Treatment of wastewater with microalgal cultures has the major advantage
of producing biomass that can be valorized to produce
bioenergy or molecules of interest. In fact, energy production and resource
recovery have been identified as one of the main challenges for
wastewater treatment systems of the future by relevant initiatives
such as the recently created European Innovation Partnership on
Water. However, microalgal wastewater treatment systems such as
high rate algal ponds (HRAP) have some bottlenecks like biomass separation
[1,2]. Since the invention and development of HRAP in California
in the 1950s, the problem of algal biomass separation has remained unsolved.
The main constraint is related to the fact that wastewater is a
product without market value, and therefore any added cost to the
treatment system (such as the implementation of an intensive harvesting
system) cannot be recovered. Nevertheless, this paradigm may
change in the near future if biomass is valorized to obtain bioenergy
or resources, since biomass will then have a market value.