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Role of Microbial Biofilms in Wastewater Management
Published in Bakrudeen Ali Ahmed Abdul, Microbial Biofilms, 2020
Anila Fariq, Anum Zulfiqar, Sidra Abbas, Azra Yasmin
A rotating biological contactor (RBC) is a fixed growth bioreactor that provides a suitable alternative to the traditional activated sludge process. An RBC reactor normally comprises of a series of tightly packed large flat or grooved discs mounted on a horizontal shaft that are partially or fully submerged in wastewater. The shaft constantly spins by a mechanical motor or a compressed air drive, and a biofilm is formed onto the whole surface area of the media to metabolize the organic materials present in the wastewater. The movement of media facilitates oxygen transfer and keeps the biomass in aerobic conditions. This movement also gives turbulence in the mixed liquor surface and allows the removal of excess solids from the media. Biomass clarification is done to remove these solids. Microscopic studies show that the outer biofilm layer in RBC reactor is complex and heterogeneous and comprises primarily of filamentous bacteria, protozoa, green eukaryotic algae, and small metazoans while the inner layer is more uniform and compact. The microbial density reduces in the innermost biofilm layer having a higher percentage of nonviable bacteria as compared to outer layer. Biofilm thickness ranges from 0.5 to 4.5 mm in thickness in full-scale disc RBCs used for municipal wastewater treatment. The thickness of the biofilm is controlled to avoid clogging (Cortez et al., 2008).
Importance of Bacterial Biofilm in Bioremediation
Published in Pankaj Chowdhary, Abhay Raj, Contaminants and Clean Technologies, 2020
Rishi Pramod Babu, Soumya Pandit, Namita Khanna, Pankaj Chowdhary, Abhilasha Singh Mathuriya, Elvis Fosso-Kankeu
The fluidized bed reactor uses a column of biofilm-coated beads in which contaminated water is slowly pumped upward and biofilm beads are suspended during the treatment of contaminated water. This is opposition to the fixed-bed reactor, where no media are suspended. Solids are suspended by the flow of liquid or gas at a certain velocity (Ingole and Burghate, 2013). Fluidization makes biofilms create a large surface area, thus producing high biomass. Aeration results in the biofilms developing on a larger surface area, thus producing high biomass. Aeration is done by an oxygenator or supplied from the bottom of the reactor. The fluidized bed reactor has been used to treat streams contaminated with organic and inorganic compounds. Rotating biological contactors (RBC) or modified forms of RBC have been used for wastewater treatment by reducing chemical oxygen demand and biochemical oxygen demand, and also for nitrification and denitrification processes (Figure 9.3).
Analysing problems and opportunities to deliver sustainable solutions
Published in Adrian Belcham, Manual of Enviromental Management, 2014
The difference between the processes is simply in how they enhance oxygen content and circulate bacterial populations to accelerate organic breakdown. The activated sludge process involves getting oxygen into the wastewater either through a diffuser or a mechanical agitator and recycling about 10 per cent of the active biomass back to the process.Trickling filters involve trickling the wastewater over a bed of stone or plastic packing material (also called percolating filters).Rotating biological contactors involve a rotating disc partially immersed in the wastewater. In the latter two processes the micro-organisms grow attached to the surfaces.
A comparative study on the performance of conventional photobioreactors and ALGADISK in CO2 sequestration—a review
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
S. Sivasangari, T. VelRajan, J. Nandhini
Rotating biological contactors (RBCs) offer an alternative treatment technology to the conventional activated sludge process. The principal advantages of RBCs is that the interfacial area generated is very high for biomass growth and the power consumption is very low since there is no need of extended aeration using power supply (Mónica Paola Guamán Guadalima, Diego Alejandro Nieto Monteros 2018). The RBCs or simply “biodisks” are part of the so-called biofilm processes. In these reactors, biofilm support material consists of disks, with a certain uniform distance between each other, coupled to a rotating horizontal shaft driven by a motor (A. W. Patwardhan 2003). The disks are partly submerged in the wastewater and partly exposed to the air. While rotation, the disks when exposed to atmosphere sloughing or slime layer formed on the disks could get the necessary oxygen from air (oxygen transfer occurs). RBCs are widely employed in wastewater treatment as shown in Figure1. The biofilm oxidizes organic matter from wastewater (BOD, COD) and/or nitrogen (joint nitrification or tertiary process), while the oxygen necessary to the metabolic activity of the microorganisms is ensured by disks rotation.
Bioremediation of dyes: a brief review of bioreactor performance
Published in Environmental Technology Reviews, 2023
Himanshu Tiwari, Ravi Kumar Sonwani, Ram Sharan Singh
Rotating biological contactor (RBC) is an open biofilm-based attached growth reactor system and the best-known application is aerobic biological wastewater treatment [217–219]. A typical bioreactor system contains a series of equally spaced discs, either flat or corrugated, partially submerged (around 40%) in the wastewater tank, and are mounted on a central rotating shaft [28,220,221] (Figure 15).