Study of ultrafiltration behaviour of emulsified metalworking fluids

Ultrafiltration (UF) has been accepted as a versatile membrane separation process for water purification and wastewater treatment in recent years. In this paper the UF separation behaviour of oil-in-water emulsion used usually for metalworking fluids was studied. The effect was investigated of different polymeric membrane materials, oil concentration in feed, transmembrane pressure, feed temperature and other process parameters on the permeate flux, oil rejection and chemical oxygen demand in the permeate in a laboratory scale. The foulant on the membrane surface was analyzed and the recovery of fouled membrane permeability was studied as well. Finally an empirical model of membrane fouling was discussed and tested experimentally.

Fig. 5. Relation between )P/J and )P for the FP 055A membrane (feed concentration 5 vol.%; flow velocity 0.9 m/s; temperature 20°C). equal to 0.0052 bar m2h/l. Therefore, (0Rm) = 0.0052 bar m2h/l. The slope of the line is 0.0078. Thus, (0Rg) = 0.0078 )P bar m2h/l. Four sets of experimental data were filled on Eq. (3) with the help of an iterative algorithm, assuming that both empirical constants of m and n are 0.5 (Fig. 4). The optimal A, B and b were calculated as: A = 171.42, B = 0.37, b = 0.62. The fouling model of FP 055A membrane for oil-inwater treatment can be expressed as follows: (4) Validity of the equation: flow velocity is less than 1.2 m/s, transmembrane pressure difference is 1–6 bar. It was found that the calculation values are consistent with the experimental results.