The Research On The Treatment Of Natural Gas Chemical Industry Wastewater With Membranes Separation Technology

The wastewater of natural gas chemical industry is high-concentration and hard-biodegradation organic wastewater. The COD is as high as 40000 mg / L. It is poisonous wastewater. People will get injury with long-term exposure. If it is discharged into the river, the water will be polluted severely. So it need to be treated in time.The Reverse Osmotic (RO) membrane ESPA2-4040 that is made by Hydranautics company of American is a kind of super and low-pressure polyamide composite membranes, This kind of membrane extensively apply in the wastewater treatment. The article apply it to the research.According to the result of research, temperature and pressures are main factor of the separation function of RO . Under other conditions are constant, the flux of membrane will increase and the stop rates of COD and n-phenylglycinonitrileto will decrease with temperature going up. The best operation temperature is in 36-38℃ With the pressure increment, the flux of membrane increase obviously The stop rate also has the trend of increasement, so increasing pressure is advantageous to the function of separation of the membrane. Flux of membrane decrease with increment of the liquid concentration. But the stop rate is hardly influenced by liquid concentration. If The times of concentration increase the flux of membrane will descend. Through 5 times concentration, flux of membrane decrease from 6.2 L/m2 · h to 2L/m2 · h .The concentration of COD and n-phenylglycinonitrile separately increase from 40000 mg/L to 71000mg/L and 8000 mg/L to 15000 mg/L. The test process for 30 days and the membrane contamination phenomenon appears. Cleaning water can't recover the flux of membrane with the clear water. After cleaning with the ethanol solution, the membrane flux come back. So the period of the chemistry cleaning is 30 days.This text built up the mathematics expression model of the solute concentration in membrane module and the mathematics expression model of solute concentration in the osmosis liquid. Solute concentration on the membrane increase with the increment of the operation time. It also has the direct relation with the concentration of the raw water, solute concentration polarization factor and therecovery rate. Because the recovery rate don't change in the certain pressure, the concentration of solute in osmosis liquid will increase with the increment of operate time. Meanwhile, more and more accumulation of solute is at surface of membrane or inner part of membrane. Membrane contamination also is more and more serious. For the RO membrane which is drived by pressure , this text built up the expression model of osmosis flux. Its quantity mainly is decided by the viscosity of liquid and the resistance of the polarization lay and the boundary lay.