DAF (DISSOLVED AIR FLOTATION) UNITS

Pilsan Construction produces DAF (Dissolved Air Flotation) units that remove pollutants such as oil, color, fine suspended solids, emulsions, flocs and organic load from industrial wastewater using chemically-assisted air flotation. The DAF system works by introducing microbubbles into wastewater to bring solid and liquid pollutants lighter than water to the surface. These micro bubbles attach to pollutants, causing them to collect on the water surface; surface accumulations are then removed from the system by mechanical surface skimmers. Pilsan's DAF units provide high-efficiency, reliable treatment that prepares treated water for safe discharge or in-plant reuse. All equipment is integrated into a compact body or container; tested at the factory and shipped ready for the field. On site, only water inlet-outlet lines and electrical connections are made for quick commissioning.

WHERE IS IT PREFERRED?

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  Industrial Production Facilities

  DAF is frequently preferred for treating wastewater with high oil, grease and suspended solids loads. Especially in food and animal production sectors (e.g., slaughterhouses, dairy processing plants, rendering units, kitchens) and processes such as machine/vehicle washing, high removal of oil and solids is achieved with microbubble flotation. The DAF unit is used as pre-treatment before biological treatment in such facilities to reduce pollutant load, or in some cases provides a standalone physical-chemical treatment solution.

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  Wastewater Containing Color and Emulsion

  High removal performance is achieved with chemically-assisted DAF in wastewater containing color, dyes or emulsified pollutants from process outlets such as textile dyehouses, chemical plants, paper mills. Since colloidal and dissolved pollutants can be flocculated and removed by flotation with coagulation/flocculation chemicals, DAF is more effective than conventional sedimentation methods, especially in color removal.

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  Organized Industrial Zone Pre-Treatment

  DAF units are a common solution for industrial facilities discharging to common treatment plants to meet legal discharge criteria. Factories in OSBs use DAF pre-treatment to reduce parameters such as oil, suspended solids and chemical oxygen demand (COD) in their wastewater before entering central biological treatment. This reduces the load on the central facility and prevents the treatment process from being affected by peak loads.

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  Integration with Biological Treatment

  The DAF system has the flexibility to work integrated with biological treatment processes. Using DAF before biological units (as a pre-treatment step) prevents high oil and solids content from entering the biological process, increasing treatment efficiency. Similarly, adding a DAF unit to biological treatment outlet enables polishing, turbidity removal and meeting discharge standards even at peak loads. Thanks to this flexibility, DAF units play a critical role in many sectors such as food, petrochemicals, paper, textiles and metal processing.

HOW DOES IT WORK?

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  Coagulation and Flocculation (Chemical Conditioning)

  Wastewater is chemically conditioned before entering the DAF unit. With dosing of appropriate coagulants (e.g., ferric chloride, aluminum sulfate) and flocculants such as polymers, colloidal substances and emulsions in wastewater are destabilized and combine to form larger flocs. This step is critical for high-efficiency separation in chemical DAF applications and facilitates flotation of difficult-to-remove pollutants such as oil and color.

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  Pressurized Air Saturation

  A certain portion of the system flow (treated water recirculation line) is saturated with air in a saturator tank at 4-6 bar pressure. Air held dissolved in water under high pressure is prepared for the flotation process when saturated water is fed to the DAF tank. At this stage, maximum air bubble potential is created in dissolved form in the water.

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  Flotation and Flotation

  Chemically conditioned wastewater is taken into the DAF tank together with saturated water. When pressure is suddenly reduced at the tank inlet, dissolved air in the water is released as microscopic bubbles (approximately 30-50 µm in diameter). These micro bubbles attach to flocculated pollutants, reducing their apparent density and causing them to rise to the surface with the buoyancy of water. Thus, oil, grease, suspended solids and color-forming substances collect as a foam layer on the upper part of the water.

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  Surface Skimming

  Treatment foam and sludge layer accumulating on the surface of the flotation tank are continuously removed from the surface with slowly moving mechanical skimmers. The skimming system pushes accumulated flotation sludge toward a special chamber or hopper to exit the system. Thus, pollutants separated from water are collected as dense sludge.

