Assessing the decontamination efficiency of a three-component flocculating system in the treatment of oilfield-produced water

• Fluorescence method was developed to show the removal efficiency of flocculants.
• Pyrene was used as a model contaminant to determine an optimal formulation.
• Efficient removal of crude oil from oilfield-produced water was demonstrated.

Produced water is a complex mixture of oil, water, dissolved solids, and suspended solids. It represents the largest volume of waste associated with the oil and gas industry, and its management is a costly aspect of oil recovery. Therefore, the development of effective treatment technologies for produced water is essential from both ecological and economic standpoints. We have developed a sensitive, fluorescence-based method to demonstrate the decontamination efficiency of a three-component polymeric flocculating system, the microencapsulating flocculating dispersion (MFD) technology. We have shown that the MFD technology can remove 90 ± 2% of the pyrene, a model wastewater contaminant, in a 0.4 ppm aqueous stock solution. The optimal flocculant concentrations used to remove pyrene was determined by fluorescence spectroscopy and zeta potential measurements. Under these conditions, flocculation and settling times were fast (i.e., <1 min). We have also demonstrated rapid removal of crude oil from an oilfield-produced water sample with a remarkable decontamination efficiency of ≥98 ± 1%. Using this fluorescence-based method, we will be better able to formulate the components of this technology and other polymeric flocculants in the treatment of oilfield-produced water, which will benefit wastewater treatment technologies.

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