Search
  • In-Pipe Technology

A Quick Guide To The Tertiary Treatment Wastewater Process

Wastewater: What Exactly Is It?

Water that has been used in any capacity must be treated before it can be released into another body of water. This will ensure that it doesn't pollute other water sources. There are many sources of wastewater - for example the water you flush down your drain or down your toilet is wastewater.


Along with other pollutants, rainwater and runoff go down the street gutters, eventually ending up at a wastewater treatment plant needing the tertiary treatment wastewater

process. You can also get wastewater from industrial and agricultural sources.

Some wastewaters are more difficult to treat than others. Industrial wastewater, for instance, can be very difficult to treat. Domestic wastewater, however, is relatively simple to treat. This is due to the increased amount of personal care products and pharmaceuticals found in domestic wastewater, which requires less effort in tertiary treatment wastewater.



Who is Responsible for Ensuring the Tertiary Treatment Wastewater Process?

The federal government has delegated wastewater treatment responsibility to the cities and communities themselves, much like city drinking water guidelines. Two federal laws may be applicable to wastewater and the tertiary treatment wastewater process.


Many city governments have laws regarding wastewater treatment standards. Operators of wastewater treatment plants must apply for permits or licenses from the government, and these permits can also be required to limit or add treatments to effluent discharges.


Every municipality must have a Liquid Waste Management Plan. Without one, discharges can be considered illegal. Municipalities are generally assisted by city governments to fund infrastructure construction and maintenance when implementing the tertiary treatment wastewater process.


The wastewater treatment process is overseen by municipal governments, who can also pass additional bylaws. This requires all commercial, industrial, and institutional facilities to limit the number of pollutants allowed to enter the sewers.



What Can Cities Do To Safely Discharge Wastewater?

There are three levels of wastewater treatment: primary, secondary, and tertiary. Many municipal wastewater treatment facilities employ primary and secondary levels of treatment. Some also employ the tertiary treatment wastewater process. Although the order and type of treatment can vary between treatment plants, this diagram of Ottawa-Carleton's wastewater treatment plant shows the basics.


Screens and settling tanks are used to remove most solids during the tertiary treatment wastewater process. This is a crucial step because solids account for approximately 35% of all pollutants that must be eliminated. Screens usually have 10 millimeter openings. This is sufficient enough to collect sticks, garbage, and other large items from the wastewater.


This material is removed from the wastewater and disposed at the landfill. The water is then placed in clarifiers or settling tanks. It sits there for several hours to allow the sludge and scum to settle. The scum is removed from the top and the sludge from the bottom are removed.


The primary tertiary treatment wastewater process typically removes approximately 50 percent of the Biological Oxygen Demand. These are substances that take up oxygen in water. It also removes around 90 percent to 95 percent of suspended solids and as much as 55 percent of fecal matter. Although primary treatment can remove a lot of hazardous substances from wastewater, it does not guarantee that all pollutants are gone.


The secondary treatment of wastewater involves bacteria to break down the remaining pollutants. This is done by forcing the wastewater to be mixed with bacteria and oxygen. The oxygen aids the bacteria in digesting the pollutants more quickly. The water is then transferred to settling tanks, where the sludge settles again.


This leaves the water free from pollutants in the range of 90 to 95 percent. Secondary wastewater treatment is used to remove approximately 85 - 90% of suspended solids and BOD, and around 90 - 99 percent coliform bacteria.


To remove more pollutants, some treatment plants add a sand filter. The water is then treated with chlorine, ozone, or ultraviolet light and then finally discharged. When it gets to the tertiary treatment wastewater process, water is treated separately from the sludge and scum from the settling tanks.


Anaerobic bacteria, which does not require oxygen, feeds off the sludge for between 10 and 20 days at 38 degrees Celsius. This reduces the odor of the sludge and the organic matter. It also creates highly combustible gases of methane, carbon dioxide, that can be used to heat the plant.


The sludge is then sent to a centrifuge before beginning the tertiary treatment wastewater

process. The centrifuge is a spinning machine that causes the liquid and solid to separate. The liquid can be combined with the wastewater to make the liquid, and the solid can be used to fertilize the fields.


The tertiary treatment wastewater process (or advanced treatment process) removes dissolved substances such as color, metals, and organic chemicals, and nutrients like nitrogen and phosphorous.


Tertiary treatment can be performed using a variety of biological, chemical, and physical treatment methods. One biological treatment process is called Biological Nutrient Removal. Treatment plant utilize the tertiary treatment wastewater process by first undergoing the primary and secondary treatment.


The bioreactors are used for the tertiary treatment. The use of bacteria to break down contaminants in water in different environments in multiple tanks. Each tank has its own unique environment, and each one contains different levels of oxygen in the tertiary treatment wastewater process.


The water passes through the tanks and is then removed from the tank. Ammonia is also broken down into nitrate gas and nitrate, something that other bacterial processes cannot do. While the tertiary treatment wastewater process can remove more than 90% of phosphates than traditional methods, it can also remove less than 90%.



How Can Smaller Communities Do Their Part to Implement The Tertiary Treatment Wastewater Process?

Smaller communities may have one or more wastewater treatment systems. These systems can be simple collection systems that discharge the wastewater directly to surface waters or municipal lagoons that are emptied every year. These facilities typically treat and disperse waste as close to the source as possible, thereby reducing operational costs and maintaining minimal maintenance.


The less likely that the waste will contaminate drinking waters sources, the longer it can stay in a lagoon. Most smaller communities don't have the resources for a detailed tertiary treatment wastewater process and instead keep the waste in lagoons while others discharge the waste directly into the water supply.

Lagoons are ground-based storage areas that hold waste until it is released to soil or water. Shallow lagoons are shallow lagoons that are less than 1.5m deep. This allows solid waste to settle to its bottom for primary treatment and takes between 6 and 20 days.


However, shallow lagoons cannot remove all contaminants that can cause problems for ground or surface water. Deep lagoons that are over three meters deep can be used for long-term storage and treatment. Small communities often empty their lagoons once a year. Many rural communities use the land around them to dispose of their wastewater.


If the soil is sufficient and there are no nearby water sources, bacteria in soil can remove or break down contaminants in wastewater. This can be an effective way to treat wastewater because of the availability land in many rural areas. There are however other communities that dump waste in a manner that could threaten the water source, such as a river, lake or groundwater source.

According to the Environmental Protection Agency, between 10-20% of American small-scale wastewater treatment plants aren't operating correctly. States have also identified dysfunctional wastewater treatment systems as the second most serious threat to water quality (after underground storage tank). Combining ineffective drinking water treatment with inadequate wastewater treatment can lead to serious contamination issues for many rural communities.

It is often difficult for rural communities to set up and maintain major tertiary treatment wastewater facilities. While many communities still have insufficient methods for treating wastewater, some communities are pioneering innovative treatment methods and water conservation measures.


The wastewater is filtered through a septic tank and then disinfected using ozone treatment. It is then used for non-consumptive purposes such as laundry and toilets. They can reuse up to 55% of their wastewater and reduce the need for wastewater treatment.

1 view0 comments