Beverley Stinson: I’m a senior vice president with AECOM and have been with the company for 22 years. My primary area of technical focus is wastewater treatment, and I currently lead AECOM’s North American wastewater team and also serve the other leads across the globe. One of the areas our group focuses on is waste to energy.
Paul Storella: I’m a senior vice president as well and have been with the company for 34 years. I work in our water business line and focus on running the water business in the New York City area. I have also been AECOM’s client account manager for the New York City Department of Environmental Protection (DEP) for 21 years. I’ve worked with it on some of its biggest water and wastewater projects, from its nitrogen-removal program to its combined sewer overflow program. AECOM has been partnering with the New York City DEP for over 40 years.
Municipal Water Leader: Please tell us about AECOM.
Beverley Stinson: AECOM is one of the largest consulting companies in the world. We work in over 135 countries. Our business lines and service offerings include transportation, which covers everything from airports and railways to roads, ports, and harbors; water; environmental services; buildings and places; and energy. We have our own construction services as well, including our own in-house construction company. AECOM works in a broad range of fields, and in general, it is number 1 in all the markets it does business in, according to Engineering News Record. We connect expertise across services, markets, and geographies to deliver transformative outcomes. We have designed, financed, operated, and managed projects and programs that significantly improve people’s lives. The tagline for AECOM is that we are built to deliver a better world. We are strongly committed to enhancing the built environment globally.
Municipal Water Leader: Please tell us about your work in the waste-to-energy sector.
Beverley Stinson: The way we look at waste to energy is increasingly connected to the concept of a circular economy. One thing Paul has done is to integrate some of our services across our energy and business lines. Previously, coming from the water side, I was familiar with biosolid energy recovery from wastewater, the codigestion of food waste and organic material, and the recovery of energy from food waste. Under Paul’s leadership, we’ve been looking a lot more at waste in general—solid waste, wood waste, landfill waste—and asking how we can integrate that into our business using technologies such as gasification, pyrolysis, and codigestion. How can we recover more energy and resolve many of the big issues that our clients are facing in urban areas?
Paul Storella: One of the big challenges in a place like New York is the limited space in landfills for solid waste. Cities are running out of space, so it’s great that they’re thinking about separating their organic waste. New York does some composting now, and it is piloting adding food waste to the digesters in its wastewater treatment plants. AECOM is involved with the DEP and with the National Grid on a project to take the digestor gas and cleaning it up to put back into the grid for home heating.
Beverley Stinson: They have been using the excess capacity at wastewater treatment plants for the codigestion of emulsified food waste. That boosts the amount of carbon going to the digesters. Paul’s team has used a relatively novel gas cleanup mechanism to inject the gas that is produced by codigestion directly into the gas pipeline. That sustainable, green waste source can produce enough energy to power 5,000 homes in New York City. It reduces greenhouse gas emissions while addressing the limitation on natural gas supplies in the New York metro area. This is the largest installation of this pressure stream absorption technology in the nation.
Municipal Water Leader: What role do new legal regulations or restrictions on landfill waste play in this development?
Beverley Stinson: Seven states now have some regulations with regard to the diversion of organics, or food waste, from landfill, but more will have them soon. Those seven states, along with seven municipal agencies, are setting a leadership standard for the redirection of food waste. The issue of landfill capacity is pressing in places like Florida, where nitrogen and phosphorus from biosolids were leaking back into waterways and creating huge algal blooms, which ultimately forced the governor to call a state of emergency.
More generally, there’s a huge push to address greenhouse gas emissions and to introduce renewable energy sources and zero-carbon electricity. Many states are on a mission to lower greenhouse gas emissions from their power sources; Los Angeles, for instance, wants to be using entirely zero-carbon electricity by 2045, which is a huge commitment.
Paul Storella: New York City wants to reduce its greenhouse gas emissions by 80 percent by 2050, with an interim goal of reducing them by 40 percent by 2035. There are a whole set of ripple effects involved: For example, by making a building more energy efficient, you can reduce the amount of energy and fossil fuels needed downstream.
