Biofilm in Wastewater Treatment

**3**

**Chapter 1**

**Abstract**

**1. Introduction**

immobilization [1, 3, 4].

*and Rune Bakke*

Biofilm in Moving Bed Biofilm

*Shuai Wang, Sudeep Parajuli, Vasan Sivalingam* 

Process for Wastewater Treatment

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.

**Keywords:** moving bed biofilm, TN removal, scaling on biofilm, biocarriers

The use of biofilm systems in wastewater treatment is being increased rapidly because of its tempting approach of pollutant removal from wastewater, which has been proved to be effective in terms of both cost and environmental perspectives [1, 2]. Biofilm can have both positive and negative effects in treatment processes depending on the type of treatment concept applied. Processes such as a moving bed biofilm reactor (MBBR) depend on biofilm development, while it can cause problems in membrane bioreactor (MBR) through membrane biofouling. Those processes taking advantage of biofilms have been widely used for the removal of organic and inorganic matters from different wastewaters [1], by mechanisms such as biodegradation, bioaccumulation, biosorption, biomineralization, and bio-

There are several benefits of using biofilm system in wastewater treatment, as compared to suspended growth system (activated sludge for example), such as flexible procedures, smaller space demand, lower hydraulic retention time, increased resilience to changes in the environment, higher biomass retaining period, high active
