Biological water purification by culturing
Ulva pertusa in coastal fish farms was estimated as a function of light intensity, dissolved inorganic nutrients and water temperature.
Ulva pertusa was cultured from 0.5 m to 8 m depths in coastal fish farms from August to November, 2002. The maximum growth of thallus area, wet weight and thickness were recorded at 0.5 m depth. The maximum growth of thallus area reached to 640 cm
2 on August. The maximum growth of thallus thickness reached to 0.11 mm on November. Average contents of total nitrogen (N) and total phosphorus (P) in
Ulva pertusa reached to 35 mg N/g dry and 2.1 mg P/g dry in October, respectively. The maximum N, P uptake rates of
Ulva pertusa were 3.6 mg N/m
2/day and 0.19 mg P/m
2/day at 0.5m depth, respectively. Michaelis-Menten's constants of N, P uptake rates were 26μg N/
l and 8.6μg P/
l, respectively. Downward irradiance of 730μmol/m
2/s resulted in the maximum N, P uptake rates. N, P uptake rates of
Ulva pertusa at 25°C were 2.5 mg N/m
2/day and 0.13 mg P/m
2/day, respectively. Water temperature coefficients of N, P uptake rates were 1.076 and 1.084, respectively. The N and P uptake rates of cultured
Ulva pertusa were formulated from dissolved inorganic nutrients, light intensity and water temperature characteristics found in coastal fish farms, and the calculated values corresponded well with the observed values.
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