**Acknowledgements**

*4.2.2. Cyanobacteria*

80 Microalgal Biotechnology

*4.2.2.1. Phormidium bohneri*

*bohneri* was observed at 3.2 mM N-NH<sup>4</sup>

stripping of ammonia or bacterial activity. P-PO<sup>4</sup>

digested with microalgae or cyanobacteria biomass.

of 329 ± 24 mg dry wt/L·d [105].

*4.2.2.2. Spirulina maxima*

**5. Conclusions**

De la Noüe et al. [103] also studied the growth of *P. bohneri.* The nitrogen toxic effect for *P.* 

nitrogen resistance than other common cyanobacteria. Moreover, an increase in temperature (from 10 to 35°C) produced an increase in biomass production. It was observed that a concentration of 0.1–0.5 mg Cu2+/L showed a toxic effect on *P. bohneri.* Seventy-five percent of COD removal from the anaerobic digestate was achieved. The higher concentration of *P. bohneri*

When *P. bohneri* was cultivated in a cheese factory anaerobic digestate at 20°C, a rapid increase in pH was observed after 4 days (from 8.4 to 10.9). No significant amount of NH<sup>4</sup>

was observed after the process, although, according to the high pH, it could be due to the

In an early study, *S. maxima* was observed to need a high concentration of bicarbonate ions for optimal growth [106]. When it was cultivated in swine manure anaerobic digestate diluted

phate removal of 99.3%, nitrogen depletion of 76%, and a reduction in volatile solids of 28%.

Microalgae are renowned as a powerful biotechnology platform for the production of a wide range of value-added products. These include biofuels, animal and aquaculture feeds, and highvalue commercial products, such as pigments, polysaccharides, bioplastics, and other organic compounds. Microalgae have also been proposed for a biorefinery model where multiple compounds can be produced simultaneously from harvested microalgal biomass grown in wastewaters and in anaerobic digestion digestates. The growth of the biomass in industrial wastewater and/ or anaerobic digestates has been proven to be a feasible alternative to synthetic mediums. Regarding the anaerobic digestion of microalgae and cyanobacteria biomass, co-digestion allows to improve the low C/N ratio of microalgae and cyanobacteria, balance the nutrients, and avoid the possible inhibitions in many cases. Furthermore, the produced digestate after the anaerobic digestion process presented better stability when a high-carbon biomass is co-

However, the wide variety of microalgae and cyanobacteria and the different types of highcarbon biomass make it difficult to ascertain a general assessment about the enhancement of methane production when these two biomasses are co-digested. In this respect, it seems that the use of microalgae/bacteria consortium could reduce drawbacks from working with

with seawater, an increase in the microalga growth rate was observed with CO<sup>2</sup>

tation. After 15 days, the anaerobic digestate presented a complete N-NH<sup>4</sup>

, which indicated that *P. bohneri* presented a higher

3− removal reached 69% with a biomass yield

+

+

supplemen-

reduction, phos-

+

(32 mg dry wt/L·d) was reached with a 2% swine manure dilution at 20°C.

The authors wish to express their gratitude to the regional government of Andalucía "Junta de Andalucía" (project RNM-1970) for providing financial support. Dr. Rincón wishes to thank the "Ramón y Cajal" Program (RYC-2011-08783 contract) from the Spanish Ministry of Economy and Competitiveness for providing financial support.
