Dr. Marco Castaldi and Demetra Tsiamis of the Earth Engineering Center at Columbia and CCNY

Sustainable waste management aims to find solutions for balancing the increasing use of materials and the finite resources of the Earth

Today I am interviewing Dr. Marco Castaldi, Director of the US Earth Engineering Center, and Demetra Tsiamis, Associate Director of the Earth Engineering Center at City College of New York.

They discuss the Earth Engineering Center’s (EEC) focus on sustainable waste management and conversion research, which aims to find solutions for balancing the increasing use of materials and the finite resources of the Earth.

Valentina Rappa: For starters, I’d like to discuss the history of the Earth Engineering Center. I understand that the EEC originated at Columbia University in 1995. Would you be able to explain the reasoning behind the formation of the EEC and their original mission statement?

Marco Castaldi: When I think of the words “Earth Engineering Center”, I think of a center that wants to look at the Earth’s resources and things that are impacting the environment of the Earth and what needs to be brought to bear for that, which is essentially their mission statement.

Dr. Marco Castaldi is Director at the US Earth Engineering Center (Source: EEC)

When Professor Nicholas J. Themelis formed the Earth Engineering Center he was at Columbia University and was a part of the Henry Krumb School of Mines, but since circa 1960 nobody does mining, the department was very outdated.

Now in a university construct you can’t just start a new department, so his vision was to leave it as the mining department but start this center where like-minded individuals in the department of mines would do more environmental and earth-resource related work.

That then expanded; it had good traction at the university and the engineering school of Columbia. So simultaneously what grew out of the Earth Engineering Center within the mining department was the Earth Institute, which is an institute at Columbia University that has a number of different centers within it.

This all started with the EEC, but out of that grew the Earth Institute and then this institute spawned a bunch of other centers. So just to be clear, the formation of the EEC led to the Earth Institute, but now the EEC falls under the Earth Institute. Shortly afterwards, the mining department transformed into the Earth and Environmental Engineering Department at Columbia University.

Now, as all centers start, they begin as a few faculty members coming together in a collaborative way, but from 1995-2003 the EEC was solely Professor Themelis; there were very few other faculty members that really embraced this center.

I joined Columbia in late 2003 and my background and training aligned with what Professor Themelis was doing. When I arrived, Professor Themelis was doing analytical and life cycle assessment work, while I was doing hardcore experimental lab work, so our research really complimented each other and allowed us to successfully develop that center from 2004 until 2012 [at which point Dr. Castaldi expanded the EEC to CCNY].

VR: I see that in 2003 the EEC formed the Waste-to-Energy Research and Technology Council (WTERT), which has sister organizations in China, Brazil, Germany, Greece, India, Italy, and the U.K. Would you say that the CCNY organization is well connected to its sister organizations? If so, how exactly do you collaborate with your fellow organizations?

MC: Professor Themelis had the idea of the WTERT for a while, so once I joined in 2003 I was part of it right off the bat.

The ultimate vision was for the Earth Engineering Center to have this center and have other units that would be subsets of it. A few faculty members cannot encompass all of that, so the idea was to start off with some line of research and then hopefully other lines will come in.

Let’s just look at the global category of municipal solid waste — that is what the WTERT started as. There is a big impact of garbage on the world, and it needs to be managed properly. However, Professor Themelis and I both have backgrounds in thermal energy, so we planned to look at the thermal conversion technologies of what garbage can be transformed into: incineration, gasification and pyrolysis.

The hope was that other professors would bring in recycling, digestion and other efforts to the Center. Unfortunately the other efforts never materialized and they still have not. So for all practical purposes the EEC and WTERT are one in the same and that is why I prefer to refer to us as the EEC at CCNY to prevent any future confusion. Now our sister organizations refer to themselves as WTERT because that is what they know.

Demetra Tsiamis is Associate Director at the Earth Engineering Center at CCNY (Source: EEC)

I’m happy to say that the WTERT is very well connected, very collaborative and is still very much engaged. I am now the Director of the WTERT in the U.S., so I can honestly say that it’s very well connected in terms of student exchange and research associate exchange. The most immediate way that the EEC provides opportunities for CCNY students is through the hands-on research experience…students get to go out on-site and see these technologies for what they really are, rather than reading about them in a textbook.

Demetra Themelis: I would like to add that the WTERT is a network of research associates, so if we are working on a project in an area that is not necessarily our expertise, but we know someone within the entire network of WTERT, then we will reach out to them and have a telecom. Even if we do not often travel across borders there is a lot of interfacing with different types of people from different countries, as well as from academia, industry and government.

