Potential application of microalgae in produced water treatment

Abstract

The current study examines pollutant removal efficiency from the produced water of a local petroleum industry by five different local microalgae species. The five microalgae strains Monoraphidium, Chlorella, Neochloris, Scenedesmus, Dictyosphaerium, Chlorella and Dictyosphaerium species showed a significant amount of biomass generation within all different concentrations of produced water. Although the biomass yield of Neochloris strain was low, it was able to remove a higher amount of organic carbon than the other microalgae strains. Although biomass yield varied significantly among the microalgae strains, nitrogen removal efficiency was similar for all strains. Similar results were also obtained for most of the BTEX components. On an average, Dictyosphaerium sp. produced 0.5 g/L biomass density on different strength of produced water. Total nitrogen removal efficiency reached up to 63.76% when Scenedesmus sp. was grown in produced water. Only in case of phosphorus and various metals, removal efficiencies were better by Dictyosphaerium specie; reached up to 88.83%. Despite low biomass generation, Neochloris sp. removed 41.61% of total organic carbon from the different concentrations of produced water. Although benzene and ethylbenzene removal efficiency was 100% for all the different produced water, small amount of toluene and xylene remained in the produced water. Thus, the results indicate that microalgae strains can be used to remediate produced water effluents-derived from petroleum industries.