The revolution that occurred in industrial sector, the continuous development in the economy, an increasing world population, and changes in the weather are some of the most dangerous global problems that have contributed to water pollution, which has become a significant harm to the environment and human health. Green metal nanoparticles prepared using green synthesis methods are ideal for water remediation because they already have a capping of biological material used in bioremediation. One of the most common methods of producing NPs is plant creation, which is effective and safe for long periods. Green creation of iron nanoparticles (Fe-NPs), silver nanoparticles (AgNPs), and gold nanoparticles (AuNPs) from microorganisms, algae, plants, and their extracts, agricultural wastes, enzymes, and biomolecules is effective for environmental remediation, especially water ecosystems. In addition, green nanoparticles derived from metal oxides, such as Fe2O3 NPs and NPs made of TiO2, are commonly used in wastewater treatment. The immobilization of NPs such as zero-valent metals (Cu0, Fe0, and Zn0), metallic oxides, bimetallic NPs (Fe/Ni, Fe/Pd, Zn/Pd, and Fe/Al), and biopolymer NPs into natural adsorbents (clay minerals) or polymer matrix has enabled significant problem solving by reducing particle loss, preventing particle agglomeration, increasing adsorption, and increasing the dissipation processes. In comparison with other technologies, adsorption technology is the largest frequent technique for purifying water avoiding provoking side pollution at a cost that can be considered acceptable. Synthesis of higher amounts of carbon-based nanoparticles (CNPs) using rice bran as natural precursors (rice bran/SnO2/Fe3O4) is effective and sustainable in the development of solid waste recycling from aqueous solutions. Rice husk (RH) and ash from rice husk (RHA) have been employed as environmental adsorbents in their natural forms and after different kinds of treatment such as silica-based nanomaterials to enhance their sorption capacities. In terms of water purification, silica and CNPs derived from RH and RHA have numerous advantages, and CNPs are important adsorbents. Several engineered nanomaterials, particularly chitosan and AgNPs, as well as photocatalytic TiO2, have been shown to have strong antimicrobial properties.