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  Treated Water Outlet

  Clear water freed from oil and solid pollutants in the DAF unit is taken in a controlled manner from the lower section of the tank or from weir mechanisms on the side surface. This treated water can be sent to subsequent treatment steps (e.g., filtration, activated carbon, disinfection) according to process requirements, or can be directly discharged if appropriate quality is achieved. DAF outlet water has become quite clear in terms of turbidity and oil-grease parameters.

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  Sludge Management

  Flotation sludge collected by surface skimming accumulates in the sludge chamber of the DAF unit and is purged from the system at certain intervals. Since this raw sludge can contain high amounts of water, it is usually pumped to a thickening tank, sludge dewatering equipment (filter press, centrifuge, etc.) or directly to a disposal unit. Flotation sludge pre-concentrated by chemical conditioning is processed with appropriate dewatering equipment to separate into solid and liquid phases. The resulting dewatered sludge is removed in accordance with relevant regulations or evaluated by methods such as incineration, composting.

TECHNICAL AND USAGE ADVANTAGES

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  Compact and Orderly Design

  DAF units have an integrated compact structure on a single chassis with flotation tank, air saturation system, pumps and dosing equipment. Operator access points (walking platforms, maintenance covers, crane lifting rings, etc.) are planned ergonomically; thus the unit offers safe and practical use while occupying minimum space in the field.

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  Durable Material

  Produced with material selection suitable for application and wastewater characteristics (optionally ST37 carbon steel with epoxy paint, 304/316 stainless steel or polypropylene/HDPE plastics). Long-lasting operation is ensured through correct material use against corrosion and chemical effects. Leak-proof welding and quality-controlled surface treatments are applied in all tank and equipment manufacturing.

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  Odor and Noise Control

  DAF systems can be designed as covered and ventilation filtered according to need. Thus, odor problems that may occur during treatment are minimized. In addition, pumps, compressors and blowers with low noise levels are preferred so that no disturbance is caused to the environment during operation.

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  Smart Control Automation

  Pilsan DAF units are equipped with instruments such as level sensors, pressure gauges and flow meters. Pumps and compressors are automatically controlled via PLC-based control panel; chemical dosing rates can be adjusted. Thanks to alarm and fault notification systems, the operator is notified early of a possible problem and can intervene.

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  Redundant and Flexible Operation

  Redundant design option can be offered for critical equipment (e.g., saturation pump); thus system operation is not interrupted in maintenance or failure situations. The DAF system is designed with flexibility to adapt to variable flow and pollutant loads. Chemical dosing and air supply rates are optimized during sudden peak load increases to maintain treatment efficiency. This feature enables DAF units to show stable performance even in different sectors and fluctuating production conditions.

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  Certification and Support

  Each Pilsan DAF unit is delivered together with a detailed user manual, maintenance plan and spare parts list. Pilsan's experienced technical team provides operator training during commissioning and continues to provide technical support afterwards. Thus, the user operates the system safely and with maximum efficiency.

MODELS

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  Single-Body Compact Unit

  For low and medium flow applications, all process steps (chemical conditioning, flotation and sludge collection) are integrated within a single tank body. Fits into narrow spaces with small footprint; easy to transport and install.

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  Modular Systems

  Multiple DAF modules can be used in parallel or series for high flow capacities. Modular design allows the facility to be expanded in the future; capacity can be increased gradually. In addition, thanks to modular structure, units can be taken out of service sequentially during maintenance, enabling continuous operation.

STANDARD EQUIPMENT

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  Chemical Dosing and Mixing Group

  Mixing tank, dosing pumps and static mixers for preparation and controlled feeding of coagulant and flocculant chemicals.

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  Flotation Tank and Air Saturation System

  Stainless or epoxy-protected flotation tank; microbubble generation arrangement (pressure reducing valves, distributors) and air saturator with compressor/pump equipment.

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  Surface Skimmer and Sludge Chamber

  Chain or paddle surface sludge skimmer system operating at adjustable speed; internal sludge chamber where collected flotation foam and sludge accumulate or external sludge tank connection.

