Which Microbes are Used in Sewage Treatment?
- Aerobic Bacteria: Aerobic bacteria are most commonly used in aerated environments in modern treatment plants. These...
- Anaerobic Bacteria: Anaerobic microorganisms are commonly employed in wastewater treatment. Primary function of these...
- Facultative Bacteria: In sewage treatment, facultative microorganisms are bacteria that...
What are microorganisms used for in wastewater treatment?
Municipal and industrial effluent is the main source of wastewater. And thanks to the use of micro-organisms, we are able to degrade the content of these organic wastes as they are used as a source of food and energy to grow and multiply. You got it, bacteria are the heart of the process.
What are facultative microorganisms in sewage treatment?
Facultative microorganisms in sewage treatment are bacteria that can change between aerobic and anaerobic depending on the environment they are in. Note that these bacteria normally prefer to be in an aerobic condition.
How many microorganisms are present in sewage?
Per ml, about 100,000 to 1,000,000 microorganisms are present in typical domestic wastewater before entering the processing plant. Mostly these microbes perform the wastewater process, but some other microorganisms are also used according to the organic materials present. But how could we know what was present in the sewage?
Why are microorganisms used in sewage treatment considered heterotrophic?
The microorganisms used in such a process are heterotrophic in nature; that means they do not synthesize their own organic materials and thus consume the organic constituents of sewage. You might think we could treat the wastewater with the utilization of chemicals.
What is a sewage treatment plant and how does it work?
A semi-solid waste or slurry byproduct of sewage treatment is called sewage sludge. Different processes like physical, chemical and biological meth...
What are the main steps in sewage treatment?
a. Primary treatment or Physical process b. Secondary treatment or Biological process
What is the major function of Microbes in Sewage Treatment?
Sewage is treated in sewage treatment plants (STPs) by the heterotrophic microbes present in the sewage before being disposed of in water bodies. M...
Explain types of microbes used in sewage treatment?
Aerobic Bacteria: These bacteria degrade the contaminants in the wastewater using free oxygen in the water, then turn into the energy that can be u...
Why is sewage treatment important?
Sewage treatment helps in reducing the rate of harmful contaminants that cause pollution of water and soil. Wastewater that is treated in these STP...
What are the different types of bacteria in wastewater treatment?
Which Microbes are Used in Sewage Treatment? 1 Aerobic Bacteria: Aerobic bacteria are most commonly used in aerated environments in modern treatment plants. These bacteria degrade the contaminants in the wastewater using free oxygen in the water, then turn into the energy that can be used to grow and reproduce. This helps the bacteria to complete their tasks, continue to grow and reproduce. 2 Anaerobic Bacteria: Anaerobic microorganisms are commonly employed in wastewater treatment. Primary function of these bacterias in sewage treatment is to reduce sludge volume and create methane gas from it. This gas can be used as an alternative energy source when properly cleaned and managed. This type of bacterias can utilize enough oxygen from its food supply and does not require additional supply of oxygen. Another advantage of anaerobic microorganisms in sewage treatment is that they remove phosphorus from wastewater. Most common anaerobic forms belong to Actinomyces, Bifidobacterium, Clostridium, Propionibacterium and Peptostreptococcus genera. 3 Facultative Bacteria: In sewage treatment, facultative microorganisms are bacteria that can switch between aerobic and anaerobic states depending on their surroundings. These bacteria like to reside in an aerobic environment.
How is sewage treated?
Sewage sludge is treated in a separate process called sludge digestion.
What are the most common forms of anaerobic bacteria?
Most common anaerobic forms belong to Actinomyces, Bifidobacterium, Clostridium, Propionibacterium and Peptostreptococcus genera. Facultative Bacteria: In sewage treatment, facultative microorganisms are bacteria that can switch between aerobic and anaerobic states depending on their surroundings.
Why is sewage mixed with air?
The sewage is often mixed with air to facilitate decomposition as oxygen is critical for the growth of bacteria. This air helps in the growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filament to form mesh-like structures).
