Water clarifierBHQ-402 is a polyether solution; it is a colorless to light yellow liquid and is used for wastewater system to reduce oil content of wastewater. It is used for wastewater treatment systems of oilfields and water treatment systems of factories and can accelerate demulsification speed of emulsified oil in wastewater and can make oil droplets rapidly flocculate to become large and floated. Used in wastewater treatment systems of oilfields, it can increase oil removal rates of equipments such as coalescers, flotation machines and hydraulic cyclones. The product has good chemical stability, is difficult to hydrolyze and has good oil removal effect on oily wastewater. Through change of interfacial tension of oil-water, the product can achieve separation of oil and water of oil water mixture with “water in oil” or “oil in water” forms. It has good compatibility with other water treatment chemicals, thus it can form many water treatment formulations and can be well applicable to treatment of produced fluid of polymer flooded oilfield.