The Impact of Organics and Bromide

Naturally occurring organic matter (NOM) such as humic, fulvic and tannic acids that are present in water being disinfected can potentially result in the formation of a variety of toxic byproducts. These include trihalomethanes (THM) and haloacetic acids (HAA5) as well as bromomethanes and bromate. The levels of THM, HAA5 and bromate are regulated in many countries. In the United States the maximum allowable concentrations are 80 ppb THM, 60 ppb HAA5 and 10 ppb bromate.

To remove organic matter, collectively known as total organic carbon or TOC, Purolite offers a variety of brine regenerable anion resins. The degree of reduction depends on the specific nature of the TOC as well as the choice of resin, its porosity, contact time and resistance to irreversible fouling. As a result, our product offering includes acrylic strong base anion (SBA) macroporous resin Purolite A860, gel-based SBA Purolite A850, as well as styrenic SBA macroporous resin Purolite A502P. For more difficult-to-treat systems that have both colloidal and dissolved TOC, we recommend Tanex™, a proprietary blend of resins, inclusive of a patented scavenger resin for colloidal particulate matter removal.

Along with organics, an increasing number of raw water supplies are showing higher levels of bromide. The result of disinfecting water supplies containing both organic matter and bromide can potentially lead to the formation of disinfection byproducts such as bromomethanes and bromate. Purolite Bromide Plus/9218 is a proprietary bromide ion selective resin that is regenerable using sodium chloride.

Proper system design is important for good performance in all cases. With the help of our technical experts, we can help custom design the treatment plant. For example, if the water quality calls for the removal of bromide and organic matter, a common regenerant can be used, e.g., chloride or bicarbonate. This simplifies the design while allowing for a reduction in capital and operating costs.

The advantages of our ion exchange resins for organics and bromide removal include:

• Low operating cost with simple system design, requiring minimum operator attention.

• Multiple brine reuses in order to minimize the volume of waste water. Layering of anion resin on top of cation softening resin to help reduce footprint and capital and operating costs.

• Multi-contaminant design approach. It is possible for simultaneous removal of organics and bromide with other contaminants.​