Following the Flow of Urban Organics

Following the Flow of Urban Organics by HarvestUpstream Emphasis: Setting the Table for Food Waste Diversion

With society’s strong appetite for addressing the issue of food waste, this article focuses on defining the players in urban organic waste streams, and the drivers that lead to organic waste policies and practices. It assumes that all upstream efforts have been made to follow the EPA’s organic waste hierarchy by reducing organic waste at the source and directing any remaining edible food towards human consumption.

Downstream Technologies: Anaerobic Digestion and Composting

Also relevant is a general understanding of downstream processing technologies. Anaerobic digestion has two primary flavors: “high solids” which accommodates “stackable” feedstocks (think yard trimmings laced with pasta); “low solids” digestion accommodates “pumpable” feedstocks (think slurries of food scraps mixed with fats, oils and grease (FOG), wastewater treatment plants, or manures). Composting, the notable aerob ic cousin of digestion, converts a range of yard trimmings and food scraps into nutrient-rich soil products. Given this context, let’s eat.

Organic Waste Generators

Typical Classifications of Organic Waste GeneratorsFork it over: know thy audience. Wherever there are people, there is organic waste. When thinking about the flow of these wastes, it’s helpful to define the waste generator and characterize the waste composition. Waste generators are typically grouped as follows:

  • Residential: Homes and properties generating yard trimmings and kitchen scraps.
  • Commercial: Grocery stores, restaurants, hotels and other business generating larger volumes of pre- and post-consumer food scraps as well as FOG.
  • Institutional, Commercial, and Industrial (ICI): Concentrated populations such as schools, prisons, campuses, and hospitals; or food-related industries such as food processors, breweries, and dairies, all generating large volumes of organic waste.
  • Other: Multi-family dwellings (housing with four or more units) and events (festivals, conferences) have their own unique characteristics.

Key Characteristics of Organic Waste

Drivers that Shape Food Waste Policies and PracticesNow that you know the audience, it’s time to recognize what they eat. In terms of the composition of wastes generated, not all rinds are created – or collected – equally. The following four drivers shape local policies and practices.

  • Energetic densities of food waste: The same foods that make humans fat help anaerobic bacteria fart and burp. Those farts and burps, known as biogas, can make electricity, pipeline grade natural gas, or vehicle fuel. If you want to optimize biogas generation, be sure to get the donuts to digestion and leave the leafy greens for other technologies.
  • Volumes of food waste: Large volumes of waste generated in a few locations are typically easier to manage than lots of smaller generators. But it’s a balance: you don’t necessarily want to get all of your eggs from one basket.
  • Geographic clusters: Dovetailing with volumes, every hauler knows that a collection route in a same region is ideal because it efficiently shares the fixed collection costs associated with starting up a collection truck and driving it around town.
  • Capture rate versus contamination rate: This can be tricky. The generator and the processor typically do a dance. The processor’s ideal “clean” load of feedstock leads to lower processing costs (removing and disposing of contaminants), increased safety (associated with removing said contaminants from equipment), and optimal product quality (improved biogas yields and fertilizer products). However, the generator might value the ability to include contaminants. This balance is typically struck via acceptance specifications and tip fees.

With this background, you will better understand the organic waste conversations in your community.


Editor and Author’s Note: Content from this post originally appeared in the February 2018 issue of BioEnergy Insight as a contributed article from Harvest.

Mark Weidman joins Harvest’s Board of Directors

Mark_WeidmanWe are pleased to announce that Mark Weidman joined our board of directors.  He brings expertise and a valuable perspective at the intersection of organics and energy generation. Learn more about Harvest’s leadership team.

Harvest Named to Global Cleantech 100 for Sixth Year in a Row!

2015_GlobalCleantech100_eBadge_Top100_071415This week Harvest is abuzz at the Cleantech Forum in San Francisco.  On Monday night, Harvest was named to the 2015 Cleantech 100; This is the sixth year in a row that Harvest Power has been recognized by the Cleantech Group for its contributions to the cleantech community.

We are honored. See the entire list of 100 companies.

Could your child’s uneaten broccoli help provide electricity?

fortuneHow Harvest Power is transforming food waste into a power source.

HIGHLIGHTS: “The site is far enough from the likes of Splash Mountain and the Cinderella Castle to keep the aroma of rotting lettuce and onions from disrupting the magic of the Magic Kingdom,” and “What we eat – or rather don’t eat – is the next frontier of recycling, and Harvest is in a unique position to capitalize.”  Read the full article.

Food Waste Ban Gets Teeth in Metro Vancouver Region

Your Food Isn't Garbage: Time to obey the food waste ban in BCThis July 1, 2015 marks the date when the food waste ban in the Metro Vancouver region of BC has some teeth.  If you live in the lower mainland, be sure to sort those scraps this Canada Day (and beyond)!

For news and support, check out:

For residents looking for easy tips for sorting scraps, check out our “3 Tips for Successful Sorting” video – easy peasy.



Interview with Burp Reynolds: Our Anaerobic Bacteria Mascot

Earlier this year Harvest Power sat down with Burp Reynolds, one of the anaerobic bacteria in our digester tanks in Orlando, Florida. The following is an excerpt of the transcript. Burp-Reynolds-300x225[1]

So Burp, what does a typical day look like for you?

My motto is to go with the flow. I mostly hang out at the 6th trophic level with the more “established” bacteria. We work hard – eating, drinking, farting, burping, and reproducing each and every day, 24 hours a day.

Wow, sounds like a lot of work!

Yes, it is, and we think it’s a very efficient use of our time. We’re not like those other renewable energy sources, like the photovoltaics sunning themselves and then sleeping at night. Or wind turbines that produce electricity that then gets lost in transmission lines on its way back to civilization. That’s just a silly situation. Give me my anaerobic bacteria tank and I’m convinced my team is the best in renewable energy.

Thanks so much for all your hard work. What can we do to keep you happy?

Keep the tank temperature steady, and the pH steady, and the fats, sugars and starches pumping in. If any of those conditions change we become “slack-teria”!

What’s your favorite holiday?

Halloween, for sure. We often get an extra batch of expired candy. I think I can speak for anaerobic bacteria around the world when I say we LOVE sugar even more than almost anything in the world. Valentine’s Day is also pretty good: hello candy hearts. Every day is good, though – I like to say that we’re #1 in the #1 and #2 business.

If you had a car, what would you have on the bumper sticker?

That’s easy: “Support Bacteria: It’s the Only Culture Some People Will Ever Have”

Anything else you want the rest of the world to know?

Tell our buddies in Ontario and British Columbia hello! And keep sending us your organic waste – we’ll use it to create power, and power plants!

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