In this chapter, we have made an overview of the whole book and summarized the environmental pollutions and their treatment with new materials and technology. We highlighted how to resolve the old challenges with new solutions. We reviewed different methods used for environmental remediation and highlighted the importance of nanomaterials in environmental remediation. Different processes related to the management of waste water polluted by bacteria, organic, inorganic pollutants, and toxic metal ions, etc. have been discussed. We discussed how nanomaterials are economical solutions for the resolution of the old challenges related to waste water treatment. We also deliberated that the waste water containing harmful metal ions, organic pollutants, bacteria etc. can be treated with nanomaterials and for this purpose, development of novel nanomaterials is paramount because nanomaterials have revolutionized the scenario of emerging catalytic and adsorption technologies with recently certified efficient removal of pollutants along with the low cost and high stability. Therefore, the molecular engineering of nanomaterials to use them to reach stable state-of-the-art efficiency for the removal of pollutants as adsorbent and catalysts is vital and the high efficiency coupled with low cost and easy treatment process of the developed nanomaterials has probability to compete and replace the established technologies.