Industrial Wastewater and Treatment Plant (EDAR)
Wastewater from an industrial activity that is discharged to the sewer or the environment; the EDAR is the wastewater treatment plant that treats it.
An EDAR (wastewater treatment plant) receives water from the sewer and treats it in stages: a pretreatment that separates coarse solids, sand and grease; a primary settling treatment; a secondary biological treatment, in which microorganisms break down the organic matter; and, where necessary, a tertiary treatment of filtration, nutrient removal or disinfection. Biological treatment works well with biodegradable organic matter, but it can be affected by extreme pH values, excess oils and grease or substances toxic to the biomass.
That is why industrial discharges are subject to authorisation. When the discharge goes to the sewer, the limits are set by municipal by-laws or the body that manages the sewerage system; when it goes directly to a public watercourse, the authorisation is granted by the river basin authority. The usual parameters are pH, temperature, suspended solids, COD and BOD5, oils and grease, nitrogen, phosphorus and certain specific substances. Many industries need their own pretreatment before discharge, such as grease separators, pH neutralisation, homogenisation or physico-chemical treatment.
In industrial cleaning, the discharge may contain residues of alkaline or acid detergents, surfactants, disinfectants and the soil removed. Adjusting the dose, neutralising solutions before discharging them when necessary and not discharging concentrated products helps to comply with the limits. Product residues and contaminated containers are not a discharge: they are managed as waste, in accordance with section 13 of the safety data sheet.
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