Traditionally, while designing MBBR process using conventional plastic carriers, it has been assumed that no biochemical removal is happening within the suspended phase or liquid phase.Rather the biochemical removal is occurring only due to attached biomass on the carriers only.
However, it has been observed that because of continuous abrasion and erosion of carriers, significant amount of active biofilms are detached from the carriers. This biomass contributes to overall removal rate at quite significant level. Also for industrial effluent application of MBBRs where HRT of the reactor tend to be quite high, the overall contribution of this detached biofilms in the achievable removal rates can not be neglected.
Thus, by recycling the settled MLSS which is being detached from the MBBR carriers and by maintaining it at certain level of MLSS, significant higher removal rates can be obtained for any MBBR reactors.
This concept traditionally known as IFAS or CFAS (Integrated Fixed Film Activated Sludge or Combined Fixed Film Activated Sludge) process has been successfully implemented for thousands of wastewater treatment projects and offers many benefits compared to once through MBBR systems.
With Levapor carriers, IFAS or CFAS process configuration seem to be more suitable compared to once through MBBR system. Because of specific carrier geometry, surface properties and pore structure, continuous erosion, attachment and detachment of biofilms is observed at much higher rates compared to plastic media. This phenomenon enables Levapor carriers acting as seeding agents for the liquid phase and thus highly active biomass is observed in suspended phase as well.
The hybrid IFAS process with Levapor carriers bringing advantages of both Suspended Growth as well as Attached growth process has achieved much better process economy in terms of volumetric and pollutant loading rates, energy consumption, process operation and maintenance.
Advantages of Levapor IFAS Process
Levapor carriers based IFAS process offers distinct advantages compared to once through MBBR processes.
Higher amount of highly active biomass per m3 of reactor volume reducing the foot print of the plant significantly
Higher amount of biomass without additional solids loading to clarifiers
Improved SVI values and settling properties
Reduced sludge Production
Higher amount of Simultaneous Nitrification and Denitrification due to fine pore structure of Levapor carriers reducing Nitrate Recycle flows for Biological Nutrient Removal (BNR) system and thus reducing energy consumption significantly
Can be applied with fine bubble diffuser system achieving higher Aeration transfer efficiency with reduced aeration energy
Plants can be operated under a wide range of operating conditions by varying process parameters like MLSS, DO levels offering better removal efficiencies under varying load conditions.
Remarkable process stability against toxic shock loads preventing complete inhibition and wash out of biological process.