## 1 Introduction  
Due to the increase in land uses and anthropogenic activities, available water sources are gradually decreasing, while the demand for clean water is increasing. Accordingly, membrane technology has been implemented in water treatment to enhance the quality and increase the quantity of available water [1, 2]. MBR, a wastewater treatment technology that uses membranes, has advantages such as superior effluent quality, low sludge generation, and a small land footprint. The MBR market was valued at USD 3.35 billion in 2022 and is expected to grow at a compound annual growth rate (CAGR) of 7% by 2030 [3]. A major problem in the MBR operation is fouling. When fouling occurs, flux decreases at constant pressure or TMP increases to maintain a certain flux, which increases the operating costs [4, 5]. The types of fouling include particulate fouling, organic fouling, inorganic fouling, and biofouling, and the main cause of membrane fouling is known as biofouling [6, 7]. Biofouling refers to the adhesion and accumulation of microorganisms accompanied by biofilm development on membranes [8]. Biofilm is a microbial community in an extracellular polymeric substances (EPS) matrix secreted by microorganisms. EPS are composed of polysaccharides, proteins, nucleic acids, and humic substances. EPS play a role in providing nutrients, sharing genes, and defending against external threats such as toxins, antibiotics, and predators [9]. There are inactive cells inside biofilms, called persisted cells. They are resistant to malnutrition and antibiotics and can revert to their normal metabolic functions and replication rate after a harsh condition passes. For these reasons, biofilms are difficult to remove and regenerate easily, even if only a few microbes survive [10]. In MBR, membrane fouling is mainly controlled by physico-chemical cleaning called chemical enhanced backwashing (CEB). Typically, CEB can be carried out daily with sodium hypochlorite (NaOCI) [11]. NaOCI is a powerful oxidant that can kill microorganisms and remove organic matter from surfaces [12]. CEB has the advantage of being cost-effective, easy to apply, and versatile in dealing with different fouling types. However, the overuse of CEB can lead to membrane damage, by-product generation, and poor effluent quality [13; 14; 15]. Typically, the PVDF membrane recommends 500,000-1,000,000 mg/L' has the max lifetime exposure to NaOCI depending on the manufacturer [16]. [PERSON] et al. (2010) reported that 24 h of soaking of the PVDF membrane in NaOCI with a concentration of 330 mg/L at 4-7-day intervals for 4, 5, 6, 10, and 12 repetitions during the MBR operation resulted in 44.1, 52.2, 63.9, 67.9, and 75.9% reductions in clean water flux, respectively, and up to a maximum of a 16.5% reduction in tensile strength with repetition compared to the virgin membrane [17]. In addition, depending on the chemical concentration of CEB, biofilm generation can be accelerated [18; 19]. Therefore, research on biological methods related to quorum sensing is underway to complement chemical cleaning. Quorum sensing is a cell-to-cell communication mechanism in microbial communities. This mechanism relies on the production, detection, and response to diffusible signal molecules in a cell density-dependent manner [20]. Through this mechanism, microbes monitor their population density and show multicellular behaviors such as symbiosis, toxin production, antibiotic production, motility regulation, and biofilm formation [21; 22]. The strategies related to quorum sensing control biofilm formation by dealing with diffusible signal molecules to regulate them or make them unrecognizable. These strategies are less efficient to clean the membranes clogged by dead cells and organic-inorganic complexes. In summary, biological methods are friendly to the membrane and environment, but they are more expensive than several chemical cleaning methods and it is difficult to design a universal cleaning strategy [11; 23; 24].