Bacteria are microscopic organisms of micron dimensions, that is of the order of 10^-6 m. Bacteria can be beneficial to us, but can also cause health and non-health related issues. Some of the advantages of bacteria are:
- Environmental engineering applications: Engineers make use of bacterial metabolism to treat municipal waste water (generated from our homes) and also for remediation of sites contaminated with heavy metals and chemicals. The municipal waste water treatment is essentially biological (or more exactly bacterial in nature) and bacteria consume the organic matter in the waste water and clean it for further processing or reuse. Several sites contaminated with metals (such as uranium) and chlorinated solvents (such as trichloroethylene) are also being studied for possible bioremediation.
- Pharmaceutical applications: bacteria are used in pharmaceutical industry to produce drugs and other useful chemicals and nutrients, such as riboflavin (Clostridium butyclicum), etc.
Hope this helps.