The aeration process involves adding air into the wastewater, which promotes the consumption of pollutants by aerobic microorganisms. Aeration is considered to be an essential component of many biological treatment systems. When the air has been effectively added to the wastewater, the dissolved oxygen levels in the water will naturally increase.
Full Answer
Why is aeration the preferred technology for wastewater treatment?
Because it is quick and efficient and causes minimal odors, aeration is the preferred technology of today and of the future for wastewater treatment plants. In an aeration wastewater treatment plant, aerobic microbes use oxygen to break down the organic, carbon-containing waste into carbon dioxide and water.
How does aeration remove organic matter from wastewater?
In the primary and especially the secondary treatment of wastewater, it is common to use aeration as a method of removing organic matter. Aeration causes oxygen to mix with the wastewater and facilitate the work of aerobic bacteria in breaking down organic waste.
How much power does aeration consume?
Aeration and its electrical systems consume anywhere from 25 to 60% of a plant’s power. The demand can vary widely from plant to plant depending on specific circumstances of the site.
How can I reduce the energy cost of my aeration system?
The best way to reduce the energy cost for an aeration system is to increase the system’s efficiency. Plants can increase an aeration system’s efficiency and decrease aeration system costs in several ways. They can change or upgrade the type of equipment they use.
Why is aeration important for wastewater treatment?
Aeration provides oxygen to bacteria for treating and stabilizing the wastewater. Oxygen is needed by the bacteria to allow biodegradation to occur. The supplied oxygen is utilised by bacteria in the wastewater to break down the organic matter containing carbon to form carbon dioxide and water.
What is the most energy intensive process in a wastewater treatment plant?
Energy is consumed throughout the plant, but the most intensive use is during the primary and secondary stages of the conventional wastewater treatment process. In the primary stage, pumping is by far the most significant use of energy.
What is aeration energy?
Aeration energy is the largest non-labor operations cost for most wastewater treatment plants. The aeration oxygen is added simply in the form of bubbles to waste water to help keep the bacteria alive that's cleaning the water. The smaller the bubble, the better the system.
Why is aeration of water important?
Proper aeration will distribute cooler oxygenated water to warmer areas with lower amounts of dissolved oxygen. This allows inhabitants to occupy all areas of the pond. Water quality and clarity is also improved through aeration. Pond debris and muck release noxious gases.
Which of the following is low energy consuming system for waste water treatment?
Clarification: Biological wave contractor, known as bio wave based on deliberate generation of wave motion, hence, it is defined as a low energy consuming system for waste water treatment, high rate bio filters usually constructed as tower models treating food waste which has considerable potential to rough high ...
Which of the following is low energy consuming system for waste water treatment *?
The correct answer is Both biogas and sludge.
How does aeration work?
Aeration involves perforating the soil with small holes to allow air, water and nutrients to penetrate the grass roots. This helps the roots grow deeply and produce a stronger, more vigorous lawn. The main reason for aerating is to alleviate soil compaction.
How does an aeration system work?
An aerator, or air pump, pushes air and oxygen into your septic system. The additional oxygen increases natural bacterial activity within the system, that then provides additional treatment for nutrients in the effluent.
Why is oxygen so important in the activated sludge?
The activated sludge is aerated to dissolve oxygen which allows the organic matter (BOD) to be utilized by the bacteria. The organic matter, or food, sticks to the activated sludge. The oxygen dissolved in the water allows the bacteria to use the food (BOD) and also to change the ammonia to nitrate.
How does aeration affect water?
Aeration raises the dissolved oxygen content of the water. If too much oxygen is injected into the water, the water becomes supersaturated, which may cause corrosion or air binding in filters.
How does aeration improve water quality?
An aerator improves water quality by circulating the water. This improve stabilizes pH balances. It also reduces alkalinity and removes excess carbon dioxide. If your pond is deprived of oxygen, sediments at the bottom release gases and metals that compromise the water quality.
How does aeration work in water treatment?
Aeration treatment consists of passing large amounts of air through water and then venting the air outside. The air causes the dissolved gases or volatile compounds to release from the water. The air and the contaminants released from the water are vented.
What is the process of adding air to sewage to promote aerobic biodegradation of the organic contaminants?
