Experiments on the nutrient removal and retention of a pond recirculation system
2003
Gál, Dénes | Szabo, Pal | Pekár, Ferenc | Váradi, László
A combined intensive-extensive fishpond system developed for the purification and re-use of intensive fishpond effluent water was studied during a three-year experimental period. The studied pond system consists of five small-size intensive culture ponds (1 ha each and 1.5 m deep), and a 20 ha extensive culture pond with 1 m average depth. The water was recirculated between the intensive and extensive ponds with retention time of about 60 days. Carbon, nitrogen and phosphorus budget and water purifying capacity are described and evaluated by regular measurements of nutrient concentrations in the water and sediment. During the three-year test period 81.5% of organic carbon, 54.7% of nitrogen and 72.2% of phosphorus were retained by the system. A significant amount of the total nitrogen input was removed by the fishery. A small percentage of the total nutrient input was discharged into the environment during fish removal. The combination of intensive and extensive fishponds with water recirculation resulted in a significant reduction of nutrient discharge to the surrounding aquatic environment.
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