Levapor carriers are made of flexible, durable, high porous Poly Ether(PE) based Poly Urethane(PU).The PU foam is impregnated with fine activated carbon to render superior properties for the development of efficient biofilm for complex and difficult to biodegrade effluents.
Ideally a carrier material must offer higher adsorbent surface area for faster and stable colonization of micro organisms on it. It should provide internal porosity to protect the microbes against toxic and inhibitory substances and shear forces imparted due to mixing/aeration. It should also ensure optimal mass transfer properties for the transport of substrate and nutrients making them available for micro organisms growing in the biofilm. It should also possess good water affinity and higher fluidization ability for economical and efficient mixing of the carriers with bulk liquid and thus ensures optimal and user friendly operation of the biological treatment process.
Higher adsorbing surface and higher surface area
Adsorption of inhibitory substances leading to better process stability and faster colonization
high internal porosity
Prevention of biomass against excessive shear forces and formation of low DO zones
Fast wetting and water binding
Homogenization of fluidised medium and maintenance of biological activity
Higher fluidization ability
Reduction of power consumption
Faster colonization of bacterial mass with higher surface
Levapor carriers possess all the above mentioned properties of an ideal carrier:
High Adsorption Surface:
PU foam has very high surface area compared to conventional plastic media. Moreover Levapor carriers are impregnated with 15-40 kg of activated carbon per m3 of foam which increases the surface area to thousand fold and also offers very adsorption capacity of activated carbon. This combination of high surface area and adsorption capacity of activated carbon leads to very fast and stable colonization of carrier material with micro organisms. The presence of activated carbon also helps in adsorption of toxic and inhibitory substances on the activated carbon fixed on carriers surface reducing its bulk liquid concentration. This eventually stabilizes the process in the reactor and as Levapor facilitates development of specialized microbial strains for the degradation of these toxic/inhibitory substances, their removal from the effluent stream becomes feasible and more efficient compared to conventional suspended growth based and plastic media based processes.
PU foam matrix provides higher internal porosity in the form of fine pore structure which enables growth of micro organisms within the internal pores of Levapor carriers and thus prevents them against toxic shock loads and excessive shear forces imparted due to aeration equipments.
The fine pore structure of the foam also provides thinner film geometries compared to conventional plastic media which allows for better diffusion gradients for substrate and nutrients resulting in optimal mass transfer efficiencies. This in turn improves the transport of substrate and nutrients to inner parts of the biofilm and thus increases the process performance.
Fast wetting and water binding surface:
Levapor carriers have fast wetting and binding surface due to hydrophilic nature of PU foam which provides faster colonization, better fluidization and homogenization capacity which results in faster process start ups, lower energy consumption for mixing and maintenance of healthy biological activity. The better fluidization also helps maintaining good mass transfer gradients across the carriers.
Surface area of Levapor carriers is the result of:
Surface of PU foam which is 2500 m2/m3
Surface of the activated carbon which is 1000 to 2000 m2/g.
The combination of PU foam and activated carbon thus results in a total BET surface area of 3.34 million m2/m3. However, only a small fraction of this total surface area is colonized but still it is extremely higher than conventional plastic media.