Date of Award

7-2014

Document Type

Thesis - Open Access

Degree Name

Master of Science in Mechanical Engineering

Department

Mechanical Engineering

Committee Chair

Peter B. Merkle, Ph.D.

First Committee Member

Mark Fugler, Ph.D.

Second Committee Member

Marc Compere, Ph.D

Abstract

An airlift device providing aeration and circulation was designed to reduce electrical power requirements for aquaponics by eliminating the need for a water pump. The airlift performed better than predicted and achieved water flow rates of 10 L/min at 25 °C, in comparison to the theoretical design performance 2.65 L/min.

Koi (Cyprinus carpio) and sweet basil (Ocimum basilicum) were cultured for five weeks in two identical aquaponics systems. The system was located indoors and consisted of a fish tank, a sump tank, and a soil-free growth media bed under artificial lighting. The total water volume in each system was 230 liters.

Test conditions of intermittent vs. continuous aeration and recirculation were studied and growth rates of plants and fish were measured. Four week-long tests of intermittent aeration and circulation (50% on/50% off) showed net total bed growth rates per 1 KWh per day of 99.4%, while the continuous operated bed showed 50.3% growth per 1 KWh for the same period. The intermittently operated system showed 44.1% more growth for the same energy consumption. This suggests electrical power requirements for aquaponics aeration and recirculation may be reduced by as much as 75% with the use of an intermittent aeration and recirculation through an airlift. This suggests that intermittent airlift technology may be useful for reducing energy costs, and increasing the feasibility of using renewable power in commercial aquaponics farms.

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