Water is one of the most important elements needed by humans to survive and is also essential for the growth of plants and animals. Of the total water on Earth, only 0.014 percent can be used, and in fact, human life depends on this small amount of water. According to FAO Indicator 6.4.2, Iran is in a high-tension zone and based on the International Water Management Institute of the United Nations; this country is in a condition of severe crisis. Non-conventional water resources are a practical way to manage the water crisis. After treatment, this kind of water can be used in different sectors. The treated effluent can be used to provide a reliable source of urban water, environment, and industrial usage. One of the methods of wastewater treatment is biological treatment. This method uses biological processes in wastewater treatment that microorganisms play a significant role in the treatment process. They use their internal mechanisms to absorb the organic matter in the wastewater and use it to produce new cells and gain energy. The essential part of biological treatment is aeration. Aeration is a mechanical method of dissolving air in water. This is achieved by increasing the level of contact between the water and air. This study used the mechanism of hydraulic jump on weirs to aerate sewage and wastewater. Aeration in weirs depends on water temperature, water quality, tailwater depth, drop height, flow rate, and weirs type. This study used four triangular, rectangular, semicircular, and trapezoidal weirs to eva‎luate the aeration efficiency at different tailwater depths and discharges. In order to place the weirs, a rectangular channel with a length of 6 meters and a width of 50 cm was created and divided into four equal parts of 1.5 meters, which is 60 cm different in height from the next part. As the flow rate and tailwater depths increased, the efficiency increased to a point, then decreased and then stabilized. Also, with declining quality, aeration efficiency is reduced. Due to the distinguishing water drop height in the triangular weirs, the depth of water infiltration in the downstream channel and the highest aeration efficiency were detected. Aeration efficiency was recorded at 33% for wastewater and 20% for sewage. Among different types of weirs, the rectangular model had the lowest aeration efficiency with about 12.5%. Therefore, since practical wastewater treatment is not a single process, aeration using weirs and other treatment steps can be beneficial and economical

منوچهر حيدرپور

محمد شايان نژاد

سعيد اسلاميان، سعيد سلطاني كوپائي