Water and Wastewater
Year:2004 | Volume:15 | Issue:1 (49) |Papers Count:12

The amount of petroleum pollutant in soil of Persian Gulf coast at 8 selected stations were determined and showed the concentration between 14.3-143.6 mg/kg.  Nickel has the highest concentration level of heavy metal with 58.6 mg/kg in Emam Hassan area at 50 kilometers of west Boushehr port. Bioremediation of contaminated soil were studied in two medium in slurry and solid state fermentation and 8 bacteria types were isolated. Four species: EM2, SH, GN1 and GN3 presented optimal PAH removal efficiency. Biodegradation efficiency under slurry condition was found after 45 days which during this period, naphthalene and phenanthrene showed 73% and 66% removal efficiency respectively. Under solid state conditions, microbial activity of mixed and pure culture was studied. The results presented that mixed culture due to high ability of different strains for growth, showed higher degradability compared to pure culture, but due to insufficient mixing under solid state condition, mass transfer velocity of nutrient reduces to the level that caused reduction in cell activity, so removal efficiency under slurry condition was found higher than solid state respectively.

In this study, an artificial neural networks (ANN) model was used to optimize the results obtained from a hydrodynamic model of river flow was evaluated. The study area is Reynolds Creek experimental watershed in southwest Idaho, USA. A hydrodynamic model was constructed to predict flow at the outlet using time series data from upstream gauging sites as boundary conditions. In the second stage, the model was replaced with an ANN model bout with the same inputs. Finally a hybrid model was employed in which the error of the hydrodynamic model is predicted using an ANN model to optimize the outputs. Simulation were carried out for two different conditions (with and without data from a recently suspended gauging site) to evaluate the effect of this suspension in hydrodynamic, ANN and the combined model. Using ANN in this way the error produced by the hydrodynamic model is predicted and thereby, the results of the model are improved.

The increasing expansion of resential areas and urbanization together with industrial and agricultural development in Iran has made it possible to destroy the ecological system of the natural society remarkably. The watershed of Latina Dam, as one of the sources to supply the drinking water of Tehran is of specific geographical and climatic important, and because it is adjutant to Tehran, it has experienced considerable change in population and residential expansion. In this research, we have tried to focus on the changes of the quality of water in the Jajrood River, by surveying the population growth of this area, in recent years. Considering the results of this research the number of tourist have also increased remarkably in the last few years and the quality of water has also been changed because of the increasing number of tourist in the region. Therefore, without regarding the ecological, hygienically and controlling necessities in this area, there may be dangerous conditions and consequences forced upon one of the important drinking water sources of Tehran in the near future.

Wastewater sludge is categorized as hazardous waste material which must be stabilized and treated before disposal and reuse. Final disposal of sludge from treatment facilities usually involves some form of land disposal. However, sludge contains different type of pathogens and heavy metals which can causes pollution of surface and ground waters, soils and spread diseases if there is human exposure to the sludge. In this respect, U.S.EPA presented requirements for using and disposing of sludge.Thus, taking into account the potential risks caused by presence of heavy metals in sludge and for the control of processes of sludge treatment and disposal and also protect of environmental health and enhancement of public health level, specially for farmers and consumers of raw crops, needs sampling and characterization of sludge. In the present research concentration of 11 heavy metals and potentially toxic elements in dried sludge of Isfahan South and North and Shahinshahr wastewater treatment plants were determined using standard methods. Samples have been taken from dried sludge of treatment plants, and been measured after being prepared through atomic absorption apparatus and were compared with EPA enacted standards in regulation 40 CFR part 503. As well, fertilizer value parameters of sludge were measured and were compared with standards and guidelines. The results showed that the average concentration of above elements in all three treatment plants, not exceeded from EPA standards, however, regarding the accumulative property of these elements and lack of necessary protective effects of EPA standards, in using these sludges in the agricultural soils, the necessary caution and care should be taken, in other uses of sludges, however, there is no limitation.

