Bio fi lm in this process various micro organisms are

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Bio fi lm In this process various micro-organisms are made to attach to a single support and the wastewater is puri fi ed when it fl ows on this surface by contact. The bio fi lm processes can further be divided into three categories which include biological fl uidized beds, biological contact oxidation and rotating biological contactors. Biological Fluidized Bed The fl uidized bed process is also referred to as the suspended carrier bio fi lm process (Chaohai et al. 1998 ). This is a new and highly ef fi cient wastewater treatment process which uses the modern fl uidization technology whose principle is to keep the whole system at a fl uidized state and in turn enhance the contact time and area between solid and fl uid particles. The substances usually used as carrier or fi lling in the system include carbonaceous materials such as sand, activated carbon, anthra- cite or other particles. The diameter of these particles needs to be less than 1 mm. A pulse of the wastewater is allowed to pass through the carrier which leads to fl uidization of the carrier particles and in turn leads to formation of bio fi lm on these particles. Smaller size of carrier particles is preferred as it leads to higher surface area (the preferred area is between 2000 and 3000 m 2 /m 3 ), which in turn can hold higher amount of biomass. This process yields ef fi ciency of 20 30 times higher than the conventional treatment processes and hence can be used for treating high consistency organic ef fl uent from textile industries. Biological Contact Oxidation Biological contact oxidation is a process which is primarily used for treating wastewater from the dyeing process (Guosheng 2000 ). Fillers are set in tanks called aeration tanks and the set-up mimics that of the activated sludge process. A bio fi lm is formed on the fi llers placed in the tank and the wastewater in the tank contains a certain quantity of activated sludge. Aerobic micro-organisms are present in the bio fi lm and these microbes degrade the organic matter present in wastewater when they come in contact with each other. Rotating Biological Contactor Rotating biological contactor is a wastewater treatment process which is modelled based on the conventional biological fi lter (Abraham et al. 2003 ). It consists of a series of discs which are usually composed of low weight materials such as plastic or glass platers. The diameter of the discs used ranges from 1 to 3 m. The disc is constructed such that half of the disc area is exposed to air while the other half is submerged in the supplied wastewater. The Rotating device makes the discs rotate slowly in the horizontal axis which in turn helps to completely mix the wastewater due to continuous rotational motion. The micro-organisms present in the wastew- ater form a bio fi lm on the disc when the disc is exposed to the wastewater. When the same disc is exposed to air, the bio fi lm comes in contact with oxygen and gets 72 P. Senthil Kumar et al.
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adsorbed. The micro-organisms oxidize and degrade the organic matter present in
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  • Fall '19
  • N. Gokarneshan

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