VR: Considering that both of you began working with the EEC at Columbia University and recently decided to expand the CCNY chapter within the last few years, do you find that there are distinct differences between the two chapters? Or would you say that the EEC is rather similar at both Colombia University and CCNY considering they have the same goals?

MC: When I left Columbia in 2012, I brought all of the experimental aspects of the EEC to CCNY and was able to hire Demetra as my Associate Director. So now the EEC is based between Columbia University and CCNY. For example, a recent master’s student at Columbia was able to do all of her experimental work at CCNY.

Unfortunately, I think it was very clear that if I did not come to CCNY after leaving Columbia, then the fate of the EEC at both CCNY and Columbia University was uncertain. If you look over the past 10-20 years of the EEC and at least the past 12 years it has really been within Professor Themelis and I. So the interest within Columbia University just does not seem to be there and they have their Earth Institute and many other centers that really attract students. Although at CCNY I know there are other research groups working on recycling, water treatment and other related topics that we can expand towards. That is why I chose the EEC over WTERT — because I knew we would be able to expand our efforts at CCNY and by primarily using the name WTERT we may confuse people when trying to develop our focus.

VR: Compared to other research groups at CCNY, how do you think the EEC provides different opportunities for student researchers and better prepares them for the industry?

DT: I became affiliated with the EEC when I was getting my master’s degree in Chemical Engineering at Columbia University, but I wanted to do research and I became very interested in what the EEC was doing. I ended up doing a thesis with the EEC, which was affiliated with the Environmental Department. Through this research I was sent to speak with the founder of a company to learn about his work with plastics pyrolysis. I had never encountered such an experience with my past research labs, where I was literally placed in the industry.

I believe the most immediate way that the EEC provides opportunities for CCNY students is through the hands-on research experience because a lot of our projects are with real companies and developing commercial technologies, so the students get to go out on-site and see these technologies for what they really are, rather than reading about them in a textbook.

Through collaborations with these companies they are also getting a professional experience when it comes to having set deadlines and not having as much leeway. These realities are exactly what one of our students, Melissa Torres, has mentioned as one of the major benefits of her experience with us.

DT: Professor Castaldi also has much collaboration abroad and through his connections some of the students in the program have been able to continue their research abroad. Also international students have come to CCNY to conduct research; we have hosted students from Brazil, Mexico, Sweden, China and France.

MC: Yes, due to the fact that the WTERT is more established in these other nations it is easier for them to send students here, while because we just recently developed the EEC at CCNY it is more challenging for us to send students abroad.

Although two of our students, Michaela Wagar and Dane Fearon, have either already traveled abroad or will be traveling in the near future. We are also very selective about who we send abroad because it is a very intense experience when you get there. Of course it is nice to see the country and experience their culture, but the primary mode is to do a project and that is the motivation that the student must have.

VR: Dr. Castaldi, I see that many of the experiments conducted by the EEC researchers are undergone in your Combustion and Catalysis Lab. Would you be able to explain the experiments used to transform feedstock into fuels and chemicals?

MC: Our lab mostly focuses on thermal conversions, which means heat applied. How do you get that heat? And then, what other co-reactants do you bring? For example, you have municipal solid waste — if you take the garbage and just heat it then that is pyrolysis, which will give you a product like an oil which is very useful. If you decide to add steam, this is known as gasification, which leaves you with carbon dioxide and oxygen, called syngas [synthesis gas], and from that you can build many other products or you could simply burn it and make electricity. It is rather alarming that there are no national regulations regarding municipal solid waste, and we see the City of New York as an ideal place to improve this concerning waste infrastructure. If you have heat and you incorporate oxygen, well now you are undergoing combustion, which means incinerating the waste. With combustion you produce carbon dioxide and water, but you also produce a lot of heat and from that you usually get electricity.

So what are the types of products that you receive? Well, of course electricity, but also energetic products, like fuels and chemicals, and then there are usable products, like the oils. Now that is what we focus on because that is where our technical strengths lie, but we are slowly branching out.

DT: A major part of our lab work lies within characterizing the waste. Municipal solid waste is not very easy to characterize in just one test because it is so varied in many ways. When characterizing the waste we look at differences in energy and moisture levels and when you thermally convert something you will have a residual left over, so we look into what is in the residual and what are beneficial uses for that residual.

