1. Introduction

The efficient handling of both the persisting and newly emerging pollutants is a must, since they are continuously defiling the limited fresh water resources, seriously affecting the terrestrial, aquatic, and aerial flora and fauna. The pressing need to overcome current major limitations of advanced oxidation processes (AOP), such as energy-intensive, toxic intermediates production, less selectivity and sensitivity for dilute solutions and catalyst leaching effects have motivated us to establish a different route for water purification called “NanoBiohybrid Catalyst” technology. Although enzymes have been used for a long time to treat wastewater, they are not stable, have low life span, highly sensitive to mechanical stresses and difficult to separate from the substrates. In order to overcome these drawbacks, this book shows how to use carbon nanotube (CNT) as an excellent support matrix for enzyme immobilization. Unfortunately, raw CNT are hydrophobic and often contaminated with various impurities, such as amorphous carbons, metals and ashes which hinder its conjugation with enzymes. Thence this book displays first how to use simple chemical methods for CNT purification and also functionalization with bioconjugating functionalities for water dispersion properties. The book then reveals the methods based on which one can immobilize enzymes onto the purified and functionalized CNT to birth a NanoBiohybrid Catalyst. Finally, the potentiality of the hybrid catalyst for organic pollutants removal from the water has been demonstrated.