Opuntia peels have several properties that can be used as an environmentally friendly and renewable synthesis of magnetic nanoparticles using the green synthesis method. The purpose of this study is to identify the properties of nanoparticles prepared from opuntia peel extract and used in wastewater treatment. In this study, the efficiency of slurry methods such as coagulation, flocculation, and adsorption were compared using magnetic iron nanoparticles (O-FeNPs) with opuntia peels. The prepared iron nanoparticles were investigated and the surface properties of the particles were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR). Several factors were applied to determine the efficiency of different treatment processes, such as contact time (0 to 60 minutes) and doses (0.1-1.0 g). The chemical oxygen demand (COD), biological oxygen demand (BOD5), total kjelidahl nitrogen (TKN), total nitrogen (TN), ammonia (NH3+), phosphate (PO43-), total suspended solid (TSS), and nitrate (NO3-), were measured for the wastewater before and after treatment. By examining the iron nanoparticles by FT-IR spectroscopy, the presence of biologically active opuntia particles on the surfaces of the nanoparticles was revealed. Also, the XRD pattern revealed that the nanoparticles are present in the oxide form as a phase of Fe2O3. The results shown among the treatment methods, flocculation and coagulation have lower efficiencies, while O-Fe NPS has higher efficiencies in removing pollutants from wastewater treatment. It was concluded that the O-Fe NPs removal efficiencies were 87.4%, 87.3%. 96.28%, 98.19%, 96.28% 34.4%, 86.4%, and 100% for COD, BOD5, TKN, TN, NH3+, PO43-, TSS, and NO3-, respectively. It confirmed that the magnetic nanoparticle/ opuntia composite is an environmentally friendly adsorbent that can be effectively used in environmental applications such as wastewater treatment.