Chemical Deoiling Unit | Physicochemical Oil Removal Equipment | Metallurgical Oily Wastewater Treatment System

Working Principle The process runs in three stages. First, demulsification and coagulation: an electrolyte coagulant such as PAC is dosed into the wastewater, neutralizing the surface charge on emulsified oil droplets so the colloids destabilize and begin to cluster. Second, flocculation and bridging: an oil flocculant — a high-molecular-weight polymer — is added, linking the coagulated particles and oil droplets into dense, coarse flocs through adsorption bridging. The two chemicals are dosed separately, and the order matters. Third, settling and separation: the formed flocs enter the inclined tube settling zone, where the tube bundles accelerate settling and the sludge collects in the hopper at the bottom. Clear water exits over the overflow weir. The settling zone uses a siphon principle for automatic backwash — once intercepted solids accumulate to a set point, the siphon forms automatically and clear water backwashes the filter media in reverse, with no electric valve control needed. Sludge is discharged periodically through the sludge pipe. Application Fields 1.Metallurgy: Turbid circulating water treatment in continuous casting and rolling mills, removing iron oxide scale and emulsified oil 2.Petrochemical: Oily wastewater purification in refineries and petrochemical plants 3.Machining: Metalworking coolant and rolling emulsion wastewater treatment 4.Oilfield & Mining: Produced water and mine oily wastewater deoiling FAQ Q1: What types of oily wastewater can the chemical deoiling unit handle? A: It mainly treats wastewater containing free oil and emulsified oil, particularly turbid circulating water from continuous casting and rolling mills in the metallurgy industry, as well as oily wastewater from petrochemical and machining operations. Inlet oil concentration should not exceed 35–45 mg/L, and outlet oil can be reduced below 10 mg/L. Higher oil concentrations require pretreatment, such as a swirl pond or primary settling tank. Q2: How many chemicals does the chemical deoiling unit require, and in what order are they dosed? A: Two chemicals, dosed separately, and the order cannot be reversed. First, an electrolyte coagulant — such as PAC, aluminum sulfate, or ferric chloride — is added to the first mixing chamber. Second, an oil flocculant, a high-molecular-weight polymer, goes into the second mixing chamber. Both are dosed at around 15 mg/L, with a dosing concentration of 2–3%. The oil flocculant must be added after the electrolyte coagulant, and the two should not be mixed together. Q3: What are the main components of the chemical deoiling unit? A: The unit consists of a mixing reaction zone, inclined tube settling zone, filtration chamber, clear water chamber, and sludge hopper. The mixing zone has an agitator to bring chemicals into full contact with the wastewater. The settling zone uses inclined tube media to increase settling area and separation efficiency. The filtration chamber is packed with filter media to intercept residual suspended solids, and the sludge hopper collects settled sludge. Backwashing runs on a siphon principle — no electric valves, simple maintenance.