Air pollution and waste removal

As we continue to develop our research into solutions, one question we keep running into is what happens currently with any captured pollutant? Scrubbers produce slurries, and those on ships can release highly acidic waste water. Filter media are typically rinsed/washed, but where does the pollutant go (I’m assuming into the soil or other water sources?)

Is there a better way to remove pollution from the air? For CO2, we have the capability to capture carbon dioxide and treat it as a source of pure CO2 for numerous applications. CO2 has some value, what about other air pollution? Would a pure stream of NOx or SOx have any kind of value? Or what about rendering the resultant ‘wash water’ harmless?

Lots of questions in there, but I really want to get at what is possible if we push the boundaries of waste treatment.

Hi @josephjjames, @hopkepk, @ckellogg, @rgschreib, @dwcollins1960, @rohan9602
Given your expertise, we would love to hear your thoughts on James queries. Please join the discussion.

That’s a great set of questions @jamesburbridge

Waste pollutants are dealt with in different ways depending on the pollutants and the operator producing them. For example:

  • dilute the pollutants (and flush them into the sewage system)
  • flow the pollutant stream through a bed of plants that absorb pollutants
  • allow bacteria or other biological entities to process the pollutants
  • send them to a hazardous landfill site (which is supposed to contain them for a long time)
  • add them to solid products that lock the pollutants in place (e.g. breeze blocks, concrete, tarmac)
  • disassociate the molecules in a high temperature process
  • use a chemical reaction and/or catalyst to neutralise the pollutant
  • stick them in a sealed container and store them on a secure site.

You can probably find limitations with all of the above approaches - there seems to be no ideal, low cost, low energy, general purpose solution to emissions that contain a range of pollutant types. Some pollutants might be handled by biological approaches and others might not. Some pollutants (e.g. metals) are toxic elements that might be absorbed by a biological entity or an inert substance - but what happens to the thing that absorbed the pollutant as that then becomes more toxic?

This is indeed a great opportunity for an XPRIZE challenge.

If we push the boundaries [speculation]:

  1. Send waste streams through a series of modules, where each deals with specific types of pollutants. [?]

  2. Use nanotechnology to strip out individual atoms by type and then use these pure sources of materials in different end user manufacturing processes. The ultimate recycling machine: element by element. This falls under the sector of nanotechnology/nano-robots. It has been predicted for many years that small molecular sized robots will be built that can use sources of atoms to build sophisticated (meta-)materials and structures. [We are still not there yet.] This recycling idea is the process in reverse: specific atoms are extracted from a complex waste stream. [audacious!]

Note: nanotechnology includes biological components too.

Hey James and all! I’m no expert on this area but it’s a question I think about a lot too… Last week I came across biochar - have you guys heard of this? Carbon chips added to soil, carbon storage and benefits for plants too as far as I can see. Read more here: and check out this company selling biochar chips as an example:

Hi @oscarr, @Shaina, @glynislough
Lets us have your thoughts on an effective way to utilize NOx or SOx captured from Air Pollution.

NOx and SOx have a tendency to form acids in an aqueous solution, so alkali based approaches are expected to be successful.

Hey @JosieAtCapture thanks for joining the community! Yeah, we explored biochar A LOT for the carbon removal prize, one of the best ways to permanently sequester CO2. Really liked this application of biochar:

Haven’t come across anything suggesting that BC is effective at removing air pollution, but soil health is important for removal and filtering of pollution as rain seeps through the ground. Might be an area for further exploration.

I am not an expert but it seems like it could be done and acid products used for fertilizer, explosives and chemical industry.

The bigger question is could strategies to capture NOx and SOx and convert them into a profitable commodity create disincentives to reduce fossil fuel combustion, which are major sources of these emissions and green house gases?

Would it make a big enough dent in the emissions to make it a viable solution for air pollution? Cutting NOx and SOx from coal power plants and reducing the cost of emission control technology seems worth it, but shouldn’t we be pushing for investment in cleaner sources of energy which are viable now?

Would it be a viable and realistically effective solution for NOx in the atmosphere after it has been emitted? That’s like trying to suck an ocean through a straw.
Check out this article by Sarath Guttikunda in the Wire

Our company has a solution - Our CO2LOC technology captures CO2, NOx and SOx in one hit and locks it into a magnesium carbonate matrix. This can be used as a construction material. We need the XPrize to get our technology exposure and encourage the investment we need to scale up and commercialise our technology. We are dealing with some of the most capital intensive and cost sensitive industries and they need full scale demonstration before they will risk an investment in a new technology. This will take many $millions so we are trapped in a catch 22, they’ll invest when we are demonstrating at scale but we need their investment to get there - we are therefore standing still whilst forests burn and our communities get flooded out or their homes blown away.

@CamCarbonCapture sounds like some cool tech. Is your solution deployed at the source of emissions or have a direct air capture capability? Or could it be coupled with a DAC unit? We explored tech like the one you described above for the Carbon Removal XPRIZE in the last round of prize designs. You might check out one of our latest projects, the Circular Carbon Network. A potentially useful resource for finding information on other CCUS tech and funding opportunities.

CO2, NOx and SOx are all products of combustion. So is particulate matter. The BEST answer to all of these is to stop using combustion for energy release. Abundant clean energy, and zero industrial waste will solve clean air. Clean cookstoves are the best first step, and many are on that.
I work in agriculture, closing the loop for some of the most environmentally impacting operations. We take manure apart in a multi step process. Biological, chemical, mechanical and thermal, to move the process to zero waste. The newest component is hydrothermal oxidization, that uses heat and pressure to make water a solvent, and O2 to cause reactions/conversions. Biomass in, nitrogen solution, phosphorus with all of the nasties the process can’t break down (metals) in a sand like ash, and acetic acid (vinegar) that has a bunch of applications comes out. We harvest sulfur from a different part of the process, and all of the components get recombined to make precision agriculture products. The next step is to add methane to protein production via microbial conversion. Calysta and UniBio are the main players were watching for this. Last step water polishing will be done with duckweed in closed containment. (phytoremediation).