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  Recirculation Pump

  Special pumps that convey a portion of treated water to pressurized air saturation tank (suitable for high pressure and air contact conditions).

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  Control Panel and Instrumentation

  Electrical panel controlling system operation (elements such as start/stop buttons, emergency stop, motor protection, PLC control); tank level switches, pressure gauges and safety valves; flow meters and quality sensors when required.

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  Connection and Safety Components

  All inlet/outlet connection flanges, sampling valves; drain and bypass lines for maintenance; emergency by-pass line for overflow situations; access ladder and railings when required.

OPTIONS

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  Remote Monitoring and Control

  PLC/SCADA belonging to the DAF system can be remotely monitored and controlled via internet or GSM. Real-time data tracking and alarm warnings from mobile phone, tablet or computer can be optionally offered.

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  Enclosed Cabin and Climate Control

  The DAF unit can be provided in a container or enclosed cabin for use in harsh climate conditions in open areas or for odor control. Heating-cooling systems, ventilation fans, gas and smoke detectors, lighting and security sensors can be integrated inside the cabin.

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  Advanced Treatment and Filtration

  Depending on desired quality in DAF outlet water, activated carbon filter, sand filter or microfiltration units can be added to the system. This increases removal of organic load, color or very fine particles, polishing water quality (especially for facilities targeting reuse).

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  Sludge Dewatering Integration

  Sludge dewatering equipment such as filter press, belt press or centrifuge decanter can be optionally included in the package system to reduce the volume of flotation sludge resulting from the DAF system. Works integrated with automatic polyelectrolyte preparation unit, reducing sludge disposal costs.

INSTALLATION AND INFRASTRUCTURE

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  Foundation

  A concrete platform or steel frame with ensured flatness and sufficient load-bearing capacity is required for installation of DAF units. It is important that the foundation is level and solid for the unit to sit properly and operate without vibration.

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  Connections

  Raw wastewater line to system inlet, treated water line to outlet and drainage/discharge line for flotation sludge should be planned. In addition, chemical dosing unit feed lines and air supply piping (if compressor is in a separate location) are drawn. Appropriate valves and flow control elements are found in pipe connections.

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  Electrical

  Electrical supply of appropriate power and grounding line should be provided to the unit. Installation for control panel supply, motor protections and automation signals is prepared according to Pilsan technical team's diagram. A closed area or protective canopy may be needed to protect the electrical cabinet from external factors.

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  Layout

  The DAF system should be installed in an area that will be accessible during operation and maintenance. Crane or hoist access should be considered above the unit for equipment to be removed for maintenance. A road should be left for service vehicles to approach for operations such as filling chemical tanks, transporting sludge containers. In addition, safe working area around the unit and operator platform when needed should be present.

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  Safety and Environmental Measures

  Chemical storage areas should be protected with a second tray (sump) against leaks; neutralization and ventilation measures should be taken for chemicals such as acids, bases when required. From an occupational safety perspective, it is recommended to have an emergency shower and eye wash station at an appropriate point in the facility. An appropriate disposal plan should also be prepared for wastes that the DAF unit may generate during operation (sludge, waste chemical packaging, etc.).

OPERATION AND MAINTENANCE

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  Daily Checks

  The system should be checked by the operator every shift. Water level in DAF tank, foam accumulation status on surface, sound/vibration status of pumps and compressors are observed. Pressure gauges and flow values are checked to see if they are in nominal range. Chemical tank levels are monitored and chemical addition is made when needed.

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  Periodic Operations

  At certain intervals (e.g., weekly or as needed), nozzles of the air saturation system and saturator tank are reviewed and cleaned if there is clogging or scaling. Surface skimmer paddles and chain mechanism are serviced, tension adjustments are checked. Flotation sludge is drawn from the system at regular intervals; sludge tank or dewatering equipment is cleaned. Maintenance and calibration of chemical dosing pumps and mixer equipment are performed. When required, maintenance and media changes of DAF outlet water filtration equipment (e.g., sand filter, carbon filter, UV disinfection) are carried out.

