If the word “compost” conjures up images of decaying food, bugs and the smell of rotting vegetables, keep reading. I used to be the same way, but I have come to embrace my green bin because not only is compost cool, it’s big business.
A couple weeks ago I got the chance to visit the Jepson Prairie Organics facility in Vacaville, CA. Jepson is a wholly owned subsidiary of Norcal Waste Systems, the company that contracts with the city of San Francisco and many other Bay Area communities to manage waste, recycling and compost pick-up programs. The facility processes all the food and green waste collected in San Francisco’s green bins. On the day I visited the processing facility, it was over 100 degrees and the air smelled faintly of peat.
Jepson’s process is enormously efficient and makes great use of a product that would normally go into a landfill where it would sit offgassing methane. The facility processes green waste (i.e. lawn clippings and other yard waste) and food waste from San Francisco. When the bins arrive, all the food waste is fed through an enormous tumbler (picture a 2 story bingo ball selector) covered with 4-inch holes. The purpose of this contraption is to de-contaminate all the non-compostables that end up in the green bins like plastic bags and soda cans. The legitimate food waste falls through the holes and the bigger chunked items (which are more likely to be garbage) are tipped onto a treadmill that runs through a 2-story tented structure sitting over two big dumpsters.
Hardworking souls stand over the treadmill and sort the garbage out by hand, dropping the non-compostables through holes in the ground into the dumpsters. Each of two full sized dumpsters are filled up every day with garbage. Our tour guide mentioned that contamination was by far the biggest challenge at the facility.
The now de-contaminated chunks of food waste continue on the treadmill to a giant mixer that cuts them up into smaller chunks, which are then fed back through the bingo ball roller to ensure that the food waste is fully decontaminated and that the size of the items is relatively similar, which makes the compost form evenly.
The food waste and the green waste are then layered together in a proprietary combination to create the proper moisture mix for optimal compost. The compost is stored for 1-3 months under big black tarps, about 6 feet wide, 4 feet high and 40 feet long. The black tarps draw in the heat, which is in ample quantity in Vacaville. Bacteria in the food/green waste go crazy eating and breeding and processing that waste into black gold. Jepson creates custom blends of green and food waste that are specific to different applications like grape growing, vegetable farming and landscaping. By customizing their blends, Jepson can capitalize on an additional income stream from their product.
In addition to creating something useful out of what would otherwise be called smelly garbage, Jepson captures methane from the black tented composters, which they use to power the facility. Right now they have more methane than they need and they would happily sell the excess to the local utility, but the grid has not been updated in 50 years, and can’t yet support the increased burst of power, so not all the methane gets used. Jepson would also like to begin processing some of the food waste at the point of origin (in this case, San Francisco) because it’s very heavy with water content, and expensive to ship.
Do you compost? If your city has a green bin program, but your landlord or office building hasn’t provided a bin, your local waste processing facility often has recourses for showcasing the benefits of composting, and the ease of use of the green bins. Share your composting challenges and successes in the comments!