ROYAL OAK, MI - This may be a dung deal you can't refuse. The Detroit Zoo is giving free buckets of poop at an upcoming event.

The first 1,000 people at the zoo's sixth annual Greenfest will receive a token good for one free 5-gallon bucket of Detroit Zoo poo, an herbivore compost processed in the zoo's anaerobic digester and produced in partnership with Detroit Dirt.

Greenfest is on Saturday, April 14, 2018. As part of the free Earth Day celebration (with zoo admission), guests will learn about the zoo's anaerobic digester, which is a first in Michigan and the only zoo-based system of its kind in the country.

Each year the anaerobic digester converts 500 tons of animal manure and other organic waste into methane-rich gas to help power the Zoo's animal hospital, leaving a nutrient-rich fertilizer as a byproduct.

The tour will also allow the zoo to show visitors what else it is doing for the environment, including the discontinued sale of bottled water on Detroit Zoo grounds and using permeable pavement in visitor pathways and a parking lot. Guests will also learn about the zoo's cricket-breeding program, rain gardens and solar energy system, among other green efforts.

Detroit Dirt will also be at the event to talk to guests about composting. The Oakland County Board of Commissioners will be there to provide information on conservation programs and green initiatives in Oakland County.