Boron Removal from Waste Water by Ion Exchange

A. There are boron-selective ion exchange resins. I don't have the technical information readily available as I write this but I will get it together for anyone who needs to know more.

You can also put in a total recycle deionization system (non-selective cation and anion resins) and return the water back to the process. The fluoborates will be removed along with all the other ions in the process. Canister rental and off-site regeneration is preferred to on-site regeneration when you have a discharge limitation. You get rid of the discharge problem by letting someone else do the regeneration. Unfortunately this also costs more.

A. Boron can be tricky to remove, especially if you do not know what form it is in. It can be as boron, as boric acid, as borate, or many others. There are several methods to remove boron from waste water, and given your location, I would say that you are likely getting hit with Malaysia B standards, right? If thats the case, then you should look at a capture, concentrate, and haul technology that will get you to the very low standards reliably. I am not aware of any polymers that have successfully been implemented to remove boron. There are specific ion exchange resins that we have used to remove it, and they fair well as long as they are taken care of and the pre-treatment is completed correctly.

A. Majority of what you see will be borate ions. Try contacting your local Rohm & Haas ion exchange resin dealer and ask for XE-243 or it's latest equivalent. You can also use a product from Purolite, S-108. These resins regenerate with sulfuric acid and allow you to crystallize boric acid in high acid concentrations, so no haul off is necessary, and the boric acid can be reused in the process where it came from. Hope this helps.

A. I would not recommend the reuse of boric acid obtained from regenerated ion exchange resin. While it is certainly a novel method of removing borate, the purity of the boric acid is so low as compared to even a moderate purity of technical grade boric acid that you would be looking for trouble in your plating quality. Same goes for metals and metal solutions - they don't even meet the most liberal purity standards required by platers.

The regeneration is a two step process, and requires sodium hydroxide [affil links] to condition the resin to accept borate. If you want to pursue that method, be prepared to have an extra waste stream to treat that is essentially just another cost center.

A. You can achieve this removal by some specialty ion exchange resins with the N-methylglucamine functional group. Capacity will vary according to background salts, and is most dependent on flow rate. Resins can be regenerated by sulfuric acid. Hope this helps.

A. Ion exchange will work, using the selective resins mentioned in a previous response, but the capacity is very low: approximately 2 ounces of boron per cubic foot of resin at exhaustion. It may be your best method, but it is a rather expensive resin, and you would exhaust 80-120 cubic feet of resin per day.

One of the problems will be what to do with the large waste volume that this would generate. There are a couple of references that suggest that the sulfuric acid can be reused several times and saturated with crystallization of the boric acid, but the last time I tried to find anyone doing this, I was unsuccessful.

If this is wastewater, another possibility is to recycle this water, by Ion exchange if the Total Dissolved Solids concentration is low, or by HERO reverse osmosis if the TDS concentration is high. Conventional RO systems will not have good boron rejection, but at a high operating pH, the rejection is > 90%. You would still have a boron containing waste, but in a much more concentrated and lower volume.

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A. Hi,

For boron removal there are some methods.

E.g., there are selective ion exchange resins (such as [brand names deleted by editor]).

Ion exchange is the method of choice, when you don't have to remove other components. Otherwise membrane processes like Nanofiltration or reverse osmosis might be helpful, too.

A. Boron removal can be achieved by commercially available ion exchange resins with the N-Methylglucamine functional group (a couple of products I know of are [brand names deleted by editor]). Though a weak base anion backbone, resin is regenerated with sulfuric acid, and boric acid is recovered as a by-product by crystallization. Hope this helps.

A. [brand name deleted by editor] resin can remove the boron.

Ed. note: If readers wish to use IX resin for boron removal, please talk to vendors about resins as described by Juzer. Sorry, we can't print brand names ( huh? why?)

A. Both boron selective medias, and also close-looping the boron containing flow in order to remove boron from discharges can be done. There are boron-selective resins that can be used to remove boron to < 1 mg/L, but they are very expensive and have a low capacity.

If the boron is > 25% of the total anion present, then a strong base resin may be a better choice.

It is difficult to crystallize the boric acid as you suggest, because it first needs to be supersaturated. The solubility of boric acid vs. temperature would appear to make this easy, but the low capacity of the boron-selective resin makes this difficult.

A. Selective resins for boron removal are available. They are extremely efficient and produce a residual boron level of a few ppb in the treated water.

They are applicable for drinking water treatment as well as industrial applications.

A. There are very few ways to remove boron from water to low concentrations. If you cannot find an alternative chemistry that does not contain boron, one way to remove boron is by a selective ion exchange resin with n-glucamine functional groups. This resin can remove boron to less than 1 mg/l. However, the resin is very expensive and has a low capacity before it becomes exhausted and must be regenerated.

In most cases, it is preferable to go to the source of the boron, and put in some kind of closed-loop recycling system. Even if there is a waste from this system, it will be a small volume with a high concentration, so even if you can only treat it down to 30 mg/l, there may be enough other dilution water to allow you to meet the 4 mg/l limit.

There are no USEPA limits for boron, but there are State and local limits in many parts of the country. Some of these are as low as 1 mg/l.

Good luck in finding a solution to your problem.

A. This is a difficult problem because, as far as I know, there is no effective way to precipitate boric acid to this concentration or below it.

There are very expensive Ion Exchange resins that can selectively remove boron from wastewater. These have very low capacity, but can reduce boron to < 1 mg/L.

Your best course of action is to minimize this boron containing waste flow at the source, before it mixes with other rinses. My advice is to recycle your nickel rinses using a combination of dragout recovery rinses and supplemental evaporation. This also concentrates impurities in the bath, so it is not a perfect solution.

Another potential solution is to use the dragout recovery method for 80-90% recovery, and then to recycle the final one or two rinses with Ion Exchange. The anion resin regenerations will contain the borates, so they must be hauled off site for disposal somewhere where they don't have the same boron limit.