نشریه علوم و مهندسی آب و فاضلاب
سال هفتم شماره 1 (بهار 1401)

Combined structure of weir and gate due to the simultaneous flow of suspended material from on the overflow and material deposited in the flow of water from the valve section, provides better conditions compared to other structures used to measure the discharge in the channels. Nowadays, numerical solution methods without the need of laboratory equipment and the ability to calculate the desired parameters, with low time and cost is considered as one of the efficient methods of flow analysis. In this research, by using CFD and numerical solution method with FLOW-3D software for different diameters of combined structure of weir and gate was simulated. Flow simulation was performed in a channel with 3 mm length, 0.4 mm width and 0.5 mm height. The models were studied in cylindrical diameter of 5, 7.5, 10 and 12.5 cm, and for openings gates of 1, 2 and 3 cm. The flow was also simulated and studied for all models at 4 discharges of 12, 16, 20 and 22 lit/s. Comparing the discharge coefficient results with the dimensionless parameter of water depth upstream to water depth downstream of the overflow-valve combined model, it was observed that the numerical results obtained using the RNG turbulence model provide closer data to laboratory results. In the validation stage of numerical results with laboratory outputs of previous researches, the error percentage of the simulated model was calculated to be less than 5%, which indicates the acceptable accuracy of numerical modeling. The results showed that with increasing the flow, when the diameter and opening of the valve are fixed, the flow coefficient increases. At a constant diameter of the overflow-valve model, the flow coefficient decreases in exchange for increasing the valve opening. For a constant flow rate and diameter, changes in flow rate decrease with increasing valve opening height. It was also observed that the curvature of the flow surface profile increases with increasing diameter of the cylindrical model.

Water is one of the most important components of sustainable life. However, the excessive use of this vital element has caused irreparable damage to the limited water resources, and the agricultural industry assumed as the largest amount of consumed water. In recent years, the significant reduction of water resources as well as the growing trend of drought necessitates a review and change in the agricultural induster. In this research the water requirement of agricultural plants of Mazandaran province including rice, wheat, barley and citrus is estimated in order to investigate the volume of green and blue virtual water, exported and imported water by these crops across the province. Meteorological data such as rainfall, maximum and minimum temperature, relative humidity, sundial of the area and information such as cultivation area, crops yield rate, exported and imported water volume collected from relevant agencies over the last ten years. FAO Penman-Monteith and USDA methods in CROPWAT software used to estimate virtual water and water needs. Results showed that rice, wheat, barley and citrus consumption accounted for the largest water requirement. Also, rice water requirement is blue water and wheat, barley and citrus plants consume green water sources which is not relocated and is not suitable for other purposes or storage. Consequently, due to the climatic potential of Mazandaran province, the pattern of cultivation alter to plants with low water requirements that are able to absorb their required water from green water sources, such as wheat, barley and citrus as well as lower plant area with abundant water requirement such as rice can save more water resources and the water crisis could be effectively in control.

One of the most important issues that has been considered by many researchers in recent years is the study of the phenomenon of land subsidence. The purpose of studying subsidence is to examine the risks and consequences that can result from it over many years. In their research, most researchers considered the occurrence of earthquakes and excessive abstraction of groundwater aquifers due to the drilling of a large number of illegal wells as the most important causes of subsidence. The aim of this study was to obtain a statistical relationship between groundwater level changes and the rate of vertical movement of the earth's surface using linear regression and grade 3 models and using InSAR radar interferometry technique in Varamin plain between 2014 and 2019. Most of the surface of Varamin plain is covered by agricultural lands and therefore it can be said that the uncontrolled abstraction of groundwater is considered as the main cause of vertical movements of the earth. In order to analyze the subsidence that occurred in this plain, Snap software was used and by applying the desired filters to eliminate the noise in the initial images, surface displacement maps were obtained in Varamin plain. The images used for the surface of the earth from 2014 to 2019 were obtained by Sentinel-1 satellite SAR sensor as ascending, and finally, by comparing the obtained statistical models from the fluctuation of the aquifer and the ground, it was found that the linear regression model has a better predictive power than the 3rd degree regression model.

Pollution of environment with heavy metals and its transfer to products is a global problem. The aim was to measure heavy metals in the effluent of Gorgan wastewater treatment plant which with 32 effluent samples of Gorgan wastewater treatment plant were sampled during 6 months in 2016 and concentration of lead, cadmium by polarograph and atomic absorption was assessed. Risk of carcinogenicity and non-carcinogenicity was calculated in three cases: minimum, moderate and maximum. Average concentration of lead in the effluent was 0.003943547 mg/L, which is value for cadmium measured 0.000143571 mg/L.The concentrations of heavy metals in wastewater effluent and dried sludge, except in returned sludge, were below the standards. Due to long-term use of effluents, necessity of treatment of other parameters, and effect of bioaccumulation of metals in sludge, caution should be taken for their agricultural application. Because of importance of this type of contaminants in soil and food products, continuous monitoring by water companies is highly necessary.In mean state, for every one hundred million people, 7.21 people, in max mode, for every ten million people, 1.13 people and in the case of min, for every one hundred million people, 2.82 people are at risk of cancer.

Increasing urbanization and industrialization of cities have led to an increase in pollutants and the production of many toxic elements. One of these pollutants is arsenic, which is known as one of the most toxic and dangerous elements in drinking water. The aim of this study was to investigate the method of minimizing the amount of this toxic substance by coagulation and flocculation in drinking water. In order to determine the optimal conditions for arsenic removal by coagulation and flocculation methods, in the first stage, the optimal pH was determined by Jar experiment, then by selecting ferric chloride as a coagulant and lime as coagulant and also the optimal pH. The optimal amount of chemical is obtained, at the end, the residual concentration of arsenic is determined by atomic hydride absorption spectroscopy. According to the concentration of arsenic in the incoming water sample which is equal to 91 micrograms per liter The jar test was performed in two stages with chloroform coagulants, which according to the optimal pH obtained in different concentrations of coagulants and also a constant concentration of coagulants, the arsenic removal efficiency in the best case in chlorofricter coagulants. It reached 98.3%, which is equal to 1.5 micrograms per liter, which according to the standard of the WHO (2011), 10 micrograms per liter had an acceptable result. The result of this study indicates that the coagulation and flocculation method with chloride-chloride coagulant and a constant amount of lime as a coagulant has high efficiency in arsenic removal.

Global water shortages and droughts, on the one hand, and population growth, dispersion of water and sewage facilities, and the growing need for drinking water, on the other hand, highlight the need for an efficient management of drinking water supply and distribution. Electro pumps, which are a kind of power system in the water industry, have a major role in extracting water as well as pumping and transferring it from one reservoir to another. One of the major challenges in this system is the protection of electro pumps against the overcurrent. The protection of electro pumps is traditionally based on the use of bimetallic relays, load control or overcurrent relays. However, in some cases, the malfunction of relays, the end of their useful life and their deviation from the specified current range result in the lack of a reliable and fast protection, which will eventually lead to burnout and social problems. On the other hand, the use of SCADA system has been considered as an undeniable necessity in the water industry to provide a safe and continuous supply of urban and rural drinking water, as well as its optimal distribution in terms of quality and quantity. Therefore, in this paper a SCADA-based method is proposed to protect surface/submersible electro pumps against the overcurrent and other faults. Examination of the practical results obtained from the implementation of the proposed method in Chaharmahal and Bakhtiari Water and Wastewater Company shows that the proposed protection method can significantly stop deviation of water industry electro pumps from the drinking water extraction cycle, and thus prevent social problems and dissatisfactions resulted from the cutting off the water.