Measurement of water current field created by paddle wheel aerators in shrimp culture pond

Abstract

Intensive cultures of shrimps produce more than 10 individuals per square meters with the use of hatchery reared post-larvae and the supply of compounded diets. The paddle wheel aerators are usually installed in the pond to supply oxygen and collect the sludge generated from the excretion of shrimps and the rest of the compounded food. The operation of paddlewheel aerators consume plenty of oil or electricity, therefore the strategy of installation density and arrangement of the paddle wheel aerators is quite important to save the energy and represent the best performance. The strategy is determined empirically, while several surveys were carried out to examine the performance of aeration. The purpose of the present study is to measure the water current field in the shrimp culture pond for obtaining the data to validate the numerical model. The measurement of water current field was carried out in the pond of culturing Penaeidshrimp. The water depth ranges between 0.6 m and 2.3 m depending on the area. Paddle wheel aerators with the power of 1 kW were installed at 8 points from the experience of local workers. Water current velocity was measured at the sampling rate of 16 Hz at every 14 m and 26 m in transverse and longitudinal directions, respectively (totally 44 points), and in several layers every 0.3m in the vertical direction. As a result, a general circulation was created successfully, while the current field just around the aerators was complex. Some small eddies were observed near the several aerators. The bottom stress was estimated by a simple equation and was compared with the distribution of the thickness of the sludge, which was obtained from the interview to local workers. The useful data were obtained to validate the numerical model which will potentially show the efficient operation and arrangement of paddle wheel aerators in any culture pond.