The lead poisoning scandal in Flint, Michigan, highlighted that access to safe drinking water is not just an issue in the developing world. And as Reuters reports, “while poverty remains a potent predictor of lead poisoning, the victims span the American spectrum – poor and rich, rural and urban, black and white.
An examination of lead testing results across the USA found “almost 3,000 areas with poisoning rates far higher than in Flint,” and the same may well be true across the world. Hundreds of years of mining, smelting, and using heavy metals such as lead, cadmium, arsenic, mercury, aluminium, antimony, chromium, cobalt, copper, manganese, selenium, tin, thallium in industry have left a legacy for us in soil and groundwater.
Landfills as a Resource
That is not to say that waste can’t be an opportunity too. As commodity prices fluctuate and recovery and separation technologies improve that landfill currently belching methane and leaking cadmium into the water – especially ones from before waste regulations were tightened in the early part of the century – may become a commercially viable resource.
The removal of contaminants from soil, or soil washing, is nothing new, but it does require huge amounts of water to remove the contaminants which then itself has to be cleaned using coagulants, flocculants and a wide variety of other chemicals. Although the chemistry works, the economics of cleaning up the water don’t.
What if there was a cheaper way to clean water?
If you talk to anyone working with graphene they will tell you how simple it is. A single molecule thick layer of material, open up some pores with the right dimensions that will filter out what you want to separate and Hey Presto! instant clean cheap water treatment for everyone.
Unfortunately, a bit of graphene with holes punched in it just isn’t a viable filter. It needs to be supported and bonded to something that will stand anything from a few to almost a hundred bars of pressure, and doing that removes many of the advantages of using 2D materials.
And then there is oil, the nemesis of most membranes. Small oil droplets, micro and nano emulsions are great at clogging tiny pores – ask any beautician. Once a tiny bit of oil gets into the water, and most landfills have a decent quantity of oily greasy stuff from old chip pans to car tyres lurking within, then a membrane can quickly become a barrier. That means back flushing, and cleaning with alkalis or acids which means more down time and more consumables.
I have yet to find a graphene membranes that works anywhere other than in theory.
Except at G2O, where we coat other people’s membranes with graphene rather than making graphene membranes, a subtle but important distinction that changes the game.
G2O’s coatings take a membrane that already works and make it work a bit, or quite a lot better. The addition of our coatings make the membranes more hydrophilic, often a problem for polymers while simultaneously making them superoleophobic. This means that on one hand more water goes through the membrane which reduces energy costs, and on the other oil ceases to be a problem which reduces downtime and consumables. Both of these mean a lower cost for treated water.
Membranes are only part of the solution for cleaning up groundwater or reclaiming landfills, but driving down the cost of water treatment opens opportunities for both public health and the environment.