| The oily emulsion wastewater by produced in large steel factories and machine works is the most difficult in the wastewater treatment. Although in recent decades the technologies have been improved much, all large-scale steel factories have been improved their technologies about coating and cleaning the surface of products in order to get stable quality in the rolling process and to gain high profits because of the higher demand to rolled plate from all fields. Thus, the molecular weight of emulsified oils is smaller and smaller, and the composition of emulsifiers is more and more complex, which results in dramatically change of the contaminative components in such wastewater. This brings forward us great difficulty and meanwhile gives us enormous challenges. So, it was chosen that the treatment of oily wastewater puzzled the metallurgical industry for long-term as the research subject of this thesis.Through comparison to many other methods, the membrane separation which developed fast in recent years was selected. According to the existing problems of organic ultrafiltration(UF) apparatus from USA, the ceramic microfiltration(MF) equipment was chosen, by means of which acid, alkali, high temperature and chemical property changes could be resisted. Systemic researches for ceramic technology to treat oily wastewater had been done in this thesis and the main conclusions are shown as follows.In the fundamental experiment part, the effects of parameters (including distribution of pore sizes, character of membrane materials, operational pressure, cross-flow velocity, feed temperature and concentration, pH value) on the membrane process, especially membrane permeability flux and retention rate were discussed in order to fix on a appropriate separation conditions. Experimental results show that zirconia membrane with pore size around 0.2 m owed high permeation flux(260Lh-1m-2) and high retention rate(99.9%), the oil content is less than 10mg/L in the permeated side. Operational pressure should be controlled in the range of 0.1-0.2 MPa. Too high or too low cross-flow velocity is no good to increase of the flux, but doesn't affect the retention rate and the proper velocity is about 5m/s. Higher temperature is good to increases of flux, but the retention rate decrease. The increase of the feed-in oil concentration has little effect to the flux when oil concentration is greater than 2-3%, but once oil concentration is above 5%, the permeated fluid's oil content may be higher than 10mg/L. pH value affects greatly flux, the proper pHshould be selected by solution property.A new measuring method, CPA-ultraviolet spectrophotometry, was proposed for the determination of tiny oil concentration accurately, which could eliminate availably the disturbance of other organic matters. Main structure parameters of membrane (distribution of pore size, porosity, thickness of surface layer) and the basic characters of feed (distribution of oil size, temperature-viscosity curve, membrane surface's oil concentration) were determined.The resistance distribution of membrane, membrane fouling control, enhanced mass transfer and methods of membrane cleaning were studied and analyzed. In this experimental system, fouling resistance of ceramic MF mainly consists of four aspects: concentration polarization, gel layer, membrane pore adsorbed stain and membrane itself. Resistance distribution is respectively as follows: gel layer is 58-65% of total resistance, concentration polarization resistance is 6-10%, pore stain resistance is 13-18%, membrane resistance is 13-17%. So, gel layer resistance is the main resistance. Set some twist components to disturb flow in the membrane tube may strengthen the process of mass transfer, thus higher membrane flux (45% higher than hollow tube) could be got under lower flow rate (flow rate get down from 4~6m/s to 2-3m/s), qualitative analysis had been done to the strengthen mechanism of the disturbance components. The gas-liquid back-flush technology can control membrane fouling efficiently,...
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