Attached growth

Figure 11.56 shows a typical attached growth arrangement. 

Attached growth processes are capable of removing up to 90 percent of BOD and are thus less effective than suspended growth methods. 

In attached growth film) methods, as with aerobic digestion, the microorganisms can be encouraged to grow attached to a support medium such as plastic packing or sand. In anaerobic digestion, the bed is usually fluidized rather than a fixed-bed... 

There are two major types of biological treatment processes attached growth and suspended growth. 

Attached growth processes Wastewater treatment processes in which the microorganisms and bacteria treating the wastes are attached to the media in the reactor. The wastes being treated flow over the media. Trickling filters, bio-towers, and RBCs are attached growth reactors. These reactors can be used for removal of BOD, nitrification, and denitrification. 

The well-known aerobic downflow process is a trickled bed filter. Attached growth is used in the biological treatment of wastewater. Air passes through the bed while the liquid is forced to down by gravity. Figure 13.2 shows the liquid gas system for the mass transfer... 

Fig. 13.2. Liquid gas mass transfer process in biological filter, attached growth system.

Attached-Growth Biomass for Sanitary Landfill Leachate Treatment. 581... 

The use of an attached growth aerobic biofilm reactor to treat leachate is relatively new. Past studies on anaerobic biofilters showed excellent organic removal up to 90%, and the retention time needed to treat high-strength effluent was between 3 and 5 d. The use of aerobic biofilters using... 

FIGURE 15.2 Schematic diagram of leachate treatment using an attached growth biofilm reactor. 

Loukidou, M.X. and Zouboulis, A.I., Comparison of two biological treatment processes using attached-growth biomass for sanitary landfill leachate treatment, Environ. Pollut., Ill, 273-281, 2000. 

Type of reactor (suspended or attached growth systems)... 

Trickling filter systems are classified under the aerobic attached growth systems (Figure 30.7). Crushed rock and stone, slag, wood, or synthetic media with higher permeability are used to fill the filter bed. The size of the media is in the range of 25-100 mm diameter. The depth of the filter... 

Figure 26.7 shows a typical attached growth arrangement. Alternatively, the wastewater can be used to fluidize a bed of carbon or sand onto which the film is attached. 

Figure 26.9 Attached growth anaerobic digestion using a fluidized anaerobic bed.

Cheng HF, Kumar M, Lin JG (2010) Assessment of di-(2-ethylhexyl) phthalate (DEHP) removal in attached growth and suspended growth biological treatment systems of a municipal sewage treatment plant. Sep Sci Technol 45 221-227... 

The anaerobic hybrid reactor is generally a combination of suspended growth and attached growth systems. Recently, this technology has become popular in the treatment of industrial wastewater, in particular in cases of high-strength wastewater. It has been reported that this... 

Anaerobic Filter. An anaerobic filter consists of packed support media that traps biomass as well as facilitates attached growth of biomass as a biofilm (Fig. 8). Such a reactor configuration helps in the retention of suspended biomass as well as gas-liquid-solid separation. The flow of liquid can be upward or downward, and treatment occurs due to attached and suspended biomass. Treated effluent is collected at the bottom or top of the reactor for discharge and recycling. Gas produced in the media is collected underneath the bioreactor cover and transported for storage or use. Volumetric loading rates vary from 5 to 20 kg COD/m day with HRT values of 0.5-4 days. 

Attached-growth waste stabilization ponds have been used to remove 65-70% TKN (total Kjeldahl nitrogen), and 70-83% NH3-N from concentrated latex and rubber sheet plant wastewaters [8]. A combined algae and water hyacinth system has been used to remove 96.41% COD, 98.93% TKN, 99.28% NH3-N, 100% NO2-N, and 100% NO3-N [9]. 

Rakkoed, A. Danteravanich, S. Puetpaiboon, U. Nitrogen removal in attached growth waste stabilization ponds of wastewater from a rubber factory. Water Sci. Technol. 1999, 40(i), 45-52. 

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