Study On The Removal Rate Of Total Hardness,Ca²⁺ And Mg²⁺ In RO

The current water treatment system, membrane technology has been widely used. The reverse osmosis technology is the most successful application in all kinds of membrane separation technology in recent years. It can produce about a third of reverse osmosis concentrate water when use the reverse osmosis membrane, then makes the production of the reverse osmosis concentrated water quickly increase. It contains a lot of difficult biodegradable organic material. And the high salt content is most difficult to reuse and harmlessly dispose, and becoming the biggest obstacle for the further recovery of RO concentrate. It not only damage the ecological environment but also harmful to human health.The ion exchange characteristics of activated zeolite and the adsorption characteristics of activated alumina are studied to remove the total hardness, Ca2+and Mg2+in RO. It can improve the reverse osmosis, and reduce the direct emissions of RO.The activated zeolite is a kind of effective method to remove the total hardness, Ca and Mg2+In the static experiment condition, the single factors include particle size, dosing quantity, time, oscillation speed and pH are discussed. At the same time, the combining orthogonal test discussed the pH, dosing quantity and time. The results show that pH is the most major factor. With the increase of pH, removal rate increases. The removal rate of total hardness, Ca2+and Mg2+increases quickly when the pH in2-4and10-13.While the removal rate of total hardness, Ca2+increases slowly, the removal rate of Mg2+is almost the same. The particle size is smaller, the removal rate of total hardness, Ca2+and Mg2+is higher. With the increase of the dosing quantity, the extension of time, the oscillation speed increases, the removal rate of total hardness, Ca2+and Mg2+are improved, and gradually achieve balance in a certain range condition. The orthogonal test data are analysised show pH=8, dosing quantity for3g every100ml, time for100min is the best conditions.The activated alumina as a new adsorbent to remove the total hardness, Ca2+and Mg2+, especially for calcium is best. Its adsorption is influenced by dosing quantity, adsorption time and pH.With the increase of the dosing quantity, the extension of adsorption time, the removal rate of the hardness, Ca2+and Mg2+gradually improve, and tend to be stable. The best dosing quantity, adsorption time and pH respectively is6g every100ml,150min and10.As the two different materials to remove the hardness, Ca2+and Mg2+,the activated zeolite and activated alumina are cheap, economic,feasible and no secondary pollution. They can be the promising methods of water treatment.