New York City's Wastewater Treatment System

How Biosolids Are Used

Land Application
Biosolids are spread on land to return nutrients to the soil. Biosolids are spread less than a quarter inch thick and are sometimes plowed into the soil. Biosolids have been directly applied to corn crops, wheat and grazing land in Colorado and Virginia.

Composting
Biosolids are mixed with a bulking agent (for example — wood chips) which allows oxygen to mix with the biosolids more easily. The biosolids decompose, creating compost. This compost is similar to peat moss and is used as mulch or soil conditioner at golf courses, nurseries, home gardens, lawns, etc. New York City's biosolids are being composted at a facility in Pennsylvania.

Alkaline Treatment
Biosolids are mixed with a highly alkaline material, such as lime or Portland cement. This process results in a product, which resembles soil and is used as an agricultural liming agent. New York City's biolosids are alkaline stabilized at a facility in New Jersey.

All of these processes destroy disease-causing organisms and reduce moisture content, resulting in products that are easy to handle and have characteristics similar to many commercial agricultural products.

Heat Drying
Biosolids are heated to a very high temperature to remove moisture and kill pathogens.What remains are fertilizer pellets. New York City's biosolids are made into pellets at a facility in the Bronx. These pellets are sold across the country, many of them for use in citrus groves in Florida.

New York City is strongly committed to the continued beneficial use of its biosolids through environmentally safe land application programs.