1. Decomposable organic compounds, heavy metals, cyanide, sulphur, lead, mercury, copper, zinc, chromium, cadmium, phenol, arsenic, nickel, ammonia, chlorine compounds, phosphates, nitrates etc. are emitted from industrial plants. All these decaying substances cause bad smell. Contaminates soil, water and air. Sometimes it causes acid rain. These substances are converted into pollution free substances with the help of microorganisms through biotechnology.
2. Insoluble chemicals such as H2S, SO2, NO2, DDT, carbon tetrachloride etc. are emitted from industrial plants. All these non-degradable substances are neutralized by biological technology.
3. Chlorine is used to bleach raw materials in the paper industry. Paper and pulp industries emit lignin, cellulose and chlorine. Decomposition of lignin and chlorine with the help of enzymes.
4. A yeast called Torula grows in wastes from paper and paper pulp. Such waste contains a large amount of protein. Amino acids are made from these wastes.
5. Single cell proteins are extracted from yeast and some bacteria. This protein keeps the environment free of pollutants.
6. A large amount of cellulose waste is released from jute industry, textile industry, cotton industry and silk industry. Cellulose is converted into simpler substances by Cellulomonas and Alcaligenes bacteria. Organic acids, proteins, amino acids, vitamins, ethanol, acetone, glycerin, gutanol etc. are produced from such waste.
7. Lactic acid is produced from milk factory waste. As a result, the environment is free from pollution.
8. Chlorinated waste water can be dechlorinated using species such as Tremetes versicolor, Pholiota mutabilis, Phlebia subserialis etc.
9. In Germany, Ferriflock is produced from waste from aluminum factories. Contaminated water is treated by Ferriflock.