7 ms·

Bog gravel filtration: Water cleaned by Mother Nature (2015)

95 points by ciconia 2y ago

Animats 2y ago
See the related "slow sand filter".[1] Slow sand filters are still a good water treatment method if you have enough space. [1] https://en.wikipedia.org/wiki/Slow_sand_filter https://en.wikipedia.org/wiki/Slow_sand_filter
- walthamstow 2y ago
  I think these are what is used in London. The water treatment plant near me (Coppermill) has dozens of rectangular sand pits
- whartung 2y ago
  Just went through a local water treatment plant tour. Fundamentally, it’s pretty simple. This processing drinking water. The water comes in and the particulates within it carry a negative ion charge. The water passes over an agitator, and a combination of ferric chloride and some kind latex are mixed with the water. The water then flows through a long channel. At this point the negative charged particles bind with the positive charged chemicals. The combinations then simply precipitate out in the long channel. At the end, small channels draw water off just the first few inches of the larger channel. This water goes to a combination aggregate and sand filter. It’s not very deep, about 3 feet total for both. The resulting water is 99+% pure now. It moves on to a large activated carbon filter. We’re talking 10 feet deep. Like a water pitcher filter. This is a recent CA requirement, installed in 2005. Designed to remove some specific by products. The water then goes through a large UV system to kill what’s left, and is finally injected with some chlorine. The chlorine is preventative to deal with anything that may potentially be introduced later in the system. I don’t know when they intrythe UV part, but the way it’s laid out, seems like that came with the carbon filter system. That means that prior to 2005, the aggregate and sand filter was considered good enough, augmented with the chlorine. But they never considered the chlorine as part of the purifying process, simply precautionary. It was very interesting, and I thought pretty simple conceptually. The trick is the actual engineering of the actual plant and respective water system. I found it interesting to learn that the large water tank near me, which roughly measured at 5M gallons is actually only 1/3rd above ground. It’s a 16M tank, one of the largest in the system.
  - aftbit 2y ago
    Does the below ground part of the tank have pumps to supply water to the above ground part to get pressurization?
    - whartung 2y ago
      All of the water delivery is gravity fed. We live on the slope of an alluvial fan. Water is pumped as/if necessary to the various reservoirs, but from there they rely on water drop for delivery. The tank may well have two sets of pipes to service the closest homes, some closer to the surface with others buried deeper(assuming those homes are even serviced by that tank). But I’m less than a quarter mile away and well below the bottom of the tank. It’s steeper here than it looks. They say they can move water from anywhere to anywhere in the system through a combination of pumps and gravity, but all consumer delivery pressure is gravity based. The water pressure at someone’s house is based on their distance in height from their servicing reservoir. If they were to move water from the lowest part to the highest, it would take 8 lifts of the water. Electricity is a significant expense to the system so minimizing pumping, for any reason, is a priority for them. An interesting trivia bit is that, according to them, where our system has 8 lifts, the CA aqueduct has a total of 11 in its system.
  - SoftTalker 2y ago
    > they never considered the chlorine as part of the purifying process, simply precautionary In many parts of the world they do not add chlorine. Our water tastes and smells like a swimming pool in comparison.
    - bongodongobob 2y ago
      I've been all over the US and no where has it smelled or tasted remotely like chlorine. A quick Google says the high end is 4 ppm. If you think you can taste or smell that, you're lying to yourself.
      - lagniappe 2y ago
- twic 2y ago
  If I understand correctly, the way these work is that microorganisms create a biofilm, and then the biofilm filters the water. The pore size is incredibly small, so particulates and bacteria and so on are filtered out. In which case, I wonder if you could make a more space-efficient version by producing biofilms, or something similar, on an industrial scale. Whether in bioreactors optimised for film production, or just by making great sheets of agarose gel or something.
stubish 2y ago
All the information I find relates to fish ponds. I'm trying to work out if a bog filter is a good idea for a frog pond, or if the clearer water will make things worse for tadpoles.
- knodi123 2y ago
  frogs are super sensitive to environmental contamination, so clean and clear is fine. as long as it's stagnant.
- deleted 2y ago
  [deleted]
- j16sdiz 2y ago
  Frog pond are loud.
  - Arrath 2y ago
    Frogs in the night are the sound of home and childhood. I love it.
po 2y ago
This is great advice and I've actually built ponds on this principle in the past. It works well. There are tons of Youtube videos on this subject as well. The channel ozponds is pretty good for this. What I am now interested in is the construction of spring boxes and finding and digging a natural spring from a wooded area. I used to do this when I was younger, but I've found that while the internet generally has all kinds of new techniques that I wasn't aware of, unfortunately, I haven't found a great source of info for this topic yet.
threatripper 2y ago
“Learn from the mistakes of others. You can’t live long enough to make them all yourself.” That's some good advice.
- atoav 2y ago
  As an university educator I would add: Take risks and try out things at times/places where you can afford to fail, e.g. during your studies. Nowadays too many students put their chips only on safe-bet-projects during their study, which traditionally would be the one time in their lives where they could really try and fail etc. Sure a lot of that is due to economic constraints, which have gotten catastropically worse in the past decades, but trying out things that you know could fail means you are operating at the edge of your abilities, rather than in an area that is safely covered by them. And traditionally that is where the interesting lessons are learned. Learning from others mistakes is a good thing as well, but for that they also have to try things that aren't safe bets.
  - pictureofabear 2y ago
    There is a great bias against failure, even for seasoned academics. I always liked this quote from Feynman "If you’ve made up your mind to test a theory, or you want to explain some idea, you should always decide to publish it whichever way it comes out. If we only publish results of a certain kind, we can make the argument look good. We must publish both kinds of result."
  - mianos 2y ago
    If you are spending masses of money and time on something, there is little to no chance anyone in their right might would take any more risk than they have to. If you are living on a trust fund, sure, give something risky a try.
    - atoav 2y ago
      I might have to add that I am an educator at an art university and work in a country with nearly non-existent admission fees. Artists that don't risk things during their studies will have a hard time producing interesting things.
123pie123 2y ago
this is interesting if it's true https://www.youtube.com/watch?v=nSBwJNDDUfc https://www.youtube.com/watch?v=nSBwJNDDUfc
hadlock 2y ago
Sponge filters do this same task as bog filtration as well, at a much smaller scale. A sponge is shaped like a cylinder, then a 1cm hole is punched through the center. An air tube goes down the middle, and a 4cm "chimney" sticks up from the hole to improve flow characteristics. The whole contraption is immersed in water. The result is that the bubbles travel upwards, pulling some water with them, and exits the top of the chimney. This water is replaced by water outside the sponge. The sponge acts as both a mechanical filter, but also as a high surface area for microbes to live and process waste. Bog filters work on a much larger scale, but sponge filters have been replacing "hang on back" filters in the aquarium hobby pretty rapidly over the last couple of years. It also helps that sponge filters only cost about $10 and have no moving parts

