<p>The aquatic ecosystem is contaminated due to the traditional method of disposing of garbage and industrial inflow. Humans and aquatic life are seriously harmed by heavy metals found in industrial waste. Effective remediations methods are required that could provide serious safety to human health and the environment. Zinc oxide nanoparticles (ZnO NPs) were synthesized and mixed with biochar to assess its potential for its bioremediation potential for treatment of industrial wastewater. By adding ZnO NPs to biochar (nanocomposite) made from Oedogonium sp. sources and their structural, morphological, and surface properties were validated through characterization (UV, FTIR, XRD and SEM). Batch studies were used (Response Surface Methodology (RSM) to evaluate heavy metals (Pb²⁺and Cr⁶⁺) removal effectiveness of pollutants at various pH, contact time, and pollutant concentration. Pollutant removal optimization was confirmed by the statistical RSM model which showed a strong association with experimental data. According to the CCD model, time interval and pH significantly influence the biosorption efficiency of sole ZnO NPs, with a maximum adsorption efficiency of 10.6% on same day and 82% after a week. Interestingly, mixture of biochar and ZnO NPs significantly enhanced biosorption efficiency reaching 13.5% on same day and rising to 99.7% after a week. The ZnO-biochar nanocomposite outperformed sole ZnO NPs in terms of Pb²⁺and Cr⁶⁺removal efficiency. Applying a newly invented hybrid nanomaterial-biochar interaction could be useful for trace metal remediation and environmental protection.</p> Graphical Abstract <p></p>