Industrial wastewaters are often produced on extremely large volumes. Many studies have shown that these wastewaters can potentially serve as a source for both carbon (essential nutrient) and water for microalgal production.

The effluent of an anaerobic internal circulation (IC) reactor, used to treat the waste of a biotechnology production facility, was chosen as the cultivation medium for Chlorella sorokiniana in batch and continuous cultures using the PBR101 photobioreactor.

The aim was to determine the relationship between the rate of waste (algae nutrients) removal and biomass production at varying dilution rates. Batch culture using undiluted wastewater showed biomass productivity of 1.33 g L-1day-1, while removing over 99% of the ammonia and phosphate from the wastewater.

Deceleration-stat (D-stat) experiments performed at both high and low light intensities of 2100 and 200 (μmol photon m-2s-1) established the optimal dilution rates to reach volumetric productivity of 5.87 and 1.67 g L-1day-1 respectively. The corresponding removal rates of nitrogen were 238 and 93 mg L-1day-1 and 40 and 19 mg L-1day-1 for phosphorous. The yield at low light intensity was as high as had been observed in any previous report indicating that the waste stream allowed the algae to grow at its full potential.

References: Jon Van Wagenen, Mathias Leon Pape, Irini Angelidaki, (2015) Water Research 75 301-311.