1. EXPANDING AERATION TO MANAGE WATER QUALITY IN SPLIT-POND AQUACULTURE
Lauren Jescovitch
School of Fisheries, Aquaculture & Aquatic Sciences
Auburn University
13 April 2016

2. Purpose
This study focuses on the possible benefits of using mechanical aeration in the waste-treatment section of the split-pond culture system.

3. What is a split-pond?
80%
20%

4. Why mechanical aeration in the waste treatment cell?
TAN=(NH3 + NH4+) NO2 NO3 N2
Plants, Animals & OM
1.Nitrification
2.Denitrification

5. Purpose
This study focuses on the possible benefits of using mechanical aeration in the waste-treatment section of the split-pond culture system.

6. Methods 5 4 3 7 8 9 10 13

7. Methods These samples were analyzed for: Secchi disk visibility pH
Chemical oxygen demand (COD); total, soluble
Total ammonia nitrogen (TAN)
Nitrite
Nitrate
Total nitrogen (TN)
Total phosphorus (TP)
Chlorophyll a

8. Methods
Dissolved oxygen concentrations were monitored by an automated system that was installed and is operated by the farmer.

9. Aerated Waste Cell Ponds (n = 4)
Results
There were significant differences (P<0.05) between control and aerated ponds for Secchi disk visibility, TAN, total nitrogen, and chemical oxygen demand (soluble and total). Significant differences are noted by letters (P<0.05)
Control Ponds (n = 3)
Aerated Waste Cell Ponds (n = 4)
Variable In
Out pH
7.90
7.88
7.93
7.87
Secchi disk visibility (inches)
10.35a
11.20ab
10.24a
12.22b
Chlorophyll a (µg/L)
212.92
262.63
202.37
208.11
Total ammonia nitrogen (mg/L)
2.73ab
3.13a
1.67b
1.73b
Nitrite (mg/L)
0.211
0.208
0.203
0.193
Nitrate (mg/L)
0.268
0.227
0.540
0.588
Total nitrogen (mg/L)
5.38ab
5.98a
4.32b
4.66ab
Total phosphorus (mg/L)
0.519
0.681
0.471
0.672
Chemical oxygen demand, total (mg/L)
38.72a
40.31a
33.06b
34.12b
Chemical oxygen demand, soluble
(mg/L)
32.25ac
32.95a
27.73b
29.05bc

10. Aerated Waste Cell Ponds
Results
Mean dissolved oxygen (mg/L) in fish cells (DO1) and waste cells (DO2) with their respected standard deviation from May-October.
Control Ponds
(n = 3)
Aerated Waste Cell Ponds
(n = 4)
DO1
DO2
May
6.58 ± 2.84
7.88 ± 3.91
6.58 ± 3.20
8.10 ± 4.05
June
6.12 ± 2.81
7.45 ± 3.97
6.12 ± 3.29
7.04 ± 4.17
July
6.07 ± 3.23
7.40 ± 4.39
5.76 ± 2.95
6.72 ± 3.70
August
4.94 ± 2.04
4.68 ± 3.21
5.67 ± 2.56
6.40 ± 3.23
September
5.08 ± 1.80
5.09 ± 3.20
5.64 ± 2.40
5.79 ± 2.65
October
5.96 ± 2.07
5.25 ± 3.71
7.30 ± 2.87
6.53 ± 2.85
June, July, August, and October had all significant DO data between DO1 and DO2 throughout the control and aerated ponds. In May, all DOs were different except DO2 in control (7.88 mg/L) and DO2 aerated (8.10 mg/L). For September, all DOs were different except between DO1 (5.08 mg/L) and DO2 (5.09 mg/L) in control ponds and DO1 (5.64 mg/L) and DO2 (5.80 mg/L) in aerated ponds.

11. Conclusions Aeration in the waste cell of the pond –
Increases: Secchi disk
Decreases: TAN, TN, COD
Aerated waste cell ponds have a higher DO in both the fish and waste cells.
All these trends indicate improvement for water quality management.

12. Complications and Limitations
Motor failures in aerators- delays when aerators could be operational in waste cells
Fish kills- three large kills: one of the aerated ponds and two of the control ponds. Fish kills were thought to be related to toxic Microcystis and to high nitrite concentration (Alabama Fish Farming Center).
Production- multiple-batch system; reliability
Practicality- management practices

13. Cost/Benefit Analysis
Further Research
This Study
Currently on-going
Circulation Study
Production
Feed
3-year synopsis
Future Studies
Cost/Benefit Analysis
Design Features
Production
Multiple Farms
Duration of Aeration

14. Thank you!
Special thanks to Dr. Boyd, SRAC, Greg Whitis, Piyajit Pratipasen, and the Unruh farm.
References:
Brown, T.W. and Craig S. Tucker (2013). Pumping performance of a slow-rotating paddlewheel
for split-pond aquaculture systems, North American Journal of Aquaculture, 75:2,
, DOI: /
Farrelly, J.C., Chen, Y., and Sagar Shrestha (2015). Occurrences of growth related target
dissolved oxygen and ammonia in different catfish pond production systems in
southeast Arkansas, Aquacultural Engineering, 64,