Pelletizing/Northeast: Recycling Sewage Waste, Making a Market in Pellets

Challenge:
When Congress enacted the Ocean Dumping Ban Act in 1988, the New York City Department of Environmental Protection (NYCDEP) needed to identify an effective alternative to managing wastewater residuals generated by the city's 8 million residents. NYC has 14 wastewater treatment plants in five boroughs that treat a combined total of 1.7 billion gallons a day of wastewater and produce 300 to 320 dry tons a day of biosolids. The city sought to efficiently and swiftly phase out ocean disposal and replace it with land-based beneficial use of its biosolids.

Solution:
In 1991 NYCDEP contracted with New York Organic Fertilizer Company (NYOFCo), a Synagro Technologies Inc. company, to design, build, own, and operate a municipal biosolids heat-drying and pelletizing facility located in the Bronx. Comprised of six biosolids drying and pelletizing units, the facility is among the largest of its kind in the world and is designed to handle 100% of the city’s biosolids production. The facility, which began commercial operation in 1993, currently converts 47% of the city’s biosolids into “Class A” fertilizer pellets. The small, spherical, hard, and dense biosolids pellets meet the US Environmental Protection Agency’s (EPA) Title 40, Part 503 regulation’s standard for Exceptional Quality.

The NYOFCo facility features an advanced air quality control process that uses high temperature in a Regenerative Thermal Oxidizer (RTO). Considered by EPA to be the “Best Available Control Technology,” the RTO destroys pathogens and removes volatile organic compounds. A cyclone and venturi scrubber removes particulate matter, while a baghouse particulate collection system collects fugitive dust in process equipment and buildings. The facility building is enclosed and negative air pressure is maintained to control noise and odors.

Result:
Since 1993 the NYOFCo facility has recycled more than 2 million tons of NYC’s wastewater residuals into biosolids pellets -- the largest amount of biosolids ever processed by a recycling facility in such a short period of time. The product-size pellets are shipped primarily by rail cars for beneficial use applications. Valued for its organic nitrogen and micronutrients such as iron, sulfur, and zinc, the fertilizer product is marketed under the name Granuliteä for use by farms throughout the Midwest and Northeast, citrus groves in Florida, and golf courses nationwide.

In 1998 NYCDEP awarded the company a 15-year extended contract for continued heat drying, pelletizing, and beneficial use.

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