Experimental study on sewage collection and related performance of square arc angle aquaculture tank

Abstract

In order to study the in uence of the diameter to depth ratio of the square arc angle aquaculture tank on the ow eld and sewage discharge characteristics in the aquaculture tank, a reduced physical model test system of the aquaculture tank with single-drain sewage discharge structure was established based on the actual size of the recirculating aquaculture tank. Under the conditions of different positions of the inlet pipe (single inlet pipe set at arc wall, double pipe set at opposite arc wall), the number of daily water cycle times (40 times, 60 times), the in ow angle (0°, 45°) and other parameters, the in uence of the variation of diameter to depth ratios (2:1~7:1) (that is, the ratio of the length of the tank to the depth of water) on the ow eld characteristics and sewage discharge effect was systematically analyzed. The results show that the appropriate diameter to depth ratio is the key to improve the sewage discharge e ciency in the tanks. The smaller the diameter to depth ratio is, the higher the sewage discharge e ciency is. When the diameter to depth ratios of the tanks with square arc angle are 2:1~3:1, the sewage discharge e ciency is good. When the diameter to depth ratio are 3.5:1~4.5:1, the sewage discharge effect is better. When the diameter to depth ratio are 5:1~7:1, the sewage discharge effect is weakened greatly. The self-puri cation capacity of aquaculture tanks and the discharge e ciency of sewage can be improved by choosing the proper diameter to depth ratio, increasing the daily water cycle times times and adjusting the placement of inlet pipes and in ow angle according to the actual needs. The the ow eld characteristics in the aquaculture tank are closely related to the distribution and discharge e ciency of sewage. The high uniformity of the ow velocity is conducive to the accumulation of sewage. And the higher the ow velocity is, the higher the discharge e ciency is. The research results can provide theoretical basis and reference for the optimal design of diameter to depth ratio of square arc angle aquaculture tank.