Design, fabrication and performance evaluation of a prototype backyard-scale airlift aquaponics system

Date

10-2010

Degree

Bachelor of Science in Agricultural Engineering

Major Course

Major in Land & Water Resources Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Aurelio A. Delos Reyes Jr.

Committee Member

Rosa B. Delos Reyes, Maurice A. Duka

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Abstract

The study aimed to develop a backyard-scale airlift aquaponics system. Red tilapia (Oreochromis mossambicus x Oreochromis niloticus) and lettuce (Lactuca sativa var. Lollo Rossa) were used as the culture species for the system. The 200-L culture tank was stocked with 75 red tilapia fingerlings with average initial weight of 2.83 ± 0.47g. The system had four hydroponic beds composed of two hybrid nutrient film-raft systems and two pebble bed systems which were randomly assigned. Each hydroponic bed were randomly planted with eight one-week old or three leaf stage lettuce seedlings using evenly distributed planting scheme with 20-cm row spacing. The system had four airlift pumps, supplied with air using a 75W Kawasaki air compressor. The air flow rate as well as the water flow rate were regulated and controlled using an air manifold. The performance of the system was evaluated in terms of water quality parameters (DO, pH, water temperature, TAN, nitrite, nitrate, TDS and EC) that directly affect fish growth. The obtained average values for DO, pH, TDS, EC and temperature were 6.49 ± 0.10 mg/L, 7.88 ± 0.10, 402.7 ± 21.9 ppm, 775.2 ± 22.9 μS, and 27.2 ± 0.2 °C respectively. TAN, nitrite nitrogen, nitrate nitrogen and phosphate were found to have an average value of 0.21±0.03 mg TAN/L, 0.23±0.08 mg NO2-N/L, 11.52±2.24 mg NO3- N/L, and 6.05±0.92 mg PO4/L, respectively. The obtained water quality values in the culture tank were within the allowable range for optimum growth of fish. Result showed an average weight of 31.62 ± 15.16 g for red tilapia grown in 90 days, with a survival rate of 93.33%, specific yield of 11.07 kg/m3

, SGR and FCR values of 2.6 % and 1.54,

respectively. The hydroponic beds were compared in terms of lettuce weight gain and removal rates of nutrients. Using a Randomized Block Design with Replication, there was a significant difference (P<0.05) between the two hydroponic subsystems in terms of lettuce weight gain, and cropping period was important as blocking variable. Removal rates of nutrients were compared using One Way: Single Factor ANOVA, which showed that there was a significant difference (P<0.05) between the two hydroponic subsystems in terms of removal rates of TAN, NO2-N, NO3-N, and percent reduction of apparent color, but no significant difference (P>0.05) in terms of removal rate of PO4. Based on the obtained results, the pebble bed system was far better than the hybrid nutrient film- raft system in terms of lettuce weight gain and nutrients removal.

Language

English

LC Subject

Aquaponics

Location

UPLB College of Engineering and Agro-Industrial Technology (CEAT)

Call Number

LG 993.5 2010 A2 G66

Document Type

Thesis

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