https://doi.org/10.15255/KUI.2021.050
Published: Kem. Ind. 71 (5-6) (2022) 317–325
Paper reference number: KUI-50/2021
Paper type: Review
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Application and Modelling of Biofilm in Wastewater Treatment

T. Štefanac, D. Grgas, B. Marjanović and T. Landeka Dragičević

Abstract

Increasingly stringent regulatory requirements, greater wastewater generation, and limited space necessitate new wastewater treatment processes. Biofilm-based treatment technologies have proven to be efficient and applicable. The results of wastewater treatment using biofilm reactors with different types of carriers and the associated community of microorganisms support their use for wastewater treatment of different origins and degradation products present. Biofilm formation begins with the adsorption of molecules on the surface to form a film that can have several effects, such as altering surface properties and suppressing or enhancing the release of toxic metal ions from the surface. Subsequently, the microorganisms begin to coalesce into a microcolony and then into a three-dimensional biofilm structure. The biofilm cells detach from the structure and form a new biofilm. Biofilm reactors are divided into three categories, which are shown in Fig. 1. Common to them is the presence of supports with formed biofilm, low sludge production, easy handling, higher concentration of active biomass, protection of microorganisms from environmental changes and allowing the growth of slow-growing microorganisms, which are important for the degradation of complex compounds. In environmental biotechnology, the planning, designing, optimising, and evaluating processes in a biological wastewater treatment plant can be done with mathematical modelling of biofilm. Mathematical models of biofilm processes are used to predict the outcome of these processes and interpret the results of biofilm research. Most experience in modelling biofilm processes in wastewater treatment is based on the operation of suspended solids reactors. In biofilm modelling, the challenge is the effect of biofilm heterogeneity on the biofilm process and the existence of a steady state in biofilm reactors. Mathematical modelling in a biofilm reactor is not straightforward due to the complexity of the biological reactions involved in substrate transformation and the lack of accurate kinetic parameters for biofilm development. The parameters required for modelling can be obtained using equations such as those in Table 1. Although modelling of biofilm reactors is not uniform, there are instructions for the most accurate modelling, so the results obtained are useful and reduce the time for modelling as well as for design/improvement of the plant and thus saving resources. The number of models available is increasing, and the choice depends on their purpose and the expertise of the operator.

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Keywords

biofilm, biofilm reactors, reactor modelling, wastewater, wastewater treatment