ABSTRACT
The best-known effect of fertilizer run-off and the other forms of nitrate pollution is eutrophication of water, which in extreme cases can result in water becoming clogged with algae, killing most other plants and animals. The application of high-rate algal ponds in wastewater treatment appears to have the greatest potential of all biotechnologies based on microalgae, if exploited fully as a multipurpose system. One of the promising fields using microalgae in wastewater treatment is the utilization of cyanobacteria. Through the appropriate use of the nutrient uptake capabilities of these prokaryotes, nutrients in the secondary effluent of wastewater treatment plants can be removed and used in the growth of algal biomass, which can then become a source of biomass. There are three major techniques to be used for cell immobilization: entrapment, adsorption and coupling. The immobilization techniques which most resemble the circumstances in which cells find themselves in nature, are their entrapment within gels and adsorption to surfaces.
