Chapter 4 - Polymer-based immobilized enzymes in environmental remediation

Abstract

Environmental pollution leads to the release of harmful substances into air, water, and soil and gets accumulated due to their recalcitrance. It has become extremely important now to develop new degradative low-cost and ecofriendly technologies that would be helpful in removal of recalcitrant pollutants from the environment. The pollutants have severe effects on the entire available flora and fauna (affect crucial processes like respiration, photosynthesis, reproduction as well as birth defects like in humans, Down’s syndrome, anencephaly, and spina bifida). Environmental pollution has affected all the countries of the world, however, with varied rate of pollutants accumulation. It has been seen that there is almost direct relationship with the development and extent of pollution. Developed countries have evolved several technologies to control environmental pollution; however, it has become more problematic for developing countries due to expensive available technologies for environmental remediation. It has become extremely important now to develop efficient and cost-effective technologies for environmental remediation. Major goals are recovery of soil health and fertility, reutilization of wastewater (removal of recalcitrant compounds), detoxification of groundwater, and production of healthy air. We have several methodologies for the remediation of polluted systems with successful results, particularly categorized into engineering (physical and chemical methods) and biological (composting, land fanning, bioreactors, bioremediation, phytoremediation, and enzyme-based remediation) methods. It has been observed that biological methods are commonly used for the remediation of soil and groundwater, while physical and chemical methods are being used for the purification of polluted air. Enzyme-based environmental remediation has been very successful in removal of recalcitrant compounds in a very short duration under mild conditions. It has been recommended to use immobilized enzyme for environmental remediation as degrading enzymes are rare (found only in specific species) leading to cost expensive isolation and purification protocols. Further, enzyme immobilization allows enzyme reusability and stability; thus decontamination of polluted sites can be carried out in both in situ (directly on contaminated site) and ex situ (away from contaminated site). There is a range of immobilizing matrices for enzyme immobilization; it is often recommended to use ecofriendly matrices especially when immobilized enzyme is to be used for environmental remediation. It has been argued that environmental remediation should be such that purified air, water, and soil could be directly used by the living organisms without producing any innocuous affects. The present chapter is based on providing an overview of enzymes important in environmental remediation, commonly used ecofriendly polymers for their immobilization, as well as patented enzyme-based technology for environmental remediation.