Effect of Chlorella vulgaris on the Treatment of Municipal Wastewaters

MARCONI P.; FERNANDEZ CUPPARI M.; GROPPA M.D.; BIGI R.; ZAWOZNIK M.S.; NADRA C.; PERELMAN P.

Miami Beach, Florida

Conferencia; 7th International Conference on Algal Biomass, Biofuels and Bioproducts Conference information; 2017

Chlorella vulgaris is a microalgae widely used for phytoremediation processes. The governmental agencies CONICET (National Council Research) and APRA (Protection of Environmental Agency from Buenos Aires Government) began to work together in order to maximize research efforts directed to develop cleaning up technologies for the water bodies of Matanza-Riachuelo Basin, along which large populations are settled. The Lugano Lake acts as a dam for this vast basin.In a first step, Lugano Lake water (LLW) was tested as substrate for Chlorella multiplication and compared to standard MS medium. In a second step, Chlorella potential as bioremediating agent for LLW was tested in two ways: i) In 2-L oxygenated bioreactors (a bubble aeration system) with the microalgae inside dialysis bags; and ii) in Erlenmeyers placed in shakers (100 rpm) with the microalgae immobilized in alginate beds, placed also inside dialysis bags. Both systems were maintained at 24 ± 2ºC under 16h photoperiod.After 15 days of incubation at room temperature in bioreactors or Erlenmeyers, water was analyzed for physico-chemical parameters (pH, nitrite, nitrate, ammonia, total nitrogen, total phosphate, BOD and COD) using standard methods. Initial to final values were compared.Biomass of Chlorella increased when cultivated in LLW; the rate of biomass production was of about 75% of that observed in MS medium. In the bioreactor model, pH slightly decreased and several heavy metals strongly reduced their concentrations: Pb 90%; Cd 65%; As 50% and Cr 50%. The other parameters tested did not change significantly. Growth of the microalgae in this model was estimated in 501 cells/ml day; in the immobilized model Chlorella growth was of about 1600 cells/ml day.Our results suggest that Chlorella vulgaris may be especially useful for tertiary wastewater treatments, to reduce heavy metal load. Immobilization of the microalgae may optimize its multiplication rate under this substrate.