Bioremediation, an overview

Lecture -1

Bio-remediation. An overview*

INTRODUCTION

The quality of life on Earth is linked to the overall quality of the environment. In olden days , we believed that we had an unlimited abundance of resources; today, however, the resources are plenty but not in utilizable form, because of , our carelessness and greediness in using them. The problems associated with contaminated sites now assume increasing prominence in many countries. Contaminated lands generally result from past industrial activities when awareness of the health and environmental effects connected with the production, use, and disposal of hazardous substances were less well recognized than today. The problem is worldwide, and the estimated number of contaminated sites is significant. It is now widely recognized that contaminated land is a potential threat to human health, and its continual discovery over recent years has led to international efforts to remedy many of these sites, either as a response to the risk of adverse health or environmental effects caused by contamination or to enable the site to be redeveloped for use.

The conventional techniques used for remediation have been to dig up contaminated soil and remove it to a landfill, or to cap and contain the contaminated areas of a site. The methods have some drawbacks. It simply moves the contamination somewhere else and may create significant risks in the excavation, handling, and transport of hazardous material. Additionally, it is very difficult and increasingly expensive to find new landfill sites for the final disposal of the material. The cap and contain method is only a temporary solution since the contamination remains on site, requiring monitoring and maintenance of the isolation barriers long into the future, with all the associated costs and potential liability.

A better approach than these traditional methods is to completely destroy the pollutants if possible, or at least to transform them to harmless/toxic free forms. Some technologies that have been used are high-temperature incineration and various types of chemical decomposition. They can be very effective at reducing levels of a range of contaminants, but have several drawbacks, principally their technological complexity, the cost for small-scale application, and the lack of public acceptance, especially for incineration that may increase the exposure to contaminants for both the workers at the site and nearby residents.

Bioremediation is an option that offers the possibility to destroy various contaminants using natural biological activity. As such, it uses relatively low-cost, low-technology techniques, which generally have a high public acceptance and can often be carried out on site. It will not always be suitable, however, as the range of contaminants on which it is effective is limited, the time scales involved are relatively long, and the residual contaminant levels achievable may not always be suitable. Although the methodologies employed are not technically complex, considerable experience and skill may be required to design and implement a successful bioremediation program, due to the need to thoroughly assess a site for suitability and to optimize conditions to achieve a satisfactory result. Because bioremediation seems to be a good alternative to conventional clean-up technologies.Research in this field, is rapidly increasing.

Some of the popular areas in which Bioremediation is being applied are:

1. Oil Spills
2. Wastewater Treatment Plants
3. Septic Systems
4. Oil Wells
5. Ground Water
6. Restaurant Grease Traps and Drains
7. Manure and Farm Waste
8. Preventive / Protective Barriers
9. Industrial and Agricultural Odor Control
10. Brownfields
11. Storage Tanks
12. Manufacturing Plants