When there is no permitted landfill alternative, on-site food waste digesters are appealing, especially with the wide range of systems offered in the market. In general, digesters use enzymes or other technologies to convert the food waste at an accelerated rate into either an effluent or a soil amendment. Proper disposal of the system end product is essential for integrity to prevail throughout the process.
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| WOP employee happy to show the on-farm digester |
For those in urban settings, the effluent generally flows into the local sewer system. It is important to monitor the effluent composition to ensure unintended consequences do not occur in the sewer system and the downstream waterways.
Elemental Impact Partner Global Enviro's on-site technology produces a quality soil amendment that may be direct-applied to soil or sent to a composting operation. The Global Enviro system comes in various sizes designed to service operations ranging from single-standing restaurants to large event venues. In the New York City area, Global Enviro has three successfully installed systems in operation: The Shops @ Riverside, The Hotel Intercontinental and Les Halles.
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| Food waste grinder in Les Halles kitchen |
For details, see the tour pictorial recap in the Ei FB album, 11-05-12 Global Enviro System Tour. The Global Enviro NJ Video is an overview of operations at The Shops @ Riverside. In Norway, the Global Enviro system was installed several years ago at the Oslo Opera House - the Oslo video shows how the system works in a large, multi-kitchen facility.
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| Global Enviro system end product |
Until recently, most A.D. systems in the market place were configured for a municipality or possibly a generator with tremendous food waste output and high electricity usage. Biosolid A.D. systems are common in city water treatment facilities and communities are starting to explore the option of adding food waste to the system's recipe mix.
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| OSM BlueStreams PAD |
According to the U.S. Composting Council, there are less than 300 permitted compost facilities in the nation that accept food waste. In regions like the Northeast where tipping fees are in the $100 per ton plus range, the investment required to install food waste systems like Global Enviro's make good business sense, especially for higher volume facilities.
Advancing Technology continues to expand horizons on the options available for food waste, . As the tides turn, food waste may soon be supported by a commodity market where generators are PAID for the material. A wild concept? Cooking oil from foodservice fryers took a similar journey a few years back - time will reveal HOW food waste becomes too valuable for a landfill destination.
A few years ago I watched a news report about recycled food waste here around San Francisco, CA.
ReplyDeleteThe Grape Vineyards here in Northern California were there #1 customer of the finished product.
It is such a rich soil amendment for the Grape Vines that they refer to it as Black Gold !
The facility that did the recycling of the food waste consisted of many acres of land, where they did a 3 or 4 step process to get to the finished product. They used shredded recycled news paper and cardboard as one of the additives, turning it every so often to get the compost effect going. I wonder if the facility I am referring to is still Operating? Thank you for writing this article !
Darin De Luca
Forum Administrator for
Sanitation Workers Alliance Network
Hello Darin! San Francisco has an active food waste recycling and composting infrastructure in-place so the facility you mention is most likely operating or replaced by another one. Compost is excellent food for the soil's microbial community and is critical to return soil to it's natural, balanced, healthy state. Thank you for liking the LinkedIN discussion and taking the time to write a comment on the post - much appreciated. Holly
ReplyDeleteVery interesting article. Like all waste streams, I am sure that a porfolio of solutions will be required to fully address the issue. I am intrigued by the digester systems that discharge to municipal waste water treatment systems. Is the primary environmental benefit that ultimately the WWT system will screen and comopost solid materials (thereby eliminating the formation of methane)? Or is the objective to couple with WWT systems that capture biogas? You mention the need to use caution about unintended consequences, but I guess I don't fully comprehend how this is better than composting or if it simply a "better" than landfilling solution when composting facilities don't exist.
ReplyDeleteIn my experience, municipalities are continuously working hard to actually reduce the amount organics in the sewer system.
ReplyDeleteA potential issue of discharging the effluent from a digester into the sewer system, particularly for restaurants and food processing facilities, is that in most municipalities these facilities are regulated on the amount of organic material they can discharge, as measured BOD (biological oxygen demand).
Municipal waste treatment plants already struggle with high BOD and the additional oxygen/air required in order to facilitate the breakdown of organics prior to discharge into the local river/water table. Additional organic loading only makes this issue worse, which is why BOD is considered a regulated pollutant, and why food facilities are typically issued a commercial or industrial waste water "pre-treament" permit which limits BOD.
I am not familiar with the typical BOD numbers from the effluent of these small-scale digesters, but I suspect this may be an issue where BOD is regulated, particularly when/if the digester system is not carefully monitored for performance.
Anyone out there know how these digesters affect BOD loading?
Thanks Rob! I appreciate your concise clear explanation of the concerns surrounding on-site digester effluent discharge. As with Rob, I appreciate comments on how these digesters affect BOD loading - thanks! Holly
ReplyDeleteI thought that the idea of food waste becoming in effect an asset, meaning that food waste producers start being paid by the biogas digestion plant operators, for the material, was hard to swallow.
ReplyDeleteThen you immediately reminded me of the fact that cooking oil from food service fryers is a close parallel, so, Yes! It obviously could happen and then the available tonnages would rise tremendously I bet! That would be a win-win for the biogas industry assuming that the price was quite low, as the producers would then be willing to segregate the food waste, presumably to be able to sell it.
Thanks for the interesting blog post.
I came on this blog searching for answer on how to manage kitchen waste and recycled it for food animal, especially for pigs. Thanks for info.
ReplyDeleteSammy, thanks for reading the article and taking the time to comment. Sorry for my delay in responding.
DeleteRemember to be very careful about feeding "human food" to pigs - if there are any pork products in the food, then you are feeding the pigs their own DNA. Also, it is important to feed animals what their digestive track was designed in ingest. The e coli outbreak was a result of feeding grain to cows, who are meant to eat grass, and changing the acidic base of their stomachs. ... and think about those hot peppers & other seasonings going into a pig's stomach, Yikes!
For Elemental Impact, the best & highest use for valuable food waste is compost where it serves as a nutrient-rich food for the soil's microbial community If there is not a commercial option in your area or you do not have space at your home, then there are most likely community gardens with small composting operations where you may take your food in accordance with their guidelines.
Note I addressed food waste here from the personal level, not the from the commercial foodservice operator viewpoint.