Prediction of polar oil and grease contamination levels in refinery wastewater through multivariate statistical modeling

A dynamic mass balance was implemented for polar oil and grease contamination in a petroleum refinery wastewater circuit through developing a predictive model for a kerosene caustic washing unit, identified as the major source of polar substances into the industrial wastewater effluent. The model was developed following the Projection to Latent Structures (PLS) approach. Comparison between analytical data for polar oil and grease concentrations in refinery wastewater in the Dissolved Air Flotation (DAF) effluent and the predictions of the dynamic mass balance calculations are in a very good agreement and highlights the dominant impact of spent caustic in increasing the oil and grease contamination levels. The results of this work have led to implementation of the dynamic mass balance in the refinery as an online tool, which allows for prevision of possible contamination situations and taking the required preventive actions, and can serve as a basis for establishing relationships between the oil and grease contamination in the refinery wastewater with the properties of the refined crude oils and the process operating conditions. The PLS model developed could be of great asset in both optimizing the existing and designing new refinery wastewater treatment units or reuse schemes.