A coed boarding and day school for grades 4-9

Where most classrooms end, ours begin.

Composting

NCS's New Rotary Drum Composter



Our novel, commercial composter has received interest from people/organizations in three different countries and eight different US states. This interest has allowed us to secure another grant to build and "gift" three more composters to two schools and one nature center.

As a result of this grant we are in the process of redesigning our composter to make it easier and less expensive to construct. Until that new design is done, and loaded back on this website page, please feel free to reach out to our Director of Facilities and Sustainability, John Culpepper, for a mock-up of that new design. John can be reached at: jculpepper@northcountryschool.org.

In-Vessel Composter Highlights



  • Units of this size on the open market range from $40,000-$140,000
  • We secured a New York State economic development grant to design a system that is much more affordable and can be containerized within a 40-foot shipping container
  • Funding was funneled through The New York Energy Research and Development Authority (NYSERDA)
  • Our hope is that this design will allow many more organizations like ours to divert food scraps from landfills and create a high value soil amendment
  • Our first year of operation we composted approximately 30,000 pounds of food scraps. (It appears that the unit could easily handle 40,000 pounds/year.)
  • All of our easily composted materials go to our pigs. All other food waste: meat scraps; egg shells; rinds; etc. go to the composter
  • Our in-vessel composter is designed with "off the shelf" components
  • The design that we came up with is four feet in diameter and 20 feet long
  • The drum itself is a polyethylene highway culvert
  • The drum is on an angle of 2.5 inches over 20 feet
  • We used a 3-phase 1.5 hp motor with a reduction gear making a rotation of about 1 rotation in 45 seconds
  • A single phase, or possibly a DC motor tied to a PV solar panel could work as long as the reduction gear is matched appropriately to the motor and drum weight
  • The materials cost is approximately $15,000 and a competent machine shop can easily produce the frame
  • The design will soon be posted on our website and available to the world.

Sustainability/Composting



  • Our hope is that others will use this design, improve upon it and find ways to reduce the material cost even more. We know that can be done
  • Retention time depends on the amount of material added
  • During our school program we are feeding approximately 150 people, three times per day and generating approximately 65 pounds of food scraps per day
  • Retention time for the food scraps/carbon bulking material is approximately 28 days
  • During our seven-week camp program our numbers double, to about 125 pounds of food scraps per day resulting in a retention time of approximately 25 days
  • We can and do easily accommodate up to 300 pounds per day on occasion
  • Design temperature is 130 °F - We are reaching temperatures of 110-150 °F continuously
  • Our end product after 30-40 days is stable, smells like compost that one would purchase at a hardware store, does not attract dogs, vermin or flies
  • While the material coming out of the drum can be used as top dressing, it still needs several weeks of additional time (in a static pile) in order to produce the most useful product, with more stabilized carbon compounds
  • We are currently using wood pellets (the same type of pellet used in pellet stoves) for our carbon bulking material. This past year we have also used wood chips and wood shavings with success.
  • The recipe of food scraps to carbon bulking agent depends on the carbon type and the type of food waste
  • Our composter is designed to stay full all of the time- the weight of food scraps and carbon bulking material when full is about 3,300 pounds
  • We are beginning to experiment with composting human urine, with the goal of demonstrating that this design is capable of handling all organics coming out of non-industrialized towns and villages all over the developing world
  • We are now collecting temperature data through a data logger, capturing those data every five minutes as the data logger travels down the drum
  • We have demonstrable data suggesting that this design has the ability to meet the US EPA guidelines for effectively composting biosolids

Since our composter became operational we have been contacted by organizations and individuals all over the country asking how they can replicate our success with food scrap composting

For more information contact:

John Culpepper, Director of Facilities and Sustainability, at 518.523.9329, or by email at: jculpepper@northcountryschool.org