Design Example of a Multi-Process Coupled Pharmaceutical Wastewater Treatment System
Design Example of a Multi-Process Coupled Pharmaceutical Wastewater Treatment System
I. Project Background and Design Basis
1.1 Company Profile and Wastewater Sources
This design example serves a comprehensive chemical pharmaceutical enterprise primarily producing antibiotic intermediates, synthetic active pharmaceutical ingredients (APIs), and some dosage forms. Its production wastewater is extremely complex in composition, highly toxic, and represents typical high-difficulty industrial wastewater. The wastewater mainly includes:
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High-Concentration Process Wastewater: Synthesis mother liquors, extraction raffinates, filter press liquors, etc., with COD as high as tens to hundreds of thousands mg/L, containing high concentrations of refractory organics, residual solvents (e.g., methanol, acetone), and high salinity.
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Medium-Concentration Rinse Wastewater: Equipment and floor wash water, reactor cleaning water, etc., containing raw material, intermediate, and product residues.
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Low-Concentration Domestic Sewage and Utility Drainage.
1.2 Design Influent Quality and Discharge Standard
|
Parameter |
Concentration Range (Mixed) |
Design Influent Value (Taken) |
|---|---|---|
|
COD (mg/L) |
8,000 - 25,000 |
15,000 |
|
BOD₅ (mg/L) |
2,000 - 6,000 |
3,500 (B/C≈0.23) |
|
NH₃-N (mg/L) |
150 - 500 |
300 |
|
TN (mg/L) |
200 - 600 |
400 |
|
Salinity (as Cl⁻, mg/L) |
5,000 - 15,000 |
10,000 |
|
pH |
4 - 10 |
6-9 (after adjustment) |
|
SS (mg/L) |
300 - 800 |
500 |
|
Specific Pollutants |
Contains benzene series, heterocyclic compounds, antibiotic residues, etc. |
Design Capacity: Comprehensive wastewater treatment flow of 500 m³/d.
Discharge Standard: Complies with the Special Discharge Limits for water pollutants specified in Table 2 of the Discharge Standard of Water Pollutants for Chemical Synthesis-Based Pharmaceutical Industry(GB 21908-2008), where COD ≤ 60 mg/L and NH₃-N ≤ 8 mg/L.
II. Overall Design of the Multi-Process Coupled Scheme
Addressing the core challenges of "high concentration, high toxicity, high salinity, low C/N ratio, and poor biodegradability," this design adopts the full-process multi-process coupled route of "Segregated Collection, Quality-Specific Physicochemical Pretreatment, Enhanced Anaerobic Treatment, Coupled Denitrification-Aerobic Treatment, and Advanced Oxidation for Advanced Safeguard." The core concept is to achieve staged, targeted pollutant removal by leveraging the targeted advantages of different processes.
2.1 Full-Process Multi-Process Coupled System Design Diagram
III. Detailed Design of Core Coupled Process Units
3.1 Quality-Specific Pretreatment & Detoxification Unit (Iron-Carbon Micro-Electrolysis + Fenton)
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Design Objective: For high-concentration process wastewater, break down refractory structures like heterocyclic and benzene rings, improve wastewater biodegradability (increase B/C ratio from <0.2 to >0.35), and remove partial COD and color.
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Coupling Principle:
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Iron-Carbon Micro-Electrolysis: Utilizes the Fe-C galvanic cell effect to generate nascent [H] and Fe²⁺, performing multiple actions like reduction, coagulation, and adsorption, decomposing macromolecular, complex-structure organics into smaller molecular intermediates.
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Fenton Oxidation: Utilizes Fe²⁺ present in the micro-electrolysis effluent, supplemented with H₂O₂ dosing, to form a Fenton-like system generating highly oxidative ·OH for deep oxidation of intermediates and remaining refractory compounds.
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Key Design Parameters:
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Iron-Carbon Micro-Electrolysis Column: HRT ≥ 2.0 h, Iron-Carbon volume ratio 1:1, pH adjusted to
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