Upflow Sludge Blanket Filtration (USBF™)

Operation of a USBF™ plant is simple and self-regulating. Wastewater enters the anoxic compartment of the bioreactor where it mixes with activated sludge recycled from the bottom of the sludge filter. Agitated and moved in a controlled manner, the mixed liquor flows into the bioreactor's aerobic compartment. From the aerobic compartment the mixture of microbial cells and water enters the sludge filter at the bottom and, as it rises, upward velocity decreases until the flocs of cells become stationary and thus form a filtering media. High degree of filtration efficiency is achieved as even particles with settling velocities too low to be removed by settling alone are filtered out. As the flocs become large and heavy by impact agglomeration, they descend to the bottom of the sludge filter and subsequently are recycled back into the anoxic zone. Filtered effluent overflows into a collection trough and is discharged from the system.

FEATURES

USBF™ Sludge Filter
Upflow sludge blanket filtration in a prism or a cone shaped filter introduces a substantially higher specific rate of separation than other commonly used separation techniques, and it facilitates operation in the region of increased mixed liquor concentrations (as it provides a "filtration/flocculation" mechanism to prevent the discharge of pin-point floc normally associated with high SRT systems).

Increased Mixed Liquor Concentration
Most traditional plants operate at low or medium sludge concentrations, typically 2,500 – 3,500 mg/l. USBF™ sludge filters by contrast operate at higher sludge concentrations, typically 4,000 – 6,000 mg/l resulting in longer sludge age and increased biological efficiency.

All Processes Integrated into One Reactor
By contrast, USBF™ technology incorporates processes of nitrification, denitrification, clarification and sludge stabilization inside a compact bioreactor, reducing equipment size and liquid handling requirements.

Patented and Proven
The USBF™ technology has been proven to consistently deliver high quality treated effluent in a variety of applications.

BENEFITS

High Treatment Efficiency Including Biological Nutrient Removal (BNR) The internal anoxic compartment provides the necessary conditions for dissimilarity nitrate reduction (denitrification) and phosphorus removal by "luxury uptake".

Alkalinity Recovery & Filamentous Bacteria Control
The integral denitrification process facilitates partial recovery of alkalinity loss during nitrification, and the anoxic compartment serves as a "selector zone" that conditions the mixed liquor to improve settleability and to control filamentous organism growth.

Hydraulic Flexibility
The sludge filter's prism or cone shape facilitates superior hydraulic flexibility. It accommodates high peak flows and flow swings in a self-regulating manner; the higher the flow, the higher the sludge blanket rises and the larger the filtration area becomes.

No Odor
Aerobic conditions throughout the bioreactor and extended sludge age eliminate or dramatically reduce the potential for bioreactor originated odor.

Reduced Operating and Maintenance Requirements
Compact design, minimal amount of moving parts, modularity of construction and self-regulating hydraulics result in reduced supervision requirements, and operating and maintenance costs.

Modular and Flexible Design
Modularity of design allows owners to stage plant development and reduce initial capital costs. The modular nature of the system also ensures that plants can be quickly expanded when demanded by population growths. The sludge filters can be fabricated from a variety of materials, and they can be retrofitted into virtually any existing tank or reactor.

Reduced Site Requirements
The process incorporates nitrification, denitrification, clarification and sludge stabilization in one compact bioreactor which reduces equipment size and liquid handling requirements and ultimately leads to a smaller plant footprint.

No Primary Clarification
USBF™ technology does not require primary clarification prior to biological treatment. Adequate screening facility and for larger plants, grit removal system are all that is required upstream of the bioreactors.

Improved Sludge Characteristics
Low microbial loading (extended sludge age of 25-30 days) produces less excess, aerobically stabilized sludge and improves sludge structure and mechanical dewatering characteristics.