IndustrialWastewater Treatment: Classification and Characteristics of Pharmaceutical Wastewater

1. Pharmaceutical Wastewater

1.1 Characteristics of Pharmaceutical Wastewater

Pharmaceutical industrial wastewater mainly includes four categories: antibiotic production wastewater, synthetic drug production wastewater, traditional Chinese medicine production wastewater, and washing and rinsing wastewater from the production process of various formulations. The pharmaceutical industry can be divided into biological and chemical pharmaceuticals according to the production process. The characteristics of its wastewater are complex composition, high organic content, high toxicity, deep color, and high salinity. In particular, the biodegradability is very poor, and it is intermittently discharged, making it one of the difficult industrial wastewaters to treat. With the development of China's pharmaceutical industry, pharmaceutical wastewater has gradually become one of the important sources of pollution. How to treat this type of wastewater is a difficult problem in environmental protection today. According to the "Emission Standard of Pollutants for the Pharmaceutical Industry," the pharmaceutical industry pollutant emission standard system consists of six sub-standards, namely fermentation, chemical synthesis, extraction, bioengineering and biological products, traditional Chinese medicine, and mixing and processing formulation categories.

1.1.1 Classification of Fermentation Biological Pharmaceutical Wastewater

1.1.1.1 Main Production Process Drainage: This type of drainage is the most important category of wastewater, including waste filtrate, waste mother liquor, other mother liquors, and solvent recovery residues. Characteristics of wastewater: High concentration, large changes in acidity and alkalinity and temperature, and drug residues are the most significant characteristics of this type of wastewater. Although the water volume may not be large, the pollutant content is high, contributing a large proportion to the COD of all wastewater, and the treatment difficulty is high.

1.1.1.2 Auxiliary Process Drainage: Including process cooling water, wastewater from the circulating cooling system, wastewater from the deionized water production process, and condensate from distillation (heating) equipment.

Characteristics of wastewater: Low pollutant concentration, but large water volume, and strong seasonality, with significant differences between enterprises. This type of wastewater has also been a target for water conservation in enterprises in recent years.

1.1.1.3 Rinse Water: Including container and equipment rinse water, filter equipment rinse water, resin column rinse water, and floor rinse water. The rinse water from filter equipment also has a high pollutant concentration, mainly suspended solids, and if not controlled properly, it can become an important source of pollution. The rinse water from resin columns has a large water volume, with high pollutant concentration in the initial rinse water and large changes in acidity and alkalinity, making it another important type of wastewater.

1.1.1.4 Domestic Sewage: Related to the number of people in the enterprise, living habits, and management status, but it is not the main wastewater.

1.1.2 Chemical Pharmaceutical Manufacturing: Chemical pharmaceutical manufacturing is the process of preparing drugs or intermediates using organic or inorganic raw materials through chemical reactions, including pure chemical synthesis and semi-synthesis pharmaceuticals.

2. Sources of Fermentation Biological Pharmaceutical Wastewater

2.1 Main Production Process Drainage

The main production process drainage of fermentation biological pharmaceuticals is one of the main sources of wastewater, with complex components and high concentration. It mainly includes waste filtrate, waste mother liquor, other mother liquors, and solvent recovery residues. The chemical oxygen demand (COD) of these wastewaters is extremely high, usually above 10,000 mg/L. For example, in the production of antibiotics, the waste filtrate and waste mother liquor contain a large amount of unused organic substrates and nutrients, such as sugars, proteins, lipids, and inorganic salts. These high-concentration wastewaters have large changes in acidity and alkalinity and temperature, with drug residues as their significant characteristics, contributing a large proportion to the COD of all wastewater, and the treatment difficulty is relatively high.

2.2 Auxiliary Process Drainage

Auxiliary process drainage accounts for a large proportion of the total fermentation biological pharmaceutical wastewater, mainly coming from process cooling water, power equipment cooling water, wastewater from the circulating cooling water system, and wastewater from water ring vacuum equipment. The characteristics of this type of wastewater are relatively low pollutant concentration, but large water volume, strong seasonality, and significant differences between enterprises. For example, process cooling water is used to regulate equipment temperature during production. Although its pollutant concentration is not high, it is frequently used and has a large discharge volume, making it an important target for water conservation and wastewater treatment in enterprises.

