• 2025-07-22

Remove tannin from water

What are tannins?

Tannins are natural organic compounds formed by plant decomposition and are commonly found in surface water sources and shallow wells in coastal areas and low altitudes. Water flowing through areas rich in humus dissolves plant particles, giving it a characteristic tea-colored appearance. This color is often mistaken for a pollutant, but is actually caused by tannins in the water.

Tannins can give drinking water an acetic or sour taste, along with a musty or earthy odor. Although they increase the color of water and can stain it when washed, they are not a health risk in themselves and only affect the sensory properties of the water.

Private wells can also be affected by tannins. When groundwater flows through humus layers or tannin-containing soils, these substances migrate into the well water reservoir.

Challenges

As a natural product of plant decomposition or flowing through peatlands, tannins can give water a dark yellow to tea-brown color and leave yellow stains on surfaces they come into contact with. Although it is safer to drink, it can cause special problems: in addition to sensory discomfort, its damp grassy smell and obvious sour taste affect the user experience, and its dye-like characteristics may also cause fabrics to fade.

The innovation of resin materials in the past decade has significantly improved the technical capabilities of the water treatment industry to remove tannins.

Solution

Tannin removal technology

The effect of tannin removal is significantly affected by the characteristics of regional vegetation, and targeted processes need to be selected. The current mainstream technologies include:

Ion exchange system

As the preferred solution for removing tannins from drinking water, the system needs to cooperate with the pretreatment process to ensure operating efficiency. Pre-softener, multi-media filter, ultraviolet or ultrafiltration device can effectively prevent resin contamination and improve the adsorption rate of tannins. It is crucial to regenerate the resin with salt solution and sodium bicarbonate regularly, otherwise the failed resin may cause odor in the water.

Reverse osmosis system

This technology uses the high molecular weight characteristics of tannins to achieve efficient interception. It should be noted that tannins are prone to membrane contamination, and pretreatment maintenance needs to be strengthened. The advantage is that the system has a strong adaptability to fluctuations in influent water quality.

Oxidation process

Oxidants such as chlorine can effectively decompose tannins, and the optimal dosage and contact time need to be determined through beaker tests. Specific activated carbon devices can also reduce tannins to acceptable levels.

Advantages

The following customized solutions are recommended:

Industrial/commercial softening system (pretreatment package)

Dedicated deionized water treatment system (core treatment unit)