Aeration is the process of adding air to the sewage to promote aerobic biodegradation of the organic contaminants. Let’s look at the reasons why sewage needs to be treated and the three main stages of doing so; primary, secondary, and tertiary and see where aeration comes in to play.
What is the primary stage of wastewater treatment?
Primary Wastewater Treatment of Sewage. The primary stage is where any organic or non-organic material that either floats or settles out via gravity is removed. This often takes place in sedimentation tanks and the process is called sedimentation. Sedimentation tanks, also called primary clarifiers, are used to let the suspended solids ...
How is sewage sludge used again?
The sludge, now activated with additional billions of bacteria and other tiny organisms, can be used again by returning it to the aeration tank for mixing with air and new sewage. The partially treated effluent then flows to another sedimentation tank for removal of excess bacteria.
How long does sewage stay in the tank?
It is then allowed to remain for several hours, during this time the bacteria break down the organic matter into harmless by-products.
How does oxygen help bacteria?
Adding oxygen will stimulate the activity of the bacteria. The resulting ‘purified’ water trickles out through pipes for further treatment. Suspended-growth systems include the activated sludge process. This is where the sewage gets pumped into an aeration tank, where it is mixed with air and sludge loaded with bacteria.
What is surface skimming in sewage treatment?
Note, mechanical surface-skimming devices are also used to remove grease and other floating materials before primary treatment begins. The sewage now has less physical objects and potentially troublesome grit in it, but there is still both organic and inorganic material that remains and needs to be removed.
What is sedimentation tank?
Sedimentation tanks, also called primary clarifiers, are used to let the suspended solids that pass through the screens and grit chambers more time to settle and sink. The settled solids, now called sludge, will be moved along the bottom of the tank by mechanical scrapers.
What are the key factors to consider when evaluating performance characteristics of various aeration mixing system options?
One of the key factors to consider when evaluating performance characteristics of various aeration mixing system options is the predicted cost of energy to operate the system over its useful life. The challenge in calculating such costs is including efficiency data from manufacturers that reliably reflects performance one could expect to measure in the field.
How deep is a surface aerator?
Surface aeration systems are typically limited to water depths up to 12 feet to optimize effective aeration and mixing. Further, the zone of influence of surface aerators may be dramatically reduced when submergence is less than 5-6 feet, due to diminishing aerator circulation capacity and corresponding oxygen transfer efficiency.
How Wastewater Aeration Works
Before you start to use a wastewater aeration system, it’s important to understand how these systems work. There are two different system types that you can select from, which include subsurface aeration systems and surface aeration systems, both of which have their advantages.
What does Aeration Do To Wastewater?
Aeration is commonly used as a kind of secondary treatment method to rid wastewater of contaminants. In many situations, this process will be a part of the activated sludge process, which can be used to oxidize biological matter and assist with the eradication of wastewater contaminants.
Why Aeration is Important for Wastewater
Aeration is important for wastewater for a number of reasons. For one, aeration is able to keep costs down compared to other treatment methods. In most situations, using a natural treatment will be more affordable than a chemical treatment or similar solution.
Why aeration?
The key pollutants in wastewater to be removed are organic matter and nutrients. These pollutants are effectively removed in aerobic biological treatment through the activated sludge process, a 100-year-old technique utilising biomass consisting of bacteria and protozoa which feed on the incoming waste.
Cost of wastewater aeration
Wastewater treatment can cost up to 100 kWhs (or €10) per person per year (4). With aeration accounting for up to 75 per cent of a treatment plants energy, costs of aeration can amount to an annual electricity cost of between €15,000 to €21,000 for a small Irish town or €0.65 to €1.3 million for an Irish city such as Cork.
Getting technical: Ideal costs versus real costs
Typical aeration technologies have an SAE of 1.8 to 3.0 kg O2/kW.h which means that the cost of aeration treatment ideally should be about 19 to 32 kWhs per person per year (based on the typical oxygen required to treat a person's wastewater per year).
Technology and approaches
In summary, there remains to be considerable inefficiencies present in the process of aeration today which is the result of a combination of factors such as choice of technology, total energy considerations, effects of process conditions and lack of control.
Acknowledgements
The research team would like to thank the Sustainable Energy Authority of Ireland (RDD/377) and Enterprise Ireland for their support in this project.
