DAF Manual
Table of Contents
Manual Overview
Operation Manual- DAF (Dissolved Air Flotation) Unit
Applicable Equipment: DAF (Dissolved Air Flotation) Unit
Document Purpose: Standardize daily equipment operation procedures, ensure wastewater treatment efficiency and equipment operational safety.
1.1 Core Functional Features
The DAF unit generates micro-bubbles with a diameter ≤30μm through its air dissolution system. These bubbles combine with flocculated particles in the wastewater, utilizing buoyancy difference to form floating sludge for solid-liquid separation. Core advantages include:
- High-Efficiency Treatment: Air dissolution efficiency and bubble release rate both reach 99%. Treatment efficiency is 3 times that of traditional DAF equipment, significantly improving suspended solids (SS) removal.
- Energy Saving & Easy Control: Entire process operates under low pressure, resulting in low energy consumption and low operational noise. Supports automated control, reducing manual operation intensity.
- Strong Adsorption: Micro-bubbles have a large contact area and strong adsorption force with flocculated particles, effectively separating fine suspended impurities and colloids.
1.2 Process Flow
The equipment follows the complete process of "Pretreatment - Reaction - Mixing - Separation - Post-treatment". Specific steps:
- Influent Pretreatment: Wastewater passes through screens, filters, etc., to remove large particles (e.g., stones, debris), preventing clogging of core components like the air dissolution pump and release device.
- Flocculation Reaction: Add PAC (coagulant) and PAM (flocculant) to the wastewater. Mixing causes impurities to aggregate into dense floc particles.
- Air Dissolution & Mixing: Flocculated wastewater first enters the flow stabilization chamber to dissipate turbulent kinetic energy, then enters the air dissolution release chamber, fully mixing with saturated dissolved air water. Micro-bubbles tightly adsorb onto the floc particles.
- Flotation Separation: Floc particles adsorbed with bubbles, having a density less than water, slowly float to the surface of the DAF tank, forming a sludge layer. Treated clean water is discharged from the bottom collection pipe.
- Sludge Handling: A rotating scraper evenly removes the floating sludge into the sludge hopper. Subsequent dewatering equipment (e.g., plate and frame filter press) processes the sludge, reducing solid waste volume.
1.3 Equipment Structure
The DAF unit consists of five core systems, with components working together to ensure treatment effectiveness:
- DAF System: Includes the flow stabilization chamber (stabilizes water flow, prevents bubble dissipation) and the air dissolution release chamber (enables efficient combination of bubbles and floc). Both are housed within the DAF tank, ensuring separation efficiency.
- Air Dissolution System: Comprises the air dissolution pump, air dissolution tank, and air compressor – the "core power" of the unit. The air compressor provides the air source, the pump pressurizes and mixes, and the tank stores and generates saturated dissolved air water (bubbles ≤30μm).
- Sludge Removal System: Utilizes a rotating scraper. The scraper blade height can be adjusted based on sludge thickness, allowing continuous, even sludge removal and preventing breakage and re-entry.
- Control System: Equipped with pressure gauges, flow meters, level gauges, etc., for real-time monitoring of key parameters like dissolved air pressure and influent flow. Supports both manual/automatic operation modes.
- Auxiliary Equipment: Includes chemical dosing units (for storing and feeding PAC/PAM) and customized chemicals. Chemical ratios are optimized based on wastewater quality to ensure complete flocculation reaction.
1.4 Scope of Application
The equipment is suitable for various wastewater treatment scenarios:
- Industrial Wastewater: Papermaking wastewater (fiber recovery + SS removal), printing/dyeing wastewater (color and suspended solids separation), electroplating wastewater (heavy metal ion adsorption), oily wastewater (oil-water separation), tannery wastewater (hide residue and grease removal), chemical wastewater (fine particle separation).
- Municipal & Environmental Water: Sludge-water separation after biological treatment of municipal sewage; purification of low-temperature, low-turbidity surface water (e.g., reservoir, river water); treatment of algae-rich eutrophic water bodies.
- Other Scenarios: Landfill leachate pretreatment, advanced purification of reuse water, solid-liquid separation in mining wastewater (tailings particle separation).
II. Pre-Operation Preparation
2.1 Electrical System Check
Confirm main power voltage is stable at 380V±10%, ground resistance ≤4Ω. Check motor wiring for looseness or damage. Jog test the air dissolution pump, feed pump, and scraper motor to ensure rotation direction matches markings. Test control panel and emergency stop buttons to ensure they immediately cut main power.
2.2 Chemical System Check
Prepare PAC and PAM according to wastewater characteristics (target: formation of dense floc particles). Chemical tank level should not be below 1/3 (for equipment with capacity >50m³/h, not below 1/2). Stir for ≥10 minutes, ensuring no sedimentation. Test run chemical feed pumps without load; check pipes for blockages or leaks.
2.3 Equipment Component Check
Vent and depressurize the air dissolution tank until pressure gauge reads zero. Check tank body and welds for leaks. Remove debris and residual sludge from the DAF tank. Ensure liquid level reaches the startup line (≥20cm for small units, ≥50cm for medium/large units). Adjust scraper blade gap from tank bottom to 3-8mm. Trial run should show no jamming or deformation.
III. Startup & Operation Procedure
3.1 Air Dissolution System Startup
Start the air compressor first. Adjust air dissolution tank pressure to 0.3-0.5MPa. Once stable, start the air dissolution pump. Maintain tank vacuum between 0.01-0.02MPa. Observe the air dissolution release chamber outlet – it should show a "milky white mist-like" stream of bubbles (≤30μm). If large bubbles appear, shut down and clean clogged release device(s).
