An Integrated System of Organic Food Production and Urban Food Waste Recycling Using On-Farm Anaerobic Digestion and Fertigation
A rumen-like machine that digests food wastes is being tested by organic farmers in Florida seeking an alternative to expensive organic fertilizers. Anaerobic bacteria in the digester convert the food waste to carbon dioxide and methane while the nutrients end up in the water, leaving behind a small amount of solid residue that can be land applied or cured to a mature compost. The digester is housed at Possum Hollow Farm, where Joe Durando recycles food waste from a cafeteria. He uses the methane to heat the digester. The nutrient-rich water is used to fertilize crops on four farms.
Objectives are to: 1) Implement an integrated system to recycle nutrients and organic matter through on-farm anaerobic digestion of urban food waste; 2) Evaluate liquid fraction fertigation methods with regard to biofouling; 3) Test the agronomic response to the liquid fraction; 4) Determine the economic feasibility and logistics of this concept from waste collection to nutrient reuse; 5) Educate farmers, waste haulers, environmental regulators, restaurant owners and extension personnel about this concept.
Field trials comparing growth responses to the digester liquid fraction and other organic fertilizers are being conducted at two additional farms and one research farm. The system has been producing a fertilizer with a nitrogen content of approximately 20 pounds nitrogen per 1,000 gallons of digester liquid. Numerous field trials, greenhouse trials and pot trials have been conducted to evaluate the agronomic properties of the fertilizer. The fertilizer has proven effective but can “burn” transplants if over applied. Additional field trials are currently in the field.
An initial irrigation evaluation was completed last Spring. The trial is currently being repeated. The financial analyses are underway and will be completed when the summaries of the field trials are finalized.
A field day was conducted in December. The field day was attended by over 50 individuals including farmers, extension agents, environmental regulatory professionals from the Florida Department of Environmental Protection, engineers, county and city public works professionals, and agricultural professors from the University of Florida. At this field day participants completed pre and post field day questionnaires to evaluate the effectiveness of our field day and the level of farmer interest in this approach to food waste recycling.
The project results have been presented at three conferences. Several hundred people were given a demonstration of the recycling system during an organic farm tour.
The project was featured in the local paper (The Gainesville Sun), the AP wire service, The Wall Street Journal, Biocycle, and Waste News. An episode of Weekend Gardner, a regional Public Television show, was devoted to this project. The program aired this fall.
The remaining work includes evaluation of questionnaire results, completion of the financial analysis, and final harvest and evaluation of the field trials.
Impacts and Contributions/Outcomes
Refine this practice and provide a new source of liquid, organic fertilizer, create a new revenue source for farmers in the form of on-farm tipping fees, and divert a significant proportion of food waste from landfills.
Full Circle Solutions, Inc
Gainesville, FL 32641
Office Phone: 3523739313