Fine Chemical Wastewater Treatment

Fine chemical wastewater is a typical recalcitrant industrial organic wastewater generated in industries such as dyes, pesticides, and pharmaceuticals, exhibiting high COD, high salt content, and high chromaticity. The pollutants in the wastewater are mostly complex, water-soluble, and difficult to biodegrade organic compounds with high salt content, which have inhibitory effects on microbial growth in the biochemical system, making the treatment of this type of wastewater difficult. The following table provides a comprehensive comparison of the main governance methods used.

Table 1 Comparison of Governance Methods

Based on the characteristics of different organic compounds in wastewater, a series of adsorbents have been developed through specific functional group modification and pore size control techniques. By relying on van der Waals forces, hydrogen bonds, acid-base, coordination and other forces, as well as high specific surface area, the adsorbents can selectively adsorb organic compounds in wastewater without being affected by salt, separating organic compounds from salt. The adsorbents have high adsorption capacity and fast adsorption speed.

Adsorbents that are saturated with adsorption can be desorbed using relevant regenerants, and the desorbed organic matter can be further recovered based on specific conditions. After detachment, the adsorbent regains its adsorption capacity, with high strength and long service life.

The adsorbed water can be directly discharged or connected to the pipeline network according to the situation. Alternatively, it can be further treated with physical and chemical technologies such as oxidation, and then discharged or connected to the pipeline network to meet the standards. Or sodium chloride brine can be used as brine for chlor alkali production. Alternatively, the salt content can be recovered through evaporation crystallization and sold as a byproduct.

Case 1

The ammonium chloride wastewater from a chemical plant in Henan Province has a COD of ≤ 50000mg/L. Treatment requirements: COD ≤ 15000mg/L, colorless appearance, for subsequent recovery of ammonium chloride. Our company adopts adsorption concentration process, and the effluent COD is less than 15000mg/L. The effluent enters the evaporation system to recover ammonium chloride.

Table 2 Water Quality Status

Figure 1 Treatment effect diagram (raw water, effluent)

Case 2

The sodium sulfite wastewater from a chemical plant in Hunan has a COD ≤ 35000mg/L and a chromaticity of about 150. The treatment requirements are: COD ≤ 8000, colorless appearance, and subsequent recovery of sodium sulfite. Our company adopts adsorption concentration process, with effluent COD below 7500mg/L. The effluent enters the evaporation system to recover sodium sulfite.

Table 3 Water Quality Status

Figure 2 Treatment effect diagram (raw water, effluent)