2.3 Rinse Water

Rinse water is another important component of fermentation biological pharmaceutical wastewater, mainly including container and equipment rinse water, filter equipment rinse water, resin column (tank) rinse water, and floor rinse water. The rinse water from filter equipment has a high pollutant concentration, mainly suspended solids. If not controlled properly, it can become an important source of pollution. For example, during the cleaning of fermentation tanks, a large amount of rinse water is generated, with a COD concentration of several thousand mg/L. The rinse water from resin columns (tanks) has a large water volume, with high pollutant concentration in the initial rinse water and large changes in acidity and alkalinity, making it another important type of wastewater.

3. Classification of Fermentation Biological Pharmaceutical Wastewater

3.1 High-Concentration Wastewater

High-concentration wastewater is a key part of fermentation biological pharmaceutical wastewater, mainly coming from the main production process drainage. The chemical oxygen demand (COD) of these wastewaters is extremely high, usually above 10,000 mg/L. For example, in the production of antibiotics, the waste filtrate and waste mother liquor contain a large amount of unused organic substrates and nutrients, such as sugars, proteins, lipids, and inorganic salts. These high-concentration wastewaters have large changes in acidity and alkalinity and temperature, with drug residues as their significant characteristics, contributing a large proportion to the COD of all wastewater, and the treatment difficulty is relatively high.

The treatment of high-concentration wastewater is the focus and difficulty of the management of fermentation biological pharmaceutical wastewater. Due to the high pollutant concentration, direct discharge will cause serious environmental pollution. Therefore, effective pretreatment and advanced treatment measures are needed. Common pretreatment methods include coagulation sedimentation and air flotation to remove suspended solids and some organic matter from the wastewater. Advanced treatment usually adopts biological treatment technology, such as the combination process of anaerobic and aerobic biological treatment. Anaerobic biological treatment can effectively reduce the COD concentration of wastewater while generating usable biogas. Aerobic biological treatment further removes organic matter from wastewater to meet discharge standards.

3.2 Low-Concentration Wastewater

Low-concentration wastewater mainly comes from auxiliary process drainage and rinse water. Auxiliary process drainage accounts for a large proportion of the total fermentation biological pharmaceutical wastewater, mainly coming from process cooling water, power equipment cooling water, wastewater from the circulating cooling water system, and wastewater from water ring vacuum equipment. The characteristics of this type of wastewater are relatively low pollutant concentration, but large water volume, strong seasonality, and significant differences between enterprises. For example, process cooling water is used to regulate equipment temperature during production. Although its pollutant concentration is not high, it is frequently used and has a large discharge volume, making it an important target for water conservation and wastewater treatment in enterprises.

Rinse water is another important component of fermentation biological pharmaceutical wastewater, mainly including container and equipment rinse water, filter equipment rinse water, resin column (tank) rinse water, and floor rinse water. The rinse water from filter equipment has a high pollutant concentration, mainly suspended solids. If not controlled properly, it can become an important source of pollution. For example, during the cleaning of fermentation tanks, a large amount of rinse water is generated, with a COD concentration of several thousand mg/L. The rinse water from resin columns (tanks) has a large water volume, with high pollutant concentration in the initial rinse water and large changes in acidity and alkalinity, making it another important type of wastewater.

The treatment of low-concentration wastewater is relatively simple, but appropriate measures still need to be taken to ensure its compliance with discharge standards. Common treatment methods include physicochemical treatment and biological treatment. Physicochemical treatment can remove suspended solids and some dissolved pollutants from wastewater through sedimentation, filtration, and other methods. Biological treatment can further degrade organic matter in wastewater through the metabolic action of microorganisms to meet discharge standards. In addition, for low-concentration wastewater, resource recovery methods can also be considered, such as recovering useful substances from it or reusing treated water, to improve the efficiency of water resource utilization.

4. Characteristics of Fermentation Biological Pharmaceutical Wastewater

4.1 High Pollutant Concentration

The extremely high pollutant concentration is one of the significant characteristics of fermentation biological pharmaceutical wastewater. High-concentration wastewater mainly comes from the main production process drainage, such as waste filtrate and waste mother liquor, with a chemical oxygen demand (COD) usually above 10,000 mg/L, and some enterprises even reaching 100,000 mg/L. These wastewaters not only contain a large amount of organic substrates and nutrients, such as sugars, proteins, lipids, and inorganic salts, but also residual drug components, posing a great risk of environmental pollution.

