Study On Treatment Of Oily Wastewater In Oil-Field By Ceramic Membrane Technology

The membrane filtration characteristics are studied in this paper with experimental ceramic membrane apparatus, the membrane pore size is 50nm.Firstly, the influences of transmembrane pressure, temperature and crossflow rate are tested with distilled water as feed liquid. It is found that the membrane flux is constant over time, increases linearly as transmembrane pressure increasing and all the correlation coefficients of linear fit are more than 0.998, increases gradually as temperature and crossflow rate increasing, but the effect of crossflow rate is less. Secondly, the affecting degrees of transmembrane pressure, temperature and crossflow rate to filtration effect while dealing with simulative oily water are analyzed using orthogonal experiment theory, the results of which show that transmembrane pressure and temperature act more greatly. Through lots of experimental studies, it is shown that the higher transmembrane pressure and temperature are, the more oil and suspended solid content and median diameter will be. Under correct operating conditions filtrating, the clean water will meet the water injection A1 standard in low permeability oil field when the oil content of penetrating fluid is less than 3mg/L, the suspended solid content is less than 1mg/L, median diameter is less than 1μm. Running under the optimal operating conditions which are:ΔP=0.12MPa,t=40℃,q=780L/h,backsurging operating per 30mins, the ceramic membrane apparatus can maintain higher membrane flux, which reaches 250L/(m~2·h). Based on laboratory experiments and field surveys, the alternative treatment process of oily wastewater is proposed in this paper. Meanwhile, the membrane fouling resistances are classified as: intrinsic resistance, reversible resistance, partial reversible resistance and irreversible resistance. Under the conditions studied, the intrinsic resistance contribute 54.8% of total resistance, the reversible and partial reversible resistances play a crucial role in flux decline and contribute more than 27.5%, irreversible resistance contribute 17.7%. At last, the chemical cleaning methods which are water cleaning-alkaline cleaning-water cleaning-acid cleaning-water cleaning are adopted to thorough cleaning ceramic membrane in this paper, after chemical cleaning, the membrane flux is back to 95%.