Pollutant removal from oily wastewater discharged from car washes through sedimentation–coagulation

摘要

Wastewater from car washes represents a potential problem for the sewer system due to itsnemulsified oils and suspended material. Treatment of wastewater discharged from four carnwashes was investigated by sedimentation and coagulation. The effect of the coagulantsnServical P (aluminium hydroxychloride), Servican 50 (poly(diallyldimethylammonium chloride)),naluminium sulfate and ferric chloride was evaluated. The achieved removal usingnsedimentation was of 82%, 88% 73% and 51% for oils, total suspended solids, COD, andnturbidity, respectively. In the treatment by coagulation we achieved average efficiencies nearlynto 74% for COD removal, greater than 88% in the case of total suspended solids removalnand 92% in the case of turbidity and except the performance of Servican 50 greater thann90% in oil removal. We concluded that the oil residual concentration and COD in the treatednwater allows pouring it in the sewer system complying with the limits of the Mexican rulenNOM-002-ECOL-1996 and it is possible even its reuse, at least in the case of the chassisnwashing of cars.