Brooklyn resident Sara Schiwal is among more than 2 million New Yorkers who have access to a brown bin.
The bins are part of the citywide curbside food scrap and yard waste collection program, already the largest in the United States.
Schiwal, who enjoys cooking with her two-year-old daughter Nora, said that recycling organics is much easier than she had originally thought.
“Everything, all food products – whether they are good, bad, spoiled or stems, parts that you were never going to use – everything goes into it. It is so simple, and it cuts down on our trash, that I can’t understand why anybody wouldn’t want to do it,” she told Reuters.
Approximately one third of New York City waste is organic material – food scraps, food-soiled paper and yard waste. And while part of it is turned into compost that goes to local farms and landfills, an ongoing pilot project at Newtown Creek Wastewater Treatment Plant aims to turn it into biogas that ultimately will go back to residents to heat their stoves and homes.
“Food waste is similar to the solids that you get at the waste water treatment plant. So we decided to try and augment our digesters using the food waste component,” explained Deputy Commissioner of Bureau of Wastewater Treatment Pam Elardo.
Newtown Creek is one of 14 wastewater treatment plants in New York, which has already produced 500 million cubic feet of biogas in its digesters from the solids collected from wastewater.
Inside the plant’s eight digester eggs, sludge is placed in an oxygen-free environment, where it is heated to at least 95 degrees Fahrenheit (35 degrees Celsius) for between 15 to 30 days. This stimulates the growth of anaerobic bacteria, which consume the organic material in the sludge. The digestion process stabilizes the thickened sludge by converting much of the material into water, carbon dioxide and biogas.
By adding pre-processed food waste, the production of biogas went up significantly, Elardo said.
“When we add the food waste we found initially about a 10 percent increase. Which is kind of sustainable over time – at about 25 to 50 tons of food waste per day. This project, the pilot project, it’s going to get us up to about 250 tons of food waste per day. So we’re going to submit, substantially increase potentially the amount of methane we produce.”
At the plant approximately 40 percent of the methane is reused in boilers that provide heat for plant buildings and the digester eggs. The excess biogas is flared into the atmosphere, but with the partnership with National Grid, a major natural gas provider in the United States, this might soon change in the future.
National Grid is scheduled to built a purification center at Newtown Creek in the second part of 2017 that will get the biogas produced clean enough to go into the pipelines for residential and commercial use.
Elardo said that if the program is a success, the 14 wastewater treatment plants can process all the food waste of New York.
“If we can get 500 tons per day here, which is our maximum, and we could get something half or similar at all the other plants, we can get thousands of tons a day for food waste. New York City produces 2,000 tons (food waste) per day residential and about the same commercial; that’s 4,000 tons per day. Potentially this system, this solution, could take all the food waste,” she said.
More than 3 million New York City households will have access to a brown bin by the end of this year. And the combined projects have the potential to produce enough energy to heat nearly 5,200 New York City homes, reduce annual greenhouse gas emissions by more than 90,000 metric tons – the equivalent of removing nearly 19,000 cars from the road.