Chemical risk in water treatment?

Industrial or domestic worn water (presence of hydrocarbons, detergents, acids, bases or toxic agents in the case of the industrial worn water) is first of all collected in a complex decontamination network in order to be treated in a purification station before finally being rejected into the natural environment. The plants specialized in the treatment of worn water are today compact, covered, deodorized and also automated.
From the entry of the worn water in the factory until its rejection in the natural environment, various stages are met between the first initial treatment and the final purification.

Consequently, the permanent or occasional personnel working in these factories can be exposed to several types of risks, such as a significant chemical risk for example.
Added to the risk of an accidental toxic contamination of the effluent, risks can also be noticed during the use of the chemical products needed for the water purification (improvement of the impurities separation by chemical agents additions) and the mud treatment (decrease of both fermentation ability and odours by chemical treatment).
A last problem is linked to the presence of polluting gases generated by these treatments.

Reactive products

The development of the purification techniques caused a notable increase of the number of chemicals used : chlorine, lime, iron chloride, soda, bleach, varied flocculating agents, sulphuric acid, methanol…
Each one of these products can involve specific risks and especially the risk of chemical burn following an ocular or cutaneous exposure.

Generated products

The polluting agents met in the water treatment factories are numerous : hydrogen sulphide, mercaptans, ammonia, amines, aldehydes, ketones, organic acids, carbon dioxide, carbon monoxide…The major risk is linked to the fermentation gas : the hydrogen sulphide, really hazardous toxic poison.

Most exposed working places

• First treatment : desanding pool, grease remover
• Chemical treatment
• Primary sedimentation tank and mud wells
• Mud dehydration systems or rooms (pressing filter, centrifuge)
• Thickeners
• Maintenance and cleaning (pumps handling, cleaning)

As the current tendency consists in building covered factories in order to get the neighbourhood out of their harmful effects, the chemical risk (added to the problems of noise, odours, moisture and lack of visibility on the outside) linked to the generation of nocive and toxic chemical gases is then all the more alarming.