Water and Wastewater
Year:2005 | Volume:15 | Issue:4 (52)|Papers Count:13

In this paper snow-cover variation of a sub basin of Zayand-e-Rood watershed (Pelasjan) have been extracted and monitored using NOAA-AVHRR satellite images of 1371-72 and 1370-71. Snowmelt Runoff Model (SRM) was calibrated using the meteorological data and snow cover variation during year 1371-72. Results show that the difference between the simulated and observed annual volume runoff is 0.25% and the square of correlation coefficient (R2) between the simulated and observed daily runoff is 0.95. The calibrated SRM was verified using meteorological data and snow cover area variation of 1370-71. Results show that the difference between the simulated and observed annual volume runoff is 0.78%, and the square of correlation coefficient (R2) between the simulated and observed daily runoff is 0.92. The results of this research show that the SRM with RS and GIS can be appropriate tools for stream flow simulation and forecasting, especially, in the watersheds which most important factor in runoff is snow melting.

One of the factors impacting quality of water resources is pollution due to urban storm runoff during first stage of storm runoff and is commonly called "firsflush". At this stage the pollution load is rather high. However, if this pollution is properly controlled and managed, the size of the required treatment facilities will be considerably reduced. The surface runoff pollution in the city of Isfahan is high and necessitates the implementation of some control system. For this purpose, ten rainfall events were studied during fall and winter between 1999 and 2000. The data were gathered through grab sampling from Sio-se-pol bridge watershed. Statistical methods were used for analyzing data. The pollution load distribution vs. runoff volume was investigated.The results indicate that total solids (TS), suspended solids (SS), organic compounds and lead concentration exceeded discharge standards. TS, SS and organic compounds were more significant during the firstflush. SPSS (a statistical software package) analyses showed that there is a correlation between TS in the firstflush and runoff flow rate.Statistical analysis of the results indicated that rainfall depth and duration increase SS washoff during first stage of runoff. Also it was found SS washoff increases with increasing average discharge during firstflush.The results also indicated a correlation exists between the SS in the firstflush and the rainfall depth, event maximum intensity, average intensity, rainfall compounds and rainfall characteristics. Finally, an equation was suggested to predict pollution loading of runoff during firstflush.

Land application of sludge is a primary means of disposing municipal and industrial sewage sludge. The objectives of this research were to determine the effect of cumulative and residual sludge application on nitrogen (N) mineralization and nitrification and corn N uptake in a sludge amended clay loam soil (fine loamy, mixed thermic Typic Haplarigid). Soil samples from 0-15 cm depth were collected in a field that had received sewage sludge once, twice or three times during 1999-2001 at 0, 25, 50, and 100 mg ha-1. Rates of nitrification and N mineralization were determined in incubated soil samples. Corn N uptake was also measured. The results showed that sewage sludge application significantly increased soil organic carbon, N mineralization and nitrification. Also, corn yield and N-uptake increased significantly with sludge rates and number of times of sludge application. Regression analysis indicated significant correlations between soil organic C  and rate of nitrification (r= 0.825, P<0.001) and nitrification and corn N-uptake (r=0.856, P<0.001). The overall results of this study showed that (i) nitrification increased with sludge dosage and application rates and of times, and (ii) since there is a significant correlation between rate of nitrification and nitrogen uptake by corn, nitrification rate can be used as an index for soil test to quantify concentration of available nitrogen that can be used by corn.

Phenol and phenolic compounds are environmental pollutants that are found in industrial wastewater of oil refineries, coal tar, and chemical plants. Presences of these compounds in Isfahan steal plant have serious consequences for regional environment. Biodegradation is the best and economic method for refinement of phenol contaminated sites. In these research 15 phenol-degrading bacteria strains were isolated from different sites of Isfahan steal plant wastewater. Five dominant strains named as B3, C1, C4, C7 and D14 that had high capacity to eliminate phenol. Effects of different concentrations of phenol (100-900 mg/ml) on growth. Respiration and biofilm formation of 5 dominant strains were investigated. All strains grown well up to 500 mg/l of phenol concentration and eliminated it. Strains B3 had the most growth and biofilm formation on 300 mg/l.  The majority strains had the best respiration growth and biofilm formation in 400-500 mg/l of phenol concentration. At 24 hours incubation time up to 500 mg/l phenol of phenol was degraded and at 48 hours incubation time 900 mg/l of phenol was degraded. By using these strains it could be possible to reduce phenol pollutant in phenol refinement pools of the Isfahan steal plant.

As a consequence of eutrophication in lakes and coastal areas requirements for reduction of nitrogen and phosphorus from wastewater introduced in Sweden in early 1990s. To meet these requirements, many wastewater treatment plants have been upgraded for biological nitrogen and phosphorus removal. As a consequence of eutrophication in lakes and coastal areas requirements for reduction of nitrogen and phosphorus from wastewater introduced in Sweden in the early 1990s. To meet these requirements, many wastewater treatment plants have been upgraded for biological nitrogen and phosphorus removal. A small-scale hydroponics system has been designed in Stockholm for domestic wastewater treatment and also removal of nitrogen and phosphorus. The treatment plant is built for research purposes and presently treats 0.6 m3 of domestic wastewater from surrounding area per day. The system uses anoxic pre-denitrification followed by aerobic tanks for nitrification and plant growth. A microalgal step further reduces phosphorus, and a final sand filter polishes the water. In this study the treatment capacity of this system was evaluated with respect to removal of organic matter, phosphorus and nitrogen. 90% COD removal was observed in the system. Nitrification and denitrification were well performed with total nitrogen reduction of 72%. Phosphorus was removed by 47% in the process. However, higher phosphorus removal values are expected, as the microalgal step will be further developed. The results show that acceptable treatment can be achieved using this kind of system. Further optimization of the system will lead to clean water as valuable plants to be harvested from the nutrient rich wastewater.