Sounds like you are on the ball @ACESChris :slight_smile:

After 13 years, and more than a million $ of my own money, I sure better be… I went from a voice in the wilderness back in 2006, to now a flute in a marching band for the “Circular BioEconomy”, and we are about to bring in the harvest I hope. To solve ALL of the global grand challenges of humanity, we just need to move up a context, and look at them together. We are now able to address food, energy, water and health together, and we must!!

Hi @arinaldi , @FatimaMaria , @greenspan , @herrvebah , @Boaz
We would love to hear your thoughts on capturing NOx or SOx from Air to reduce air pollution and creating value out of it.

Currently roughly 2/3 of the coal ash produced from power stations in the US is recycled, primarily in the production of cement ( nearly 50 million tons out of 70 - 75 million tons produced). The remainder is usually sent to lined ponds. Under the right circumstances, the material can “set up” and be structurally strong enough to support construction of new buildings. SO2 scrubbers can be arrnaged to produce calcium sulfate, which is the primary component of wall board. In Europe, wall board production is a requirement. In the US, naturally occurring calcium sulfate is usually more competitive, although some 10 - 15 million tons is utilized. That which is not used is sent to lined ponds. When the water evaporates, the resulting land is suitable for reuse. As these materials are taken from the ground, they are most likely to be returned to the ground. For example, China uses 3 billion tons/yr of coal. That produces in the neighborhood of 500 million tons/yr of ash materials. There are very few useful products that we use at the rate of 500 million tons/yr. It’s not that we can’t make some useful products. It’s that there is too much of the stuff. The oil and gas industry recovers sulfur from natural gas and crude oil. In 1970, sulfur was worth $40/ton. Today, it is hardly worth anything. Sulfur is no longer mined and that which is “recovered” is usually reinjected into the ground. There have been many processes for recovery of sulfur to make products. Other than the gypsum products mentioned above, all of the rest have resulted in bankruptcy for the developers.

NOx is currently reduced by controlled combustion followed by catalytic reaction with ammonia to form nitrogen gas and water vapor. There is no waste product there. Nitrogen and water vapor already exist in the atmosphere. NOx emissions in the US are now very low and nearly all areas are in attainment for ambient NOx standards.

Technology already exists to collect particulate emissions to the level of 99.99997%. Most power plants being built in the world today have some particulate control devices, although perhaps not as efficient as that mentioned above. In my opinion, the problem is that in some parts of the world, the equipment is present but not used. Most governments have some requirements for air pollution control equipment on power plants. They adopt standards similar to the US and Europe. Banks typically do not lend money for plant construction without the inclusion of such equipment. However, it is much more difficult to determine if these plants actually use such equipment. In the US, we have stringent standards for continuous emissions monitoring equipment and required electronic reporting of emission rates. Operating a plant that is known to be in violation of an emissions standard is considered to be a “willful violation” and carries jail time as one of the penalties. That is not the case in other parts of the world. If your 5 year plan requires the production of a certain number of megawatt hours and you look like you might be short, you start turning off equipment that reduces output, which in most cases is air pollution control equipment. Of course, no one will admit to this publicly, but it is a well known phenomenon. I would suggest that different incentives are needed for these places where pollution control equipment is present, but not used to the proper extent. This will likely do more to reduce emissions than another new technology.

@carlbozzuto great post, very informative. This lines up with everything we’ve researched and I totally agree, the most effective way to clean the air is to keep the pollution from reaching the atmosphere in the first place.

However, we both acknowledge that pollution control is not universally applied, and so then what? The long-distance dispersal of air pollution is a major focus of our research and what can be done to defend air quality from incoming pollution? There seem to be a variety of ways to capture or decompose pollution, but all struggle with efficiency given the trance amounts of pollution in the oceans of air that make up the urban air shed. Would love to get your thoughts on existing tech or natural solutions to remove or decompose pollution in ambient air.

Co2 can be a valuable commodity with compelling prospects for example feeding the planet - there is a NASA technology spin off based in Finland Finland that produces high protein yield fit for human consumption and bofc animal feed - you can find them on twitter at this is what is comming out in my support network since we have ben putting this together - the process requires a high volume input of Co2 and of course this would have to be isolated from other waste flue gas biproducts such like Nox and Sox but yes Co2 captured for sequester can be a valuable commodity. Solar Foods is a recent new proposal that ties in with Kenta waste heat recapture for load balancing and a cheap profitable source of energy. They say it tastes and has a wheat like character.

Solar Foods (@Solar_Foods) | Twitter

The latest Tweets from Solar Foods (@Solar_Foods): "Electric food – the new sci-fi diet that could save our planet | @GeorgeMonbiot #FutureofFood #food # …

Kenta energy storage battery for solar energy load balancing release at night and incidentally sequester of Co2 Nox and Sulphur waste treatment. Some of it would be a valuable commodity with incidental benefit potentials. This potential was alerted to me by Angela Gibson JPL ambassador - NASA Social on Twitter. There are also algea farming potential thjat may be attractive but not requiring nearly as much Co2 sequester - last but not least there is the potential use as biofeuls which would also use a quantity of captured Co2 from LNG - Coal Plants and manufacture such like cement manufacture an ominous emitter of Co2 unecessarily.

Thanks for your time…

From: Stefan Tubman