A comparison of Aqwise MBBR/IFAS Technology with Levapor Technology

Property/Attribute Aqwise Levapor Significance
Material of Construction HDPE : virgin /Recycled Poly Ether based Poly Urethane The properties of HDPE are more often fixed and can not vary/modify to meet requirement for particular application. While PU properties are highly variable and can be modified to meet the properties required for individual application
Water Affinity Hydro Phobic Hydrophilic
  • Due to hydrophobic nature of HDPE plastic, it offers poor water affinity to  water and thus biofilm development in wastewater treatment application  requires significant time. While Poly Ether based PU are hydrophilic in nature  and thus biofilm development is very fast compared to HDPE. 
  • Hydrophilic nature of the PU material also helps in better fluidization of the  moving carrier bed and wetting takes place at very faster rate compared to  HDPE. 
Adsorbent Capacity Nil

Very high due to impregnation of PU foam matrix with 15-50 kg highly adsorbent activated carbon per m3 of foam

 
  • Adsorbent capacity of carrier material is very important property as adsorbent  capacity provides , faster adherence of micro organisms on the carrier surface  and also adsorbs toxic pollutants on the carrier material which then can be  biodegraded by micro organisms causing reversible regeneration of the  adsorbing surface.  
  • Levapor carriers are impregnated with activated carbon which provides very  high adsorbent capacity rendering remarkable faster colonization of the carrier  material, adsorption of toxic material and their degradation which offers far  better process stability due to reduction of toxic pollutant concentration in the  bulk liquid and its subsequent degradation 
  • On the contrary Aqwise carriers offer no adsorbent capacity and thus the advantages offered by adsorbent surface are not available with Aqwise carriers
and MBBR/IFAS processes.
Internal Porosity Very low Very high
  • Due to the fine pore structure of PU foam matrix, Levapor carrier offers very  high internal porosity. The high internal porosity allows for better substrate  and DO gradients in the carrier material offering ideal habitat for Nitrifying  bacteria and other slowly growing micro organisms which requires varying  substrate/DO conditions compared to micro organisms growing in bulk liquid  with higher substrate/DO concentration. 
  • The internal porosity also allows for growth of micro organisms in films as well  as discrete micro organisms adhering to the carrier material preventing their  complete wash our against excessive shear conditions due to mixing and  aeration requirement.  
  • Levapor carriers have porosity of 40 pores per inch of carrier length allowing for  easy transport of a particle of 370-450 micron through it rendering self cleaning  ability and better transport of particulate substrate in it.  
  • The Aqwise carrier material is highly dependent on the shape of the carrier for  its internal porosity and not much internal porosity is offered per m2 effective  surface area. 
Surface Area 600-650 m2/m3 effective surface area 20,000 m2/m3
  • The effective surface area offered by Aqwise is 600-650 m2/m3 while un  modified PU foam has a surface area of 2500 m2/m3 but the impregnation of  PU foam with activated carbon results in surface area as high as 20,000 m2/m3. 
  • The higher amount of surface area results in more amount of micro organisms  per m3 of media provided and requires lower degree of filling. 
Weight 100-150 kg/m3 (general data as no information available from Aqwise) 25-45 kg/m3 The bulk weight of Aqwise carriers due to HDPE material would be very high requiring additional amount of energy for mixing and fluidization while the PU based Levapor carriers have weight of 25-45 kg/m3 which requires quite less amount of energy for mixing and fluidization reducing the energy consumption of the plant to a significant level. Even the colonized Levapor carriers have weight in the range of 65-80 kg/m3 which is nearly 30-50% lower than the HDPE based Aqwise carriers.
Filling Ratios 40-50% 12-15%
  • Due to higher surface area to volume ratios , the degree of reactor filling  required for Levapor carriers is less compared to Aqwise carriers resulting in  smaller foot print, lower energy consumption.
  • It also reduces the media requirement for particular treatment resulting in  lower capital costs. 
  • The lower degree of filling also enables significant amount of biomass growth  in the suspended phase making the reactor truly hybrid in its configuration. 
Bulk DO concentration 3-5 mg/lit 2-3 mg/lit
  • Due to the surface geometry and film thickness Aqwise carriers based  MBBR/IFAS reactors require to operate at higher bulk DO concentration of 3-5  mg/lit to facilitate better transport of DO within the internal parts of film.
  • While due to fine pore structure and thus film geometry , Levapor based  MBBR/IFAS reactor can be operated efficiently with bulk DO concentration of  2-3 mg/lit resulting in lower aeration requirements and thus lower energy  consumption for the required treatment. 
Simultaneous Nitrification – Denitrification NA Observed lower Total Nitrogen Leaving the reactor We have observed lower nitrogen concentration leaving the Levapor based reactor which could be contributed to simultaneous nitrification-denitrification due to anoxic conditions prevailing in the internal pores of the carrier materia resulting in lower Total –N concentration and thus if configured for Pre-Anoxic denitrification then lower recirculation of nitrates required for complete nitrogen removal.
comparison of Aqwise MBBR/IFAS Technology with Levapor Technology
Fig. Colonized Levapor Carriers showing internal pores