Phycoremediation of Municipal Wastewater by the Cold-Adapted Microalga sp. Dek19

ABSTRACT  Present municipal wastewater treatment technologies often require substantial energy inputs, and fail to completely remove nitrate and phosphate before discharging effluent. In contrast, using the cold-adapted oleaginous microalga sp. Dek 19 decreased levels of both these polluting ions to 0 mg/dL. Concurrent biomass production was greater at 10 °C than at 22 °C, showing that phycoremediation occurred at low temperatures previously thought to be unsuitable for algal-based treatment. Algal growth with uptake of nitrate and phosphate required only short bursts of aeration to suspend cells and maintain CO₂ supply for photosynthesis. To save energy, culture aeration for 1 hour, 4 times per day, including during the dark cycle, yielded cell productivity and phycoremediation nearly equivalent to using 24-hour aeration. The authors conclude that sp. Dek19 algae represent an economical effluent treatment at cool temperatures found in the high proportion of water resource recovery facilities in geographical areas experiencing cold winters.