Removal of inorganic ions from wastewaters by immobilized microalgae.

Anabaena doliolum and Chlorella vulgaris immobilized on chitosan were more efficient at removing NO3 (-), NO2 (p-), PO4 (3-) and CR2O7 (2-) from wastewaters than cells immobilized on agar, alginate, carrageenan or even free cells. Carrageenan-immobilized cells, however, were better at removing NH4 (+) and Ni(2+). The PO4 (3-) uptake capacity was significantly increased in cells starved of PO4 (3-) for 24 h. Agar-immobilized cells, though having good metal and nutrient uptake efficiency, had only a slow growth rate. Chitosan is recommended as an algal support for wastewater detoxification.