Can Bokashi Fermentation “Juices” be Turned into Liquid Fertilizers?

According to USEPA and USDA, the United States spends about one billion dollars a year to dispose of food waste. Americans throw away more than 25% of the food they prepare. In 2008, about 13% of the total municipal solid waste generated in the US was food scraps. However, less than 3% of the 32 million tons of food scraps were recovered and recycled. The rest – 31 million tons–was thrown into landfills or incinerators. In New York City alone, exporting organic matter to land-fills costs tax payers $100 million each year, not to mention the adverse environmental impact of toxic greenhouse gases. Landfills produce methane, a greenhouse gas which is 23 times more damaging to the environment than carbon dioxide. Landfills account for 34% of all methane emissions making them the largest human-related source of methane in the United States. Therefore, diverting organic materials from landfills and incinerators would significantly reduce greenhouse gas emissions.

One of the available technologies, which is currently being used in 6 continents and in over 120 countries in the agricultural and environmental fields, may be used for food waste recycling in the United States. EM Technology®, developed and launched in Japan in 1982, uses large populations of beneficial microorganisms and their metabolites to out-compete pathogens, increase the growth of beneficial microbes, as well as control odors and the production of various greenhouse gasses. EM Technology applied to food waste management utilizes the EM•1® Bokashi method. EM•1® is the highly active, microbial-inoculant which when added to any natural carbon product, i.e., sawdust, wheat bran, or dried leaves, creates a beneficial starter for the two-stage fermentation process.

The first stage is the stabilization of organic matter in a closed container such as a 5-gallon bucket with an airtight lid. The food scraps are inoculated with the EM•1® Bokashi and allowed to ferment for two weeks. Once the fermentation has started, the contents of the buckets can be added to a trench or hole in the ground and covered with 4-6 inches of soil where the materials will be easily broken down by other microbes, worms, fungi and insects. This second stage is called “Trench Composting.” Compared to other small-scale windrow composting which can take up to 6 months, the Bokashi method, including both the fermentation and the trench composting processes, can take just 6-10 weeks.

The Bokashi method is less known in the United States, due to a number of factors including the lack of published studies and stringent government regulations on the safety of dealing with food waste. Based on recent experiences around the world, the Bokashi method could dramatically increase the number of households recycling their food waste (see Wasteminz, NZ 2009).

Fermented and properly composted food waste is an ideal fertilizer to improve soil quality in urban environments. Food scraps contain high percentages of organics and nutrients (C, N, P, K) and other micro-elements that are essential for plant growth.

This organic fertilizer has many advantages compared to chemical fertilizers:

1. It’s a beneficial use of a waste material, and helps to solve a difficult problem in urban areas;
2. It does not require energy, land, and resources to manufacture (as chemical fertilizers do);
3. It does not produce environmental pollution during production process. Chemical fertilizer plants are a well known pollution source;
4. The nutrients are released slowly upon application, therefore can meet the nutrient needs of plants over time (i.e., needs fewer applications);
5. Composted food waste contain more complete major and micro-nutrients than chemical fertilizers;
6. It does not lead to nutrient-rich runoff that pollutes bodies of water. Chemical fertilizers are known to have low-use efficiency, and are a major threat to the health of water systems;
7. The Bokashi composts contain effective microbes that can help improve the soil and nutrient-use efficiency. It is a biologically enhanced organic fertilizer.

Vokashi’s summer 2014 Science Project will focus on one of the by-products in the Bokashi fermentation process – the “juice” or leachate produced during the fermentation process. In most food waste composting practices, the leachates are not collected and are generally discarded into nearby water systems. These leachates have very high nutrient contents and can potentially be used as a liquid fertilizer. Leachate from a variety of food scraps will be collected and evaluated for nutrient levels, pH and salt contents. These parameters are important to determine whether the juices are actually suitable as liquid fertilizers, and whether treatments (dilutions, lime addition, etc.) are necessary prior to being used.

Laura Castelnuovo (senior Chemistry Major at University of Chicago) and Melissa Lee (senior Medical Science Program at Midwood High School) will work with Vandra Thorburn (Vokashi Inc), and Dr. Zhongqi (Joshua) Cheng (Brooklyn College) on this Project.

Samples of leachate from the fermented food scraps collected through the Vokashi composting service will be tested. Vokashi will also test samples of leachate from similar community based composting initiatives, including the Lower East Side Ecology Center (aerobic composting) and Global Enviro (a company that manufactures equipment for small scale food waste composting). The analysis will be conducted at the Brooklyn College Environmental Sciences Analytical Center.

Through this Special Summer Science Project, and with the support of the Marine Park Golf Course, we will also compare the impact of various leachates with commercial chemical fertilizers on the growth of grasses and the enrichment of soils. We also hope to show that using the leachates created from fermented food scraps will leave little to no harmful environmental effects.

Laura Castelnuovo is entering her senior year at the University of Chicago, majoring in Chemistry and minor in statistics. This summer she is working with a team at Brooklyn College to turn food waste into useful products. At the conclusion of this endeavor, she plans to continue involvement in innovative research projects in graduate school and beyond.

Melissa Lee is a senior in the Intel science program at Midwood High School. She is one of the five students from Midwood conducting research this summer at the Brooklyn College Environmental Sciences Analytical Center.

Vandra Thorburn is the founder and president of Vokashi, Inc. a unique composting service to help households and small businesses manage their organic waste. Vokashi has just received NYS’s WBE certification.

Many thanks to Professor Joshua Cheng for his guidance and for hosting this Project at Brooklyn College’s Environmental Science Analytical Center (ESAC)