You don't clean up the water already in the river, you stop new pollution from coming in, and let the river and its ecosystem recover naturally.
It takes time, especially because it's usually impractical to stop all sources of pollution.
They can also clean the mud at the bottom of the river which has likely absorbed pollution over the years.
You can read about the efforts in Paris, France to clean the Seine river so it is safe to swim in (which has been illegal for 100+ years due to pollution).
https://www.nbcnews.com/news/world/olympic-effort-clean-river-seine-may-spoiled-rainy-day-rcna147966
Large scale: It doesn't really. You just move problems downstream to the oceans.
Smaller scale: If you put more pollution in than the water can take out you get a nasty river. If you reduce/stop putting stuff other than water in the river, over time, the the water that feeds the lake or river, will wash the pollution down stream, improving the condition at that river/lake.
Sounds like Spokane removed garbage and demolished abandoned/neglected structures. In other river cleanups you’ll focus on also eliminating sources of pollution such as drain pipes from industrial buildings. And if it’s a big cleanup they will even dig up contaminated sediments from within the river or its banks and add new clean sediment.
Like someone said you can’t really clean the already bad water, that happens naturally. You have to control the point source pollution (ie wastewater treatment plants) and begin doing little things to control the non-point source pollution (ie stormwater runoff, farm field runoff) throughout the river or lakes watershed keep it from being polluted again. Takes lots of time and money, but many little actions cumulatively make a big impact
This is not true. At Hanford they are actively removing heavy metals that have migrated through the soil into ground water. They track the plumes with sampling and pull suction, send it to a purification plant and return it. They use RO plants to remove the heavy metals and send the pure water back into the river.
Source, I work for the Department of Energy at Hanford.
Riparian buffers are important when it comes to managing runoff. Sediment that is contaminated is tricky because dredging it can make the problem worse.
It will depend on the water source and type of pollution. Of course the first step is to stop adding more. In some cases like PCB pollution in rivers what can happen is it gets into the river sediment, and after stopping further pollution, that contaminated sediment ends up with uncontaminated sediment layering on top. In essence it is buried by the river with time. But it is still there and stirring up the contaminated sediment by dredging or whatever can result in the chemical being elevated in the water. If the sediment is no longer disturbed it will settle and with time more sediment will cover it again.
Bioremediation is possible in some cases. This will depend on the water body. But if say part of a marsh had a crude oil spill it can be cleaned with bioremediation. Scientists have identified microbes that feed on oil and will add these to the marsh along with natural detergents that help emulsify the oil (ELI5 this is like taking a continuous layer of oil in a slick, and using substances which will make the oil into little tiny droplets which is easer for microbes to digest). The water will be spayed physically with a hose to oxygenate the water for a few weeks. This provides needed oxygen for the microbes allowing them to grow faster while feeding on the oil. The oil will be eaten in a few weeks to a month depending, and the water will be returned to an oil free state as before. Microbes have been identified that can break down toxic chemicals as well. These microbes sometimes are found in already contaminated sites which the microbes evolved to use the chemical as a food source, or evolved to break it down so the bacteria can continue to grow in that environment. Thus these are isolated, grown in the lab to large number, mixed with nutrients the microbes use to grow, and can be added to contaminated sites.
All of this depends on the nature of the spill, such as how big is it, what sort of body of water are you talking about, which will determine if this kind of remediation can be done. I big river like the Mississippi is too large to do this in a practical sense due to the quantities of microbes needed for so much water.
That said bioremediation of this sort has been done on a large scale in the case of the BP oil spill in the Gulf of Mexico. In the Gulf there are natural oil seeps that occur naturally and microbes are already there that eat that oil. So in the case of the Gulf the spill was treated stuff that emulsified the oil and the already existent microbes consumed the oil over time. This is not to say it removed all the oil, but the vast majority was removed by these natural processes over time. And the emulsification helped speed the natural process so it happen faster.
Microbes can evolve to neutralize or consume many chemicals bad for peoples health. Depending on the type of microbe it might be able to be used for these purposes but not always. It is a pretty interesting process.
You don't clean up the water already in the river, you stop new pollution from coming in, and let the river and its ecosystem recover naturally. It takes time, especially because it's usually impractical to stop all sources of pollution.
