Role of Microorganisms to reduce BOD and organic compounds in STP plant
The removal of the contaminants is usually done during the sewage treatment procedure. The ultimate goal of sewage treatment is the production of an effluent that won't harm the environment. Sewage can disturb the ecology, thus the consequences of not treating it can be disastrous.
Microorganisms are used in biological wastewater treatment to filter out organic materials from wastewater. Aerobic and anaerobic metabolism is typically used by the microorganisms, to break down the biological material in the liquid sludge. Let’s understand the role of microorganisms in sewage treatment plants, and also their role in reducing the BOD, COD and organic compounds in sewage treatment plants.
Stages of sewage treatment
Primary, secondary, and tertiary treatment are the three main stages of sewage treatment.
Sewage is physically separated into solids and liquids during first treatment using a settling basin. The liquid sewage is then moved on to secondary treatment, which uses microorganisms to remove the dissolved biological material. The sewage must next undergo tertiary treatment to make it safe for release into the environment.
After basic treatment, the solid sewage is moved to a tank for sludge digestion, which uses anaerobic degradation powered by microorganisms.
Physical settings for bacteria in STPs
Bacteria are sensitive to changes in oxygen, pH, temperature, and nutrient levels, so the environment of the sewage treatment plant needs to be accurately managed. These variables are manually adjusted in order for biological matter to degrade effectively.
Role of microorganisms in sewage treatment plants
These are the effects of using microorganisms in wastewater treatment:
· removing FOG (Fats, Oil, and Grease)
· lowering of BOD (Biochemical Oxygen Demand)
· lowering of COD (Chemical Oxygen Demand)
· lowering of TSS (total suspended solids)
· Eliminating odours
Important microorganisms in sewage treatment plants
Nitrosomonas: A gram-negative bacterium belonging to the Nitrosomonas genus is in charge of the initial nitrification process in sewage. Ammonia is converted by them into nitrite. This bacterium loves a pH of 6 to 9 and nitrifies best at 20 to 30 degrees Celsius.
Nitrobacter: A gram-negative bacterium belonging to the Nitrobacter genus is in charge of the second step of nitrification in sewage. With oxygen serving as the terminal electron acceptor, it converts nitrite to nitrate. The bacterium thrives best at pHs between 6 and 8, and at temperatures between 0 and 40 °C.
Pseudomonas: A genus of gram-negative bacteria called Pseudomonas uses the chemical energy in organic matter, to denitrify nitrate into di-nitrogen gas. Moreover, the gram-negative bacteria that cause the anaerobic fermentation of solid sludge, are members of the phylum bacteroidetes.
Role of microorganisms in reducing/removing COD via microbial action in sewage treatment plants
The addition of bacteria or other types of microbes that break down the organic components in the wastewater, is an effective method for the COD removal. Both aerobic and anaerobic microbes can be found in sewage treatment procedures.
COD elimination involves the introduction of bacteria or other microorganisms, which break down organic waste-derived substances, into the carbon dioxide and water when there is air. Aerobic COD treatment is ideal for the wastewater, with COD levels under 3000 mg/L.
When oxygen is absent, the microorganisms are used for anaerobic COD removal, to transform the organic waste components into the biomass. The biofuel produced by the process can be used as a substitute energy source for power, heating, and drying purposes, making it a very advantageous approach. Anaerobic COD treatment is ideal for wastewater with COD > 2000 mg/L.
Role of microorganisms in reducing/removing BOD via microbial action in sewage treatment plants
Increasing aeration in treatment basins and lagoons is one of the best techniques to lower BOD in wastewater/sewage. Activated sludge process, which is one of the most widely used techniques for removing contaminants from wastewater, requires aeration.
To function, activated sludge needs oxygen, and BOD relies on depriving hazardous bacteria and germs of oxygen. Therefore, air diffusers in the activated sludge provide the helpful bacteria an oxygen support, so they stay alive long enough to decompose the waste.
BOD in wastewater can be significantly decreased by using activated sludge. The beneficial bacteria and the waste sludge microorganisms are effectively formed in the aeration basin and secondary clarifier. Pollutants can be gradually transformed into waste sludge that is filtered out and disposed of in the secondary clarifier, by mixing them together through aeration.
Techniques used by bacteria to remove pollutants from wastewater
Microorganisms primarily use two techniques to lower the amount of contaminants in wastewater:
Aerobic: Aerobic digestion is a main wastewater treatment method that transforms wastewater into an effluent, which is more useful and environmentally beneficial. Trillions of bacteria are involved in the process, and they need on oxygen to live and grow. By stealing oxygen from organic waste, microbes digest it, changing its chemical composition into something less harmful to the environment.
Liquid and solid phases are physically separated after first treatment. Aeration is applied to the liquid phase to enable aerobic breakdown of the nutrients. Nitrification and phosphorus elimination are the two key microbial activities at this stage.
Nitrification takes place in two distinct stages. By using a procedure called "enhanced biological phosphorous removal," phosphorus can be removed organically. When the biomass is filtered, the process is exhibited by the cell absorbing phosphorus inside of its own cell.
Anaerobic: The biological fermentation of organic waste is known as anaerobic digestion. Biogas is created by the conversion of organic materials, which aids in removing impurities and pollutants from the water. To make wastewater more ecologically friendly, anaerobic treatments are employed to change the chemical makeup of the organic material present in the effluent.
Nitrate is released from the sewage as di-nitrogen gas by denitrifying bacteria in the liquid portion of the sewage. Anaerobic bacteria ferment the solid part of the sewage that was isolated during basic treatment.
Facultative: In sewage treatment, facultative microorganisms are bacteria that can switch between anaerobic and aerobic states, based on their surroundings.
Numerous municipal and industrial wastewater treatment facilities and sewage treatment plants use bacteria and other microbes, to assist in the cleansing of sewage. Choosing the proper bacteria can be challenging, because your choice will depend on how well your environment supports its utilisation. If the anaerobic bacteria are properly managed, wastewater treatment can also be a fantastic source of alternative energy.
It doesn't have to be a one-person job to learn the names of the microbes employed in sewage treatment, and the function that bacteria perform in sewage treatment. To understand more about the role of microorganisms in sewage treatment, and how microorganisms in the wastewater treatment process may help keep your water healthy, take a look at the sewage treatment solutions offered by Netsol Water Solutions.
Are you still confused about the role of microorganisms in sewage treatment plants? You do not need to worry!
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