What is sewage water?
Sewage refers to the municipal wastewater that is generated in cities and towns on daily basis. Researchers estimate the indicator species, such as coliform bacteria or Pseudomonas aeruginosa in the sewage water.
How does sewage treatment help the environment?
Wastewater that is treated in these STPs can be reused for several purposes. Thus, sewage treatment helps in conservation of water as well as the environment.
What is the process of treating sludge?
Sewage sludge is treated in a separate process called sludge digestion. Secondary Sewage Treatment: This process is also called the biological process. In secondary treatment, dissolved and suspended biological matter are removed, often with the help of microorganisms in a controlled environment.
What is biological wastewater treatment?
Biological wastewater treatment is the most common sanitation method in the world. This technology uses different types of bacteria and other microorganisms for the treatment and purification of polluted water. Wastewater treatment is as essential to human health as it is to the protection of the environment.
Why is sewage treatment important?
Wastewater treatment is as essential to human health as it is to environmental protection. Indeed, the use of these bacteria accelerates the treatment of pollution on a small surface: the purification plant. It’s better than letting the river handle it, because even though it’s the same purification process that occurs in nature, the quantities of pollution discharged today are too high to keep the natural cycle intact. Thus, sewage treatment plants can prevent eutrophication of rivers, for example, but also prevent the diffusion of diseases.
What are they used for?
Biological wastewater treatment is the most common method of sanitation in the world. This technology uses different types of bacteria and other micro-organisms for the treatment and cleaning of polluted water.
How long does it take for bacteria to colonize a medium?
The colonization of a medium by the necessary bacteria and microorganisms required for depollution generally takes between 4 and 8 weeks. Once again, it is the temperature that has the greatest impact on this growth time.
How is the use of bacteria different from current treatment techniques?
The use of bacteria is different from current treatment techniques because it uses simple and natural means whose final result allows the elimination of pollution without generating new pollution. Most of the time, their installation requires the use of a dedicated bioreactor, as well as the nutrients necessary for their multiplication in large numbers. Dosing is easy and requires little operating time.
How to restore water to a healthy environment?
First, by changing the operating settings, and waiting for the right species to colonize the environment again. Second, by completely removing the microorganisms in place when the first solution did not work. Be careful, this method is not recommended because the biomass will take several days to develop, so the water will not be properly treated during this period. The third solution consists in injecting specially selected, cultured and multiplied bacteria in order to recover the advantage over the undesirable bacteria present in the environment.
What is the name of the mass of bacteria that agglutinates?
Usually, these organisms swarm and agglutinate into a flake-like mass in free cultures, called the floc. These flocs, visible to the naked eye, contain living and dead cells of bacteria, fungi, protozoa and metabolic products. They agglomerate around the suspended organic matter on which they feed. This is the case for example with activated sludge. In addition, in fixed cultures, similar biofilms develop on contact surfaces. For example, biofilters and biological disks are fixed cultures.
What is sewage treatment?
Sewage treatment is a process in which the pollutants are removed. The ultimate goal of sewage treatment is to produce an effluent that will not impact the environment [1] . In the absence of sewage treatment, the results can be devastating as sewage can disrupt the environment. The general processes of sewage treatment are primary, ...
How is sewage transferred to secondary treatment?
The liquid sewage is then transferred to secondary treatment which focuses on removing the dissolved biological compound by the use of micro-organisms. The micro-organisms usually use aerobic metabolism to degrade the biological matter in the liquid sludge. Then tertiary treatment is required to disinfect the sewage so that it can be released ...
What is the gram negative bacterium responsible for the second stage of nitrification in the sewage?
Members of the Nitrobacter genus is a gram negative bacterium responsible for the second stage of nitrification in the sewage. It oxidizes nitrite to nitrate using oxygen as a terminal electron acceptor. The bacteria has an optimum pH of 6~8, and an optimum temperature of 0~40°C [4] .
What is the process of sewage reducing nitrate?
