Most of us is not well aware of the fact that odor coming out from the wastewater and sewage treatment plants is a crucial factor of air pollution. The worst thing is that these harmful gases carry pollutants like ammonia, hydrogen sulphide and other organic volatile compounds. These pollutants are dangerous for animal health. In such a situation, it is quite important to use effective odor controlling techniques to control these harmful aqueous gases coming out from the industries.
Among all the effective methodologies that are used in controlling toxic pollutants, biological filters are the cheapest. This process is quite different than the chemical and wet scrubbers. In biofiltration, micro-organisms are used to degrade the pollutants into harmless forms. This technique is highly flexible and efficient in removing all sorts of pollutants, ranging from ammonia, hydrogen sulphide to other volatile organic compounds. It can control the toxic gases even at higher concentration and strength. Bio-filters are environment-friendly and easy to maintain at the same time.
Mechanism of The Biological Filters:
The working of the biological filters involves recirculation of the waste water or spraying of the nutrient-rich and biological active pollutants over the media bed. The scrubber force the odorous air to move upwards and thus, the toxic pollutants is settled below. This process is quite similar to the chemical or wet scrubbers. Unlike the wet scrubbers, biological organisms are used in the biofiltration. The pollutants served as the food for the microorganisms. The media offer areas where the biological organisms can grow and multiply. Here, biological oxidation takes place.
Depending on the organisms that are used in the filters, these odor controlling techniques are classified in two different categories. The autotrophic organisms help in removal of hydrogen sulphide and other inorganic compounds from the waste water. The heterotrophic organisms help in removal of the aqueous organic compounds from the water. The autotrophic organisms help in oxidizing the sulfides to elemental sulphur or sulphate compounds. The heterotrophic organisms are effective in removing the organic odors, but they are not so effective in removing hydrogen sulphide. A two stage system can be made by the combination of both types of microorganisms, autotrophic and heterotrophic. The combined technique is helpful in removing VOCs and hydrogen sulphide as well.
The design of the biological filters:
- Irrigation: Steady flow of wastewater is required to keep the media in good condition and maintain the moisture of the same. But an excessive flow of the waste water may deplete the concentration of oxygen in the media. The irrigation cycles should not be too much frequent.
- Media: The media bed should have sloughing characteristics, like low-pressure drop and good absorption properties. The area to volume ratio should be too high. To treat organic compounds, activated carbon can be used to impregnate the biological media.
- Nutrients: They should be supplied fresh for keeping the biomass healthy and long lasting. It is required to identify the requirements of the nutrients by the different bacterial species. The waste water is a good source of nutrients for the microorganisms.
Apart from these, the air distribution and the construction materials are also considered. Biofilters are capable in removing varieties of pollutants from the sewage water. You can purchase one, according to your requirements for a reputed company.