مجله آب و فاضلاب
پیاپی 44 (زمستان 1381)

The water quality of the Latiyan reservoir, which is supplying about 30% of Tehran’s water needs, has deteriorated because of extensive basin development and construction activities during recent years. The one-dimensional water quality model HEC-5Q was applied to this dam. The model was calibrated and validated against field data and shown to reproduce the observed thermal, oxygen and salinity stratification successfully. The result of this simulation indicates that there is a seasonal stratification in the Latiyan reservoir, which forms at the beginning of fall, and the turn over occurs at the end of winter. The changes of dissolved oxygen are between 1 and 12 mg/L. The critical situation considering dissolved oxygen occurs at the bottom of the reservoir by the end of summer. The changes of total dissolved solids are between 125 and 220 mg/L, affected mostly by leaching and turn over in the reservoir.

Zayandehrud is one of the largest river (270 km) in IRAN. It emerges from Dimeh spring continuing to Isfahan city and received to Gavkhoni wetland. Due to placed in semi-arried area and also plenty of consumption for agricultural, industrial and public services it reci ved considerable attention.Zayandehrud dam is costructed in 110 km of west Isfahan and consist of main dam, water power and adjustable dam. The aim of this study is to assess the environmental change due to instruction and operation of this dam.The method used for analysis is based on Wooten and Rau Matrix Method. In this method subactivities of Zayandehrud dam project are classified into two steps (instruction and operation) and effect of each one on the environmental parameters such as climate, soil, noise, water etc. were assessed.In this study the magnitude of an interaction was described by the asignment of anumerical value from one to three, with three representing a large magnitude and one a small magnitude. Depend on positive and negative effect the magnitude value was positive or negative respectively.Summation of the number of rows and columns designed as having interaction can offter insight into impact assessment and interpretation. Based to this methodology total value of +62 was obtained which indicate of positive effect of Zayandehrud dam on the envionment.

A hydrochemical analysis was made the groundwater and surface water in the Lenjanat district, which lies between Esfahan and Chadegan Dam along the Zayande Rud. The analysis is based on two data sets, both kindly made available by the ministry of energy (Esfahan Regional Water Organization). The first one consists of chemistry data for over 750 samples from wells, qanats and springs in the area. Collected from 1986-1997. The second comprises 328 analysis of Zayandeh Rud River water collected at six station along the river during the period 1991-1998.The evalution of the hydrochemical facies is described through the use of piper and stiff diagrams. While source rock deductions are made by means of the program WATEVAL. (Hounslo, 1995). Spatial distribution of the EC values in the district is determined through application of Kriging methods and examples are given for temporal chages in EC at a few representative locations.It is shown that the groundwater is of a limestone origin. However, because of frequent contacts with gypsum deposits, gypsum dissolution is strongly affecting the groundwater chemistry of most samples.Furthermore the analysis reveals that there is a natural groundwater flow from northward which seeps into the Zayandeh Rud eventually. The irrigation return flow component is added to this. Although both flow components are small, they carry a significanty higher solute load than the Zayandeh Rud in this strerch of the river. Thus causes the change in the chemical composition of the river as it flows through the lenjanat Distric.Finally it would appear that so- called mixing cell methods may be used to quantify natural groundwater seepage and irrigation return flow components, provided information is available with respect to their chemical composition. Groundwater flow and mass transport modelling would be of practical importance in the study of surface water-groundwater interaction along the Zayandeh Rud.

Nitrogen compounds have received special consideration among various and complex pollutants of wastewaters because of certain problems they cause after discharging into water resources. Nitrification and Ion exchange are two major methods for removing of nitrogen compounds. Combination of these two methods is implied in this research. In this study, the capacity of graded Clinoptilolite from Semnan supplied in three meshes of 20, 30 and 40 had been determined for ammonium removal in batch system. For the cultivation of nitrify bacteria a sludge sample taken from domestic wastewater treatment plant and the other required nutrients were added in the batch reactor and the effect of nitrate anion and MLVSS on nitrification process has also been determined. In the continuous of the study, biological regeneration of saturated zeolite with ammonium has been down by contact of zeolite and nitrifies bacteria in batch system.The results show the ammonium exchange capacity for the different mesh was 6.65 to 16mg ammonium per gram of ion exchanger as total capacity in batch system. According to the results obtained from nitrification test it could be concluded that nitrification is accelerated by increase in MLVSS concentration and concentration of nitrate remain in the range of 100 to 300 meq/l.The results obtain from bioregeneration tests by nitrifying bacteria show the efficiency of regeneration was 78 to 91 % in the period of 2 to 5.5 hours for batch wise operation.Thus the use of nitrifying bacteria in bioregeneration of zeolite is possible and in regard to high concentration of nitrate after regeneration, the use of nitrifying sludge in several cycles is possible.

Demand management is one of the efficient ways in water supply management for decreasing water consumption, protection, and taking care of the precious resources.Demand management includes two alternatives, hardware management, and software management. Software management is preferable because it is an efficient and cheap method. Correct pricing is one of the software management methods in the urban water supply.In this article, linear programming method for water pricing for Yazd is discussed. In the pricing model, attempt was model to consider various and real constraints and justice in order to acquire maximum benefit.In this study the percent price increase for all domestic classes and non-domestic classes in 1380 were suggested.In this suggestion we have considered five groups of different constraints and domestic, non-domestic consumption quantity and approved water price of Yazd in 1379.Increase of 5 percent is offered price for domestic class range of 5 to 10 m3.Increase of 5.3 percent is offered for the rest ranges.

In this research the effect of usual coagulants, alum and ferric chloride has been investigated on treatment of activated sludge effluent in Mazandaran wood and paper plant which uses neutral sulfite semi chemical (NSSC) pulping process. Performance of two coagulants in removal of pollutants from sulfite mill plant effluents were studied. The effect of different coagulants dosage on pH was investigated. The economical considerations and the operating parameters for two coagulants were compared.This study shows that ferric chloride caused the better results. This feature of ferric chloride supports the idea that the Fe is more amenable to hydrolysis than Al. Economic consideration show revealed by using ferric chloride instead of Alum in wood and paper industry, the chemical costs reduced significantly.

In this paper, methods and scientific fundamentals of the wellhead area delineation for the quality control of the drinking water resources in the cities, have been presented. At first, the available literature on criteria and methods of wellhead area calculation has been introduced. Then, the characteristics of each method has been evaluated by performing some calculations for drinking water well number 20 in Urmia City. At the end, the wellhead area of well number 20, along with the contaminant plume for a wastewater well near well number 20 were calculated using the computer code WHPA and the hydrogeologic data. The results of this study showed that if reliable hydrogeologic data are available, the semianalytical-numerical methods of the wellhead area delineation, have acceptable applicability for the users in the water industry.