Microbial Functional Activity in Bioremediation of Contaminated Soil and Water

Introduction

Soil and water, as two main elements of the environment and interacting systems, play an important role in maintaining the environmental balance and preserving ecological stability. Soil, as the top layer of the earth, consisting of organic and inorganic fractions alongside various species of fauna and flora, undertake the supreme responsibility of embracing the biodiversity in order to protect and nourish. On the other hand, water, covering 71% of the earth’s surface, including aquatic biodiversity, plays a fundamental role in dynamism preservation for both water body biodiversity and other forms of life all over the planet Earth. By all means, soil and water are two entangled founders of the planet. An inattentive interference in either of soil and water media can lead to disruption of favorable characteristics, and due to human activities, which have never been so considerably planned; a common intrusion aspect has been anthropogenic pollution. With the beginning of the industrialization era, utilization of chemical compounds on lands or disposal of contaminants directly or indirectly to soil and water systems has caused numerous sorts of alterations in soil and water properties and affected the inhabitant biodiversity. Hazardous compound entrance may result in a decrease in soil and water fauna and flora, leading to a balance loss. Besides, pollutants are capable of entering the food chain and eventually human body, causing serious health problems. Soil, as a capable and dynamic system with physical, chemical and biological properties, deriving from soil forming factors and processes, might be able to buffer the alteration to some extent, but water on the other hand, seems to be more vulnerable according to non-buffering medium which can be affected immediately after introduction of the pollutant. To reduce the negative effects and remediate contaminated soil and water numerous methods have been developed. By the mid-1980s, remediation technologies started to appear under the spot light, and in the late 80s, the technology could have been called a beneficial business even for those with few years of experience, meanwhile, an increase in competition forced companies to search for new cost-effective methods to survive (Havrank, 1998). These methods apply varieties of in situ and ex situ physical, chemical and biological techniques to generally remediate the medium by stabilization, transformation or elimination of the pollutants. Physical and chemical methods have been observed to be unable to completely abolish the contamination, and only transform the pollution in to other types. Among three applications, biological techniques, known as bioremediation, have been enhanced due to their low cost, safety and natural structure (Williams, 2001). This chapter will briefly define soil and water contamination, but the main focus will be on the bioremediation and recent technologies.