4 Cases to Solve the Problem of 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 ammonia nitrogen, and high chromaticity. The pollutants in the wastewater are mostly complex, toxic, and difficult to biodegrade organic substances. The salt content in this type of wastewater is generally at least 5%, and high ones can be over 20%. The high salt content has an inhibitory effect on the growth of microorganisms 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.

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 rate.

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. Or further processed with physical and chemical technologies such as oxidation and biochemistry, and 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 production wastewater from a fine chemical plant in Shandong has a COD of around 60000mg/L. It is required to remove COD and chromaticity from the raw water. After adsorption treatment by our company, the effluent COD is less than 30000mg/L and enters the evaporation system to recover salt with appearance and purity that meet the requirements of salt recovery.

Table 2 Water Quality Status

Figure 1 Treatment effect diagram (raw water, effluent)

Case 2

The production wastewater from a chemical plant in Shandong mainly contains poly (methyl ether) with a COD of around 50000mg/L. It is required to remove COD and ensure that the effluent meets the requirements of the biochemical system. After adsorption treatment by our company, the COD is around 12000mg/L, and the biodegradability is significantly improved, meeting the requirements of subsequent biochemical systems.

Table 3 Water Quality Status

Figure 2 Treatment effect diagram (raw water, effluent)

Case 3

The treatment requirements for the production wastewater of methyl ortho aminobenzoate in a factory in Jiangxi are: the effluent should be connected to the park's pipeline network and the salt should be recovered. After our resin adsorption treatment, combined with subsequent evaporation crystallization, it can meet the customer's relevant requirements. The adjacent aminobenzoic acid in the wastewater is effectively recovered, and the adsorbed water evaporates to meet the requirements of the park takeover. The salt can be recovered as a by-product.

Table 4 Water Quality Status

Figure 3 Treatment effect diagram (raw water, effluent)

Case 4

The production wastewater of a pesticide enterprise in Anhui mainly contains acetic acid, with a COD of about 8000mg/L. The treatment requirements are: COD ≤ 1000mg/L. After adsorption treatment by our company, the effluent COD is within 1000mg/L. This is used for subsequent entry into the biochemical system to reduce COD load and improve biochemical treatment efficiency.

Table 5 Water Quality Status