Optimization of rectangular secondary sedimentation tanks inlet (Case study: Tehran Wastewater Treatment Plant)
Subject Areas : Environment Pullotion (water and wastewater)
Akbar Akbarpour
1
,
Alireza Mardookhpour
2
1 - M.Sc. of Civil Engineering Department, Lahijan Branch, Islamic Azad Univeristy, Lahijan, Iran.
2 - Assistant Professor of Civil Engineering Department, Lahijan Branch, Islamic Azad Univeristy, Lahijan, Iran.*(Corresponding Author)
Keywords: sedimentation tank, turbulence energy, Velocity, solids, Optimization,
Abstract :
Background and Objective: One of the most important parts of treatment plants is the sedimentation tanks in them, which play an important role in wastewater treatment. Due to this issue, a correct understanding of the behavior of sediment reservoirs is essential for the design and operation of reservoirs. Therefore, it is not far-fetched that engineers are thinking of designing new tanks as best as possible and improving their efficiency. In order to achieve these goals, various methods have been proposed, among which improving the efficiency of reservoirs by changing the geometry in the reservoir is not only important but also an economic method and attracts the opinion of engineers from different aspects. Has attracted.Material and Methodology: The studied model has been removed from the existing wastewater treatment plant in Tehran. In the basic paper, different inputs of flow to the sedimentation pond are analyzed and by comparing the efficiency of different inputs, a specific input is presented as a suggestion. In the present study, the same inlet and reservoir will be used and by adding the sediment parameter as a new parameter, the hydraulic and flow and sedimentation characteristics in the said reservoir will be determined. It is 13 meters wide and 4/4 high. In order to observe the distribution of suspended solids during the settling process, the water in the reservoir at the beginning of the process is free of sediment (clear) and then with the entry of wastewater containing suspended solids, the method of releasing suspended solids and then settling of solids can be Observed in full.Findings: In the model at the entry points, distances of 10, 20 and ... to 60 (output overflow) by creating virtual sensors, flow parameters were used to produce and analyze comparative graphs. The findings indicate that time The analysis is in accordance with the residence time of the regulation is 6500 seconds, which in the range of about 800 to 1000 seconds of analysis (16 minutes) the flow and movement conditions of sediments are balanced and is constant until the end of the residence timeDiscussion and Conclusion: The results show that the contour particles of sediment particles in the reservoir are at times 50, 300, 500 and 1000, respectively. After 1000 seconds to 6500 seconds, the situation is completely stabilized and there is no change in the contours compared to 1000 seconds. On the other hand, the amount of suspended solids in wastewater decreases by moving downstream and reaches zero within 10 meters of the end, which indicates the complete removal of suspended solids in the sedimentation process. The results also show that the most turbulent energy is at the outlet at a distance of 10 meters from the inlet, which is due to the eddy current and rotation in this area. By moving downstream, the turbulence current decreases and at a point 10 meters from the outlet is close to zero, which indicates the correct operation of the tank.
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