The rate at which raw sewage enters a treatment tank is givenby E (t) = 850 + 715cos (πt 2 /9) gallons per hour for hours. Treated sewage is removed from thetank at the constant rate of 645 gallons per hour.
Full Answer
What is the primary level of treatment in wastewater treatment?
Typical Urban Wastewater Treatment Plant The primary level of treatment uses screens and settling tanks to remove the majority of solids. This step is extremely important, because solids make up approximately 35 percent of the pollutants that must be removed.
How does a wastewater treatment plant work?
The water is then put into settling tanks (or clarifiers), where it sits for several hours, allowing the sludge to settle and a scum to form on the top. The scum is then skimmed off the top, the sludge is removed from the bottom, and the partially treated wastewater moves on to the secondary treatment level.
How is wastewater treated and reused?
Wastewater is passed through a septic tank, filtered, and disinfected with ozone treatment; it is then reused for non-consumptive uses, such as toilets and laundry. These conservation measures allow them to reuse up to 55 percent of wastewater, while decreasing pressure on wastewater treatment and storage processes.
What is the difference between primary and secondary treatment of wastewater?
While primary treatment removes a significant amount of harmful substances from wastewater, it is not enough to ensure that all harmful pollutants have been removed. Secondary treatment of wastewater uses bacteria to digest the remaining pollutants. This is accomplished by forcefully mixing the wastewater with bacteria and oxygen.
Where does our raw sewage go?
The big sewer pipes take all the sewage to a place where it is treated. This place is called a sewage treatment plant. All towns and cities have th...
What happens to sewage when it leaves your house?
When the wastewater flushed from your toilet or drained from your household sinks, washing machine, or dishwasher leaves your home, it flows throug...
How does raw sewage get treated?
Primary Treatment As sewage enters a plant for treatment, it flows through a screen, which removes large floating objects such as rags and sticks t...
How does the wastewater from homes arrive at the treatment plant?
Most sewer systems operate by gravity flow, which pulls wastewater toward the treatment plant. It first enters the plant at the headworks and passe...
What are the different levels of wastewater treatment?
There are several levels of wastewater treatment; these are primary, secondary and tertiary levels of treatment. Most municipal wastewater treatment facilities use primary and secondary levels of treatment, and some also use tertiary treatments.
What is tertiary wastewater treatment?
Tertiary (or advanced) treatment removes dissolved substances, such as colour, metals, organic chemicals and nutrients like phosphorus and nitrogen.
How to reduce pressure on septic system?
Following some water conservation practices can greatly reduce pressure on your septic system. For more information about conserving water, see the fact sheet about Water Consumption. Here are a few things that you can do to care for your septic system: 1 Do not use your drain or toilet as a garbage disposal; avoid putting dental floss, diapers, coffee grounds and paper towel down the drain, as they can clog up your septic system. 2 Spread your loads of laundry out over the week. When too much water is added to the septic tank, it does not have time to treat wastes, and you could be flooding your drainfield with wastewater. 3 Plant grass on your drainfield, but keep trees and shrubs away from it, because roots can clog the system and cause damage. 4 Do not drive on your drainfield, because this can compact the soil and damage the septic system components.
Why is oxygen important in wastewater treatment?
The oxygen helps the bacteria to digest the pollutants faster. The water is then taken to settling tanks where the sludge again settles, leaving the water 90 to 95 percent free of pollutants. The picture below shows the settling tanks in the Winnipeg Wastewater Treatment Plant.
What is the process of removing pollutants from water?
Another natural method is called rapid infiltration, which is a process where a basin is filled with wastewater, which has already gone through a pre-treatment. The ground acts as a filter and removes the pollutants from the water. This method is similar to what happens in a septic system.
What is the process of tertiary treatment?
One of the biological treatment processes is called Biological Nutrient Removal (BNR). This diagram shows the treatment steps that Saskatoon wastewater goes through. Biological Nutrient Removal Process.
Where does BNR process occur?
In this treatment plant, wastewater first undergoes primary and secondary treatment. For the tertiary treatment, the BNR process occurs in the bioreactors. The BNR process uses bacteria in different conditions in several tanks, to digest the contaminants in the water.