The treatment difficulty of high-concentration wastewater is mainly reflected in the following aspects:

- Large changes in acidity and alkalinity and temperature: The acidity and alkalinity of high-concentration wastewater can vary widely, with a pH value fluctuating between 2 and 12. The temperature may also change significantly due to different production processes, bringing challenges to the stability and efficiency of wastewater treatment.

- Biological toxicity: Residual drug components in wastewater, such as antibiotics and their degradation products, have an inhibitory effect on microorganisms. For example, when the residual concentration of certain antibiotics exceeds a certain threshold, it will significantly inhibit the activity of microorganisms in the wastewater treatment system, leading to a decline in biological treatment effectiveness.

- High treatment cost: Due to the high pollutant concentration, complex pretreatment and advanced treatment processes are required, such as the combination process of coagulation sedimentation, air flotation, anaerobic biological treatment, and aerobic biological treatment. This not only increases the investment cost of treatment equipment but also raises operating and maintenance costs.

4.2 Complex Composition

The composition of fermentation biological pharmaceutical wastewater is extremely complex, mainly including organic matter, nitrogen, phosphorus, sulfates, etc. These components come from a wide range of sources, covering various raw materials, intermediate products, and metabolic products in the fermentation process.

- A wide variety of organic substances: The wastewater contains a large amount of organic substrates, such as sugars, proteins, lipids, etc. These organic substances are not only highly concentrated but also complex in composition and difficult for microorganisms to completely degrade. For example, the waste filtrate and waste mother liquor contain a large amount of unused organic substrates with complex components and poor biodegradability.

- High nitrogen content: The nitrogen in fermentation biological pharmaceutical wastewater mainly exists in the form of organic nitrogen and ammoniacal nitrogen. The wastewater has a high concentration of ammoniacal nitrogen, and the ammoniacal nitrogen index is often not ideal after biological treatment. This not only affects the compliance discharge of wastewater but may also cause eutrophication pollution to the aquatic ecosystem.

- High sulfate concentration: Ammonium sulfate is a commonly used nitrogen source in the fermentation process, and sulfuric acid is an important pH regulator in the refining and purification process. Therefore, the concentration of sulfates in fermentation biological pharmaceutical wastewater is high, which brings difficulties to the anaerobic treatment of wastewater.

- Many refractory substances: The wastewater contains substances that are difficult for microorganisms to degrade and even inhibit microorganisms, such as emulsifiers, defoamers, potassium ferrocyanide, oxalates, residual antibiotics, and their degradation products. The presence of these substances not only increases the difficulty of wastewater treatment but also may lead to the treated wastewater failing to meet discharge standards.

5. Conclusion

The classification and characteristics of fermentation biological pharmaceutical wastewater are of great significance for the selection and optimization of wastewater treatment processes. High-concentration wastewater mainly comes from the main production process drainage, with extremely high COD, usually above 10,000 mg/L, and some enterprises even reaching 100,000 mg/L. This type of wastewater has large changes in acidity and alkalinity and temperature, and residual drug components have an inhibitory effect on microorganisms, making the treatment difficulty high and requiring complex pretreatment and advanced treatment processes. Low-concentration wastewater mainly comes from auxiliary process drainage and rinse water, with relatively low pollutant concentration but large water volume, strong seasonality, and significant differences between enterprises. The treatment of this type of wastewater is relatively simple, but appropriate measures still need to be taken to ensure its compliance with discharge standards.

The composition of fermentation biological pharmaceutical wastewater is complex, mainly including organic matter, nitrogen, phosphorus, sulfates, etc., and these components come from a wide range of sources, covering various raw materials, intermediate products, and metabolic products in the fermentation process. The wastewater contains a wide variety of organic substances, high nitrogen content, high sulfate concentration, and a large number of refractory substances. These characteristics make wastewater treatment face many challenges. Therefore, when treating fermentation biological pharmaceutical wastewater, it is necessary to comprehensively consider factors such as the source, concentration, and composition of the wastewater, and choose appropriate treatment processes and methods to achieve the compliance discharge and resource recovery and utilization of wastewater.