Development of a Recirculating Flood and Drain Aquaponic System Using Palm Kernel Shells as Growth and Biofiltration Media

Abstract

A less complex, flood and drain Recirculatory Aquaponic System (RAPS) was developed. The growth medium for the system was palm kernel shells instead of the more commonly used materials like gravel, quartz and pebble balls. This paper reports the development considerations, materials used and the effectiveness of the system, based on water analysis, fish growth rate and plant growth rate. The system consists mainly the culture tank, media bed, 0.5hp pump, twin timer and storage tank. These components were developed based on specific parameters which include: capacity of culture tank, stocking density, fish biomass, daily feed need, area of media bed, hydraulic loading rate, hydraulic retention time and bulk density of the growth medium (PKS). The system was operated for 6 hours (11am-5pm) daily between the periods of 45 days under controlled condition. A total of 40 African catfish (Clarias gariepinus) of average initial weight of 148 g were stocked in two culture tanks (20 fish in each tank) at 15 kg/m³ density. Twelve days old healthy Amaranthus cruentus seedlings were transplanted to the grow bed after stocking of the fish. The efficacy of the system was determined based on quality of treated water compared with WHO standard for aquatic life. The average gained in weight per fish was 109.83 g and average feed consumed was 188.26g throughout the experiment, an average FCR of 1.71. For the control tank, the corresponding values were 103.8 g, 187.43 g, and 1.81; respectively. The survival rates of fish in the aquaponic system and control tank were 100% and 95%, respectively. A higher plant growth rate was observed in the aquaponic system (1.06 cm/day) than in traditional method (1.01 cm/day).