Effects of aerated and non-aerated biofilters on effluent water treatment from a small-scale recirculating aquaculture system for Nile tilapia (Oreochromis niloticus L.)

Water quality parameters in the sump (fish tanks outlet/biofilter inlet) and aerated and non-aerated biofilter outlets. Mean values (± standard deviations) within a row with different superscripts are significantly different (a > b > c, p < 0.05).

Tabelle 1. Wasserparameter im Sammelbehälter (Übergangsbereich vom Fischtanks zum Biofilter) sowie jeweils am Ende der aeroben und anaeroben Biofilterkette. Mittelwerte (± Standardabweichung) innerhalb einer Zeile mit unterschiedlichen Hochzahlen unterscheiden sich statistisch signifikant (a > b > c, p < 0,05).

Parameters	Units	Sump	Aerated biofilters	Non-aerated biofilters
Temperature	[°C]	25.18 ± 1.48^a	25.37 ± 1.70^a	25.50 ± 1.92^a
pH		7.81 ± 0.11^b	7.78 ± 0.09^b	7.70 ± 0.09^a
Dissolved oxygen	[mg L⁻¹]	2.89 ± 0.41^c	2.11 ± 0.77^b	1.45 ± 0.39^a
Alkalinity	[mg L⁻¹]	242.69 ± 32.83^a	216.79 ± 46.93^a	234.23 ± 56.13^a
Ammonia	[mg NH₃-N L⁻¹]	3.41 ± 0.39^b	1.96 ± 0.60^a	1.95 ± 0.65^a
Nitrates	[mg NO₃-N L⁻¹]	2.49 ± 0.60^b	3.16 ± 0.74^c	1.47 ± 0.89^a
Nitrites	[mg NO₂-N L⁻¹]	0.36 ± 0.16^a	0.55 ± 0.15^a	0.18 ± 0.07^a
Phosphorus	[mg L⁻¹]	2.14 ± 1.15^b	1.71 ± 1.25^ab	1.22 ± 0.78^a

Table 2

Water quality parameters in the fish tanks (Mean ± standard deviation)

Tabelle 2. Wasserparameter in den Fischtanks (Mittelwerte ± Standardabweichung)

Parameters	Units	RAS_1	RAS_2
Temperature	[°C]	26.25 ± 2.72^a	26. 23 ± 2.67^a
pH		7.71 ± 0.19^a	7.72 ± 0.16^a
Dissolved oxygen	[mg L⁻¹]	2.37 ± 0.76^a	2.54 ± 0.79^a
Alkalinity	[mg L⁻¹]	226. 28 ± 36.70^a	223. 68 ± 38.48^a
Ammonia	[mg NH³-N L⁻¹]	2.43 ± 0.87^a	2.58 ± 0.76^a
Nitrate	[mg NO³-N L⁻¹]	2.92 ± 1.63^a	2.76 ± 1.54^a
Nitrite	[mg NO²-N L⁻¹]	0.26 ± 0.18^a	0.24 ± 0.08^a
Phosphorus	[mg L⁻¹]	1.48 ± 1.08^a	1.57 ± 1.06^a

Ammonia (NH₃-N), nitrates (NO₃-N), nitrites (NO₂-N) and P (phosphorus) concentrations in the aerated and non-aerated biofilters. Error bars show standard deviations (n = 3).
Abbildung 2. Konzentrationen von Ammoniak (NH₃-N), Nitrat (NO₃-N), Nitrit (NO₂-N) und Phosphor (P) in den aeroben und anaeroben Biofiltern. Die Fehlerbalken stellen die Standardabweichungen dar (n = 3).

Boxplot showing nutrient removal efficiencies in aerated and non-aerated biofilters. Median values are shown in each box, vertical bars correspond to maximum and minimum values. Different letters (a, b) above boxplots indicate significant differences between the two types of biofilters (Student t-test) (p < 0.05).
Abbildung 3. Boxplotdarstellung der Nährstoffreduktion in den aeroben und anaeroben Biofiltern. Unterschiedliche Buchstaben bei den jeweiligen Box-plots zeigen signifikante Unterschiede zwischen den beiden Filtertypen (Student t-test) (p < 0,05).

Table 3

Growth performance of O. niloticus in the recirculation aquaculture systems with aerated and non-aerated treatments. All values are means ± standard deviations obtained from three replicates.

Tabelle 3. Wachstumsentwicklung von O. niloticus in der Kreislaufanlage mit aeroben und anaeroben Filtern. Alle Werte stellen Mittelwerte ± Standardabweichungen aus den drei Wiederholungen dar.

Parameters	Units	Treatments
Parameters	Units	Aerated biofilter	Non-aerated biofilter
Initial Mean Weight	[g]	54.5 ± 4.7^a	56.2 ± 2.7^a
Final Mean Weight	[g]	132.0 ± 18.0^a	129.8 ± 12.8^a
Weight gain	[g]	77.5 ± 17.2^a	73.6 ± 12.5^a
Specific growth rate	[% day⁻¹]	0.42 ± 0.07^a	0.38 ± 0.07^a
Final density	[kg m⁻³]	12.76 ± 2.45^a	12.84 ± 1.36^a
Feed conversion ratio		2.67 ± 0.62^a	3.04 ± 0.65^a
Survival rate	[%]	95.6 ± 4.44^a	93.3 ± 4.24^a

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DOI: https://doi.org/10.2478/boku-2019-0019 | Journal eISSN: 2719-5430 (formerly 0006-5471) | Journal ISSN: 0006-5471

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Language: English, German

Page range: 209 - 219

Submitted on: Apr 3, 2019

Accepted on: Sep 17, 2019

Published on: Apr 21, 2020

Published by: Universität für Bodenkultur Wien

In partnership with: Paradigm Publishing Services

Publication frequency: Volume open

Keywords:

Aerated,

Related subjects:

Ecology,

© 2020 Zipporah Gichana, David Liti, Silke-Silvia Drexler, Werner Zollitsch, Paul Meulenbroek, Joseph Wakibia, Erick Ogello, Peter Akoll, Herwig Waidbacher, published by Universität für Bodenkultur Wien
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Volume 70 (2019): Issue 4 (December 2019)

Effects of aerated and non-aerated biofilters on effluent water treatment from a small-scale recirculating aquaculture system for Nile tilapia (Oreochromis niloticus L.)

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