At the dawn of the 21st century, biotechnology is emerging as a key enabling technology for sustainable environmental protection and stewardship. This text offers a state-of-the-art account of environmental biotechnology both in emerging and in more mature technological applications of soil remediation and the clean-up of contaminated sites. Harnessing the potential of micro-organisms and plants as eco-efficient and robust cleanup agents in a variety of practical situations is not only possible but is becoming widespread practice. Chapters are featured on current experience and trends in bioremediation of contaminated soil, life cycle assessment software tools for remediation planning, ex situ cleanup technologies using slurry reactors, implementation of anaerobic and aerobic in situ processes including monitored natural attenuation, complementary technologies on pesticide immobilisation in soil or humification of nitroaromatics, and, finally, phytoremediation of recalcitrant organic compounds and heavy metals. These contributions should be of value to environmental scientists, engineers and decision-makers involved in the development, evaluation or implementation of biological treatment systems. For more information on Strategy and Fundamentals, see Focus on Biotechnology volume 3A, and for more information on Waste Water and Waste Gas Handling, see Focus on Biotechnology volume 3C.