Wastewater generated during the painting process mainly includes pretreatment wastewater, paint wastewater, and spray paint wastewater. Pretreatment wastewater comes from processes such as degreasing and phosphatizing the surface before painting, containing emulsified oil, surfactants, phosphates, heavy metal ion fillers, solvents, etc.

Painting wastewater is generated from the cleaning process of floating paint and bath liquid adhered to painted parts, typically including negative ion wash water and ultrafiltrate; its composition is identical to that of the bath liquid, containing water-soluble resins (such as epoxy resins, phenolic resins, etc.), pigments (such as carbon black, iron oxide red, lead and mercury, etc.), fillers (such as titanium dioxide, talc, etc.), solubilizing aids (such as triethanolamine, butanol, etc.), and a small amount of heavy metal ions.

The wet spray booth uses water to wash the air in the painting area, transferring paint particles and organic solvents into the water, forming wastewater. The wastewater contains a large amount of paint particles, whose water quality is determined by the paint material (mainly nitrocellulose, amino, alkyd, and epoxy paints) and solvents (such as ethanol, acetone, fats, and benzene derivatives), as well as cosolvents.

Painting wastewater treatment water quality analysis:

Coating, water quality varies depending on the materials used, with a variety of formulations for degreasing solutions alone, and an even greater variety of paint types.

Two, emissions are irregular. Apart from the continuous overflow discharge of water from some washing operations, the wastewater or waste liquids from the painting line are mostly intermittently and concentratedly discharged.

Three, there are significant fluctuations in water quality and quantity, with no discernible pattern.

Four: Contains many toxic and harmful substances.