Energy-efficient Mechanical Aeration System in Aquaculture

Abstract

Mechanical aeration is by far the most common and effective means of increasing DO concentrations in ponds. Impeller aerators, paddle wheel aerators and propeller aerators are probably the main traditional mechanical aerators. Due to high efficiency, easy installation and slightly lower price, impeller aerator market share is more than 80% in China. But its working noise is relatively large. Biofan’s power is only tens of watts, but it can enable a wide range of pond water circulation. Through photosynthesis of aquatic plants, DO concentration in surface water increased rapidly on sunny days and it can make the whole pond water rich in oxygen. It’s far more efficient than other mechanical aerators on clear days. But it can’t play the role of emergency aeration, especially on rainy days or at night. Therefore, it must be used with other mechanical aerators. Six 0.4-ha ponds were stocked with high-density of 4 perches/m2. Each of them was equipped with automated DO concentration data acquisition devices. Three of them were each equipped with an impeller aerator. An impeller aerator and a Biofan were configured to rest every pond and these ponds water was aerated in multi-aeration mode. Impeller aerators(3kW) were automatically activated when DO fell to 4.5mg/l and ceased when DO rose to 5.5mg/l. Biofans were automatically ceased when impeller aerator worked and activated when impeller aerator stopped. Experiments found that the survival rate and yield of fish in single aeration mode were slightly lower than those in multi-aeration mode. Net income and yields per kWh increased significantly in multi-aeration mode.