Biology does not afford treatment of CSO’s (Combined Sewer Overflow) waters under fair technical conditions. Due to limited upflow velocities during the settling phase, the usual physico-chemical processes do not afford treatment of such high flow rates under fair economic conditions.The ACHFLO process, using recycled microsand as a ballast to increase the settling speed of flocculated particles, overcomes this economic problem through lowering by a factor of 10 (approx) the lamellar area required to treat a given water flow.Removal of 80% of TSS, 60% of BOD, 15% of NTK and 80% of P is achieved with a consumption of about 60 g FeCl3, 0.8 gpolyelectrolyte and 3 g of microsand per m3 of CSO’s water, within a total area of only 0.03 m2/m3 influent per hour.Plant start-up is achieved within about 15 minutes.Microsand weighted flocculation appears to be a good way for disposing of the COS’s water from large and medium urban catchments economically.
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- High Speed Settling of Stormwater with Microsand
- Springer Berlin Heidelberg