In the liquid component of sewage, denitrifying bacteria reduce nitrate into dinitrogen gas which liberates nitrate from the sewage [13]. The solid component of the sewage separated in primary treatment is fermented by bacteria anaerobically [12] .
What is sewage made of?
Sewage is composed of organic matter such as carbohydrates, fats, oil, grease and proteins mainly from domestic waste. It also contains dissolved inorganic matter such as nitrogen species and phosphorous species mainly from agricultural use [3]. It is essential to remove the nutrients before they are released to the environment because it interferes natural habitats by altering the chemical composition such as pH or oxygen level both directly and indirectly.
Why is acidity important in sewage treatment?
Acidity plays a crucial role in the breakdown of organic matter because pH affects the solubility of compounds which indirectly affect the accessibility by bacteria [8]. Also, bacteria responsible for organic matter degradation are sensitive to the pH of the environment. Extremely high or low pH levels are able to kill bacteria, deposition of organic matter occurs due to lack of degradation [6]. Hence, the pH of sewage treatment is controlled to be around 7. A nitrifier in secondary treatment, Nitrosomnas requires a pH between 6~9 in order to be viable [7] .
How is oxygen provided in secondary treatment?
Oxygen in secondary treatment is provided manually by pumping oxygen into the sewage continuously which occurs in an aeration tank [5]. In tertiary treatment, the removal of excess organic matter is enhanced by settling the sewage in a lagoon. This process is also aerobic, but it depends on the diffusion of oxygen because most organic matter has ...
Why are microbes important in sewage treatment?
In today’s world, microbes became essential for any kind of industrial process, and thus, various techniques are discovered where microorganisms are utilized for solving multiple problems. In that way, the role of microbes in sewage treatment is critical.
What is the most exciting part of sewage treatment?
However, the most exciting part of sewage treatment is that those microbes we need to eradicate ...
What is the objective of wastewater treatment?
Thus, we can say the principal objective of wastewater treatment is to decrease biological oxygen demand (BOD), Chemical Oxygen Demand (COD) and also eutrophication, and much more , so that it won’t spread toxicity in the environment . Moreover, microbes have an essential role in fulfilling the purpose of sewage treatment.
How many steps are there in sewage treatment?
And the large-scale treatment involves lots of other physical, chemical, and biological processes. Besides these two parts, the entire sewage treatment process comprises four significant steps and various sub-steps. These four steps are: Also Check: Ways to prevent ocean acidification.
What is the purpose of sewage treatment?
Purpose of Sewage Treatment 1 To remove pollutants 2 Destruction of the deadly pathogens 3 To counterbalance coarse particles. 4 Elimination of poisonous substances
What is the product of sewage after sedimentation?
The sewage water after sedimentation or settling is now called effluent, and the settled down product is known as sludge.
How could we know what was present in the sewage?
But how could we know what was present in the sewage? For that reason, the analysis of wastewater is first performed to identify the types of components present with their quantity. Then required microbes are added from the outside. Generally, three types of microbes, bacteria, fungi, and protozoa, are utilized for different functions.
Which organisms have the most sentient wastewater?
Metazoa (animals) are in my opinion the most sentient wastewater organisms per unit of metabolism, but this is debatable, and I'm uncertain how I feel about the sentience of protozoa. Metazoa, unlike protozoa, have nervous systems.
Where does organic matter end up in sewage?
While some of the organic matter in sewage is eaten and respired during secondary treatment or when released to a receiving water body, the rest of the organic matter in sewage ends up as sludge that falls to the bottom of tanks in the treatment system.
Why is incineration the best way to reduce bacteria?
Insofar as we also want to reduce bacteria populations in addition to invertebrate-animal populations, incineration seems best because it releases the energy the sludge contains in a non-sentient way, while digesting or composting sludge creates large numbers of bacteria. A downside of incineration is that, if sludge contains invertebrates (does it?), incinerating to death may be painful for those animals. The idea that heating to death may be painful for nematodes is not purely speculation, since "upon exposure to noxious temperature, Caenorhabditis elegans reacts by a withdrawal reflex. [...] the nociceptive response of C. elegans to heat resembles, in several aspects, that of higher organisms" ( Wittenburg and Baumeister 1999 ).
