Common treatment methods for pharmaceutical and chemical wastewater

With the rapid development of the pharmaceutical industry, the discharge of pharmaceutical and chemical wastewater continues to increase, causing an increasing burden on the environment. Meanwhile, pharmaceutical and chemical wastewater has the characteristics of high salinity, difficult degradation, and complex composition, making it difficult to treat. In the governance process, adopting a single conventional governance method often fails to meet governance standards. Therefore, in response to the use of pharmaceutical and chemical wastewater treatment methods, further scientific solutions should be proposed to improve the level of wastewater treatment.
Basic characteristics of pharmaceutical and chemical wastewater
1. High content of inorganic salts: In the pharmaceutical and chemical manufacturing process, a large amount of acid-base substances are involved, and a neutralization reaction will produce a large amount of inorganic salts. The total salinity in some wastewater exceeds 100000 mg/L. The concentration of inorganic salt ions such as CI and SO2- in pharmaceutical and chemical wastewater is very high, and the high content of inorganic salt ions will limit the growth of microorganisms in the water. Research has shown that when the CI - content in water exceeds 2000 mg/l, the activity of microorganisms will be inhibited; When the content exceeds 8000mg/l, it can cause microbial cells to lose water and undergo mass wall separation, even leading to microbial death. A low or even no total number of microorganisms will result in the inability to degrade the macromolecular components in the water and cause sludge bulking, leading to excessive effluent quality.
2. High concentrations of COD and BOD5: The concentration of BOD5 is usually high. If pharmaceutical and chemical wastewater is discharged into normal water bodies without treatment, it will consume a large amount of dissolved oxygen in the water, leading to water hypoxia. This will threaten the survival of animals, plants, and microorganisms in the water, and have a serious impact on normal water bodies. In addition, the types of substances involved in pharmaceutical and chemical wastewater are complex, and the variability of the water body can lead to high levels of organic matter in the water, which can easily lead to an imbalance in the proportion of nutrients in the water. To this end, the treatment of pharmaceutical and chemical wastewater, which is discharged after the water quality meets the standard, not only benefits the ecological environment, but also indirectly affects people's living environment, promoting harmonious coexistence between humans and nature.
3. Containing harmful components: Pharmaceutical and chemical wastewater contains a large amount of COD, BOD5, inorganic salts and other components, as well as many harmful chemicals to organisms such as nitrogen heterocycles, aromatic amines, phenols, and cyanide. These substances are usually difficult to decompose. When these harmful ingredients enter normal water bodies, they are like invisible killers threatening species in the water, and they can also enter human drinking water environments, posing a threat to human health. These harmful ingredients pose a serious safety threat to the lives of organisms, disrupt normal water structures, and disrupt human production and living spaces.

Wastewater quality and treatment process of a pharmaceutical and chemical enterprise
A certain pharmaceutical and chemical enterprise mainly engages in the production of cardiovascular drugs and intermediates. The wastewater contains ethanol, acetic acid, triethylamine, sodium chloride, DMF, etc. The designed effluent meets the second level standard of the Comprehensive Wastewater Discharge Standard (GB 8978-1996), and the designed effluent quality is shown in Table 1.
Because the wastewater from this enterprise is weakly acidic and contains many aromatic compounds that are extremely difficult to biodegrade, its biodegradability is poor. Therefore, the Fe/C microelectrolysis catalytic oxidation A/O biochemical method can be chosen to treat this wastewater. The process flow is shown in Figure 1.
According to Figure 1, the project wastewater first enters the regulating tank to complete the water quality and quantity adjustment, and then rises to the acidification tank through a submersible pump. After adjusting the wastewater to strong acidity by adding sulfuric acid, the wastewater flows to the iron carbon micro electrolysis tank, thereby removing some organic matter, COD, chromaticity, and improving the biochemical properties of the wastewater. The effluent from the iron carbon micro electrolysis tank enters the neutralization tank, where lime solution is added to adjust the wastewater to strong alkalinity. Then, it enters the aeration tank, where some ammonia is blown out of the wastewater through aeration before entering the flocculation and sedimentation tank to remove the solid suspended components in the wastewater. After passing through intermediate pool 1 (acid regulation), it enters the catalytic oxidation tower to degrade large molecules and difficult to degrade substances in the water. Finally, it is treated in the A/O biochemical tank and can meet the discharge standards.
Common methods for treating pharmaceutical and chemical wastewater
The common methods for treating pharmaceutical and chemical wastewater currently include physical, chemical, biological, and physicochemical methods.
Physical method:
*Distillation method: Based on the difference in boiling points of different components in wastewater, distillation method separates useful components from wastewater according to the difference in boiling points of different components. Then classify the distilled liquid according to its physical properties.
*Sedimentation method: Combining the density difference of residual components in pharmaceutical and chemical wastewater. Sedimentation method is a process that combines the density difference of residual components in pharmaceutical and chemical wastewater, allowing the wastewater to settle for some time before introducing the top water into the next treatment process to separate the lower sediment from the water body.
Chemical method:
*Neutralization method: Neutralization method is the use of chemical reactions to remove excess acid or alkali from wastewater, making the wastewater liquid neutral. Generally, acidic wastewater selects alkaline substances as neutralizing agents. Conversely, acidic substances should be used for neutralization.
*Chemical oxidation method: Chemical oxidation method is the process of using oxidants to transform the pollutants in wastewater into harmless and stable substances. Common oxidants include ozone, hydrogen peroxide, and other commonly used ones, such as ozone oxidation, which is very effective for many difficult to decompose substances in wastewater.