As indicated by de-Bashanetal., nutrient removal rate of 100% ammonium, 15% nitrate, and 36% phosphorus with in 6 days was achieved by co-immobilization of microalgae and microalgae growth-promoting bacterium Azospirillum brasilenseCd. A much lower removal rate (75% ammonium, 6% nitrate, and 19% phosphorus) was achieved by the microalgae alone under similar conditions. Co-cultivation of immobilized or suspended microalgae with other organisms is an emerging field and has a great potential in microalgae biotechnological applications.