Water-based inks have almost no VOCs emissions due to safety and environmental protection. At present, the application range of water-based ink is more and more extensive, especially in the human skin contact items, such as books, magazines, corrugated paper and other printed matter, as well as the packaging printing of alcohol, tobacco, medicine, cosmetics, children's toys, and milk and beverage food grade packaging printing. In the production and printing of water-based ink, due to equipment cleaning and other reasons, it will inevitably produce wastewater. Because these wastewater contains a small amount of chemical auxiliaries, if it is discharged directly, it will pollute the environment. In order to make the use of water-based ink more environmentally friendly, it is necessary to do some treatment of these wastewater.
 
  First of all, let's take a look at the characteristics of water-based ink wastewater.
Although the water-based ink itself and the printed products are safe enough and environmentally friendly, a lot of additives are needed to assist printing in the printing process, such as organic pigments, azo pigments, phthalocyanine pigments, nitro pigments, lake pigments, VAT pigments, nitroso pigments, heterocyclic pigments and other types of pigments. In addition, it also contains more than ten kinds of additives such as stabilizer, defoamer, blocker, surfactant and preservative. The wastewater produced by water-based ink is weakly alkaline, contains some organic matter, high chroma, low BOD/COD ratio, and needs to be treated to meet the "Comprehensive sewage discharge Standard" (GB8978-1996).
 
  Here are the specific implementation measures:
 
  1. Adjust the pH, concentrate the workshop ink wastewater to the underground sump, lift it once to the acid evolution tank, add sulfuric acid to the acid evolution tank, and adjust the pH value to 2.0~3.0.

  2. Filter: The acrylic resin dissolved in the wastewater is converted into a solid, precipitated from the wastewater, filtered through the sand filtration tank, filtered out the liquid, and removed the solid matter, precipitation of acrylic acid, the CODcr of the filter water can be reduced to about 1500mg/l, the wastewater after acidification and slag removal flows into the middle tank, because the pH value of the wastewater at this time has been reduced to 2.0~3.0. Subsequent treatment is more clear, this hydrolysis acidification process is mainly used for organic matter concentration, solid suspended solids are higher wastewater, is a more important step in the whole process.

  3. Degradation: If the solid suspended matter in the water is high, the hydrolytic bacteria will capture it through the extracellular mucosa, and use external enzymes to hydrolyze it into molecular fragments and then enter the intracellular metabolism, incomplete metabolism will degrade the solid suspended matter into soluble organic matter, and the water quality will become clear. Hydrolytic bacteria hydrolyze organic matter, so that organic matter covalent bond break bond, release bond energy, so as to use this bond energy to complete life activities.

  4. Neutralization and precipitation: The wastewater is then raised to the neutralization sedimentation tank, the pH is adjusted to 8.0-9.0, and PAC (polyaluminum chloride) and PAM (polyacrylamide) are added at the same time. Under the action of PAC and PAM, the wastewater coagulates and forms a large number of alum flocs. After treatment, the sludge is settled by secondary sedimentation tank.

  After these operations, the wastewater generated in the production process basically meets the discharge standards. Leave a clean sky for future generations.