Pretreatment design of production sewage in triphenylbenzene combined plant

A new 100 kt / a Ethylbenzene / styrene and 40 kt / a expandable polystyrene unit (EB / sm-eps unit) were built in a petrochemical company. In this unit, the catalytic dry gas and petroleum benzene of the refinery are used as raw materials, the ethylene to ethylbenzene and ethylbenzene negative pressure dehydrogenation to styrene technology developed in China are used, and the expandable polystyrene production technology imported from abroad is used to produce styrene monomer and expandable polystyrene.

There are a lot of benzene, toluene, ethylbenzene, styrene, polystyrene and other pollutants in the sewage discharged from the combined unit. Although the company has an original sewage treatment plant, the concentration of CODCr, BOD5 and SS in the sewage discharged from the combined unit is too high to be directly discharged into the sewage treatment plant. Therefore, it is necessary to build a set of sewage pretreatment facilities.

Operation condition

The pretreatment facility covers an area of 513 m2, with a design investment of 8.59 million yuan. It was completed in October 1999. According to the progress requirements, en / SM was put into trial operation in November 1999. Under the condition that the sewage discharge of the production unit is abnormal and the water quality and quantity change greatly, the water quality monitoring conducted by the monitoring station of the company shows that the effluent meets the design requirements (SS is mainly contained in EPS wastewater, so it is not monitored). See Table 2 for details. The practical operation shows that it is feasible to use neutralization, sedimentation, coagulation air flotation and contact oxidation processes to treat the production wastewater of the triphenylbenzene unit.