Beverley Stinson: AECOM is supporting Metro Vancouver in a project it is considering, which would involve taking all the biosolids, food waste, fats, oils, and greases that often clog up the sewers and using it to produce what it calls biocrude. It would use a high-pressure, high-temperature treatment to produce what is essentially crude oil. After going through the refinery process, that biocrude would enter the conventional hydrocarbon cycle as jet fuel or petroleum or whatever. A process like that would leave zero waste left behind. It would also allow for the recovery of phosphorus, which is a finite resource as well. We’re seeing innovative technologies like these that would allow us to go from recovering 40–50 percent of the carbon energy in our biowaste all the way to 80–100 percent, while recovering things like phosphorus and nitrogen, which are great fertilizers, as well. There is also a lot of innovation in the treatment of solid waste and wood waste involving gasification and pyrolysis.
Paul Storella: To reflect that shift, New York City has actually renamed its water treatment plants water resource recovery facilities.
Municipal Water Leader: Have these new processes been enabled by new discoveries, or are they the application of technologies that have always been known to be theoretically feasible?
Beverley Stinson: It’s a bit of a mix. Thermoliquefaction was being tested under the auspices of the U.S. Department of Energy for 30 years, but with fuel sources such as algae. Five years ago or so, we started to wonder if the same technology, which was well advanced by that stage, could be used on biosolids. We adopt technologies that were perhaps developed for one particular application and use them for other types of waste that are causing a concern in our business. Technologies such as gasification have been around for a long time—the gas lamps in Victorian London were powered by the gasification of coal. Now we’re using similar technology to produce high-quality gas that can be stored and easily transported in pipelines. It doesn’t actually involve burning the carbon— we recover the carbon energy in the form of a gas without incinerating or burning it. We’ve known about a lot of these technologies for a long time, but we haven’t always developed them. New materials, new challenges, and an emphasis on sustainability and energy recovery have pushed them forward.
There are some new technologies as well. Per- and polyfluoroalkyl substances (PFAS) leaching from landfills are an increasing concern. We’ve always known that these compounds are difficult to manage and contain. But now that we can completely avoid putting some of this waste into landfills and instead immediately recover energy while also eliminating PFAS contamination, why would we not begin to move in that direction? The increasing salience of that issue helps advance the discussion.
Municipal Water Leader: Is there a size at which deriving energy from waste treatment starts to make sense for a municipal water utility?
Beverley Stinson: According to an energy optimization evaluation research study we did for the Water Research Foundation, wastewater treatment facilities that process 5 million gallons per day (MGD) or more can cost-effectively implement proven technologies such as anaerobic digestion and combined heat and power. That is a purely economic analysis. When you add in other drivers, such as the desire to reduce greenhouse gas emissions, trucking, waste, sludges, and so forth, it could look even more attractive today than it did 5 years ago. Some of these new technologies tend to be a little more complicated than just straightforward anaerobic digestion or combined heat and power—they tend to be the types of technologies that larger facilities, maybe in the 20–30 MGD range, would be thinking about.
Municipal Water Leader: What is your vision for the future?
Paul Storella: The vision is to take a whole metro area and incorporate our solutions to food waste, algae, and wastewater treatment to create a zero-waste, carbon-neutral city powered by renewable energy. By combining our technologies, we can provide a comprehensive solution to a lot of the waste problems that a major city has.
Beverley Stinson: I would add that the opportunity to recover finite resources like phosphorous from waste, rather than putting it in a landfill, adds to the incentives to move forward with some of these innovative technologies. We currently import 10 percent of our phosphorus from overseas every year.
Another part of our vision is to centralize and regionalize a lot of these facilities, thus making them more efficient. One of the places where we’ve been doing this is Hong Kong, where we are combining multiple facilities into a centralized regional facility. Because a lot of the innovative technologies in wastewater treatment allow for smaller, faster, cheaper facilities, we’re able to open up all sorts of waterfront property in Hong Kong that was once used for an old-fashioned wastewater treatment plant. We are actually putting our new facilities inside a man-made cave in a nearby mountain. The entire facility will be hidden from view. It will have a smaller footprint and be more sustainable in its energy use. We will colocate the source-separated organics and fats, oils, and greases. This facility will be similar to one we’re building in Singapore.
I think the beauty of the way we do things at AECOM is that we can bring together the skill sets of our environmental group, which is looking at solid waste; our water team, which is looking at water and wastewater; and our energy team, which is looking at the cutting edge of energy recovery technologies and produce holistic solutions to multiple problems and yield benefits such as recovering waterfront property, parkland, and green space. I think we’re going to see a lot more of that type of activity across all of North America. By bringing together multiple skill sets, we can deliver on this vision.