puricarexfiles: HUMIC SUBSTANCES - Humic substances come from the accumulation and natural chemical reaction of by-products produced by the biodegradation of organic matter. They are commonly present in soils, surface water, sewage, compost heaps, marine and lake sediments, peat bogs, carbonaceous shales, and lignites.

Humic Substances

The drop on water

Humic substances are the end product of decaying organic matter.

Tannin and lignin are organic compounds similar to humic substances.

Tannin is a complex organic compound found naturally in soil and in certain tree barks.

Lignin is a natural compound common in woody plants and trees.

Source

Humic substances come from the accumulation and natural chemical reaction of by-products produced by the biodegradation of organic matter.

They are commonly present in soils, surface water, sewage, compost heaps, marine and lake sediments, peat bogs, carbonaceous shales and lignites.

There are three types of humic substances, which differ slightly in acidity and chemical composition. They are:

- humic acid,

- fulvic acid, and

- humin.

Tannin is abundant in the bark, fruit, and leaves of plant material. Lignin is one of the principal constituents of the woody structure of seed plants.

Tannin and lignin are part of a natural group of organic substances in soil, produced by decaying vegetation.

The main source of humic substances, tannin, and lignin is natural organic material. They may also be present in groundwater due to:

• the proximity to areas underlain by coal

• the dissolution of bark mulch

• buried organic debris such as tree stumps

• the wastewaters of leather and wood-working industries (tannin and lignin)

• pulp and paper mill effluent (lignin)

QUICK FACTS

• Humic substances are the end product of decaying organic matter.

• Tannin and lignin are natural organic substances found in plants and soil.

• Humic substances, tannin, and lignin may be present in well water that is hydraulically connected to surface water, but may also be found in certain bedrock types, such as those containing coal.

• No numerical drinking water quality guidelines exist for humic substances, tannin, or lignin. Their presence may sometimes be inferred from measurement of color and dissolved organic carbon.

• Humic substances, tannin, and lignin may affect the taste, color, or smell of drinking water.

The presence of humic substances, tannin, or lignin in well water may indicate a natural benign source or the presence of other contaminants in the water.

• Several treatment options can reduce the concentration of humic substances, tannin, and lignin in drinking water.

Humic substances, tannin, and lignin are most common in surface water and shallow groundwater hydraulically connected to surface waters or wetlands.

These organic substances may occasionally be found in well water, particularly if the well is not properly constructed.

Maximum Acceptable Concentration for Drinking Water

No numerical drinking water quality guidelines exist for tannin, lignin, or humic substances.

Humic Substances in Drinking Water

Humic substances are not believed to be harmful to human health.

At higher concentrations, humic substances can impart a characteristic yellowish to brownish color in water, and can cause drinking water to have a bitter taste or unpleasant odor.

The odor is not from the humic substances themselves.

Humic acid may stimulate the growth of aquatic micro-organisms, some of which may produce an odor.

The presence of humic substances in drinkingwater may be due to natural organic sources, but may also indicate contamination from surface water sources.

The presence of pathogens or other contaminants present in surface water may cause adverse health effects.

Humic substances can adsorb a variety of organic substances.

Many metals present in drinking water can also react with humic substances in water, which can increase the concentration of metals in the water.

Tannin and Lignin in Drinking Water

Tannin and lignin can impart a yellow or light brown color, bitter taste, and unpleasantodor in drinking water.

The presence of tannin or lignin in drinking water may be from benign natural sources, but could be cause for concern if contaminants present in surface water are also present in well water.

Solutions

If humic substances, tannin, or lignin are suspected or found to be present in well water, it may be due to natural conditions.

Or may mean that the groundwater in the well is under the direct influence of surface water.

To determine whether humic substances, tannin, or lignin are naturally present in the groundwater or if microbial pathogens are able to travel from nearby surface water to the groundwater source, you should:

• have a water quality professional investigate the source of the contamination

• check the bacterial quality of the water

• inspect the well construction If bacterial quality and well construction are acceptable, and there is no evidence of other contamination, treating yourwater is optional.

You may wish to

• Obtain drinking water from an alternate source, such as bottled water or a nearby well that has been tested and found to be safe.

• Install a treatment system to improve the appearance of your water.

Treatment

There are currently no treatment units certified specifically for the reduction of humic substances, tannin, or lignin.

Effective treatment methods for reducing their levels in drinking water include

• activated carbon

• anion exchange

• chlorination/filtration

The best treatment option may depend on the source of the humic substance, tannin, or lignin.

Once installed, re-test your water to ensure the treatment system is working properly.

Maintain the system according to the manufacturer’s instructions to ensure a continued supply of safe drinking water

Considerations

The characteristics of iron, iron bacteria, and humic substances can be very similar in drinking water.

It is important to determine which of these is causing water problems, because the treatment options are very different.

Chlorine can be used to treat iron and ironbacteria, but chlorine added to water containing humic substances may contribute to the formation of trihalomethanes (THMs).

Eliminating humic substances, tannin, and lignin is extremely difficult, especially at higher concentrations.

The presence of humic substances, tannin, and lignin may also affect the efficiency of several other types of treatment units for other parameters.

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