Validation of a Process for the Elimination of Naphthenic Acids in Oil Sands Process-affected Water

In this work, a comparative study consisting of 44 experiments was conducted in irradiated oil sands process-affected water (OSPW), using two strains of algae, Dunaliella tertiolecta and Spirulina platensis. The performance metrics for the study were based on the algae’s ability to degrade the naphthenic acids (NAs) present in the irradiated OSPW media and their potential to generate biomass. The factors being adjusted in the experiments were the temperature, ranging from 25 C to 32 C, and the light intensity, ranging from 1.65W/L to 3.0W/L. Results showed the viability of both the cyanobacteria Spirulina Platenis, and green alga Dunaliella tertiolecta to grow in irradiated OSPW. In the case of Dunaliella tertiolecta, dry weights of up to 0.114g dry cell weight/L were achieved, with the NA concentrations being reduced by up to 95.7%. In comparison, for Spirulina platensis reductions of only up to 72.3% were observed, however, up to 0.635g dry cell weight/L were generated. The results from this study were interpreted using statistical analysis to determine the significant factors and their impacts on algae growth and reduction of NAs. From this analysis coupled with the results of the NA reduction and biomass generated in the comparative study; Spirulina platensis was selected for a 4L large scale replicate study, under optimal growth conditions. From the study, after 32 days of growth, a dry cell weight of 10.69g/L and a 100% reduction in naphthenic acid concentrations were achieved.