The need for predictive water quality modeling has arisen largely as a result of increased eutrophication of lakes throughout the world. In 1919 Nauman introduced the concept of oligotrophy and eutrophy, distinguishing oligotorophic lakes with little panktonic algae and eutrophic lakes containing much phytoplankton. The phytoplankton consist of the assemblage of small plants having no or very limited powers of locomotion. A variety of formulations have been developed to represent the effect of temperature, light, and nutrient on phytoplankton growth. A number of processes contribute to the loss rate of phytoplankton. These processes are: respiration, excretion and predatory losses. The zooplankton includes animals suspended in water with limited power of locomotion. Phytoplankton as well as zooplankton are usually denser than water, and constantly sink by gravity to lower depths. System dynamics is a method of solving problems by computer simulation. The typical purpose of a system dynamics study is to understand how and why the dynamics of concern are generated and to search for managerial policies to improve the situation. In this paper phytoplankton and zooplankton are simulated by system dynamics approach. Then we integrated a limiting nutrient into our phytoplankton-zooplankton scheme to complete our fundamental picture of how nutrient/food-chain interactions are modeled.

History reveals that waterworks began thousands of years ago in ancient Iran. The main objective in operation and maintenance of an irrigation network is to increase the efficiency of the system. In this study , the performance of regulating structures of Doroodzan Irrigation Network (mainly slide and radial gates)were compared with those of Neyrpic module orifices, in Zayandeh-rood Irrigation Network. The comparison was based on perfomance and operation of each system. Based on the results obtained, the following recommendations are made: Performance of the structures becomes poorer with time due to the operation and maintenance of both systems. Department of Agriculture should be more involved in the management of the irrigation networks. Land consolidation is a key parameter in better performance of the systems. Government should stop subsidizing the water tariff for the farmers. Instead, the budget should be allocated for operation and maintenance purposes. This will help minimizing the water losses of the systems. Establishment of the independent irrigation and drainage cooperations run by the farmers. With an overall project efficiency of around 46%, about 20% of the total delivered water was distributed unreliably. Water distribution equity along tertiaries was also found to be poor. A contributing factor could be the poor operation and maintenance of gates.

Methyl Tertia Butyl Ether (MTBE) is an organic compound with widespread use in unleaded gasoline. Although use of MTBE had some environmental advantages, it was soon cleared that this compound has adverse effect on environment and human health. MTBE is highly soluble in water, it binds weakly to soil and doesn’t readily biodegrade in the environments. However it is known as a contaminant in environment specially for groundwater resources. Different methods have been introduced for treatment of MTBE from groundwater. These methods are generally expensive and inefficient. Phytoremediation introduce as an effective and inexpensive technology for removal of MTBE from groundwater and soil. In this paper the ability of Eucaliptus globules for removal of MTBE from water has been investigated. The Transpiration Stream Concentration Factor (TSCF) was used for evaluation of the ability of this plant. The calculated value for TSCF was 0.79 so it can be concluded that MTBE can be absorbed by this plant.

Generally any type of dam is considered as an integral part of the water management system, which is effective in the regulating of surface flows especially in areas with nonuniform spatial distribution of rainfall and temporal. Considering the worldwide, developing trend for dam construction, especially in Iran, the necessity of reviewing the environmental impact of dam construction thus becomes apparent. In this paper the general conditions of the area surrounding the Sardasth dam was reviewed and the environmental inventory was checked using simple checklists. Also the environmental impact of the dam during operation phase was assessed. Results of this study indicate that construction of Sardasht Dam would have positive environmental impacts, especially during operational phase. The environmental indices number obtained was +508.

Orumieh WTP was established based on nominal capacity of 18000 m3/d in 1962. By the last extension, its capacity was increased up to 30,000 m3/d. The raw water is transmitted from the sited intake on the Shahre Chaie River from the sited intake by gravity channel toward the WTP. The different units of treatment plant include manually coarse bar screen, grit chamber, accelerators, (5 units), gravity rapid sand filters (8 units), pressure rapid sand filters (7 units) and gas chlorination unit.One of the major problems of treatment plant is the disturbance of system in floating conditions, because of extreme increase in river turbidity. In such cases, sludge production increases extraordinarily and the influent of filter is a high turbid water that reduces the filter run time, So that the required water for filter backwash will be higher than total treated water production. It causes the plant shut downing and /or considerable reduction in plant reception. During 2003, 19 times the plant was stopped operation and 57 time it was operated in lower capacity that in spring 2004, the values were 6 and 18 days respectively. This problem causes lack of water and frequent water interruption in large areas of the city. For solving this problem, establishment a pretreatment unit is necessary. For this achievement, the potential of plain sedimentation in turbidity reduction was evaluated. Several samples were taken in floating conditions, and then they were analyzed by settling column.The results showed that in high turbidities, the efficiency of turbidity removal is 66.1% in 80 min and it is 79.74% in 90 min. for 75% TSS removal the SOR was 35 m3/ m2.day and retention time was 87 min. Using the factor 0.7 for SOR and 1.5 for retention time, an off-line sedimentation unit (65m×26m) was designed near intake site.