Study On Freezing Desalinization Technology Of High Concentration Seawater

The high concentration seawater which produced after desalination is double concentration compare to ordinary seawater. The size of emission is almost same as the size of yield of freshwater. With the development of desalination industry, it has bought pollution problems and ecological damage of the marine more seriously. The common treatment is to discharge the brine to the sea directly that not only damages the fragile environment, but also becomes a restrictive factor of desalination industry. Meantime countless of chemical resources in seawater were lost without utilization. It is necessary to study the desalinated seawater and solve the pollution issues to make it be positive to the environment and the shortage of resources.Our studies focus on freezing centrifugation to dispose the high concentration seawater besides the various methods of desalination. The mechanism of freezing desalinization technology of high concentration seawater and effect of centrifugal rotational speed on high concentration seawater ice by centrifugal experiments are studied at the laboratory. Under different condition of time or speed of the centrifuge, the freezing high concentration seawater is desalted into two parts that including the freshwater-ice and higher concentration brine.The experimental results show that the effect of rotational speed variance on the desalination and its efficiency are obvious under the same experiment condition. The desalination removal rate value is above 88.5% and the removal of Ca2+ and Mg2+ is above 87.4% under different rotational speed. The desalination removal rate value increases with the raise of rotational speed. When the centrifugal rotational speed is 4000 r/min, the rate of desalination of high concentration seawater ice turns maximum. But rate change is getting small. The impact of raising rotational speed is not obvious towards desalination removal rate and the removal of Ca²⁺ and Mg²⁺. The results of continuous experiment of desalting show that the ice salinity removal rate is 99.0% after first freezing treatment. Compare with the original desalinated seawater, the content of main ion of K⁺Ca²⁺ Na+ Mg²⁺ is only 3% after first freezing treatment. And the salinity of brine is 3.3 times as the original desalinated seawater. The effect of removal of trace elements is different by the freezing desalination technology. The removal rates of Cu,Co,U are 94.3%,98.4% and 60.6%. By every steps of the experiment, the ice of low salinity and low content is left and the amount of ice was 2/3 of the original amount of desalination seawater.