Relevant requirements for using waste brine in ion-exchange membrane caustic production
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This post was last edited by sunjl1981 on 2013-1-7 00:05. Our company plans to use some of the waste brine to produce ion-exchange membrane caustic soda; are there any requirements regarding the organic content and salt content? # hcbbs
It is recommended to first send it to the salt-removal process, and then convert it into qualified brine before feeding it into the electrolyzer
Can organic substances evolve salt-producing processes? Can current saltwater purification processes remove organic substances?
Regardless of the type of brine used as raw material for ion-exchange membrane caustic production, it must meet the uniform requirements for ion-exchange membrane caustic production before being fed into the process. If it does not satisfy the purification standards, it cannot be used as a primary raw material for caustic production.
The ammonia nitrogen content must be strictly controlled, with a value of less than 2 mg/l on a nitrogen basis.
With the goal of keeping the TOC in the primary brine below 50 PPm, I also wonder if the brine in question is intended to be fed directly into the primary brine tank without going through any pretreatment Otherwise, why would they ask about the salt content? Why not proceed with saturation treatment?
Our company utilizes treated waste brine by feeding it into the primary brine process before it enters the production system; however, the organic substances contained in it can cause certain damage to the resin in the resin towers.
There are many methods and requirements for removing various inorganic substances during the purification of saltwater, but few exist for organic substances. Who can state the requirements for organic substances as well as the methods for removing them?
Organic matter is a rather troublesome issue
The salt content in your waste brine is quite high – it reaches a concentration of 300±5 g/l. That’s why you focus only on impurities. If you go for desalination, I believe appropriate treatment measures are available; free chlorine can remove organic matter.
Ammonia nitrogen must be strictly controlled, and free chlorine in organic matter should be controllable; if not, other processes need to be employed for control
Organic matter in waste brine has a significant impact on the electrolyzer and membranes, while there are many ways to remove ammonia nitrogen; therefore, ammonia nitrogen is not a major issue – levels of 5 ppm can be handled. However, removing organic matter is a real problem. As mentioned earlier, the TOC level needs to be reduced to a certain threshold, and as for what level is considered acceptable, it depends on the capacity of your system; there is no universal standard.
The removal of organic substances from saline water relates to the issue of saline organic wastewater, and there are many discussions on this topic in Water World and Sea Rivers as well. You need to choose the appropriate method based on the type and concentration of organic substances in your brine; these methods include flocculation, hypochlorite oxidation, advanced oxidation (Fenton’s method, UV method), iron-carbon oxidation, electrolysis, etc.