Study On Pretreatment Process Of Ultrafiltration In Brine Refining

Soda ash is one of the important basic chemical products. Soda ash industry is developed in China, ammonia soda and Hou’s process are the production technologies of soda ash, the brine production materials is needed to be refined and the traditional ammonia soda brine refining process such as chemical precipitation method with shortcomings that the process is more complex and the cost is more higher. Membrane water treatment technology as a new type of water treatment technology in the 21st century has received the widespread attention. Nanofiltration membrane technology is recently widely used in the salt water purification, which needs pretreatment.Ultrafiltration membrane technology is one of the most widely pretreatment technology applied in the nanofiltration membrane and reverse osmosis membrane technology. Continuous membrane filtration (CMF) is a commonly used process of ultrafiltration with many engineering examples. Engineering benefit maximization and membrane fouling are the main problems needed to solve.Using" ultrafiltration-nanofiltration" double membrane to purify underground brine which is the raw materials of ShanDong Ocean Chemical Group LTD.’s ammonia alkaline soda plant. This paper mainly studied the CMF process operation in the underground brine, examined the trend of TMP with different working conditions, water quality, chemical maintenance cleaning effect, the optimization selection and equipment operation stability. Also examined the chemical maintenance cleaning reagent membrane silk on the scanning electron microscopy and on energy spectrum.In the CMF process, the membrane flux of the two operation conditions were respectively 40L/m2.h and 50L/m2.h. Through comprehensive analysis and comparison, the process one is better than the process two. The average value of SDI15of CMF process water is 2.3, which can meet the requirements of the nanofiltration; The average TOC removal rate is 60%; The turbidity is below 0.1 NTU. The stability of CMF process system is great, which can be used as a pretreatment technology of nanofiltration.The effect of cleaning of hydrochloric acid was studied and the membrane cleaning method was optimized, analyzing the silk before and after using the optimization cleaning methods on scanning electron microscopy (sem) and energy spectrum analysis. The results showed that cleaning effect of the hydrochloric acid is better; "1000 PPM+1000 PPM" sodium hypochlorite sodium hydroxide is the optimized cleaning method, whose cleaning effect is the best; The results of scanning electron microscopy (sem) and energy spectrum analysis show that the cause of membrane pollution are such as Ca, Fe, Si salt inorganic salt, the optimized washing process can fully wash away the pollutants, membrane water flux can be recovered to 414 L/m2.h; During the membrane cleaning process, the sodium hypochlorite can oxide some organic pollutants of film surface; Sodium hydroxide removes the organic matter; oxalic acid can complex inorganic salt ions; Using the following cleaning method can achieve the best cleaning effect:(1) Using NaClO and sodium hydroxide can better satisfy the maintenance cleaning; (2) Using different detergent cross cleaning on a regular basis (3) The high concentration of chemical cleaning for pollution is serious, or need a higher membrane flux.