Experimental Research On Treatment Of Oilfield Wastewater By Lamella Dissolved Air-Flotation

The merits and drawbacks of domestic and foreign treatment process technology of treating oil-field wastewater is summarized in this paper,and the trend of technology development and the mechanism of Board Dissolved Air Flotation treating oil-field wastewater is analyzed and discussed.Through analysis of single factor about lamella spacing,surface load,reflux ratio,bubble layer thickness and coagulant dosing, the result showed that the best parameter is oil content of water less 400mg/L,turbidity 50~100NTU,inclined plate distance 60mm, the surface load 9m~3/ (m~2·h),reflux ratio 30%,the bubble-layer thickness 30cm, and PAC and PAM dosing 60mg/L and 1mg/L respectively,oil content in the effluent are able to less than 10mg/L, the removal rate reached 96% or more;water turbidity less than 15NTU,turbidity removal rate reached 94%. The results indicate that BDAF is obviously superior to the traditional DAF, with the load increased from 7m~3/ m~2·h to 11m~3/ m~2·h, and it has greatly increased the separate efficiency. The pure water test showed that the separate district in traditional DAF has mixed directions which have no help to the separation of water and oil. The board devices help to improve the flow pattern drawbacks of separation and reduced the Reynolds number. The DAF technology is more effective and stable to used in oil-field wastewater treatment. This paper studies the bubble-layer filter separation mechanism,and the establishment of mathematical model with flow and reflux rate, pressure and bubble-layer can play a theoretical guidance for the application of flotation technology on treatment of oil-field wastewater.On-site test with BDAF is conducted in Dongying,and the results showed that the effluent oil content is less than 10mg/L with the condition of R=30%, bubble layer thickness 30cm,lamella spacing 60mm,pressure 0.45MPa and the content of wastewater 65~200mg/L. After repeated trials of different influent concentration,it has been proved that the device is adaptable to the fluctuations in oil content of the water with great efficient,and the effluent can achieve the"oil-chemical water pollutant discharge standard"(GB 428119-1984) first order standard.