Source: What's Up in the Environment?
When we recycle glass, plastic, or cardboard containers, we save resources and energy. But your soda cans and plastic bottles aren't the only things that are recyclable. Contaminated lands, known as brownfields, can also be recycled. In this What's Up In The Environment? video segment, see how biosolids produced by a wastewater treatment facility are used to improve the soil in a contaminated plot of land in Philadelphia called Liberty Lands.
Download and ShareIn the last thirty years, many factories, industrial plants, and military bases shut down or moved, leaving behind vacant properties. The old, abandoned land often was contaminated with harmful chemicals and biological pathogens, making it unsafe and unusable to the community. This kind of site is commonly known as a brownfield.
Currently, there are land reclamation groups working to recycle brownfields by converting the contaminated, hazardous land into clean, safe, usable land for city dwellers. In order to recycle these contaminated sites, clean-up teams take four key steps: they assess the site's damage; work to prevent further contamination; clean up the hazardous materials; and, then, design plans to re-use the land.
Biosolids can play a key role in the recycling and re-vegetation of brownfields. Biosolids are nutrient-rich, organic materials that come from the treatment of sewage at a water treatment facility. Billions of gallons of wastewater can travel to a facility each day from homes, businesses, and street runoff. The wastewater contains solid material and pollutants, for example food particles, human waste, oils, and chemicals. A series of physical, chemical, and biological steps treat and clean the water and filter out the biosolids, which are then used as fertilizer to improve soil and stimulate plant growth. The processed water, called effluent, is released back into the environment.
The Liberty Lands project in northeastern Philadelphia demonstrates how recycled biosolids are used to improve a piece of land. The project began when an abandoned industrial site, previously known as the American Street Tannery, was donated to the Northern Liberties Neighbors Association in 1995. Members of the community hoped to create a multi-use open space for the public. Once the pollution from the tannery was cleaned up and contaminated materials were removed, biosolids were used to improve the quality of the land. The organic matter found in biosolids is rich in nutrients, so it acts as a natural fertilizer. As a result, the soil is able to retain more water and nutrients, which supports plant growth.
With the help of a grant from the Philadelphia Urban Resources Partnership, the resulting two-acre park, called Liberty Lands, features community garden plots, a farmers' market, artwork, and space for events. The park is open to the public and hosts a variety of community events, helping to revitalize the community. Liberty Lands is still managed by the Northern Liberties Neighbors Association without any financial support from the city, but additional grants from organizations help maintain and improve the site.
To learn about conserving top soil, check out Organic Farming: Conserving Top Soil QuickTime Video.
To learn more about recycling, check out Visiting a Recycling Plant QuickTime Video.
Host 1: Liberty Lands is a place where kids in northeast Philadelphia can get together and hang out.
Host 2: It’s an urban oasis.
Host 1: These are some of the parents who put a lot of work into this park. That’s right neighborhood people planted all these flowers and fresh fruit and veggies.
Nina Sostre: Everything comes out larger than what you buy at the store. It comes out sweeter.
Host 2: Would you believe that just four years ago, this...looked like this?
Brian Mitchell: Before this was a park, this was an old abandoned building. And I used to be scared to walk by here sometimes.
Luther Wayman: We wanted to build something available for children and for the community. And we started from scratch. There was an old tannery here, and it was torn down.
Host 1: A tannery is a factory that makes leather from animal skins. It requires a process that uses chemicals that can be dangerous.
Ken Pantuck: There were thousands of drums of hazardous waste and transformers that were buried here at this site. EPA, in 1987 and 1990, undertook a clean-up project removing the contamination of these sites and improving the health of this area.
Dennis Haugh: More and more cities are finding open empty space and trying to find a reuse for what was industrial.
Samantha: We have our grandma’s garden growing lettuce, tomatoes, squash, hot peppers.
Host 2: OK, the federal government cleaned up the pollution from the tannery, but how do you get a vacant lot to grow grass and trees? They improved the soil with something called biosolids.
Host 1: See, this stuff that looks like soil is actually biosolid. It's a byproduct of wastewater treatment. At Liberty Lands, they used it as lawn fertilizer. First, what is wastewater anyway?
Host 2: Wastewater comes from our homes and offices – our sinks, toilets, washing machines, dishwashers. In some cities, it also comes from the storm drains on our streets. The dirt in wastewater consists of all kinds of stuff. Wastewater treatment plants are designed to get those out before the water is discharged back into our rivers.
Host 1: A big challenge they face is what to do with the solids that come out of the water. Usually, they end up being dumped in landfills.
Host 2: Landfill space is starting to run out. We recycle paper, not only to save trees, but also to save landfill space. So, what if we could recycle the solids that come from wastewater treatment?
Host 1: Well, sure, we can. Liberty Lands is one example. For us to get an idea of how this works, let’s visit one of the most advanced wastewater treatment plants in the world.
Jerry Johnson: We treat 370 million gallons of sewage a year on a daily basis, and from that we generate two products. We generate a very clean effluent and we then discharge that into the Potomac River. The other product that we produce is a biosolid – used to be known as sludge, more politically correct now is biosolids because they’re reusable.
Host 2: Water that comes into the Blue Plains plant goes through a variety of processes to separate out contaminants, water, and recyclable solids.
Mike Marcotte: This is part of our primary treatment train here at the plant. Some of the oldest buildings, some of the smelliest buildings because we’re dealing with the sewage as it comes in from the two million plus people in the area.
Host 1: That's gross, that's going to a landfill. Those plastics and garbage aren't reusable. Once all that's gone it's time to get the good stuff out of the water.
Mike Marcotte: These aeration basins are really the heart and soul of our treatment process. What goes on out here is that these bugs, these bacteria, in the presence of oxygen, chew on the dissolved organics. It’s a real soup of what’s washed off of your dinner plate, what’s washed off of your body in the shower or bathtub. Once the bugs have eaten on the waste and gotten fat and happy and removed substantially all the dissolved organics, those bug bodies basically, become the very core of our biosolids.
This is one of several points in the plant where we actually add chemicals, which involves the addition of iron salts to remove the phosphorus. We actually use a biological process for the nitrogen removal, using bacteria. The two nutrients of nitrogen and phosphorus then also become part of our biosolids and allow those to be more valuable as a fertilizer.
Host 2: Like we saw in the Everglades we want nitrogen and phosphorus in our fertilizer, but not in our waterways.
Host 1: What you see here at Liberty Lands is mostly the result of hard work by the local community. But it also took the efforts of environmental engineers, biologists and chemists, some of whom work at Philadelphia’s wastewater treatment plant.
Brian Mitchell: When we come together and play football, we have so much fun, now that there’s a place where we can hang out, like, this park.
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