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  Spare Parts and Emergency

  Pilsan DAF systems come with spare parts and equipment list for critical equipment. Optionally, backup units can be kept for basic equipment such as pumps. This prevents the process from stopping by activating backup in possible failure situations and eases the repair process. In DAF unit operation, the automation system protects the system at critical alarm levels (e.g., high pressure, high level, motor failure), preventing larger problems.

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  Training and Support

  Pilsan provides comprehensive training to operating personnel when commissioning the system. This training covers safe chemical use, daily maintenance routines, actions to be taken in possible failure situations and record keeping. In addition, Pilsan Construction's technical team based on field experience contributes to uninterrupted and efficient operation of the facility by providing remote or on-site support when needed.

PERFORMANCE AND LIMITATIONS

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  High Removal Efficiency

  DAF units achieve very high efficiency in oil and suspended solids removal; with a properly designed system, removal of over 90% of oil, grease and TSS is possible. Thanks to microbubble technology, particles too small to be captured by traditional sedimentation and emulsified substances are separated from water. As a result, DAF outlet water is of a quality with very low turbidity, oil-free and largely particle-free.

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  Organic Load and Color Removal

  Chemically-assisted DAF also provides significant improvement in dissolved organic pollution (COD/BOD) and color removal. Especially in dye and textile wastewater, the color parameter that biological treatment cannot reach can be significantly reduced with DAF through coagulation-flotation. However, DAF is essentially a physical/chemical treatment method and removal of dissolved organics may not be as high as biological processes; therefore DAF is generally used as a pre-treatment or polishing step for strict COD/BOD limits.

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  Nutrients (Nitrogen/Phosphorus)

  Nitrogen and phosphorus removal with DAF is limited. Nitrogen forms such as ammonia, nitrate and dissolved phosphorus types such as phosphate cannot be removed by flotation process. Therefore, if there are total nitrogen or phosphorus constraints in discharge standards, biological treatment stages or chemical precipitation steps should be added after the DAF unit. For example, a nitrification/denitrification biological unit for nitrogen removal, or a chemical phosphate precipitation process for phosphorus removal can be integrated.

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  Special Pollutants

  In wastewater containing dyes, solvents, heavy metals or toxic chemicals, these pollutants may need to be separated at source or neutralized before proceeding to DAF process. Heavy metals can generally only be captured with DAF after being chemically precipitated; otherwise they remain in dissolved form. Similarly, using an oil separator (such as API separator) first when free-floating oils are very high will reduce the load and chemical consumption of the DAF system.

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  Flow Fluctuations

  DAF systems are more tolerant to instantaneous flow and pollution changes compared to traditional sedimentation systems. The effect of shock loads on outlet water quality can be minimized by quickly adjusting chemical dosing and recirculation rates. Still, expected maximum peak flow and pollution load should be considered at design stage, and system sizing should be done with safety margin. Otherwise, flotation efficiency may decrease or chemical consumption may reach uneconomical levels at loads well above design capacity.

INFORMATION REQUIRED FOR QUICK QUOTE

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  Flow Rate

  Approximate daily average flow rate of wastewater and maximum flow rate at peak hour (as m³/day and m³/h).

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  Wastewater Source

  Information about the source and characteristics of the waste (e.g., industrial process type, domestic/social wastewater or mixed) and prominent pollutants or problems in wastewater (high oil, intense color, heavy odor, high temperature, etc.).

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  Treatment Target

  Receiving environment where treated water will be discharged or reuse purpose (e.g., discharge to sewer, discharge to surface water, irrigation water, process recovery) and related quality criteria. Especially if reuse is targeted, desired water quality parameters should be specified.

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  Installation and Layout

  Physical characteristics of the location where the system will be installed (open area/indoor area, existing ground condition, approximate area that can be allocated). Details such as whether container-type package is preferred, whether there are noise/aesthetic constraints, infrastructure that will feed the unit (energy, existing tanks, etc.).

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  Preferences and Options

  Your special material preference (e.g., stainless steel AISI 304/316, epoxy-painted carbon steel, polypropylene tank, etc.), automation level (remote monitoring request), special standards or integration requirements (ATEX certification, compatibility with existing systems, use of specific brand equipment) and other project-based requests.