention, EIA transboundary Convention

 

 

Abstract

The Caspian Sea with an area of about 400,000 km2 is the biggest lake in the world. It is enclosed by five countries -- the Islamic Republic of Iran, Russian Federation, Azerbaijan, Kazakhstan, and Turkmenistan -- and is increasingly endangered by a combination of land, river, and marine polluting sources. Nowadays, due to its valuable biotic and abiotic resources, the Caspian Sea has become more and more important. On the one hand, the existence of crude oil and gas reserves in the Sea which are extracted and exploited by some littoral countries contaminate the environment and on the other hand, pollution sources located on the coasts such as pollutants originating from industrial centers, farmlands, and municipal waste waters that enter such a closed ecosystem exert increasing pressures on it and this requires further attention and cooperation by the Caspian Sea littoral countries and the concerned environmental organizations. It is to be mentioned that most environmental problems in the Caspian Sea are of a transboundary nature and cannot to be solved without regional cooperation.

If environmental considerations are taken into account in the development plans performed by the bordering countries, the adverse impacts on this ecosystem will be prevented.

At present, the only legal framework for environmental cooperation among these countries is the Convention for the Protection of the Marine Environment of the Caspian Sea or Tehran Convention signed by all Caspian littoral states in Tehran in 2003. The Tehran Convention will come into force once the Convention is ratified by all the parties. At present, four of these countries (Islamic Republic of Iran, Russian Federation, Turkmenistan, and Kazakhstan) have ratified the Convention and the Republic of Azerbaijan will do so within the current year. .Although the necessity of regional environmental cooperation in the field of EIA has been pointed out in the context of the Convention, the details for the responsibility of the countries and the mechanism of cooperation in performing EIA in a transboundary context have not been mentioned in the Convention.

International efforts to reduce adverse transboundary environmental impacts, the importance of adopting prospective policies, and the necessity for improving international cooperation all resulted in the development of a Convention on Environmental Impact Assessment in a Transboundary Context (ESPOO). It is noteworthy that with the implementation of ESPOO Convention, some regional programs could reach agreement on reducing transboundary environmental impacts.






J.Env.Sci. Tech., Autumn 2006, No.30


The economic and technical evaluation of

the electrical wind turbines in Boroojerd

 

Abdolrahim Rahimi

Faculty of Management and accountancy, Branch, Islamic Azad University South Tehran

Majid Saghafi

Bureau of planning and economic studies, Iranian Atomic Energy Organization

 

Key words: electricity, energy, wind turbine, potential measurement, Boroojerd

 

Abstract

Over the past few years, the average annual growth rate of electrical energy has been 8.29% and considering the high growth rate of electricity consumption in the current year, we should expect electricity shortages in the future.

One of the solutions to this problem is the use of small wind turbines for residential and commercial units, especially the ones far away from the electricity network. 

In this study, economic and technical evaluation of a 5.5- KW wind turbine was carried out using the most advanced software for simulation and potential measurement.

In the end, the total obtainable energy and the benefits of the wind turbines were estimated.






J.Env.Sci. Tech., Autumn 2006, No.30


Identification of environmental factors

determining the site of new cities in Iran

 

Sayyed Masood Monavari*

Jafar Noori*

Sahar Tabibian*

*Faculty of Envrironment, Science and Research Branch, Islamic Azad University

 

Key words: Mc Harg, site selection, criteria, ecological model, environmental

 

Abstract

New cities established in every period of time anywhere have their own specifications, and most of their settlement impacts have produced many environmental problems.

In fact, new cities are built to meet certain requirements such as absorption of excess population, provision of dwelling, and many other needs, but no attention is paid to their origin in the process of sustainable development as far as environmental planning and design are concerned.

In Iran, there was a need for new cities, due to population increase over the years. Therefore, the construction of 26 new cities was approved by the Higher Council for Architecture and Urbanization.

The location of many of the new cities in Iran is determined by certain factors such as socio-economic parameters, but the environmental criteria are usually ignored in this regard. The new city of Hashtgerd, which is located in the west of Tehran Province and which is to provide residence for some 500,000 people by 1390, is selected as the biggest new city of the country.

In this study, the location of Hashtgerd is assessed based on Mc Harg criteria and on the ecological model of development for urban, rural, and industrial land use. The results show that some environmental parameters such as slope, bed rock, depth, structure of soil, and planting are considered appropriately in selecting the site of the new city of Hashtgerd. However, some parameters such as earthquake and supplying water resources seem to have been ignored.

The results of the study also show that certain criteria such as air pollution, water resources, soil, wildlife, and some infrastructures should be considered as the main environmental criteria in the selection of the site for any new city in Iran.