Industry Indigestion

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Why is it taking so long for the hundreds of wastewater treatment plants with anaerobic digesters to become net energy producers?


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Reducing energy demand and costs through codigestion, as well as generating revenue from tip fees, enables a facility to improve the balance sheet. So why don’t more treatment plants consider alternative feedstocks for codigestion? One reason is that operators are concerned contaminants could be introduced into their digesters. This means more maintenance to clear the buildup of inert material and clogs in pumps and piping.

But the leaders in codigestion – East Bay Municipal Utility District, Sheboygan, Gloversville Johnstown, and Des Moines, among others – didn’t let maintenance stand in the way. Why not?

Earth Day 2014

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Without plumbers who connect homes and businesses to wastewater treatment plants, there would be no collection or transport of sewage, let alone food waste sent down the drain by disposers. So this Earth Day, I salute the local plumbers, trade associations and code officials that help make our world a safer place.

This past week I authored an article for Plumbing & Hydronic Contractor that mentions how food waste disposers can help the environment. My hope was that plumbers become the missing link between homeowners and resource recovery (aka treatment) plants. After all, it is the plumbers who normally install our toilets, sinks and disposers, and they have the first opportunity to help people understand plumbing products, as well as providing advice on their proper use. Moreover, they are usually considered by homeowners to be the voice of authority and knowledge, inspiring confidence.

Voices of Authority Can Be Very Persuasive!

Voices of Authority Can Be Very Persuasive!

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Code officials are another important group in this industry because without their input, our plumbing would not properly convey sewage in a safe and efficient manner. Later this week, IAPMO (International Association of Plumbing and Mechanical Officials) will convene in Arlington, VA. A panel discussion on the first day entitled “Solutions for Wastewater Problems” will feature InSinkErator’s Casey Furlong, who will discuss why municipalities are now encouraging disposer use as a way to divert organics from landfills to wastewater facilities. Casey will also address misconceptions about disposers including water use and clogging of sewers. Clogs in sewers caused by deposits of calcium soaps are sometimes blamed on disposers (see Clear the FOG). But these blockages occur in sewers everywhere, including places where disposers are non-existent, putting the falsehood to rest.  If you are at the symposium, drop by and see Casey.

New & Improved or Old & Forgotten?

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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.

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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.