A large textile dyeing factory recently upgraded its Dissolved Air Flotation (DAF) system to improve wastewater clarification performance. However, shortly after commissioning, the flotation system experienced unstable sludge separation, high effluent turbidity, and frequent scraper blockage.
By introducing Hengfeng Flocculant C9202 and implementing on-site process optimization, the plant successfully restored stable operation and achieved continuous, compliant discharge.
Site Overview
Industry: Textile dyeing & finishing
Wastewater capacity: 2,500–3,000 m³/day
Wastewater characteristics:
High COD (3,500–4,200 mg/L), suspended solids 1,200–1,800 mg/L, strong color, high surfactant content, and fine colloidal particles typical of dyeing processes.
Flotation system configuration:
Two 150 m³/h Dissolved Air Flotation (DAF) units
PAC prepared at 5% concentration
Polymer manually prepared at 0.1% concentration
Designed hydraulic retention time: 25–30 minutes
Initial Issues:
Flotation retention time exceeded 40 minutes. Sludge layer was thin and unstable. Effluent SS fluctuated between 250–400 mg/L. Sludge moisture remained above 82%. Sludge accumulation frequently caused scraper blockage, leading to intermittent production interruptions.
Problem Analysis
After on-site inspection and process monitoring, our technical team identified several key causes:
1. Insufficient Floc Strength
The previously used polymer had relatively low molecular weight and charge density. The formed flocs were small and fragile, easily breaking under hydraulic shear and reducing bubble attachment efficiency.
2. Improper Coagulation–Flocculation Coordination
PAC dosage fluctuated between 40–50 kg/h due to manual adjustment, resulting in incomplete charge neutralization. Meanwhile, operators reduced polymer dosage out of concern for overdosing, leading to insufficient bridging.
3. High Surfactant Interference
Textile wastewater contains dispersants and surfactants that weaken bubble–floc adhesion, requiring stronger and denser floc formation to ensure stable flotation.
4. Operator Misinterpretation
Previous surface foaming was incorrectly attributed to polymer overdosing, when in fact it was caused by residual surfactants. This misunderstanding led to chronic under-dosing and unstable clarification performance.
Technical Solution
Optimized Chemical Strategy
Hengfeng introduced a coordinated PAC + C9202 dosing program.
PAC was maintained at 5% concentration with a stabilized dosage of 65–75 kg/h to ensure sufficient destabilization of colloids.
Hengfeng Flocculant C9202 was prepared at 0.15% concentration with proper aging time of at least 60 minutes. The polymer dosage was dynamically adjusted between 3.5–4.5 kg/h (dry basis equivalent), based on floc formation and effluent clarity.
C9202, with optimized cationic charge density and higher molecular weight, significantly enhanced bridging capacity and produced larger, more compact flocs suitable for flotation systems.
Dosing Point Optimization
PAC was injected at the rapid mixing tank inlet to ensure full charge neutralization.
C9202 was added in the slow mixing zone before DAF entry, reducing shear intensity and preserving floc integrity before contact with dissolved air bubbles.
Operator Training & Standardization
Our team conducted on-site training to:
Standardize solution preparation procedures
Clarify correct interpretation of foam phenomena
Establish visual floc assessment guidelines
Implement routine dosing records and adjustment protocols
This eliminated inconsistent manual operations and ensured stable chemical control.
Performance Results
After three days of process optimization and continuous monitoring:
Flotation retention time returned to the designed 25–28 minutes.
Effluent suspended solids decreased steadily to below 80 mg/L.
COD removal efficiency improved to approximately 70–75%.
Sludge moisture content decreased to 75–78%, improving downstream dewatering performance.
The sludge layer became thick, uniform, and stable, without collapse or “floating patch” defects.
Scraper blockage was eliminated, and uninterrupted production was achieved.
The DAF system resumed stable operation, meeting discharge standards while reducing operational risk.
Project Outcome
Through formulation optimization, dosing control, and operator training, Hengfeng successfully transformed an unstable flotation system into a reliable, continuous wastewater treatment process.
This project demonstrated that flotation efficiency depends not only on equipment design, but also on proper chemical synergy, correct dosing strategy, and field-level technical expertise.
Hengfeng Commitment
At Hengfeng, we provide more than flocculants —
We deliver complete process solutions supported by:
• Advanced polymer technology
• Site-specific dosage optimization
• On-site technical guidance
• Long-term operational support
With Hengfeng Flocculant C9202, textile wastewater flotation systems can achieve higher efficiency, improved sludge performance, and sustainable, stable operation.
