نشریه علوم و مهندسی آب و فاضلاب
سال هشتم شماره 2 (تابستان 1402)

Analysis and control of water consumption in water supply and distribution networks is important issues, given the country's climatic conditions and the fact that they can be of great help to designers and managers of water resources. Copula functions are suitable tools for multivariate analysis that do not have the limitations of classical multivariate distribution functions. In this study, two and three variables of factors affecting water consumption prediction using the copula functions of the Archimedean family in zone one of Isfahan city were investigated. The results showed that based on the goodness-of-fit criteria and Q-Q plot diagram, Frank joint function between two variables of monthly water consumption and network pressure for this region was selected as the superior function with a model parameter of -2.02 and in the three variables Gamble joint function was selected with correlation parameters 1, 1.05 and 1 for all cases. Considering the best copula function, the conditional cumulative distribution functions of the two variables and the conjunctive, seasonal and conditional return periods were analyzed to predict water consumption, which can be determined according to the specified return period and the numbers obtained in used managerial planning and finally the three-variable analysis was not evaluated due to inadequate correlation.

Due to the importance of identifying low water consumption subscribers, in this study, using data mining methods, segmentation and identification of water subscribers based on the life cycle value and RFM model are discussed. First, the values of RFM model indices for Shiraz water subscribers were extracted from the subscribers' database and pre-processed. After weighting these three indicators using hierarchical analysis, subscribers were segmented using self-organizing neural network; Then the lifetime value pyramid was drawn to identify key subscribers and clusters of key and valuable subscribers were identified. The results show that the water supply index is the most important and the recent payment index is the least important in determining the value of subscribers and based on this, subscribers were divided into six clusters. According to the life cycle value pyramid, the most valuable subscribers are located in cluster 3, which are mainly residential, commercial and industrial uses, are mainly residents of Zone 2, most of these subscribers have paid their bills on time and their water's amount is mostly low. By identifying valuable and key subscribers, suggestions were made to improve the service to subscribers by considering their value.

In this paper, the removal of nitrates from urban raw sewage (Tehran) by walnut tree sawdust using the surface absorption method was introduced as an efficient green method, and the effect of various parameters was studied. The results obtained from Langmuir isotherms R2=0.9951 and Freundlich R2 = 0.9936 indicated better absorption in low concentrations, which follows the Langmuir model. To complete the present studies, the adsorption diagram, the effect of pH, thermodynamic and kinetic studies were investigated. Kinetic studies showed that the surface adsorption process of nitrate by walnut tree sawdust follows the pseudo-first order kinetic. The absorption capacity obtained from this equation was 34.2 mg/g (its experimental value of 32 mg/g). The results showed that this process is controlled by reversible physical adsorption. According to the FT-IR spectrum of the absorbent, the phenomenon of nitrate absorption takes place with the help of the cellulose structure of the absorbent. The use of walnut tree sawdust (micro size) without chemical modification as a natural, green, environmentally friendly, efficient, and effective adsorbent in removing nitrates from the raw sewage of Tehran city was one of the important features of this research.

Burst of the water pipe causes soil settlement, which can cause deformation in structures and trees, depending on the type of soil and weight of structures. Damages caused by this phenomenon in Iran are covered by fire building insurance. Fire station is under the supervision of the municipality of Tehran. The analysis of four-year data of urban water pipe burst in District 5 of Tehran has been done. This analysis helps to find places with burst to find a way to preserve trees after water pipes burst. In this research, the bursting of the water pipe, which has caused damage to the building, asphalt, etc., has been selected in the places where the data was available, and then the effect of the bursting of the water pipe on the trees has been investigated and analyzed. In these accidents, trees and utilities around the place where the water pipe burst were examined to eliminate the effects of wind or pests and sunlight, etc., that affect the trees, so that by comparing the pipe burst on them, the area of ​​the urban water pipe burst could have been managed to cause less damage to the trees and utilities.

This study was conducted on the feasibility of improving processes of thickening, anaerobic digestion, and sludge dewatering at wastewater treatment plants on a laboratory pilot scale, aiming to reduce polyelectrolyte consumption by 50% and replace it with chemical sludge. Parameters of Sludge Volume Index (SVI), Specific Filtration Resistance (SRF), compressibility coefficient, filtration rate, and biogas production rate were investigated. It is shown that by applying 200 mg/g of water treatment plant sludge to wastewater sludge, the compressibility coefficient was decreased by 27%, the filtration rate was increased by 70%, and SVI and SRF were decreased by 64.9% and 43.3%, respectively. Therefore, it has facilitated the sludge sedimentation and release of its free water. On the other hand, adding the sludge from a water treatment plant led to the proper access of microorganisms to micronutrients and improvement of their performance resulting in an increase of 7.77% in the total biogas production. The iron present in the digestion process caused an increase in biogas production by increasing the activity of enzymes, reducing oxidation-reduction potential, and improving the direct interspecies electrons transfer. In conclusion, adding the optimal amount of water treatment plant sludge, along with the environmental management of a meaningful portion of water and wastewater residuals, may play an important role in significantly reducing polyelectrolyte consumption and improving biogas production.

Water scarcity is one of the most important distinguishing features that development theorists have paid attention to in explaining the characteristics of eastern societies in the social transition. This attitude has led to the presentation of theories such as the Asiatic mode of production, Oriental Despotism, and Iranian Despotism, each of which, considering some characteristics of the society, has tried to explain the relationship between the development of the East and its connection with water, but they have not been able to. This study, by using the qualitative research method and historical studies, reviewing the documents, observation, and interviews with farmers, policymakers, and people living in the Zayandeh-Rud basin area, has tried to get an accurate picture of the connection between water and development of this region in Iran. The results obtained in this research show that the problem of water scarcity in Iran has caused the formation of a system that arises from the two arms of political legitimacy and social acceptability with the processes of appointment and selection, and the development of Iranian society depends on the balance of The powers of these two parts. if the balance disturbed, the society moves towards political despotism or social revolution.