Inorganic and organic chemicals industry involves the production of a broad range of chemicals. Large volume organic chemicals industry covers a large range of chemicals and processes mostly taking refinery products and transforming them into commodity chemicals or bulk chemicals. The chemicals produced in the industry are not directly used by the consumers but used as raw materials by other industries.

Wastewater sources of organic chemicals manufacturing are mainly; storage tank overflows, mixing vessel overflows, mother liquors from processing products, wash water from purification of products, vapour condensates, quench water, wastewater from the treatment of exhaust gases or flue gas treatment, wastewater streams from rinsing and cleaning, contaminated water from vacuum generation, spent neutralization agents, spills and leakage. The main polluting parameters are; organic matter expressed as COD, TOC, BOD5, and VOC; oil and grease; SS; and pH. Nitrogen, phosphorus, cyanide, heavy metals, chloride, bromide, and sulphate also exist in the wastewaters. Organic matter content in the wastewater varies in a wide range. COD values of wastewaters are between hundreds to thousands mg/L. The main aspect of water pollution of organic chemicals industry lies in the toxic pollutants.

Ozone is one of the most commonly used oxidants for degradation of organics. Although, direct ozonation has a moderate power, ozonation is a suitable oxidation method for partial oxidation or increasing the biodegradation of organic matter. However, ozone has proven to be very effective on some substrates such as phenol, even complex organics such as 3,4-dichloro-but-1-ene which is present in synthetic rubber process wastewaters. In one instance, pre-ozonation of 2,4-dichlorophenol increased the BOD5/COD ratio from zero of the original solution to 0.25 at the point where all initial compound has been removed. Other AOP methods can also be employed for the same.