Defining wastewaters used for cultivation of algae

Employing algae to remove wastewater nutrients, as a treatment option, and employing wastewaters for algal cultivation for the production of biomass and bio-products are a growing field of research. Nevertheless, wastewaters are of a wide range of sources and consequently have a wide range of properties. Synthetic wastewaters of various nutrient profiles are often employed, likely as a means to normalize experimental results. Considering that the capability of an algal species to utilize nutrients in a certain chemical form and at certain concentrations and ratios may vary, an adequate understanding of both wastewater parameters and algal requirements, both kinetic properties, would benefit algal cultivation. A review of the available literature shows that reporting of experimental results does not follow a standardized protocol and thus much of the information available in the peer-reviewed literature cannot be always easily explained, compared and replicated. Moreover, while the often employed motivation for such research is the integration of wastewater treatment and production of algal biomass, the results commonly support the utility of algae for removal of wastewater nutrients paradigm and less so the conjoint paradigm of wastewaters as a reliable source of nutrients for algal production. This, arguably, leads to inconsistencies in reporting of experimental results which limits a concerted approach and thus a more rapid advancement of the technology. It would be recommendable that reporting of experimental conditions include a clear characterization of nitrogen and phosphorus concentrations and ideally also offer an account of the speciation of these nutrients in wastewater substrates.