In this work, we synthesized two types of zeolite nano-adsorbents termed HZ1 and HZ2. For further improving the effluent quality and reduction of membrane fouling, these two synthesized zeolite nano-adsorbents were used in a membrane bioreactor (MBR). Particle size distribution (PSD), soluble microbial products (SMP), and extracellular polymeric substance (EPS) for sludge were measured. In addition Fourier-transform infrared spectroscopy (FTIR), excitation-emission matrix (EEM) fluorescence spectroscopy, gel permission chromatography (GPC), and EPS analysis were performed for characterization the properties of the formed cake. The results showed that both HZ1 and HZ2 had better function in reducing the membrane fouling and decreased transmembrane pressure (TMP) by 47% and 66%, respectively. For both synthesized zeolite nano-adsorbents, the ratio of protein to polysaccharide in the sludge EPS was increased. GPC analysis also revealed that HZ2 zeolite nano-adsorbent exhibited better performance in small-molecular weight organic compound adsorption due to having high crystallinity and larger pores in comparison to HZ1. EEM analysis indicated that some proteins and even fulvic acid-like compounds were adsorbed by both nano-adsorbents, especially HZ2, therefore the fouling in the membrane pores was decreased (about 84%). Resistance measurements of the membrane showed that pore resistance was negligible for the reactor included HZ2.