A large textile dyeing factory recently upgraded its Dissolved Air Flotation (DAF) system to improve wastewater clarification performance. However, shortly after commissioning, the flotation system experienced unstable sludge separation, high effluent turbidity, and frequent scraper blockage.
By introducing Hengfeng Flocculant C9202 and implementing on-site process optimization, the plant successfully restored stable operation and achieved continuous, compliant discharge.
Site Overview
Industry: Textile dyeing & finishing
Wastewater capacity: 2,500–3,000 m³/day
Wastewater characteristics:
High COD (3,500–4,200 mg/L), suspended solids 1,200–1,800 mg/L, strong color, high surfactant content, and fine colloidal particles typical of dyeing processes.
Flotation system configuration:
Two 150 m³/h Dissolved Air Flotation (DAF) units
PAC prepared at 5% concentration
Polymer manually prepared at 0.1% concentration
Designed hydraulic retention time: 25–30 minutes
Initial Issues:
Flotation retention time exceeded 40 minutes. Sludge layer was thin and unstable. Effluent SS fluctuated between 250–400 mg/L. Sludge moisture remained above 82%. Sludge accumulation frequently caused scraper blockage, leading to intermittent production interruptions.
Problem Analysis
After on-site inspection and process monitoring, our technical team identified several key causes:
1. Insufficient Floc Strength
The previously used polymer had relatively low molecular weight and charge density. The formed flocs were small and fragile, easily breaking under hydraulic shear and reducing bubble attachment efficiency.
2. Improper Coagulation–Flocculation Coordination
PAC dosage fluctuated between 40–50 kg/h due to manual adjustment, resulting in incomplete charge neutralization. Meanwhile, operators reduced polymer dosage out of concern for overdosing, leading to insufficient bridging.
3. High Surfactant Interference
Textile wastewater contains dispersants and surfactants that weaken bubble–floc adhesion, requiring stronger and denser floc formation to ensure stable flotation.
4. Operator Misinterpretation
Previous surface foaming was incorrectly attributed to polymer overdosing, when in fact it was caused by residual surfactants. This misunderstanding led to chronic under-dosing and unstable clarification performance.
Technical Solution
Optimized Chemical Strategy
Hengfeng introduced a coordinated PAC + C9202 dosing program.
PAC was maintained at 5% concentration with a stabilized dosage of 65–75 kg/h to ensure sufficient destabilization of colloids.
Hengfeng Flocculant C9202 was prepared at 0.15% concentration with proper aging time of at least 60 minutes. The polymer dosage was dynamically adjusted between 3.5–4.5 kg/h (dry basis equivalent), based on floc formation and effluent clarity.
C9202, with optimized cationic charge density and higher molecular weight, significantly enhanced bridging capacity and produced larger, more compact flocs suitable for flotation systems.
Dosing Point Optimization
PAC was injected at the rapid mixing tank inlet to ensure full charge neutralization.
C9202 was added in the slow mixing zone before DAF entry, reducing shear intensity and preserving floc integrity before contact with dissolved air bubbles.
Operator Training & Standardization
Our team conducted on-site training to:
Standardize solution preparation procedures
Clarify correct interpretation of foam phenomena
Establish visual floc assessment guidelines
Implement routine dosing records and adjustment protocols
This eliminated inconsistent manual operations and ensured stable chemical control.
Performance Results
After three days of process optimization and continuous monitoring:
Flotation retention time returned to the designed 25–28 minutes.
Effluent suspended solids decreased steadily to below 80 mg/L.
COD removal efficiency improved to approximately 70–75%.
Sludge moisture content decreased to 75–78%, improving downstream dewatering performance.
The sludge layer became thick, uniform, and stable, without collapse or “floating patch” defects.
Scraper blockage was eliminated, and uninterrupted production was achieved.
The DAF system resumed stable operation, meeting discharge standards while reducing operational risk.
Project Outcome
Through formulation optimization, dosing control, and operator training, Hengfeng successfully transformed an unstable flotation system into a reliable, continuous wastewater treatment process.
This project demonstrated that flotation efficiency depends not only on equipment design, but also on proper chemical synergy, correct dosing strategy, and field-level technical expertise.
Hengfeng Commitment
At Hengfeng, we provide more than flocculants —
We deliver complete process solutions supported by:
• Advanced polymer technology
• Site-specific dosage optimization
• On-site technical guidance
• Long-term operational support
With Hengfeng Flocculant C9202, textile wastewater flotation systems can achieve higher efficiency, improved sludge performance, and sustainable, stable operation.
