Evaluation of Galdieria sulphuraria and Chlorella vulgaris for the Bioremediation of Produced Water

Produced water (PW) is the largest waste stream generated by the oil and gas industry. Traditional treatment of PW burdens the industry with significant expenses and environmental issues. Alternatively, microalgal-based bioremediation of PW is often viewed as an ecologically safe and sustainable platform for treating PW. Moreover, the nutrients in PW could support algal growth. However, significant dilution of PW is often required in algal-based systems due to the presence of complex chemical contaminants. In light of these facts, the current work has investigated the potential of cultivating Galdieria sulphuraria and Chlorella vulgaris in PW using multiple dilutions; 0% PW, 5% PW, 10% PW, 20% PW, 50% PW and 100% PW. While both algal strains can grow in PW, the current results indicated that G. sulphuraria has a higher potential of growth in up to 50% PW (total dissolved solids of up to 55 g L-1) with a growth rate of 0.72 +/- 0.05 g L-1 d(-1) and can achieve a final biomass density of 4.28 +/- 0.16 g L-1 in seven days without the need for additional micronutrients. Additionally, the algae showed the potential of removing 99.6 +/- 0.2% nitrogen and 74.2 +/- 8.5% phosphorus from the PW.

Automated summary

Produced water (PW) is the largest waste stream from the oil and gas industry, and traditional treatment methods are costly and environmentally problematic. Microalgal-based bioremediation of PW is seen as an ecologically safe and sustainable option, with nutrients in PW supporting algal growth. Galdieria sulphuraria shows higher growth potential in up to 50% PW, achieving significant nitrogen and phosphorus removal within seven days.