Chemical fiber fabric printing and dyeing wastewater mainly includes:

Scouring wastewater, alkali reduction wastewater, dyeing wastewater, washing wastewater and so on.

Scouring wastewater:

The wastewater is alkaline. The wastewater mainly contains scouring agent, degreasing agent, alkali, etc., the amount of water is less and the concentration of pollutants is high.

Alkali reduction wastewater:

It is the waste water produced by the polyester imitation silk alkali reduction process. The wastewater mainly contains terephthalic acid, ethylene glycol and other polyester hydrolysates, of which terephthalic acid content is as high as 75%. The wastewater is strongly alkaline, and the PH can reach more than 12. The concentration of organic matter is high and it is difficult to biodegrade.

Dyeing wastewater:

Wastewater mainly contains dyes, levelling agents, auxiliaries and so on. The general color is high, the amount of water is large, the concentration of pollutants is high, and the biodegradability is poor.

Washing wastewater:

wastewater mainly contains acetic acid, soap detergent, softener, fixing agent and so on. Generally neutral, low chroma, large amount of water, low concentration of pollutants.

Process design

Process design introduction

The comprehensive wastewater includes scouring wastewater, alkali reduction wastewater, dyeing wastewater, washing wastewater, etc.

Alkali reduction wastewater is treated by acid precipitation process. The alkali reduction waste water first goes through the mechanical grating to remove most of the suspended matter and enters the alkali reduction waste water regulating tank. Then through the lifting pump to the acid evolution reaction tank, adding acid for acid evolution reaction. Under the condition of pH 3 acidic, terephthalic acid (TA) can be precipitated in the acidic solution, separated from the wastewater, and then recycled by press filtration. The filtrate enters the comprehensive wastewater conditioning tank.

The comprehensive wastewater first enters the mechanical grille to remove most of the suspended matter and enters the comprehensive adjustment tank. Then it is lifted to the initial settling reaction tank by the lifting pump, and the pH value is fine-tuned. At the same time, chemicals are added to make SS and some colored substances in the sewage undergo physicochemical reaction and flocculation precipitation, and most of them are removed in the air flotation tank. The supernatant of the initial sedimentation tank enters the hydrolysis tank and the aerobic tank. The supernatant from the primary sedimentation tank flows into the acidification tank and the aerobic tank. The macromolecular organic matter which is difficult to biodegrade in the wastewater is further decomposed into small molecular organic matter pollutants which are easy to degrade through the hydrolysis acidification of the hydrolysis tank, and the biodegradability is improved. Through the action of aerobic microorganisms in the aerobic tank, most of the pollutants are degraded and the sewage quality is further purified. After the sludge water is separated in the secondary sedimentation tank, the supernatant flows to the mixed sedimentation tank by itself. Part of the sludge is returned to the activated sludge tank through the sludge return pump, and the remaining sludge is discharged to the sludge thickening tank. Coagulant is added to the reaction area of the mixed sedimentation tank, the effluent enters the mixed sedimentation tank after stirring reaction, and the pollutants in the effluent are further reduced after coagulation reaction. The supernatant of the mixed sedimentation tank flows into the outlet tank for metering and discharge, and the sludge is discharged into the sludge thickening tank.