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Significant factors affecting the economic sustainability of closed aquaponic systems. Part I: system design, chemo-physical parameters and general aspects
Autor: Palm, Harry W.; Seidemann, R.; Wehofsky, S; Knaus, U., 2014
In:
AACL Bioflux
Bandangabe: 7
Auflage: 1
ISBN: 1475-2697
Seite: 20 - 32
Jahr: 2014
Einordung:
Institut: Professur Aquakultur und Sea-Ranching
Abstract:
Abstract. Two identical closed ebb-flow substrate aquaponic systems for warm-water fish were tested
for their chemo-physical characteristics under the production of fish and plants in a freshwater
environment with an experimental increasing feed input. Each system contained 3.7 m3 water, and the
relationship of the water volume in the aquaculture tank to the settling basin (sedimenter), the biofilter
and the hydroponic units was 2.25:1:0.075:0.6 (fish tank:hydroponic unit = 3.75), with a daily water
input of 5.77% (±0.20) and a water removal rate of 1.37% (±0.04) per day. The experiment was
divided into three sub-experiments (49 days SE I, 56 days SE II, 55 days SE III), characterized by
increasing mean (24.85 g (±0.36)) and total (1,217.50 g (±17.68)) feed input levels in SE I, 131.12 g
(± 4.99) and 7,342.50 g (±279.31) in SE II, and 221.72 g (±8.78) and 11,751.00 g (±465.28) in SE III,
respectively. Sub-experiment I was the run-in phase, characterized by low nutrient loads, fish and plant
weights. This phase showed increasing values of oxygen, phosphate, salinity and conductivity. SE II was
the exponential phase, with increasing feed input, fish and plant weights, until a distinct drop in oxygen
levels occurred, and increasing conductivity, salinity and nutrient loads. SE III was the steady phase,
where the feed input of 200 g day-1 balanced the oxygen level, salinity, conductivity and nutrient load,
with a water input of 6.53% (±0.02) and a lower removal rate of 1.23% (±0.00) per day. Nile tilapia fry
(Oreochromis niloticus) of 0.50 g initial weight resulted in an individual fish weight gain of 60.93 g
(±28.95), a specific growth ratio (SGR) of 3.04% d-1 (±0.34), 24.25 kg of biomass weight gain and a
feed conversion ratio (FCR) of 0.83 in system I, and a non-significant weight gain (p < 0.05) of 51.29 g
(±16.20), an SGR of 2.98% d-1 (±0.21), 20.42 kg of biomass weight gain and an FCR of 0.93 in system
II. The overall yield of tomato biomass was 20.03 kg. In this communication, we describe our
experimental ebb-flow aquaponic system to demonstrate the influence of system design on the chemophysical
parameters, system stability, and fish and plant growth. The importance of other, as yet
untested, parameters that may influence economic sustainability, e.g. feed design, fish welfare, parasite
and pathogen control, fish physiology, fish/plant combinations and product quality, are discussed.
Key Words: aquaponics, ebb- and flow system, physical parameters, system design, Tilapia. Ansprechpartner Weitere Information im WWW
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Letzte Änderung des Eintrages:
01.02.2017
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