How much land use is 100 kg of food waste?
Diggelman and Ham (2003) report (Table 2, p. 505, "POTW" column) that disposing of 100 kg of wet food waste down the drain is responsible for 2.4 * 10 -4 m 2 of land use due to wastewater infrastructure. e I'm not sure if vegetation is prevented on all of this land area, since wastewater-treatment plants can have grass between the different buildings, but let's conservatively assume that vegetation is prevented on this entire land area. Since a wastewater-treatment plant is designed to last 30 years (p. 507), this is actually (2.4 * 10 -4 m 2) * (30 years) = 7 * 10 -3 m 2 -years of land use, which I'll round to 10 -2 for convenience.
What is activated sludge?
The activated-sludge process is a common type of large-scale secondary wastewater treatment.
How many micrometers are a rotifer?
To see this, consider that bacteria are typically 0.5 to 5 micrometers, while rotifers are typically 0.1 to 0.5 millimeters. Even if we conservatively assume a bacterium is 5 micrometers and a rotifer is 0.1 millimeter = 100 micrometers, that implies a difference in volume and mass of roughly (100/5) 3 = ~10 4.
What is the purpose of a biofilm filter?
Biofilms of bacteria, protozoa and fungi form on the media’s surfaces and eat or otherwise reduce the organic content. The filter removes a small percentage of the suspended organic matter, while the majority of the organic matter supports microorganism reproduction and cell growth from the biological oxidation and nitrification taking place in the filter. With this aerobic oxidation and nitrification, the organic solids are converted into biofilm grazed by insect larvae, snails, and worms which help maintain an optimal thickness.
How does sewage treatment work?
Our sewage treatment process includes several steps that start from waste water collection, odour control and screening. Then we go into the primary, secondary, bio-solids handling and tertiary treatment phase. In our secondary treatment, we add seed sludge and allow it to mix with the waste water, for the rapid process of biological decomposition to take place. We pump air into huge aeration tanks to fuel the growth of aerobic bacteria and other microorganisms. These bacteria functions reduce the volume of sludge and produce methane gas. The organic material that has been broken down from the fine particles that are clumped together are then separated from the solids and the liquids. The last two steps will be disinfection and sludge treatment.
What is wastewater treatment?
Wastewater treatment is society’s way of giving nature a hand in protecting the environment. It is the use of a combination of processes – physical, chemical, biological – to get rid of polluting substances that makes the water impure.
What are the benefits of sewage treatment?
When we treat our waste water properly, we are actually protecting the health and safety of the public, wildlife and fish. Having a sewage treatment facility in place, can also increase the value of your property in some cases, in case you decide to sell it.
Introduction
Physical Environment
- The environment of the sewage treatment plant has to be controlled precisely because bacteria are sensitive to the oxygen level, pH level, temperature, and level of nutrient. In order for efficient degradation of biological matter to occur, these factors are controlled manually.
Microbial Processes
- There are several microbial processes, and the microbial processes can be catergorized into aerobic and anaerobic.
Current Research
- A research has shown the correlation between nutrient removal efficiency, light wavelength and light intensity. Xu et al. discovered that red and high intensity light maximizes the nutrient removal efficiency . Also, the use of pre-treated sludge is found to generate electricity in a microbial fuel cell . This can potentially lead to production of renewable energy.
References
- (1) Zhao, H., Duan, X., Stewart, B., You, B., Jiang, X., “Spatial correlations between urbanization and river water pollution in the heavily polluted area of Taihu Lake Basin, China.” Journal of Geographical Sciences, 2013, 23(4):735-752.(2) Canler, J.P., Perret, J. M., “Biological aerated filters: assessment of the process based on 12 sewage treatment plants.” Water Science and Te…