**1.2. Biofouling due to bacterial colonization**

Biofouling occurs due to the adsorption of the biological cells on a membrane surface [5]. Biological organisms are usually identified by their length scale. Microorganisms, which lie within very small length scales (1–200 μm), include bacteria, fungi, and algae. Furthermore, length scale >200 μm is referred to macro-organisms such as larvae, barnacles, hydroids, tubeworms, mussels, and bivalves [1]. Bacteria are a common biofouling agent and are found extensively in nature. Bacterial colonization of a surface is an extremely complex process, where several phenomena can take place at multiple length and time scales [6–8]. Colonization on the surface starts with adhesion of bacteria to a solid-liquid interface. The interaction of bacteria with the surface leads to the formation of extracellular polymeric substance (EPS), where bacterial cells are embedded in a matrix. These matrix-encapsulated, surface-associated bacterial communities are referred to as a biofilm [9, 10]. EPS, the binding material of biofilms, is composed of long-chain biomolecules such as polysaccharides, nucleic acids, protein, DNA and lipids [11–14]. Biofilms can play an important role in chronic infections [1]. Moreover, they are prevalent in industrial and shipping environment, causing significant problems related to environmental impacts and health risks [15].