3.2 Influent & Chemical Dosing System Startup
Start the wastewater feed pump. Use the flow control valve to set influent flow ≤110% of the unit's rated capacity, ensuring steady flow into the stabilization chamber. Once wastewater enters the flocculation zone, start the chemical feed pumps. Adjust dosing rates based on floc formation. If wastewater pH <6.0, simultaneously add alkali to adjust pH to 7.0-8.0.
3.3 Sludge Removal System Startup
Start the scraper when the surface sludge layer thickness reaches 10-20cm and the texture is dense. Control scraper speed at 0.5-1 m/min (slower for loose sludge, can increase slightly for dense sludge). Avoid excessive speed that can break up the sludge.
3.4 Operational Monitoring
Record air dissolution tank pressure, influent flow, DAF tank level, and effluent SS concentration (required ≤30mg/L) every 30 minutes. If sludge is loose, increase PAM dosage or raise dissolved air pressure. If effluent is turbid, reduce influent flow and check flocculation effect or release device status. If dissolved air pressure fluctuates abruptly, inspect the air dissolution pump seal or pipelines for leaks.
IV. Shutdown Procedure
4.1 Normal Shutdown
Follow the sequence: "Stop influent → Stop chemical dosing → Stop air dissolution → Clean sludge → Flush pipelines".
Close the feed pump. When the DAF tank level drops to 1/3, close the chemical feed pumps. Close the air dissolution pump, then 5 minutes later, close the air compressor. Open the air dissolution tank vent valve to depressurize to zero. Start the scraper to remove residual sludge. After closing the scraper, flush chemical feed lines with clean water for 30 minutes. Clean the sludge hopper.
4.2 Emergency Shutdown
Immediately press the emergency stop button and cut main power in case of:
- Abnormal air dissolution tank pressure (>0.6MPa or <0.2MPa)
- Motor abnormal noise/smoke (bearing temperature >80°C)
- Severe pipeline leak (leakage >5L/min)
- Effluent SS concentration exceeds 90mg/L and adjustments are ineffective
Record the fault time and phenomena. After maintenance personnel resolve the fault, restart following the normal startup procedure.
V. Maintenance Specifications
5.1 Monthly Maintenance
- Circulate and clean the air dissolution tank and pipelines with 5% hydrochloric acid solution (or dedicated descaling agent) for ≥2 hours to remove internal scaling. After cleaning, rinse with clean water until effluent pH is neutral.
- Inspect mechanical seals of air dissolution pump and chemical feed pumps. If drip leak >10 drops/minute, replace seal gaskets. Clean impurities from pump inlet strainers.
- Calibrate pressure gauges and flow meters. Adjust or replace if error exceeds ±0.05MPa (pressure) or ±5% (flow).
- Drain wastewater from DAF tank. Clean accumulated sludge from tank bottom (clean if thickness >5cm). Inspect inner wall anti-corrosion coating; repair peeling areas promptly.
5.2 Annual Maintenance
- Disassemble the air dissolution release chamber. Remove and clean clogged release devices. Check release device aperture uniformity; replace if worn or deformed.
- Disassemble motor end covers. Clean dust from stator and rotor. Measure winding insulation resistance with a megohmmeter (required ≥0.5MΩ). Dry or replace motor if standard not met.
- Adjust scraper chain tension (adjust if sag >20mm). Replace worn scraper blades (if edge wear >3mm). Apply lithium-based grease to chains and tracks.
- Comprehensively inspect pipelines. Replace aged pipes with wall thickness reduced by >20%. Replace flange gaskets to ensure no leakage.
VI. Safety Specifications
6.1 Personal Protection
Wear acid/alkali-resistant gloves, safety goggles, and anti-slip work shoes during operation, chemical handling, and maintenance. Add protective clothing when handling oily or toxic wastewater. In case of skin contact with chemicals, immediately rinse with flowing water for ≥15 minutes. For eye contact, rinse thoroughly and seek medical attention promptly.
6.2 Equipment Safety
Do NOT open the air dissolution tank manhole, motor casing, or electric control cabinet doors during equipment operation. Before entering the DAF tank for maintenance: drain wastewater, ventilate for ≥30 minutes, verify oxygen content ≥19.5%, and arrange for a dedicated supervisor. For shutdowns exceeding 7 days: drain water from pumps, turn off main power, and post "Shutdown for Maintenance" signs.
6.3 Emergency Response
- Electrical Fire: Cut main power. Use ABC dry chemical fire extinguisher. Do NOT use water. Call 119 (Fire emergency number) if fire spreads.
- Chemical Spill: Close chemical tank outlet valve. Cover spilled chemicals with sand or absorbent pads (neutralize strong acids/bases first). Prevent seepage into soil or drains.
- Electric Shock: Immediately cut power or separate victim from source using insulated tools. Perform CPR if unconscious. Simultaneously call 120(Hospital Emergency Number).
6.4 Personnel Requirements
Operators must receive professional training from the manufacturer or company, familiarizing themselves with equipment structure, process flow, and key operational points. They must pass both theoretical and practical assessments (independently completing full startup-operation-shutdown cycle) before being authorized to operate the equipment.
This section provides comprehensive documentation for all products in the DAF category. Please select a specific product below to view its detailed manual.
Available Products
65-SS316-Air flotation machine
65-SS304-Air flotation machine
10-SS304-Air flotation machine-
SS316-3-Air flotation machine
SS304-15-Air flotation machine
3-Air flotation machine
10-Air flotation machine
Carbon Steel-20-Air flotation machine
100-Air flotation machine
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