The Use of Response Surface Methodology (RSM) in Experimental Design of Membrane Treatment in Treating PW from Oil and Gas Field

Abstract

Produced Water (PW) is a byproduct in the production of oil and gas. With various types of heavy metals and pollutants, it may harm human being and marine life. The objectives of this study are; 1) to study the performance of the fabricated membranes and 2) to verify the results by using the experimental design. The PW samples which is from Dulang field is treated using Polysulfone membranes that prepared by casting solutions consisting of polysulfone (PSf), N-methyl pyrrolidone (nmp), Bentonite, and polyvinyl pyrrolidone (PVP). The influence of PVP (0-7wt%) and Bentonite (0-7wt%) addition were investigated in terms of PW Flux (mL/cm2h) and TDS rejection rate (%). The amount of TDS in PW sample is 12g/L and the PSF membrane successfully reduced it up to 14%. The experimental results then used in Central Composite Model (CCM) under RSM which designate parameters (X) as Operating Pressure (bar), PVP (wt%) and Bentonite (wt%) to compute the optimum response condition (Y) as PW Flux and and TDS rejection rate in Design Expert software. The optimum condition achieved by PSf membrane is where the composition of 4.5wt% PVP, 6.0wt% Bentonite and Operating Pressure of 5.0 bar were used. Both methods showed the value of TDS decreased up to 14% after run through the membranes for several hours. Experimental and predicted result (DoE) for optimum condition is then compared to verify the error. The percent error calculated is 2.4% and 25.5% for PW Flux and TDS Rejection Rate respectively.