Overall we focus on how to convert waste, what is the optimal way to do so and what is in this waste that can truly benefit us. For the future we are also looking into how to use the fuel products of waste conversion and understand how they perform in different applications, such as in gas turbines.

VR: What are the current projects that the EEC is working on and how long have these projects been in action?

DT: We have projects that have been active since Professor Castaldi came to CCNY, which was about four years ago.

We do a lot of work with plastics and how to convert them because plastic is still heavily landfilled. For starters, we have projects looking at how plastics impact methanol production from gasification plants. We are currently conducting pilot testing with a company in Canada that is looking to commercially produce methanol from waste gasification. This is a really big step for gasification of solid wastes and many other companies are waiting to see if this company will succeed.

We also work with a plastics pyrolysis company to understand the efficiencies of their process and how they can improve their process of generating fuel oils from non-recycled plastics. In addition, we work with the American Chemistry Council (ACC), which is a trade group that represents plastic manufacturers; their sustainability team is constantly looking for ways to divert plastics from landfills to make an alternative end of life use for non-recyclable plastics.

Waste-to-energy has the issue of corrosion due to chlorine and other halides in the waste so we have students trying to understand what materials are the most corrosion resistant.

Another really exciting topic that many companies are looking into is the beneficial reuse of that residual that we previously spoke about, which is commonly referred to as ash. This ash contains metals. A lot of our efforts reside in determining if we can recover these metals for reuse or utilize the ash for other beneficial application, such as use as a material in concrete

As we have discussed, there is the field-testing where we visit companies, and then there is the lab side, where we conduct bench scale investigations in areas such as corrosion, ash reuse, and waste characterization. Lastly, EEC has also done market assessments — there is growing interest in the market potential for waste gasification and what is needed for this industry to grow.

VR: The infamous gasifier! I understand that our very own Steinman Hall at CCNY has a gasifier. Are there specific solid wastes that produce optimal energy?

DT: I have found that in engineering it is always difficult to define what is optimal. Immediately I thought, well, if we want to get energy from it, it should be the wastes that have the highest energy content, which is a plastic when you are looking at municipal solid waste. Just to be clear, municipal solid wastes describes the waste that is generated by residents and businesses, which is different from construction and demolition waste — we primarily work with municipal waste.

In some ways I would say plastics, because it has the most energy to extract from it, but the downside with plastics is that there are many other chemicals that are with the plastics that can result in corrosion. For example, there is a type of plastic called PVC (Polyvinyl chloride), which is not often thermally converted because it contains chlorine that will eat away at the materials. In addition, you want to be sure that these chemicals do not impact the emissions. On the other hand we can look at food waste, which has a lower energy value and can have high moisture resulting in high-energy consumption to dry that material, but this waste will often have fewer harmful chemicals.

As for the gasifier that we have in the Steinman cellar, it was donated to us by Sustainable Waste Power Systems. That gasifier is designed to handle wet waste. Most thermal technologies prefer that the waste has as little moisture as possible, but that is the niche market that SWPS is looking to.

VR: What are your plans for the future of the EEC? Do you feel that the mission statement of the EEC at CCNY will alter from the EEC’s original mission statement?

DT: I think the original mission statement of the EEC is still applicable, but now we are interested in connecting municipal solid waste with wastewater treatments. As always we are determined to identify how to extract as much value as possible from the waste.

As for our most immediate steps, we are to working towards increasing the Center’s visibility at CCNY and within the City of New York. We recently met with the Commissioner of the Department of Sanitation of New York to present on the research of our center and share our concern with the lack of education regarding municipal solid waste.

It is rather alarming that there are no national regulations regarding municipal solid waste, and we see the City of New York as an ideal place to improve this concerning waste infrastructure.

That being said, we are collaborating with the AIChE [American Institute for Chemical Engineers] Institute for Sustainability to host our first conference this April at CCNY, titled the Megacity Waste Management Dialogue: The NYC Roadmap for Waste as a Resource.

We plan to bring industry, government academia, and the public together to discuss the most important and pressing issues in the area of municipal solid waste. There will be experts from around the world sharing best waste practices that are being employed and explored abroad.

In the end, the outcome of this conference will be a road map for New York City that can be adapted as a model for sustainable waste management in megacities spanning technology, social, environmental, and policy aspects. We hope to have all supporters throughout New York attend this crucial conference. You can learn more about the Megacity Waste Management Dialogue: The NYC Roadmap for Waste as a Resource — April 25-26, 2016 — at the AIChE website

Leave a Reply

Your email address will not be published. Required fields are marked *