Microalgae and other phototrophic bacteria: Culture, processing, recovery and new products

Microalgae are primary producers of oxygen and exhibit an enormous potential for biotechnological applications. Microalgae cultivation is also an interesting option for wastewater treatment. These microorganisms are efficient in recovering high amounts of nitrogen, inorganic phosphorus, and heavy metals from effluents. Furthermore, microalgae are responsible for the reduction of CO2 from gaseous effluent and from the atmosphere, reducing the green house gases effect. On the other hand, microalgae biomass can be used for the production of pigments, lipids, foods, and renewable energy. The culture of microalgae is not a new issue, since for many decades they have been employed with aquaculture purposes. In fact, some species of Nostoc, Arthrospira (Spirulina) and Aphanizomenon species have been used as food for thousands of years for food applications. The treatment of wastewaters employing microalgae has been reported for decades (specifically for the elimination of phosphorus and nitrogen compounds). Nowadays, there is an increasing interest in the production of biofuels. Bioethanol, biohydrogen, bio-methane, biodiesel and other novel products can be obtained using microalgae as biomass or metabolic products (sugars, lipids, etc). In the near future, microalgae can be oriented (via molecular engineering) to the production of the hole biofuels, such as biodiesel or bio-turbosins.