**1. Introduction**

The increase in human activities triggers environmental pollution through the generation and disposal of hazardous wastes in aquatic and terrestrial habitats [1]. Most of these pollutants include inorganic (heavy metals) and organic matter (polyaromatic hydrocarbons (PAH), petroleum hydrocarbons compounds (PHC)) which may cause negative effects on the ecosystem and possibly react with other abiotic factors that attribute to the effect on the structural arrangement of terrestrial and aquatic habitats [2].

In terms of the environment and ecology system, the proper and safe disposal of these hazardous wastes is a key priority for a sustainable ecosystem. This involves the use of various treatment procedures to clean up hazardous waste. For detoxifying heavy metals, radionuclide and organic polluted soils, physicochemical techniques such as filtration, precipitation, electrochemical treatment, soil washing and chelating, oxidation/reduction, ion exchange, reverse osmosis, and stabilization/

solidification have been employed. These environmental clean-up procedures have various disadvantages, including inefficiency, the need for a large number of chemical reagents, energy, and high cost, as well as the formation of secondary by-products [3].

Bioremediation is a cost-effective and environmentally tolerable technology that employs a biological process to reduce environmental risks caused by toxic substances and other hazardous pollutants. To treat polluted multiphase systems and sustain the native ecosystem, a combination of bioremediation techniques will be effective. The fundamental premise of bioremediation is to reduce contaminant solubility by adjusting pH, modifying redox processes, and adsorbing toxic substances from polluted sites [3]. Environmental remediation always requires human assistance to achieve effective remediation of contaminants and restoration of ecological balance. However, remediation can be destructive to the ecosystem [4], if the application is not properly addressed to meet the eco-friendly standard required to combat the contemporary issues of pollution [4, 5]. Most small-scale applications of bioremediation approaches using bioremediation agents such as bacteria, fungi, plants, and organic materials have been successful with variation in results, although bioremediation on a large scale has not been widely validated [4]. This chapter aims to propose a cost-effective and eco-friendly bioremediation strategies that could reduce or remove contaminants from the environment and thus stabilizing the ecosystem from heavy metal pollution and oil spills.
