New & Improved or Old & Forgotten?

Posted on

A syndicated and widely circulated story last week on NPR reported how New York’s Newtown Creek Wastewater Treatment Plant is now processing food scraps to create renewable energy. The full story provides a glimpse into the growing trend of co-digesting food scraps with sewage sludge to boost biogas production with anaerobic digestion.

Michael Utech/Vetta/Getty Images

 

Wastewater treatment plants protect human health and the environment by efficiently processing raw sewage. Anaerobic digestion is simply one part of the treatment system used to reduce harmful pathogens and the overall volume of solids left at the end of the process that must be managed. In New York, some biosolids are beneficially used (land applied as fertilizer), and some are landfilled as far away as Pennsylvania and Virginia.

In reading some of the comments, I am reminded how sewage treatment is out of sight and out of mind, and largely taken for granted by the public.

Newtown Creek is simply utilizing existing infrastructure to maximize its potential. What is unique is that the system is relying on separate collection of the food scraps from commercial establishments, which then must be processed to remove contaminants and be converted into pumpable slurry for injection into the digesters.

InSinkErator’s new Grind2Energy™ system prepares pumpable, contaminant-free slurry ready for anaerobic digesters, completely eliminating the need for pre-processing at a wastewater treatment plant. David Krems, Business Development Director for Grind2Energy™ said, “Food waste to energy via anaerobic digestion is in the nascent stage in the U.S. – however new technologies and businesses such as Grind2Energy™ offer food waste generators an alternative to divert their food scraps from landfills and create renewable energy within local communities!”

Missing in the story is that food waste disposers already divert residential food scraps from homes in New York directly to Newtown Creek. A prohibition on residential disposers was lifted in 1997.

Mean Sewers

Posted on

Just what makes a sewer nice?

Does it offer to buy you coffee? Say please and thank you?

At the recent New York Water Environment Association’s 86th Annual Conference named, “Utilities of the 21st Century: Going from Net Zero to Net Positive” ‒ the hot topic was maximizing energy production utilizing additional feedstocks for anaerobic digestion, especially from commercial and industrial sources.  A panel discussion by five wastewater people spent a lot of time on the addition of food waste to digesters from source-separated organics processed at the treatment plants. That’s a lot of work. Nobody on the panel mentioned food waste disposers.  One of disposers’ chief benefits is that the waste generator does all of that work for you.

When prompted by a question from the audience about using “in-sink grinders” a panelist stated “…They only make sense for other cities with nice sewers.”

I guess that would make his city’s sewers mean. Of course not– the panelist was referring to his home city’s combined sewers.  With that type of system, there is the potential of a wet weather combined sewer overflow, when food waste may end up in local waterways. The greater environmental health hazard from combined sewer overflows are the pathogens in raw sewage, not microscopic ground food waste. (I have noted numerous times in this blog that despite some misconceptions, “chunks” of food are not disbursed to sewers by disposers.)

Furthermore, according to Metcalf & Eddy’s 5th Edition of Wastewater Engineering, ground food waste makes up only about 20% of the suspended solids and biochemical oxygen demand in sewage.

Communities with combined sewers should be eliminating them, and are required by the EPA to do so as part of their Long Term Control Plans.  Hopefully some day we will see the demise of the mean sewer.  In the meantime, food waste is, and will continue to be, a small fraction of the total composition of wastewater.

Football’s super amounts of food waste

Posted on

It’s “Super Bowl” time of year, and the national news is full of all your critical need-to-know’s such as psychic zoo animals predicting the game’s outcome.  I’m about as clairvoyant as those creatures are – but there’s one thing about the game I could put money on:  at the end of it, there will be lots of food waste to discard.  That will be as true for households across America as it will be for MetLife Stadium at the Meadowlands, which is expected to produce several tons of food waste.  Take a guess how many.

 

It should be roughly 7-8 tons.  All due to one short game…think about it.  Does that not make you wonder how much food waste the game of football is indirectly responsible for generating, from August to February? And what do stadiums do with all that food waste?

 

Used to be, it was all sent to the landfill though lately, more stadiums tried composting. But now there is another option, as undertaken by the Cleveland Browns at the end of the season just concluded.  FirstEnergy field now has an organics recycling system that grinds food scraps into slurry and discharges it to a holding tank, which is pumped and hauled to an anaerobic digester for conversion into renewable energy and soil amendment.  The Browns estimate they will produce enough methane to heat 32 homes for an entire month. Think of the energy that could be produced if all college and pro football stadiums used an organics recycling system. (I could come up with the calculation myself, but I need to get ready for the game now, which means a trip to the store for nachos ingredients, among other things.)

 

Full disclosure:  the system installed at the Browns’ stadium is called Grind2Energy™ and it’s from InSinkErator, my employer. So I am not going out on a limb with this football-related prediction: by Super Bowl Sunday next year, there will be more football stadiums and sports arenas of all kinds converting food scraps into renewable energy.  And to those who follow this blog and care about food scrap diversion — that will be something to cheer.