Organic contaminants

136 0 0 25 March, 2022

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What are the organic contaminants?

Organic contaminants are all compounds containing a “CHONX” composition and structure. They are highly covalent compounds such as hydrocarbons, halogenated hydrocarbons, sulfurized hydrocarbons, aromatic compounds, etc.

There are compounds of natural origin (sugars, proteins, alcohols, etc.) that are synthesized in the cells of living organisms, and there are also organic compounds that are formed in natural chemical processes such as crude oil and coal.

Organic chemicals can also be synthesized in laboratories and chemical companies. An increasing number of these synthetic organic compounds are being produced. These can include pesticides used in agriculture, plastics, synthetic fabrics, dyes, gasoline additives such as MTBE, solvents such as carbon tetrachloride and many other chemicals. Some synthetic organic chemicals, such as benzene, carbon tetrachloride and vinyl chloride, evaporate easily into the air and are grouped under the category of volatile organic chemicals (VOCs). Methyl tert-butyl ether (MTBE) is a common synthetic organic chemical used for several years as a gasoline additive.

How to treat water for organic matter retention?

The following table shows, according to NOM-127-SSA1-1994, the maximum permissible limits for the organic compounds reported in the standard.

Organic compound.	Value	Units	Treatment
Phenols or phenolic compounds	0.001	mg / l	Adsorption on activated carbon or oxidation with ozone.
Pesticides: Aldrin and dieldrin (separately or in combination)	0.03	µg / l	Adsorption on granular activated carbon.
Chlordane (total isomers)	0.30	mg / l	Oxidation-filtration or adsorption on activated carbon.
DDT (total isomers)	1.00	mg / l	Oxidation-filtration or adsorption on activated carbon.
Gamma-HCH (lindane)	2.00	mg / l	Oxidation-filtration or adsorption on activated carbon.
Hexachlorobenzene	0.01	mg / l	Oxidation-filtration or adsorption on activated carbon.
Heptachlor and heptachlor epoxide	0.03	mg / l	Oxidation-filtration or adsorption on activated carbon.
Methoxychlor	20.00	mg / l	Oxidation-filtration or adsorption on activated carbon.
Methylene blue active substances (SAAM)	0.50	mg / l	Adsorption on activated carbon.
Total trihalomethanes	0.20	mg / l	Aeration or oxidation with ozone and adsorption on granular activated carbon.
Total coliform organisms	2.00	MPN / 100 ml	Disinfection with chlorine, chlorine compounds, ozone or ultraviolet light.

There are compounds called “emerging”, which have the characteristic of not being completely studied to establish a maximum permissible limit in this standard, some examples of these compounds are: pharmaceuticals, hormones, drugs of abuse, personal hygiene products, etc. A great advantage of these compounds when removing them from a water source is that they have a high affinity with activated carbon, this is due to the fact that most of these compounds are highly covalent and carbon adsorbs these types of compounds with great efficiency. Due to this characteristic, adsorption with activated carbon is usually one of the best options for the treatment of these organic compounds.