95 points by ciconia 2y ago

See the related "slow sand filter".[1] Slow sand filters are still a good water treatment method if you have enough space. [1] https://en.wikipedia.org/wiki/Slow_sand_filter https://en.wikipedia.org/wiki/Slow_sand_filter

walthamstow 2y ago
I think these are what is used in London. The water treatment plant near me (Coppermill) has dozens of rectangular sand pits
whartung 2y ago
Just went through a local water treatment plant tour. Fundamentally, it’s pretty simple. This processing drinking water. The water comes in and the particulates within it carry a negative ion charge. The water passes over an agitator, and a combination of ferric chloride and some kind latex are mixed with the water. The water then flows through a long channel. At this point the negative charged particles bind with the positive charged chemicals. The combinations then simply precipitate out in the long channel. At the end, small channels draw water off just the first few inches of the larger channel. This water goes to a combination aggregate and sand filter. It’s not very deep, about 3 feet total for both. The resulting water is 99+% pure now. It moves on to a large activated carbon filter. We’re talking 10 feet deep. Like a water pitcher filter. This is a recent CA requirement, installed in 2005. Designed to remove some specific by products. The water then goes through a large UV system to kill what’s left, and is finally injected with some chlorine. The chlorine is preventative to deal with anything that may potentially be introduced later in the system. I don’t know when they intrythe UV part, but the way it’s laid out, seems like that came with the carbon filter system. That means that prior to 2005, the aggregate and sand filter was considered good enough, augmented with the chlorine. But they never considered the chlorine as part of the purifying process, simply precautionary. It was very interesting, and I thought pretty simple conceptually. The trick is the actual engineering of the actual plant and respective water system. I found it interesting to learn that the large water tank near me, which roughly measured at 5M gallons is actually only 1/3rd above ground. It’s a 16M tank, one of the largest in the system.
- aftbit 2y ago
  Does the below ground part of the tank have pumps to supply water to the above ground part to get pressurization?
  - whartung 2y ago
    All of the water delivery is gravity fed. We live on the slope of an alluvial fan. Water is pumped as/if necessary to the various reservoirs, but from there they rely on water drop for delivery. The tank may well have two sets of pipes to service the closest homes, some closer to the surface with others buried deeper(assuming those homes are even serviced by that tank). But I’m less than a quarter mile away and well below the bottom of the tank. It’s steeper here than it looks. They say they can move water from anywhere to anywhere in the system through a combination of pumps and gravity, but all consumer delivery pressure is gravity based. The water pressure at someone’s house is based on their distance in height from their servicing reservoir. If they were to move water from the lowest part to the highest, it would take 8 lifts of the water. Electricity is a significant expense to the system so minimizing pumping, for any reason, is a priority for them. An interesting trivia bit is that, according to them, where our system has 8 lifts, the CA aqueduct has a total of 11 in its system.
- SoftTalker 2y ago
  > they never considered the chlorine as part of the purifying process, simply precautionary In many parts of the world they do not add chlorine. Our water tastes and smells like a swimming pool in comparison.
  - bongodongobob 2y ago
    I've been all over the US and no where has it smelled or tasted remotely like chlorine. A quick Google says the high end is 4 ppm. If you think you can taste or smell that, you're lying to yourself.
    - lagniappe 2y ago
twic 2y ago
If I understand correctly, the way these work is that microorganisms create a biofilm, and then the biofilm filters the water. The pore size is incredibly small, so particulates and bacteria and so on are filtered out. In which case, I wonder if you could make a more space-efficient version by producing biofilms, or something similar, on an industrial scale. Whether in bioreactors optimised for film production, or just by making great sheets of agarose gel or something.

