Sequential adaptation of Nannochloropsis gaditana to table olive processing water

ABSTRACT

The main objective of this study was to evaluate the suitability of Nannochloropsis gaditana to grow by sequential adaptation to TOPW (Table olive processing water) at increased substrate concentrations (10–80%). Sequential adaptation allows growing Nannochloropsis gaditana up to 80% TOPW, although the maximum microalgae biomass productions were achieved for percentages of 20–40%, i.e. 0.308 ± 0.005 g VSS (Volatile Suspended Solids)/L. In all growth experiments, proteins were the majority compound in the grown microalgae biomass (0.44 ± 0.05 g/g VSS), whereas phenols were retained up to a mean concentration of 12.1 ± 1.9 mg total phenols/g VSS. The highest microalgae biomass production rate at rate of 80% TOPW took place in the first two days when most nutrients were also removed. Average removal efficiencies at this percentage of TOPW were 69.1%, 50.9%, 54.3% and 71.8% for total organic carbon, total soluble nitrogen, phosphate and total phenols, respectively. Sequential adaptation can ensure the obtaining of a sustainable microalgae culture as a treatment method for TOPW.

KEYWORDS:

• Microalgae biomass
• phenols
• sequential adaptation
• table olive processing water
• wastewater valorization

Funding

The authors are very grateful to the Marie Curie's International Research Staff Exchange Scheme (IRSES) “Renewable energy production through microalgae cultivation: closing material cycles” (PIRSES-GA-2011–295165) for funding this research. The authors would also like to thank the Spanish Ministry of Economy, Industry and Competitiveness for providing financial support through Project CTM2014-55095-R.