Surfactants are classified into anionic, cationic, and non-ionic types and are widely used in various industries such as fiber washing, dyeing and printing, papermaking, and mechanical processing. In the production wastewater of nitrile rubber medical gloves, there are high concentrations of anionic surfactants (such as sodium alkylbenzene sulfonate) generated during leaching and rinsing processes, as well as emulsified colloids, auxiliaries, oils, and other organic compounds. Additionally, the wastewater contains high levels of nitrate and hardness (due to the consumption of calcium nitrate coagulant). These organic compounds are difficult to biodegrade and tend to accumulate on the surface of activated sludge, inhibiting microbial activity. When the concentration of anionic surfactants reaches a certain level (15 mg/L), it significantly impacts the performance of the aeration tank's biological treatment and the sedimentation separation efficiency of the secondary clarifier. This is because surfactants have the characteristic of reducing the surface tension of liquids by aggregating at the liquid-gas interface.

The characteristics of such wastewater include high biotoxicity, low B/C ratio, poor biodegradability, poor sedimentability, high nitrate nitrogen content, and high hardness. For example, the production wastewater from the nitrile rubber medical gloves project at Shandong Luffy Medical Industrial Park amounts to 6,000 tons per day, with the following treatment process: collection/adjustment tank → M⁺FLO primary sedimentation tank → DN denitrification tank → aeration tank → secondary clarifier → M+FLO sedimentation tank for deep treatment → discharge/regeneration and reuse. The water quality before and after treatment in the M+FLO primary sedimentation tank is as follows: COD = 390/250 mg/L, SS = 310/12 mg/L, anionic surfactants = 45/13 mg/L. The water quality before and after deep treatment in the M+FLO sedimentation tank is: COD = 129/90 mg/L, SS = 50/5.0 mg/L, anionic surfactants = 5.0/0.3 mg/L (Note: The M+FLO sedimentation tank uses the magnetic flocculation water purification system from Qingdao Pacific Chemical Equipment Co., Ltd.).

In the deep treatment unit of the M+FLO sedimentation tank, the addition of alkali, Na2CO3, CO2, LDH, and TMT15 can effectively remove heavy metals, fluorides, silica, hardness, sulfate ions, and other salts, meeting the pre-treatment requirements for reverse osmosis membranes or reuse/discharge standards (including total salts/TDS). The effluent turbidity can be reduced to below 1.0 NTU.