THE MEMBRANE BIOREACTOR

A MBR IS AN ACTIVATED SLUDGE PROCESS that uses membranes to filter out suspended solids, including harmful microorganisms such as viruses, bacteria and cysts.

THE MBR
In a MBR, one or more SMUs are connected via common permeate, air supply and diffuser cleaning pipes.

THE SUBMERGED MEMBRANE UNIT (SMU)
Each SMU is comprised of an integral air diffuser assembly and one or two membrane cassettes. The air diffuser provides air for scouring, mixing and cellular activity. A membrane cassette contains between 25 and 208 membrane cartridges that are connected to, or form, a common permeate manifold. Multiple SMUs are connected to a common header in each MBR.

Mixed liquor circular flow pattern

Integral air diffuser assembly

THE MEMBRANE CARTRIDGE
Each membrane cartridge is constructed by ultrasonically welding a sheet of thin polymeric material to the back and front of a support panel. Between the panel and the membrane material is a porous spacer material that distributes water to a series of grooves that channel filtered water to the top of the cartridge.

Membrane Catridges

MULTIPLE BARRIERS
In an Enviroquip MBR, flat-sheet membranes are used to filter a concentrated mixture of microorganisms commonly referred to as mixed liquor. The microorganisms consume BOD, nutrients and refractory organic compounds such as NDMA. In addition, they attach themselves to the membrane surface to form a thin film called a biofilm.

Within seconds, cells begin to form a biofilm that functions like a dynamic membrane. Properly maintained, the biofilm protects membrane material from fouling and creates a second densely packed barrier to pathogen breakthrough.

1. Air Bubbles
2. Biofilm
3. Microorganisms
4. Crossflow
5. Membrane Material
6. Filtered Permeate

BIOHYDRAULICS
Irrespective of the type or shape of a membrane, biofilms do most of the filtering and create the most resistance to water flow. Maintaining biofilm thickness and porosity through effective air scouring and proper biological process control is the key to optimizing the hydraulic performance of any submerged membrane technology in MBR applications. The link between biological process conditions and membrane hydraulics is referred to as biohydraulics.

Kubota SMUs are engineered to maximize air-scouring efficiency and eliminate opportunities for hair and debris to accumulate. Efficient and equal air scouring dramatically reduces the pressure it takes to filter solids from treated wastewater, often referred to as transmembrane pressure (TMP). The ability to operate at low TMP reduces the propensity for membrane fouling and eliminates the need for weekly chemical cleanings and or backpulsing common to other technologies.

WHY DO KUBOTA FLAT-PLATE MEMBRANES LAST LONGER THAN OTHER TECHNOLOGIES?

• Equal and effective air scouring
• Low transmembrane pressure (TMP) operation
• No backpulsing or weekly chemical cleans
• Infrequent chemical cleaning
• No fiber buildup