Application Of CAF&BAF Combination Technique To Oily Wastewater Treatment Project

Oily wastewater is enormous quantity of industrial wastewater, it be derived rfom ironand steel,machinery,petroleum chemical and other industries. At present "grease traps-airfl"otation-biochemical combined process as traditional cratfs is used to deal with oilywastewater of refinery, but this combined process in the actual project has many faults such asneeding large area, high investment and expensive chemical agents. In order to reduce theoperation cost and using area, to improve the operating speed and treatment effect, theCavitation Air Flotation (CAF)-Aeration Biological Filter (BAF) combined process was studyfor oily wastewater from refinery. Results and conclusion are as follows:(1) The removal rate of CAF to suspended matter is as high as90%，but the removalrate of COD from oily wastewater, COD must be removed by subsequent biologicaltreatment system.(2) The relationship between the organic loading and the removal ratio of COD ispositively correlated when influent COD concentration is as high as lOOOmg/L; therelationship has no obvious linear relationship when COD concentration is low(66-160mg/L).(3) When influent petroleum concentration range from0to10mg/L5eflfuent qualityof BAF is best and the removal rate of petroleum is more than90%; the removal rate ofBAF decreased significantly when the inlfuent petroleum concentration is more than30mg/L.(4) The removal efficiency of COD achieve the best effect and the removal rate ofCOD can reach90%when COD and Pratio for200.Engineering practice shows that the refinery oily wastewater by CAF-BAF，the water ofthe water quality indicators are stable up to the provincial standard "water pollutant emissionlimits"(DB44/26-2001).Project scale of oily wastewater is600m3/d.The investment of perton matwr is from8000RMB to9000RMB5the direct operation cast of one ton water is2.18RMB, the area of whole treatment facilities is5502m，the area of one ton water is0.922m.The combined process in the refinery oily wastewater treatment works will have wideapplication prospects.