Development of a solar updraft aeration system for pond aquaculture in resource-constrained environments

Abstract

Aquaculture is a major driver of economic growth in rural Southeast Asia where many families rely on small-scale fish ponds to supplement their livelihoods. However, due to lack of aeration and other advanced aquaculture technologies, yields in those rural ponds have been low. Aeration systems are typically not employed due to lack of access to reliable electricity, as well as prohibitive capital, operating, and maintenance costs. In this paper, we describe a design concept for an innovative, low-cost, solar-thermal aeration system that is appropriate for pond aquaculture in resource-constrained, rural settings. The Solar Updraft Aeration (SUpA) system consists of a solar collector and an externally-insulated draft tube, which conduct heat to the oxygen-depleted deeper layers of the pond. This induces convective circulation, which mixes oxygen generated naturally by phytoplankton in the epilimnion throughout the pond depth, while preventing oxygen losses to the atmosphere due to supersaturation at the pond surface. The result is an increase in the overall oxygen content of the pond, which improves the health of the fish and allows for greater pond productivity. This paper presents the preliminary models developed for concept evaluation. These models describe the oxygen generation and consumption within the aquaculture pond and evaluate the convective water circulation using computational fluid dynamics (CFD). In the next design phase, the results from these models will be used to tailor a prototype system for field testing in Vietnam.