The Bugs Are in the Tanks

Curbside Recycling of Food Scraps and San Diego County’s First Anaerobic Digester


BY LEORAH GAVIDOR


EDCO's new anaerobic digester in Escondido is one of about 100 in the world. Image courtesy of Jim Ambroso


San Diego has one of the largest green waste recycling programs in the country. But the current set-up does not accommodate curbside recycling of food waste for homes and businesses. EDCO, trash and recycling service provider for many cities throughout San Diego County, is working to change that. The final stages of construction are underway for the county’s first anaerobic digestion facility, in Escondido, which will collect organic waste from around the county and convert it to renewable natural gas (RNG) and fertilizer. Soon EDCO residential customers (and later businesses) will be able to put food scraps in their green bins along with regular yard waste.


EDCO’s new anaerobic digester is the first of its kind here in San Diego, built on the site of a former Titleist factory that produced golf balls. The process of anaerobic digestion breaks down organic material without the presence of oxygen, relying on bacteria to get the job done. That means things that don’t usually go in the compost pile—like dairy, meat, and bones—can go in the digester.


In early 2021 EDCO will distribute kitchen caddies for their customers and roll out an education campaign, in conjunction with CalRecycle, on how to collect food scraps at home for effective recycling. Single family homes that already have green bins can start commingling food scraps in mid-2021. EDCO plans to work with businesses, apartment dwellers, and multi-family units that don’t currently have green bins to come up with a way to collect their organic waste.


“The bugs are already in the tanks,” said EDCO General Manager Jim Ambroso. “A few months of conditioning and the tanks will be ready to go.”


Decomposition of organic waste in landfills is the third-largest source of human-related methane emissions in the United States. Methane is 28-36 times more potent than CO2 as a greenhouse gas. As of 2016 organic waste made up 39% of material disposed of in San Diego landfills. That adds up to 1.7 million tons of compostables. California has passed several bills to regulate organic waste in landfills and mitigate methane emissions. The new digester helps San Diego County comply with SB 1383, AB 1594 and AB 1826. The closed system does produce biogas, but it is collected and used instead of emitted into the atmosphere as a greenhouse gas.


“EDCO’s AD facility will divert over 93,000 tons per year of organic waste from landfills, reducing greenhouse gas emissions by 33,480 MTCO2e per year,” said Ambroso. When the new bio-digester comes online and becomes fully operational, it will produce fuel to power EDCO’s fleet of net zero trucks. “It will be a carbon neutral, or even carbon negative, solution,” said Ambroso. Fuel from the digester produces much less nitrous oxide when burned than regular gasoline. “It will be like taking 7,000 cars off the street.”


As the county’s need to recycle organic waste increases with progressively stricter mandates from the state that require 75% diversion from landfills by 2025, EDCO will increase capacity. Two of the four tanks at the Escondido digester will operate in the initial phase and the other two will come online as necessary and feasible. Ambroso said plans are in the early stages for a second digester south of downtown San Diego.


But organic waste recycling is “not a substitute for reducing food waste overall,” said Ian Monahan of I Love A Clean San Diego. The organization supports backyard composting, meal planning, donation, and other local efforts to reduce the amount of food we throw away.


The Solana Center for Environmental Innovation, founded as Solana Recyclers in 1983, pioneered the first curbside recycling program in San Diego. The non-profit currently focuses on zero waste, composting, and water conservation. Its community composting program, Food Cycle, accepts buckets of food scraps from residential and commercial members.


While the new anaerobic digester does represent major progress towards California’s mandated organic waste reduction, EDCO and its partner EDI do not serve all of San Diego. Parts of the city do not have residential curbside green yard waste collection. Many businesses, which are legally required to divert organic waste, haul their own food scraps to collection sites. And, quite frankly, we waste way too much. Find some ideas on how to mitigate food waste here.


“How do we make it easy for people?” said Ambroso of organic waste recycling. “How do we change habits so people will think about separating food waste from trash?” His own wife was reluctant to try the new kitchen caddy in their home. Ambroso assured her that it would not attract bugs and it would be easy to use—and now she’s on board. If rodents and bugs are a concern, “wrap the scrap” in a food waste burrito using a paper towel—or even newspaper—and put it in the freezer until trash day. The soiled paper can go in the green bin, too.


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