The Wastewater Treatment Process of a Biological Pharmaceutical Factory in Xi'an

The biological pharmaceutical factory in Xi'an produces gentamicin and tetracycline using biological methods, with a daily inflow of 1,000 cubic meters. The wastewater has a COD of 2,000 mg/L, BOD of 1,100 mg/L, and SS of 8,400 mg/L. The original water has a high concentration, containing substances that are difficult to biodegrade and antibiotics with inhibitory effects, as well as high sulfate concentrations. The wastewater has a complex composition, a small volume, intermittent discharge, and high shock loads.

To address the characteristics of the wastewater from the production of gentamicin and tetracycline in the biological pharmaceutical factory, such as high concentration, difficulty in degradation, presence of inhibitory substances, high sulfate concentration, complex composition, small volume, intermittent discharge, and high shock loads, the following wastewater treatment process can be adopted:

1. Pretreatment Stage

Here is a detailed explanation of the logic and function of this process:

Inflow

The wastewater from the pharmaceutical factory is collected through pipelines and flows into the wastewater treatment system. This is the starting point of the entire treatment process, providing water for subsequent treatment.

Intermediate Screen

The intermediate screen mainly intercepts larger floating and suspended materials in the wastewater, such as paper, leaves, and plastics. It prevents these materials from entering subsequent equipment, which could cause blockages or damage, and reduces the burden on subsequent treatment units to ensure the stable operation of the treatment system.

Inflow Pump House

The inflow pump house uses pumps to lift the wastewater to the height required by the subsequent treatment facilities, ensuring that the wastewater can flow smoothly into the next treatment stage. The pump house also has the function of regulating flow and pressure, allowing the wastewater to enter the subsequent treatment units in a suitable state.

Regulation Tank

The main function of the regulation tank is to regulate the flow and quality of the wastewater. Since the pharmaceutical wastewater is discharged intermittently and has a small volume, the regulation tank can balance the fluctuations in water volume and quality, avoiding shocks to subsequent treatment units. It can also carry out preliminary sedimentation and anaerobic fermentation, improving the biodegradability of the wastewater.

Grit Chamber

The grit chamber uses the principle of gravity separation to remove inorganic particulate matter such as sand from the wastewater. If these inorganic particles enter subsequent treatment units, they may wear out equipment and affect treatment efficiency. The grit chamber can effectively avoid these problems, extend the service life of equipment, and improve treatment efficiency.

Dissolved Air Flotation (DAF) Tank

The DAF tank adds coagulants and flotation agents to the wastewater, causing suspended solids, colloidal substances, and some organic matter in the wastewater to form flocs, which are then separated by flotation. The DAF tank can effectively remove large particulate suspended solids and some organic matter from the wastewater, while also reducing the color and toxicity of the wastewater, creating favorable conditions for subsequent biological treatment.

SBR Reactor Tank

The SBR reactor tank is the core part of the entire wastewater treatment process. It integrates functions such as homogenization, initial sedimentation, biological degradation, and secondary sedimentation in one tank. By controlling the time program, the SBR reactor tank can achieve processes such as reaction, sedimentation, and drainage. During the reaction stage, microorganisms degrade and adsorb organic matter in the wastewater; during the sedimentation stage, sludge is separated from water, further removing suspended solids and organic matter from the wastewater; during the drainage stage, the treated supernatant is discharged. The SBR reactor tank has an ideal plug flow process, which increases the driving force of the biochemical reaction, improves efficiency, and alternates between anaerobic and aerobic conditions, resulting in good purification effects. It also has the advantages of high resistance to shock loads, stable operation, and good effluent quality, making it particularly suitable for the treatment of pharmaceutical wastewater with intermittent discharge and large flow variations.

Effluent

After the above treatment, the wastewater has reached the national discharge standards and can be safely discharged into natural water bodies or reused, achieving the recycling of water resources and reducing environmental pollution.

2. Process Flowchart

3. Biological Treatment Stage

Hydrolysis Acidification Tank

- Function: Under anaerobic conditions, hydrolysis acidification bacteria decompose large molecular organic matter in the wastewater into small molecular organic matter, improving the biodegradability of the wastewater and creating favorable conditions for subsequent aerobic biological treatment.

Anaerobic Reactor (e.g., UASB or EGSB)

- Function: Under anaerobic conditions, anaerobic microorganisms further decompose organic matter in the wastewater into gases such as methane and carbon dioxide, effectively reducing the COD and BOD concentrations in the wastewater and having a certain decomposition effect on the refractory organic matter in the wastewater.

Aerobic Aeration Tank

- Function: Under aerobic conditions, aerobic microorganisms further oxidize and decompose organic matter in the wastewater into inorganic substances such as carbon dioxide and water, further reducing the COD and BOD concentrations in the wastewater and bringing the wastewater up to discharge standards.

4. Advanced Treatment and Reuse Stage

Activated Carbon Adsorption

- Function: Using the adsorption properties of activated carbon, residual organic matter, color, and odors in the wastewater are removed, further improving the quality of the wastewater.

Ultrafiltration, Reverse Osmosis, and Other Membrane Separation Technologies

- Function: By using ultrafiltration and reverse osmosis membrane separation technologies, salts, small molecular organic matter, and other impurities in the wastewater are removed, achieving higher water quality standards and enabling the reuse of wastewater.