1. [n]  the act of treating waste or pollutants by the use of microorganisms (as bacteria) that can break down the undesirable substances
2. [n]  the branch of biotechnology that uses biological process to overcome environmental problems

BIOREMEDIATION is a 14 letter word that starts with B.

1. The use of microorganisms to remedy environmental problems. See Bioaugmentation, Bioenrichment
2. The use of biological organisms such as plants or microbes to aid in removing hazardous substances from an area.