MEMBRANE BIOREACTOR SYSTEMS

MEMBRANE BIOREACTOR SYSTEMS

The term "membrane bioreactor" (MBR) is generally used to describe waste water treatment processes in which a permeable selective membrane, for example microfiltration or ultrafiltration, is integrated into a biological process - a suspended growth bioreactor.

All commercial MBR processes available on the market today use the membrane as a filter and ensure a clear and disinfected product by not penetrating the solid materials developed by the biological process.

A membrane bio reactor is essentially a version of the conventional activated sludge (CAS) system. The CAS process uses a secondary sedimentation tank for solid / liquid separation, while an MBR uses a membrane for this function. This provides a number of advantages regarding process control and product water quality.

Separating HRT and SRT

An important advantage of the membrane bioreactor process is the complete retention of sludge solids in the bioreactor. This means that the solid retention time (SRT) in the bioreactor can be controlled separately from the hydraulic retention time (HRT).

This is different from the CAS process in which the flocculating solids (‘flocs getiren) that make up the biomass must be allowed to grow to the point where they can collapse in the precipitation tank. In a CAS, HRT and SRT are therefore coupled because the floc size and therefore its location is related to HRT.

High quality waste

The small pore size of the membrane (<0.5 umm) means that the treated effluent has a very high clarity and a significantly reduced pathogen concentration. MBR processes provide a highly cleaned and disinfected waste of high quality to be discharged to the sensitive receiving environment or recovered for applications such as urban irrigation, utility or toilet washing.

Need Smaller Space

The biomass concentration increases with the increase in SRT bin and the required space requirement is reduced.

Better Bio-Removal

Finally, longer solids retention times generally tend to provide better biological treatment. Conditions promote the growth of slow growing microorganisms, especially nitrides. MBRs are particularly effective in the biological removal of ammonia (‘nitrification’).