RIASSUNTO
ABSTRACT
We attempted to evaluate the possibility of using Chlorella pynenoidosa to remove ammonia and COD from mariculture effluent through a series of experiments. The results showed that Chlorella pynenoidosa can depend on ammonia as necessary nutrient for growth after the process of domestication culture. High concentration ammonia has a toxic effect on Chlorella pynenoidosa. The higher the concentration, the stronger the effect is. The appropriate ammonia range is below 50mg/L. The best working condition of Chlorella pynenoidosa for ammonia removal is pH 7-9,temperature 25-30℃, algae delivery amount 8×105cell/mL. Further experiment results showed that the acclimated algae can reduce the ammonia concentration below 0.02mg/l in 7 days.
INTRODUCTION Researches on the application of biological nitrogen removal techniques to mariculture have recently attracted much attention due to the increase in the numbers of seafood farms and the pollution of the coastal area(Seo, 2001). Traditional nitrogen removal process depends on aerobic nitrification and anaerobic denitrification to eliminate nitrogen from the water system(Abeysinghe, 1996). The nitrification process transforms ammonia to more oxidized nitrogen compounds such as nitrite or nitrate, which are converted to nitrogen gas in the following denitrification process(Chang, 2005; Anthony, 1998). Biofiltration by plants, such as algae, is assimilative, and therefore adds to the assimilative capacity of the environment for nutrients(Cheng, 2003; Lin, 2005). With solar energy and the excess nutrients, plants photosynthesize new biomass. Algae, and in particular seaweeds, are most suitable for biofiltration because they probably have the highest productivity of all plants and can be economically cultured (Zimmo, 2003). Algae use sunlight to build their biomass, while assimilating dissolved inorganic nutrients removed from the water. If properly cultured, the organisms of both extractive groups can turn pollutant nutrients into commercial crops and loaded effluents into clean water( David, 2002).