With plastic in bringing water in and out of homes and businesses, doesn’t that add more microplastic into our water much in the same way plastic in clothing leaches?

Charles: While I am not aware of studies looking at microplastics coming from plastic water pipes (which are significantly more robust than fibrous cloth), eventually microplastics will be emitted from them – everything breaks, it’s just a question of how slowly. This is certainly a question worth studying.
Adi: There are many sources of microplastics in the environment, therefore it is not surprising we are finding them in every environmental compartment (ocean, rivers and lakes, soils, plants, animals, and even inside our bodies). We therefore target the areas that increase human exposure – drinking water sources, agricultural fields, etc. These studies will hopefully inform us how to better prevent or decrease the risks.

These four ideas are wonderful to help the world fix its sustainability problems. Right now they are functioning in labs, how much time and dollars will be needed to reach a scale to solve even 5% of the earth’s pollutants?

Charles: We currently recycle 9% of our plastic waste. Increasing it by 5% is not a significant challenge, particularly PET and HDPE, which are ca. 25% of the waste and are easy to recycle – as long as you get them separated. Many countries started requiring plastic bottles to be made from a single plastic type. If this was done for all drink bottles in every country, more than 5% would be easily addressed. The main issue in plastic is what to do with all the LDPE, or the “single-use plastic,” such as soft plastic bags, etc. This plastic can be recycled but the price tag is too high (compared to HDPE or PET, which are also more expensive than virgin plastic but the price difference is less significant). The technology exists (not including multilayered that I described in the seminar), but the issue is price – which can only be changed by regulation. Virgin LDPE is just too good and too cheap.

Can you speak more about using algae to create portable fuels?

Noam: There are a few answers below that explain about the processes we use. The algae (seaweeds) are of many different types – there are red, green, and brown. Many of the red types are used in agriculture, for instance the Japanese Nori used in sushi. Some green algae (like Ulva) are also not only edible, but very healthy. Kelp is another type of seaweed that is found around the world and can grow to immense sizes in rather cold water and without a lot of sunlight.

How can these technologies be used to clean brown fields?

Adi: Remediating soils is a lot more challenging than cleaning water sources. The heterogeneity of the solid particles makes it very difficult to spread adsorbents or oxidants. Highly polluted soils that can not be treated biologically by bacteria are often excavated and buried rather than cleaned. However, the reactions I mentioned (adsorption and degradation) can, under certain conditions, be employed in soils. This depends on the type of pollutants and the type of soil. We have several projects that we are developing that attempt this type of technology.

Will growing algae effect the eco system they exist in and make the environment out of sync? Will there be issues like with fish farms that sound good but then create more hazards?

Noam: Seaweed is completely natural. There are hundreds of species, each part of their natural ecosystem. Some seaweeds (like the Ulva that I mentioned) can be grown in vats on the shore using seawater. The seaweeds actually purify the water when it is returned to the sea (this is how it is done in the Seakura company in Israel) that grows Ulva for food). Seaweed do not need any fresh water, any herbicides, or fertilizers. So, I would have to say that even growing them in many ton amounts would not have an effect on the environment. They can also be grown in the sea themselves – this is done in Asia and even in the Faroe Islands – where the water is cold and there is much less sun than in Israel.

Isn’t encouraging growth of seaweed in the ocean the most scalable, cost-effective way to reduce atmospheric CO2?

Noam: Absolutely! There are other photosynthetic organisms that can sequester large amounts of CO2, in other areas of the world as well. But seaweeds are great for this purpose and are very useful as well.

Exactly HOW can you get electricity from seaweed?

Noam: This is of course not an easy question to answer here (you are all invited to come to the Technion and learn about photosynthesis!). But briefly, in natural photosynthesis the sunlight drives an electrical current that runs through special molecules that are mostly bound to proteins. The electrons eventually end up in a molecule called NADPH (by the way, we have a similar molecule called NADP in our mitochondria). We found that the photosynthetic organisms release this molecule into our electrochemical cell at high fluxes, and when NADPH comes near our electrode, the electron “jumps” and starts the electrical current. There are additional molecules that can transfer the electrons to our electrochemical cells, depending on the type of organism.

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