Biofilm in Moving Bed Biofilm Process for Wastewater Treatment

Abstract

A brief introduction of the long history of biofilm-based wastewater treatment is given together with basics of biofilm behavior and mechanisms in removal and transformation of pollutants. Moving bed biofilm reactor (MBBR) principles and applications of such are presented. Advantages and limitations of such solutions are given together with evaluations of emerging MBBR applications. The basis of biofilm processes and biofilm layer classification based on dissolved oxygen gradient is discussed. Organisms grow at the protected surface of the biocarrier where oxygen gradients create aerobic, anoxic, and anaerobic layers allowing simultaneous nitrification and denitrification in one MBBR (nitrification, nitritation, autotrophic, and heterotrophic denitrification). Combination of MBBR with activated sludge, continuous flow intermittent cleaning (CFIC®), and integration with anaerobic digestion increases the potential usage of MBBR for enhanced efficiency and energy recovery and is partly discussed as case studies (COD, ammonium, and solid removal). Biofilm thickness and scaling control can be crucial for MBBR performance. The type of carriers, filling degree, and operational conditions play a major role for process performance; hence, the effect of those parameters is presented.

A Comparison of Biosolids Production and System Efficiency between Activated Sludge, Moving Bed Biofilm Reactor, and Sequencing Batch Moving Bed Biofilm Reactor in the Dairy Wastewater Treatment

“…The analysis of the results presented in Figure 2 shows that all the proposed systems allow compliance with the discharge value for the organic matter (measured as COD) in industrial wastewater emission defined in Portuguese legislation (Decree-Law 236/98 of August 1) [50], which is 150 mg COD L −1 , except for AS with an OLR of 5.44 g COD L −1 d −1 . Santos et al [19] used dairy wastewater with COD concentrations of 600-800 mg O2 L −1 and 1100-1200 mg O2 /L −1 , in batch and continuous operation, to remove COD using an MBBR. For a carrier filling fraction of 40%, the authors achieved higher COD reductions than for 20% [27].…”

“…For instance, attached growth processes increase the biofilm surface area, increasing the volume of substrate able to be adsorbed from wastewater, improving the overall efficiency of the process [18]. Biofilm in the carriers might promote aerobic, anoxic, and anaerobic mechanisms, with the substrate limitation being responsible for the thickness of the biofilm [18][19][20]. This type of reactor opens a variety of positive perspectives for its recognized ability to oxidize carbon and nitrogen, for requiring a smaller reactor than an activated sludge system, for not requiring any sludge recycle, for the reduced costs combined with a smaller carbon footprint, lower requirement for settling volume and sludge formation, and for its biomass retention capacity in floating mobile plastic carriers [18,[21][22][23][24][25].…”

“…The MBBR allows upgrading performance and volumetric treatment capability in existing wastewater treatment plants with minimal additional costs and a reduced footprint [26]. The main characteristic of these systems is the biofilm growing on a protected area with different species of microorganisms coexisting in the carriers' surface, enhancing protection and resilience to environmental conditions [19]. The treatment system does not require any sludge recycling, and only the surplus biomass should be separated, which constitutes a considerable advantage over the AS and SBR systems [21,27].…”

Comparative environmental impact evaluation using life cycle assessment approach: a case study of integrated membrane-filtration system for the treatment of aerobically-digested palm oil mill effluent

“…As much as 52 MJ of electricity was consumed for the treatment process in Combination III, which exceeds that of Combination II (41.6 MJ). Although Combination III bypassing the UF-membrane unit has reduced the use of electricity by the UF-membrane unit, the MBBR nonetheless consumes appreciable electricity due to continuous air supplied by the air compressor for the biofilm growth [61]. As electricity consumption is the main input factor leading to all environmental impacts imposed by Combination III, the RO membrane unit, with its use of high-pressure pumps, consumes the greatest amount of electricity and is thus the dominant unit operation promoting for aforementioned environmental impacts under operating processes in Combination III.…”

Facilitated lignocellulosic biomass digestibility in anaerobic digestion for biomethane production: microbial communities' structure and interactions

“…High-density polyethylene (HDPE) with a protected area of 650 (BWTX ®) and 828 (BWT15 ®) m 2 /m 3 are two different types of plastic carriers, the biofilm on the carriers grows and holds active species in thin layers. 165 In AD, methanogenic archaea grow at smaller rate than fermentative and acetogenic bacteria, making them vulnerable to changes in surrounding. The crucial factors affecting the efficiency of the AD reactor are the densities and species of methanogenic bacteria, special importance should be given to exploring the effective AD reactor for the production and maintenance of huge density, stable, and viable biomethane-producing bacteria population.…”