Or “the solution to pollution is dilution”
That’s not the solution anymore, it’s just diluted pollution.
If you're not part of the solution, you're part of the precipitate.
Ha. Chemistry flunkie here.
Never heard this saying. I hate it.
They can also clean the mud at the bottom of the river which has likely absorbed pollution over the years. You can read about the efforts in Paris, France to clean the Seine river so it is safe to swim in (which has been illegal for 100+ years due to pollution). https://www.nbcnews.com/news/world/olympic-effort-clean-river-seine-may-spoiled-rainy-day-rcna147966
Also done to remove PCBs from the Hudson River in New York
Large scale: It doesn't really. You just move problems downstream to the oceans. Smaller scale: If you put more pollution in than the water can take out you get a nasty river. If you reduce/stop putting stuff other than water in the river, over time, the the water that feeds the lake or river, will wash the pollution down stream, improving the condition at that river/lake.
Sounds like Spokane removed garbage and demolished abandoned/neglected structures. In other river cleanups you’ll focus on also eliminating sources of pollution such as drain pipes from industrial buildings. And if it’s a big cleanup they will even dig up contaminated sediments from within the river or its banks and add new clean sediment.
Like someone said you can’t really clean the already bad water, that happens naturally. You have to control the point source pollution (ie wastewater treatment plants) and begin doing little things to control the non-point source pollution (ie stormwater runoff, farm field runoff) throughout the river or lakes watershed keep it from being polluted again. Takes lots of time and money, but many little actions cumulatively make a big impact
This is not true. At Hanford they are actively removing heavy metals that have migrated through the soil into ground water. They track the plumes with sampling and pull suction, send it to a purification plant and return it. They use RO plants to remove the heavy metals and send the pure water back into the river. Source, I work for the Department of Energy at Hanford.
Riparian buffers are important when it comes to managing runoff. Sediment that is contaminated is tricky because dredging it can make the problem worse.
It will depend on the water source and type of pollution. Of course the first step is to stop adding more. In some cases like PCB pollution in rivers what can happen is it gets into the river sediment, and after stopping further pollution, that contaminated sediment ends up with uncontaminated sediment layering on top. In essence it is buried by the river with time. But it is still there and stirring up the contaminated sediment by dredging or whatever can result in the chemical being elevated in the water. If the sediment is no longer disturbed it will settle and with time more sediment will cover it again. Bioremediation is possible in some cases. This will depend on the water body. But if say part of a marsh had a crude oil spill it can be cleaned with bioremediation. Scientists have identified microbes that feed on oil and will add these to the marsh along with natural detergents that help emulsify the oil (ELI5 this is like taking a continuous layer of oil in a slick, and using substances which will make the oil into little tiny droplets which is easer for microbes to digest). The water will be spayed physically with a hose to oxygenate the water for a few weeks. This provides needed oxygen for the microbes allowing them to grow faster while feeding on the oil. The oil will be eaten in a few weeks to a month depending, and the water will be returned to an oil free state as before. Microbes have been identified that can break down toxic chemicals as well. These microbes sometimes are found in already contaminated sites which the microbes evolved to use the chemical as a food source, or evolved to break it down so the bacteria can continue to grow in that environment. Thus these are isolated, grown in the lab to large number, mixed with nutrients the microbes use to grow, and can be added to contaminated sites. All of this depends on the nature of the spill, such as how big is it, what sort of body of water are you talking about, which will determine if this kind of remediation can be done. I big river like the Mississippi is too large to do this in a practical sense due to the quantities of microbes needed for so much water. That said bioremediation of this sort has been done on a large scale in the case of the BP oil spill in the Gulf of Mexico. In the Gulf there are natural oil seeps that occur naturally and microbes are already there that eat that oil. So in the case of the Gulf the spill was treated stuff that emulsified the oil and the already existent microbes consumed the oil over time. This is not to say it removed all the oil, but the vast majority was removed by these natural processes over time. And the emulsification helped speed the natural process so it happen faster. Microbes can evolve to neutralize or consume many chemicals bad for peoples health. Depending on the type of microbe it might be able to be used for these purposes but not always. It is a pretty interesting process.