Experiments and modeling of Komvophoron sp. Growth in hydraulic fracturing wastewater

Abstract

The high management cost of wastewater generated during oil and gas production using hydraulic fracturing technology necessitates economically viable alternative technologies for remediation and reuse. In this study, an Oklahoma native microalgae strain, Komvophoron sp., was grown in four different flowback and produced water samples generated during hydraulic fracturing. Biomass production profile and pollutant removal efficiency of the strain were evaluated. The experimental data demonstrated that this strain was able to grow in all wastewater samples examined when suitable light intensity and CO2 flow rate were provided. Biomass productivity of the strain varied from 5.5 to 12 g m−3 day−1 depending on the wastewater sample used in the cultivation experiments. Very high nitrogen and phosphorus removal from the growth medium, up to 99 and 63%, respectively, could be achieved by growing and harvesting algal biomass in the wastewater samples. A mathematical model developed based on pH, light intensity and CO2 enriched air flow rate as system variables well described the experimental biomass productivity and pollutant removal efficiency data. The proposed mathematical model was successfully used to identify sets of operating conditions which would maximize biomass productivity and macronutrient removal efficiencies. Hence, the model developed in this study is a useful tool to assess technical viability and design of an efficient algal wastewater remediation process to reduce the impact of hydraulic fracturing on environment while producing biomass that can be converted to industrial bio-products including biofuels.