attached growth process

Attached growth MBBR / IFAS Process

Fixed film or attached growth processes have been utilized for biological wastewater treatment since late 1800s. In the attached growth process micro-organisms responsible for organics and nutrient removal from wastewater are allowed to grow on specific support medium which provides habitat/surface for microbial growth.

Though having same metabolic pathways for removal as suspended growth process, attached growth processes offer distinct advantages over suspended growth processes such as:

  • Smaller foot print
  • Minimized needs for settling equipment
  • Operational simplicity
  • Protection Against Toxic Shock loads
  • Reduced operating and energy costs.

Earlier applications of attached growth processes involved use of gravel media as support mechanism in biological filters developed as early as 1890. Since then due to continuous research and innovation, variety of media types and process configurations have been developed. These different media types include simple wood sheets, blast furnace slag, coarse sand, rocks and pebbles, cords, textile and asbestos sheets. These media have been incorporated into different process configurations like biological filters, contact beds, Trickling filters, Rotating Biological Contactor(RBC), Biological Aerated Filters (BAF) and Submerged Aerated Fixed Film Filters(SAFF).

Over the years, with more understanding and knowledge, there has been a trend towards developing attached growth process utilizing free floating media for biological growth in the reactors. This variant termed as MBBR or IFAS utilizes tiny floating carriers which are kept in suspension just like the floc particles of suspended growth process. These tiny particles made of different materials like PP,HDPE,LDPE, PU foam and having different shape and structure allows growth of biomass responsible for the degradation of target pollutants.

The free floating variant of attached growth configuration enhances the advantages of traditional attached growth processes overcoming some of the limitations present in the traditional attached growth processes.

Over last few decades free floating Media based attached growth process solutions have been successfully implemented for various wastewater treatment applications like BOD removal, industrial effluent treatment from different industries, Nitrogen removal and upgradation of existing Sewage Treatment Plant and Industrial effluent treatment plants for higher capacity and/or better removal efficiencies.

Advantages of free floating attached growth process:

  • Simplicity of design
  • Flexibility of operation and ease of maintenance
  • Can be configured with variety of settling equipment
  • Smaller foot print
  • Higher volumetric loading rates and removal efficiencies