Considering the problem of water shortage in Iran specially in arias such as yazd province that is located in the center of the country, wastewater reuse is one of the most important successful methods to overcome the problem of water shortage. In order to supply water for irrigation and to control the environmental pollution in the Shohada-e-Kargar hospital, the wastewater treated and then reused for irrigation of trees and green fields by using the extended aeration activated sludge system. According to this research, the average of wastewater effluent is approximately 250 m3/day. In this study pH and the content of BOD5, COD, TSS, and MPN in raw wastewater was 7.2, 330 mg/l, 460 mg/l, 280 mg/l and 4.1×108/100 ml respectively. The same parameters in the effluent were found 7.6, 45 mg/l, 75mg/l, 60mg/l and 3.5×104/100ml respectively. The efficiency of this system for removal of BOD5, COD, TSS, MPN was 86.4%, 83.7%, 78.6%, 99.15% respectively. With respect to the water quality standards prepared by Iranian Environmental Protection Organization, the quality of this effluent is considered to be suitable for agriculture except for MPN which is decrease by increasing the detention time during chlorination. The important parameters of water quality such as EC, SAR, Na% in the effluent were 420 µs/ml, 2.5, 37.5 respectively and the quality of this effluent is classified as acceptable for irrigation.

The study of dam's break needs the definition of various parameters such as the break cause, its type, its dimension and the duration of breach development. The precise forecast for different aspects of the breach is one of the most important factors for analyzing it in embankment dam. The characteristics of the breach and determination of their vulnerability has the most effect on the waves resulting from dam break. Investigating, about the parameters of the breach in "Silveh" earth dam have been determined using the suitable model. In Silve dam a trapezoid breach with side slope z=0.01m and the average base line b=80m was computed. The duration of the breaches development is 1.9 hour. Regarding the above results and the application of DAM Break software the consequences of the probable break of the dam was determined. The analysis of the results of water covering of the city of Piranshahr located 12km from silve dam confirms that in 3 hours the water will reach the height (level) of 1425 meters.

The main sources of wastewater in Iran are divided in three sections: domestic, large polluting industries and industrial estate effluents. Out of 3.9 million cubic meters of municipal wastewater, only 9% is treated in 75 wastewater treatment plants (until April 2004) and the rest (91%) is discharged directly to the sewage wells, rivers, lakes and sea, and agricultural lands without any proper treatment. The amount of industrial wastewater, from main polluting industries, is estimated over 91 million cubic meters from which only 31% treated poorly. The situation in industrial estates is the same; only 10 industrial estates have recently equipped with proper wastewater treatment plants and another 15 are under construction. The rest (over 200) are get without any treatment facilities. The total BOD loads of existing wastewater treatment plants are about 30,000 ton/yr. 76% of this load is treated by aerobic systems and 24% by anaerobic aerobic combination. Over 7 billion dollars capital investments are needed for wastewater collection and treatment facilities for the rest of towns. Having done so, apart from pollution prevention of water resources, about 500,000 hectars of agricultural land will be irrigated by treated effluents. As concluding remarks, the role of government and existing challenges are discussed and some suggestions are given.

Fluoride is one of the important elements. There are so many controversial scientific points of view regarding fluoride and its presence in food chain. Water fluoridation is the best and most reliable method for the control of dental caries. In this research, the presence and concentration of fluoride in drinking water resources in the city of Damghan and DMF index (decayed, missed, filled) between 560 school students (12-15) was investigated. The mean concentration of fluoride in water supplies of Damaghan city was measured in low rain seasons 0.37 mg/l and high rain seasons 0.6 mg/l the DMF index for 12 years old student was equal 2.00 that comparing these data with the WHO classify cation for DMF index, showed them to be considered in the second surface (low) classification. For conclusion, based on the mentioned data, a significant correlation may be found between the two parameters in different communities, and the most logic solution for the control of dental cavities in these communities, is the adjustment of fluoride concentration in drinking water.

Drought and flood phenomena, including frequency, rate and persistency are one of the current important problems in Iran and many other countries. In addition to lack of rainfall, improper distribution of it, leads to destructive floods. On the other hand causes the interval droughts and water scarcity which in turne makes different socio- economic and environmental problems. Awareness of these challenges is useful for governmental making policy. According to the present paper, combination of two programs, the basic measures and the non active measures (crises management) in a single national and global measure will be more effective for reducing the different hazards involved in flood and droughtness situation.