Application Study On Desalination Of Discharge Of Circulating Cooling Water By Nanofiltration

The pretreatment of desalination from discharge of circulating cooling water by nanofiltration has been investigated . It can prevent the scale of CaCOs on membrane surface successfully and avoid the damage to mambrane performance which result from alkaline discharge of circulating cooling water by adjusting pH of raw water to make langelier saturation index less than zero . The antiincrustation corrosion inhibitor(polypropylene acid and organic phosphine) in the discharge of circulating cooling water are beneficial to nanofiltration treament. The concentration of remaining chlorine in the discharge of circulating cooling water should be between 0.5 mg/L and 1.0 mg/L to prevent nanofiltration membrane from damage of remaining chlorine .Operation conditions , e.g. operation pressure , inlet temperature and inlet velocity , have a great effect on nanofiltration separation performance. The suitable operation pressure and inlet temperature are l.OMPa and 30癈, respectively.The factors that influence the service time of membrane are pollution , compaction, hydrolyticity and cocentration polarization of membrane, and its precaution measures are to clean membrane in time and properly , and to choose rational operation pressure, inlet pH, inlet temperature and inlet velocity .The technology of magnetic water treatment has been applied to membrane treatment for the first time and the hypothsis that the magnetic field has an effect on separation performance of nanofiltration membrane has been proposed . By means of the related experiment study and the analysis of its results , a conclusion is drawn that the magnetization can prevent and clean precipitate in the process of nanofiltration. As a result, the pollution of nanofiltration membrane can be slowed down and the service time can be prolonged.After the discharge of circulating cooling water is handled by nanofiltration membrane , its outlet water quality have an advantage over the present compensation water quality of circulating cooling water . This recycling process which is a new and creative application technology in China may bring considerable economic benefit and environment benefit. Its application will have a good future in industry .