An Application of Innovative Isolated Device to Water Quality Improvement of Industrialized Turtle-breeding

摘要

In the industrialized aquaculture, water quality is the primary factor influencing fish growth. This study investigated the effects of an isolated device installed in a turtle-breeding tank on the water quality, which separates turtle living area fromdeposition area containing excrements and residual feeds. In a controlled environment laboratory, a contrast test about the water quality variation and water exchange was carried out in two small size turtle culture tanks<0.87 mx0.58 mx0.62m>, one withan isolated device, and the other without. Soft-shelled turtles in each tank had the similar total weight. During the experimental period, one third of water in tank would be exchanged when the chemical oxygen demand concentration of culture waterexceeded 230mg/L. The results showed that the average change rates of nitrite concentration and COD concentration for the water in the tank without the device were higher than that of tank with the device, the differences were significant (P<0.05). The water exchange period of the tank without the device was about 5 days, while the other as long as 18 days. Additionally, the total water exchange volume, total nitrogen and total phosphorus in the tank without the device were 681.21L, 68.77g, 7.26g respectively, while 302.76L, 50.80g, 5.81 g in the tank with the device during the study. The total water exchange volume, TN and TP without the device was obviously higher than that of the tank with the device. Therefore, installing an isolated device in turtle-breeding tank is a simple and effective way to improve water quality and to reduce waste water discharge.