Upflow Sludge Blanket Filtration (USBF®)

ECOfluid’s proprietary USBF® technology delivers high wastewater treatment efficiency, including biological nutrient removal (BNR), with very competitive capital and operating costs. The technology and components can be delivered as self-contained package plants or they can be site constructed for larger capacity installations.

The integrated USBF® bioreactor incorporates anoxic and aerobic  compartments, and upflow sludge blanket filter(s). Operation of a USBF® plant is simple and self-regulating. Influent wastewater (see 1 on diagram) enters the anoxic compartment of the bioreactor where it mixes with activated sludge recycled from the bottom of the sludge blanket filter (2). Agitated and moved in a plug flow manner, the mixed liquor flows into the aerobic compartment (3).

After aeration, mixture of microbial cells and water enters the USBF® filter at the bottom (4). As it rises within the filter towards the effluent overflow trough at the toUSBF bioreactorp, upward velocity decreases as the cross sectional area of the filter increases. No longer supported by the decreased upward velocity, the flocs of cells become stationary and thus form a filtering media themselves. Becoming larger and heavier by contact and agglomeration, the flocs eventually descend to the bottom of the filter and are subsequently recycled back into the anoxic compartment (2). Filtered effluent overflows into a treated effluent overflow trough and is discharged from the system (5). A high degree of filtering efficiency is achieved as even very fine particles are filtered out.

Incoming nitrogen is removed by nitrification and denitrification processes. All USBF® integrated bioreactors are designed for complete nitrification of ammonia to nitrate. The technology’s single-sludge denitrification uses an endogenous carbon source to maintain the denitrifiers. Influent is mixed with recycled activated sludge in the anoxic compartment providing the carbon source needed for denitrification.

Incoming phosphorus is reduced by biological phosphorus uptake, also known as luxury uptake, where the cells store more energy in the form of phosphorus than needed for their survival. Unlike most other methods of clarification, the sludge blanket filter maintains oxide conditions, which enable phosphorus retention by the cells and its subsequent removal with excess sludge.

USBF® benefits 

  • high treatments efficiency, including BNR
  • modular, expandable, compact
  • reduced odor and noise
  • minimal amount of moving parts, gravity flow
  • reduced capital and operating costs
  • fluidized bed filtration efficiency
  • self-regulating hydraulic flexibility: as the flow grows the sludge blanket rises the filtration area increases – see illustration below.

Low flow rate


High flow rate