Lower Mainland BC Plastics Recycling Plant: DAF Case Study
A complete dissolved air flotation system – DAF unit, flocculator, polymer make-down and chemical dosing skids – treats the wash water of a plastics recycling plant in the Lower Mainland, BC.
The application
The client, in the Lower Mainland of BC, recycles post-consumer plastics. Washing the shredded plastic produces a wastewater loaded with suspended solids, grease and dissolved organics – the lab sample used for design had 3,813 mg/L TSS and 11,450 mg/L COD.
Archer supplied a complete physico-chemical treatment line built around an Ekoton DAF with lamella plates. The wash water is conditioned in a pipe flocculator with pH control, coagulant and polymer, then the floated solids are scraped off the top while heavy solids settle and are drawn off from the bottom.
Instead of an air compressor and saturator, a multiphase EDUR recirculation pump makes the micro-bubbles, which keeps the system compact and simple to run.
What Archer supplied
- Ekoton FT-15L dissolved air flotation unit in 304 stainless steel with FRP lamella plates, scum scrapers on a stainless chain and motorized bottom-sludge valves
- Ekoton KF-15 pipe flocculator in Sch 80 PVC with static mixers and injection points for coagulant, pH adjustment and polymer
- EDUR multiphase recirculation pump (4 kW, 6 bar, 10 m³/h) for micro-bubble generation, with valves, gauge, flowmeter and pressure switch
- Archer polymer make-down system with 600 L two-compartment HDPE tank and SYDEX progressive cavity feed pump
- Pre-piped chemical dosing skids for acid, base and coagulant, each with metering pump, calibration column and turbine flowmeter
- Victor self-priming feed and effluent pumps (two duty, one shared standby) and an air-operated diaphragm pump for thickened sludge
- Endress+Hauser pH, turbidity and flow instruments, and a CSA-certified control panel with PLC and 15″ touch screen
Design basis
| Wastewater | Plastic recycling wash water, screened |
|---|---|
| Flow | 60 US gpm average (13.63 m³/h), up to 70 US gpm (15.89 m³/h) |
| Influent TSS | 3,813 mg/L average (lab test) |
| Influent FOG / BOD₅ / COD | 420 / 3,630 / 11,450 mg/L |
| Operation | 8 h/day, 5 days/week |
| Guarantee | DAF effluent TSS ≤ 300 mg/L |
Design figures from Archer proposal 9121601 (Section 4, Rev 8).
Related
- DAF Systems: dissolved air flotation for industrial wastewater.
- Plastic Recycling: decanters for plastics and PVC dewatering.
- Chemical Systems: metering skids and chemical feed systems.
- Polymer Systems: dry and emulsion polymer make-down.
- Control Panels: pLC control panels designed and built in BC.
- All case studies: more Archer projects in the field.