4 ms·

> What did the CPG companies think was going to happen when they dumped a billion tiny little pieces of plastic directly down the drain? I'm willing to put par

> What did the CPG companies think was going to happen when they dumped a billion tiny little pieces of plastic directly down the drain? I'm willing to put part of the blame on the cities for this one. In many cities, wastewater treatment has not been given the necessary investments to properly filter the water before piping it into the lake. Plastic's not the only problem, unfortunately. http://greatlakes.org/CSOs http://greatlakes.org/CSOs

ceejayoz 11y ago
No wastewater treatment process is going to filter out microbeads - they're between 0.01mm and 1mm in size. You'd have to change the filters every five minutes. Properly treated wastewater is just that - treated, to make it safe (i.e. fewer pathogens). It's still not something you'd want to drink out of a tap.
- zeveb 11y ago
  > No wastewater treatment process is going to filter out microbeads - they're between 0.01mm and 1mm in size. You'd have to change the filters every five minutes. Rather than filter, why not settle them out?
  - ceejayoz 11y ago
    Most of the problem with untreated sewage in the Great Lakes is burst capacity - when you get a rainstorm, the sewers overflow and dump raw sewage into the lakes. Having to store an entire storm's worth of water long enough for 10 micrometer beads to filter out simply isn't feasible.
    - slavik81 11y ago
      If you build separate sanitary and storm sewers, then you don't have that problem. About a decade ago, developing a proposal for solving that problem in Kingston, ON was part of my first-year engineering coursework. Obviously, I was not an expert, but after some research, my conclusion was that building storage was the cheapest solution in the short term. Opportunistically separating the sewers made the most sense over the long term.
  - astine 11y ago
    Is that possible? They're much lighter than water and super tiny. Is there even a way to know that you got all of them? You'd almost have to run the affected water through a still.
    - mapt 11y ago
      If they were much lighter than water it wouldn't be as much of a problem for water filtration - they'd float, and settle at the top rapidly. It would remain a large problem as far as untreated discharges though. Stokes' Law gives settling times (or terminal velocities) for small spherical particles. Terminal velocity is proportional to (difference between particle density & water) * (particle diameter ^2) A 0.1mm microbead at 0.9 specific gravity will float to the top at 0.54mm/s, or at 1.1 specific gravity will drop to the bottom at the same speed. A 1mm microbead will move 100x as fast. A 0.01mm microbead will move 1% as fast. I don't see the technical issue with trying to incorporate them into settling plant workflows, only the sociological issue that we routinely underfund municipal works. It's much cheaper to ban the selling of microbeads than to deal with them via settling in a universe where engineers run everything and the environment is sacrosanct, but even so, we don't live in that universe: Raw sewage discharges are common, and such things are not seen as important so long as we're not getting cholera outbreaks. Municipal works don't have the power, political or regulative, to levy new taxes on specific consumer-good industrial practices to pay for any expansion. Food for thought: "there are 330,000 plastic beads in a single bottle of Clean & Clear facial scrub" Edit: From a student study of microbeads, it looks like sizes have a mean of 260um with a standard deviation of 100um. http://nature.berkeley.edu/classes/es196/projects/2013final/ChangM_2013.pdf http://nature.berkeley.edu/classes/es196/projects/2013final/...
  - jussij 11y ago
    I think that is one of the reasons they are so bad for the environment, they don't settle. Instead they end up suspended in the oceans of the world and fish eat them and slowly die.

ceejayoz 11y ago

No wastewater treatment process is going to filter out microbeads - they're between 0.01mm and 1mm in size. You'd have to change the filters every five minutes. Properly treated wastewater is just that - treated, to make it safe (i.e. fewer pathogens). It's still not something you'd want to drink out of a tap.

zeveb 11y ago
> No wastewater treatment process is going to filter out microbeads - they're between 0.01mm and 1mm in size. You'd have to change the filters every five minutes. Rather than filter, why not settle them out?
- ceejayoz 11y ago
  Most of the problem with untreated sewage in the Great Lakes is burst capacity - when you get a rainstorm, the sewers overflow and dump raw sewage into the lakes. Having to store an entire storm's worth of water long enough for 10 micrometer beads to filter out simply isn't feasible.
  - slavik81 11y ago
    If you build separate sanitary and storm sewers, then you don't have that problem. About a decade ago, developing a proposal for solving that problem in Kingston, ON was part of my first-year engineering coursework. Obviously, I was not an expert, but after some research, my conclusion was that building storage was the cheapest solution in the short term. Opportunistically separating the sewers made the most sense over the long term.
- astine 11y ago
  Is that possible? They're much lighter than water and super tiny. Is there even a way to know that you got all of them? You'd almost have to run the affected water through a still.
  - mapt 11y ago
    If they were much lighter than water it wouldn't be as much of a problem for water filtration - they'd float, and settle at the top rapidly. It would remain a large problem as far as untreated discharges though. Stokes' Law gives settling times (or terminal velocities) for small spherical particles. Terminal velocity is proportional to (difference between particle density & water) * (particle diameter ^2) A 0.1mm microbead at 0.9 specific gravity will float to the top at 0.54mm/s, or at 1.1 specific gravity will drop to the bottom at the same speed. A 1mm microbead will move 100x as fast. A 0.01mm microbead will move 1% as fast. I don't see the technical issue with trying to incorporate them into settling plant workflows, only the sociological issue that we routinely underfund municipal works. It's much cheaper to ban the selling of microbeads than to deal with them via settling in a universe where engineers run everything and the environment is sacrosanct, but even so, we don't live in that universe: Raw sewage discharges are common, and such things are not seen as important so long as we're not getting cholera outbreaks. Municipal works don't have the power, political or regulative, to levy new taxes on specific consumer-good industrial practices to pay for any expansion. Food for thought: "there are 330,000 plastic beads in a single bottle of Clean & Clear facial scrub" Edit: From a student study of microbeads, it looks like sizes have a mean of 260um with a standard deviation of 100um. http://nature.berkeley.edu/classes/es196/projects/2013final/ChangM_2013.pdf http://nature.berkeley.edu/classes/es196/projects/2013final/...
- jussij 11y ago
  I think that is one of the reasons they are so bad for the environment, they don't settle. Instead they end up suspended in the oceans of the world and fish eat them and slowly die.