C14.3 - Treating waste water Flashcards
What happens to all the waste that leaves our homes down the drains?
What happens to everything that drains from washing machines, dishwashers, sinks, baths and toilets?
Everything that drains from washing machines, dishwashers, sinks, baths and toilets flows down pipes and enters the larger sewer pipes
Sewage
Everything that drains from washing machines, dishwashers, sinks, baths and toilets, along with waste water from businesses and industry
What has to be treated at sewage treatment plants?
Everything that drains from washing machines, dishwashers, sinks, baths and toilets, along with waste water from businesses and industry (sewage), together with waste water from farming activities has to be treated at sewage treatment plants
Why does everything that drains from washing machines, dishwashers, sinks, baths and toilets, along with waste water from businesses and industry (sewage), together with waste water from farming activities have to be treated at sewage treatment plants?
Everything that drains from washing machines, dishwashers, sinks, baths and toilets, along with waste water from businesses and industry (sewage), together with waste water from farming activities has to be treated at sewage treatment plants, to make it safe before it can be returned to the environment, usually into rivers or piped out to sea
1st step of sewage treatment
The 1st step of sewage treatment is:
Screening - Once the sewage arrives at the sewage treatment plant, the first step is to remove large solid objects and grit from the rest of the waste water
The sewage passes through a metal grid that traps the large objects
2nd step of sewage treatment
The 2nd step of sewage treatment is:
Primary treatment - In the first circular tank, the solid sediments are allowed to settle out from the mixture
Large paddles rotate, pushing the solids, called sludge, towards the centre of the tank
There the sludge is piped to a storage tank for further treatment
In the 2nd step of sewage treatment, what does the watery liquid (effluent) above the sludge do?
In the 2nd step of sewage treatment, the watery liquid (effluent) above the sludge flows into the next tank
Although no solid matter is visible, this effluent still contains many potentially harmful microorganisms
3rd step of sewage treatment
The 3rd step of sewage treatment is:
Secondary treatment - In the second tank, useful bacteria feed on any remaining organic matter and harmful microorganisms still present, breaking them down aerobically (in the presence of oxygen)
The tank is aerated by bubbling air through the waste water
In the 3rd step of sewage treatment, the tank is aerated by bubbling air through the waste water.
How long can this take?
In the 3rd step of sewage treatment, the tank is aerated by bubbling air through the waste water
This can take from several hours to several days
In the 3rd step of sewage treatment, the tank is aerated by bubbling air through the waste water.
This can take from several hours to several days, depending on what?
In the 3rd step of sewage treatment, the tank is aerated by bubbling air through the waste water.
This can take from several hours to several days, depending on the quality of the waste water, size of the tank, rate of aeration and temperature
4th step of sewage treatment
The 4th step of sewage treatment is:
Final treatment - In the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated
At this point, the treated waste water is safe enough to be discharged back into rivers
In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment.
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated.
At this point, the treated waste water is safe enough to be discharged back into rivers.
However, what can happen if the river is a particularly sensitive ecosystem?
In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated
At this point, the treated waste water is safe enough to be discharged back into rivers
However, if the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand
In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment.
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated.
At this point, the treated waste water is safe enough to be discharged back into rivers.
However, if the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand.
If necessary, what then can happen?
In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated
At this point, the treated waste water is safe enough to be discharged back into rivers
However, if the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand
If necessary, the water can then be sterilised by ultraviolet light or by chlorine
In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment.
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated.
At this point, the treated waste water is safe enough to be discharged back into rivers.
However, if the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand.
If necessary, the water can then be sterilised by ultraviolet light or by chlorine.
However, what does the release of chlorine into rivers do?
In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated
At this point, the treated waste water is safe enough to be discharged back into rivers
However, if the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand
If necessary, the water can then be sterilised by ultraviolet light or by chlorine
However, the release of chlorine into rivers does cause concern
In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment.
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated.
At this point, the treated waste water is safe enough to be discharged back into rivers.
However, if the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand.
If necessary, the water can then be sterilised by ultraviolet light or by chlorine.
However, why does the release of chlorine into rivers cause concern?
In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated
At this point, the treated waste water is safe enough to be discharged back into rivers
However, if the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand
If necessary, the water can then be sterilised by ultraviolet light or by chlorine
However, the release of chlorine into rivers does cause concern, as toxic organic compounds of chlorine can be formed in the environment
What can dried sludge be used as?
Dried sludge can be used as a renewable energy source, along with biogas and biomethane
Dried sludge can be used as a renewable energy source, along with biogas and biomethane.
What are all of these made from?
Dried sludge can be used as a renewable energy source, along with biogas and biomethane
All of these are made from sewage
What happens when sewage sludge is dried?
When sewage sludge is dried, it takes up a lot less space, so it becomes easier to transport it away from the sewage treatment plant
What happens to the sludge separated off during the primary treatment of the sewage?
The sludge separated off during the primary treatment of the sewage is not wasted
After further treatment, most can be dried and used as fertilised
The sludge separated off during the primary treatment of the sewage is not wasted.
What can happen after further treatment?
The sludge separated off during the primary treatment of the sewage is not wasted
After further treatment, most can be dried and used as fertiliser on farmland to improve the soil or used as a source of renewable energy
The sludge separated off during the primary treatment of the sewage is not wasted.
What does the sludge contain?
The sludge separated off during the primary treatment of the sewage is not wasted
The sludge contains organic matter, including human waste, suspended solids, water and dissolved compounds
The sludge separated off during the primary treatment of the sewage is not wasted.
The sludge contains organic matter, including human waste, suspended solids, water and dissolved compounds.
What do microorganisms do to the sludge?
The sludge separated off during the primary treatment of the sewage is not wasted
The sludge contains organic matter, including human waste, suspended solids, water and dissolved compounds
It is digested anaerobically by microorganisms beneath the surface in the treatment tank
The sludge separated off during the primary treatment of the sewage is not wasted.
The sludge contains organic matter, including human waste, suspended solids, water and dissolved compounds.
It is digested anaerobically by microorganisms beneath the surface in the treatment tank.
At what 2 temperatures can this biological treatment be carried out?
The sludge separated off during the primary treatment of the sewage is not wasted
The sludge contains organic matter, including human waste, suspended solids, water and dissolved compounds
It is digested anaerobically by microorganisms beneath the surface in the treatment tank
This biological treatment can be carried out at a relatively high temperature of about 55 degrees Celsius or a lower temperature of about 35 degrees Celsius
The sludge separated off during the primary treatment of the sewage is not wasted.
The sludge contains organic matter, including human waste, suspended solids, water and dissolved compounds.
It is digested anaerobically by microorganisms beneath the surface in the treatment tank.
This biological treatment can be carried out at a relatively high temperature of about 55 degrees Celsius or a lower temperature of about 35 degrees Celsius.
How long can this take to complete?
The sludge separated off during the primary treatment of the sewage is not wasted
The sludge contains organic matter, including human waste, suspended solids, water and dissolved compounds
It is digested anaerobically by microorganisms beneath the surface in the treatment tank
This biological treatment can be carried out at a relatively high temperature of about 55 degrees Celsius or a lower temperature of about 35 degrees Celsius, which can take up to 30 days to complete
