Machine-building enterprises: Carriages
The composition of engineering wastewater is fully connected with the production technology. The pH of such waters is 4-11. They contain impurities, oils, petroleum products, metal salts (iron, chromium, zinc, copper, nickel), residues of cutting lubricants, acids, alkali. Different methods of cleaning are used depending on the specifics of the facility. For this purpose, coagulants with or without flocculants are used. The method of separation of coagulated pollutants, as well as the amount of reagents may vary. To clean drains, contaminated with oils (50-400 mg/l), and mechanical impurities (100-300 mg/l), settlement with pre-coagulation (with the addition of calcium hydroxide (slaked lime)) is used. Then, water with low content of impurities (2-10 mg/l) is chlorinated and recycled for reuse. For highly contaminated wastewater, e.g., discharge cutting lubricants or washing solutions, high doses of coagulant and pressure flotation method are used. The amount of reactants is determined depending on the level of substances concentration.