stubish 2y ago

All the information I find relates to fish ponds. I'm trying to work out if a bog filter is a good idea for a frog pond, or if the clearer water will make things worse for tadpoles.

knodi123 2y ago
frogs are super sensitive to environmental contamination, so clean and clear is fine. as long as it's stagnant.
deleted 2y ago
[deleted]
j16sdiz 2y ago
Frog pond are loud.
- Arrath 2y ago
  Frogs in the night are the sound of home and childhood. I love it.

po 2y ago

This is great advice and I've actually built ponds on this principle in the past. It works well. There are tons of Youtube videos on this subject as well. The channel ozponds is pretty good for this. What I am now interested in is the construction of spring boxes and finding and digging a natural spring from a wooded area. I used to do this when I was younger, but I've found that while the internet generally has all kinds of new techniques that I wasn't aware of, unfortunately, I haven't found a great source of info for this topic yet.

threatripper 2y ago

“Learn from the mistakes of others. You can’t live long enough to make them all yourself.” That's some good advice.

atoav 2y ago
As an university educator I would add: Take risks and try out things at times/places where you can afford to fail, e.g. during your studies. Nowadays too many students put their chips only on safe-bet-projects during their study, which traditionally would be the one time in their lives where they could really try and fail etc. Sure a lot of that is due to economic constraints, which have gotten catastropically worse in the past decades, but trying out things that you know could fail means you are operating at the edge of your abilities, rather than in an area that is safely covered by them. And traditionally that is where the interesting lessons are learned. Learning from others mistakes is a good thing as well, but for that they also have to try things that aren't safe bets.
- pictureofabear 2y ago
  There is a great bias against failure, even for seasoned academics. I always liked this quote from Feynman "If you’ve made up your mind to test a theory, or you want to explain some idea, you should always decide to publish it whichever way it comes out. If we only publish results of a certain kind, we can make the argument look good. We must publish both kinds of result."
- mianos 2y ago
  If you are spending masses of money and time on something, there is little to no chance anyone in their right might would take any more risk than they have to. If you are living on a trust fund, sure, give something risky a try.
  - atoav 2y ago
    I might have to add that I am an educator at an art university and work in a country with nearly non-existent admission fees. Artists that don't risk things during their studies will have a hard time producing interesting things.

123pie123 2y ago

this is interesting if it's true https://www.youtube.com/watch?v=nSBwJNDDUfc https://www.youtube.com/watch?v=nSBwJNDDUfc

hadlock 2y ago

Sponge filters do this same task as bog filtration as well, at a much smaller scale. A sponge is shaped like a cylinder, then a 1cm hole is punched through the center. An air tube goes down the middle, and a 4cm "chimney" sticks up from the hole to improve flow characteristics. The whole contraption is immersed in water. The result is that the bubbles travel upwards, pulling some water with them, and exits the top of the chimney. This water is replaced by water outside the sponge. The sponge acts as both a mechanical filter, but also as a high surface area for microbes to live and process waste. Bog filters work on a much larger scale, but sponge filters have been replacing "hang on back" filters in the aquarium hobby pretty rapidly over the last couple of years. It also helps that sponge filters only cost about $10 and have no moving parts