Why is aeration important in wastewater treatment?
Aeration causes oxygen to mix with the wastewater and facilitate the work of aerobic bacteria in breaking down organic waste. Because it is quick and efficient and causes minimal odors , aeration is the preferred technology of today and of the future for wastewater treatment plants.
How to reduce energy cost of aeration system?
How to Reduce the Energy Cost for an Aeration System. The best way to reduce the energy cost for an aeration system is to increase the system’s efficiency. Plants can increase an aeration system’s efficiency and decrease aeration system costs in several ways. They can change or upgrade the type of equipment they use.
How does aeration work?
Mechanical surface aerators churn the wastewater and produce sprays of droplets just above the wastewater surface. This churning action creates a large surface area for oxygen to transfer from the air via the liquid droplets. Aeration also occurs as the mechanical equipment draws oxygen into the wastewater. The highest level of dissolved oxygen is closest to the surface and the aerating equipment. Especially in older models, the aeration equipment also does the mixing. These aerators are easier to install over wastewater and can install as a single unit.
Why are surface aerators more expensive than surface aerators?
They have a higher installment cost than surface aerators because of the complexity of the system, but they incur fewer maintenance costs. Because they are submerged, they will not get icy in cold temperatures. They contribute to a safer work environment because maintenance crews don’t have to work above the water.
What is the purpose of aerobic microbes in wastewater treatment plants?
In an aeration wastewater treatment plant, aerobic microbes use oxygen to break down the organic, carbon-containing waste into carbon dioxide and water. Without oxygen, the waste breaks down much more slowly. It also produces methane and hydrogen sulphide, which give off strong, foul odors.
How much power does wastewater use?
This hefty power usage costs $7.5 billion per year.
What happens to aerobic bacteria after they digest organic material?
After the aerobic bacteria grow and digest the organic material, it settles out, and it is incubated in a settling tank where bacteria continue to do their work. The resulting activated sludge, full of bacteria, then returns to the aeration tank to increase the rate of aeration and make it more efficient.
What is wastewater aeration?
Wastewater aeration is the process of adding air to assist the aerobic microorganisms in the consumption of pollutants. Wastewater aeration is a vital part of most every biological treatment system. A well designed and operated wastewater aeration system will accomplish two main jobs:
What is the second job of wastewater aeration?
The second job of wastewater aeration is mixing the wastewater. Proper mixing keeps solids in suspension thus avoiding a buildup of sludge. Mixing also ensures that there are no anaerobic (without air) zones in the wastewater. A common problem, especially with lagoons, is that there is less oxygen present on the bottom.
How does aeration work in activated sludge?
Aeration in an activated sludge process is accomplished by pumping air into the tank or lagoon. Proper aeration promotes the growth of microorganisms or microbes in the wastewater. The microbes feed on the organic pollutants and form flocs which can easily settle out. The flocs are allowed to settle out in a separate settling tank or lagoon.
How does a subsurface aeration system work?
A sub-surface aeration system provides oxygen to microorganisms by injecting air into the wastewater. Blowers or air pumps compress the air which is delivered through airlines to diffusers installed on the bottom of the tank or lagoon. The diffusers are installed in a pattern on the bottom of the tank or lagoon for uniform coverage. The diffusers have tiny holes that create bubbles that come into contact with the water. Diffusers come in two basic types: fine bubble and course bubble.
What equipment is used for surface aeration?
Equipment used for wastewater surface aeration includes low waterfalls, jet fountains and spray nozzles. These can be fixed or on pontoons. Wastewater comes into contact with the air through the agitation created when it is sprayed or transported. This type of aeration creates the maximum possible mixing and a high level ...
Do course bubble diffusers work?
Course bubble diffusers typically have a few larger holes that produce larger bubbles. These larger bubbles travel faster to the surface than the fine bubbles. This aspect creates more turbulence and mixing in the wastewater. Course bubble diffusers are an excellent choice in situations where mixing is most important. It should be noted that course bubble diffusers can require twice as much air to operate as fine bubble diffusers.
Do microorganisms need oxygen?
These microorganisms require adequate dissolved oxygen or “DO” to thrive. Without sufficient oxygen, microorganisms are not able to consume the incoming organic pollutants in a reasonable time. In order to maintain DO levels, an aeration system is a must.