Studies on the Relationship Between the Emission of Sludge and Flow Fields in Aquaculture Pond
Date Issued
2011
Date
2011
Author(s)
Liao, Yung-Li
Abstract
ABSTRACT
When the owners of aquaculture pond use various kinds of aerators to aerate the water, they encounter the difficulties in the management of sludge. By comparing the eel ponds experiments in Chiayi and Yilan, the sediment accumulation rate and hypothetical flow fields are confirmed with using the simulations of computational fluid dynamics (CFD). The framework of different positions of aerators and the hypothetical flow fields are built based on the experiments of trapped contaminated solids.
Advices are able to be given by knowing the sludge sediment area and the particle concentration flux. There are six aperture ratio models in different amounts and quantities of orifices of negative pressure discharge pipes that are designed for the eel ponds of Yilan. We discuss the differences in flow fields nearby the orifices, and then analyze the amount of water flow whether corresponds to the suggestion of negative pressure sewage.
The results have suggested that changing the feeding settling if the feeding sites are in low velocity area, in order to avoid it turns into sludge settling. The velocity under 60cm and from the water surface in Chiayi eel pond is less than 0.17m /s. The bottom velocity is less than 0.14 m/s. In front of the paddlewheels is the highest velocity and then decreases gradually and vice versa.
The aperture ratio of the negative pressure discharge pipes is better to be smaller. According to the investigation, the maximum velocity is 2.5 times difference between the aperture ratio being 0.38 and 3.04. The velocity of model which is reduced its orifices from ten to six is close to the model of aperture ratio being 1.74 from aperture ratio being 3.04 to 1.82. It is clear that the aperture ratio is the main factor to affect the velocity. The distance from the outflow department and velocity correlation in the model of aperture ratio is 0.62 R2 is 0.994 which brings out the conclusion that the velocity around the discharge pipes and the distance from the outflow department are in negative correlation. The amount of water flow of the negative pressure discharge pipes in Yilan is 105.1 gpm(gallons per minute) meets the suggestion that IDEQ(1998) proposed to be 100gpm. According to the achievement of this study, we can continue to investigate the experiments of collecting contaminated solids and discuss the efficiency of sewage.
Subjects
Aquaculture pond
Aeration
Waste disposing
Sediment
Computational fluid dynamics
SDGs
Type
thesis
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