Wastewater nutrient removal with microalgae immobilized in carrageenan

Two species of the green freshwater microalga Scenedesmus have been immobilized in beads of κ-carrageenan. Growth curves were similar to those observed with free cells. The uptake of nitrogen and phosphorus from wastewater was similar for free and entrapped microalgae. The reduction of N-NH⁺₄ was 90% within 4 h at pH 9.0 and 70% within 5 h at an adjusted pH of 7.7. From these experiments, we conclude that immobilized Scenedesmus microalgae can grow well within gel beads and that they are as physiologically active for wastewater nutrient removal as free cells.