What is Microorganisms in the Activated sludge process?
Microorganisms are combined with wastewater in the activated sludge process. Microorganisms in the wastewater come into contact with biodegradable materials and eat them as food. Furthermore, bacteria produce a slimy covering surrounding their cell walls that allows them to cluster together and create bio-solids or sludge, which is subsequently separated from the liquid phase.
The efficiency with which bacteria eat organic material and their capacity to adhere together, form floc, and settle out of the bulk fluid are both important factors in the successful elimination of pollutants from water. The microorganisms in inactivated sludge have flocculation (clumping) qualities that allow them to aggregate and form solid masses large enough to settle to the bottom of the settling basin. As the sludge's flocculation qualities increase, the settling and wastewater treatment enhances as well.
What happens after the aeration basin?
The mixture of microorganisms and wastewater (mixed liquor) runs into a settling basin or clarifier after the aeration basin, where the sludge is allowed to settle. To guarantee that enough levels of microorganisms are maintained in the aeration tank, some of the sludge volume is continually recirculated from the clarifier as Returned Activated Sludge (RAS) back to the aeration basin. The bacteria are revived by mixing them with incoming wastewater and allowing them to ingest organic substances. The procedure then begins all over again.
Under the right circumstances, the activated sludge process is extremely efficient. It eliminates 85 to 95 of the solids while also lowering the biochemical oxygen demand (BOD) by about the same percentage. The efficiency of this system is determined by a variety of parameters, including the climate and properties of the wastewater. Toxic wastes can cause biological activity to be disrupted in the treatment system. Excessive foaming can be caused by wastes high in soaps or detergents, causing aesthetic or annoyance issues. Industrial wastewater must often be applied to eliminate harmful chemical components before being discharged into the activated sludge treatment process in places where industrial and sanitary wastes are mixed. Nonetheless, the most natural and effective method of eliminating pollutants from water is microbial treatment of wastewater.
Major groups of micro-organisms
In the aeration basin of the activated sludge process, there are five major groupings of microorganisms:
· Bacteria—Aerobic bacteria take organic nutrients from the environment.
· Protozoa-Eliminates and digests microorganisms and suspended particles that have become scattered.
· Metazoa predominate in older age systems, such as lagoons
· Bulking sludge with filamentous bacteria (poor settling & turbid effluent)
· Algae and fungi-Fungi can be found in older sludge and with pH changes.
1. Bacteria are responsible for the removal of organic nutrients from wastewater.
2. Protozoa are important players in the treatment process because they remove and digest free-swimming bacteria and other suspended particles. The clarity of the wastewater discharge is improved as a result. Some protozoa, like bacteria, require oxygen, while others require very little and may thrive without it.
3. Metazoa are multicellular organisms that are larger than protozoa and play a minor role in the removal of organic matter from wastewater. They consume bacteria and algae, but they also devour protozoa and algae. Longer age systems, such as lagoon treatment systems, are more likely to have a metazoan dominance. Although they play a little role in the activated sludge treatment system, their presence indicates the state of the system.
4. Filamentous bacteria can be found when operational conditions change dramatically. These bacteria begin to acquire an advantage when they proliferate in long filaments. Temperature, pH, DO, sludge age, and even the levels of accessible nutrients like nitrogen, phosphate, oils, and grease can all have an impact on these bacteria.
Filamentous bacteria's dominance in the activated sludge treatment system can cause sludge settling issues. Excessive populations of filamentous bacteria can obstruct floc settling, causing the sludge to bulk up. This thickening sludge settles poorly, leaving a murky effluent in its wake. Foaming in the aeration basin and clarifiers may be caused by filamentous microorganisms.
5. Photosynthetic organisms such as algae and fungi generally do not cause difficulties in activated sludge treatment systems, but their presence in the system usually indicates concerns related to pH shifts and aged sludge.
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