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Waste not, save a lot

2014 May 29

By Jennie Saxe

Most people think of wastewater treatment plants as the end of the pipe: it’s where the water from our sinks, showers, toilets, and sewers ends up. They’re viewed as the place we send liquid waste from our homes and businesses. It’s even right there in the name of the place: “waste.”

These pipes deliver digester gas and natural gas to the 8 microturbines which generate power for the treatment plant on-site.

These pipes deliver digester gas and natural gas to the 8 microturbines which generate power for the treatment plant on-site.

Believe me: the York Wastewater Treatment Plant doesn’t waste anything.

I had heard about the sustainable technologies that were being put into place at this treatment plant in York, Pennsylvania, and decided I had to make the trip to see for myself. General Manager Andy Jantzer led me and a small group of my colleagues on a tour of the treatment process from the head of the plant, through some repurposed aeration basins to aid in nutrient removal, past the clarifiers and sand filters, and all the way through to the treated, disinfected outfall to Codorus Creek, a tributary of the Susquehanna River, which eventually drains to the Chesapeake Bay.

So far, things looked pretty standard: primary and secondary treatment, nutrient removal, and disinfection.

Then we got to the second part of the tour. That’s where we learned that there was some serious technology hiding out in a repurposed building on the site. Only the small gas conditioning units outside might have tipped you off that inside there are 8 sophisticated microturbines – which sound much like jet engines – 3 of which are powered by gas from the facility’s anaerobic digesters and 5 of which are natural gas-powered. These allow the facility to generate nearly 7,000kW on site. Without the microturbines, the plant would be wasting methane (a greenhouse gas) from its digesters and purchasing all of its electricity from the grid. EPA’s Net Zero Energy team promotes technologies like this to help water and wastewater treatment plants become more energy efficient, and potentially “net zero” energy consumers.

Ammonia and phosphorus are recovered from the treatment plant’s digester centrate to create this pelletized fertilizer.

Ammonia and phosphorus are recovered from the treatment plant’s digester centrate to create this pelletized fertilizer.

What about the centrate (liquid waste) from the digesters? Most plants recycle that back to the head of the plant, which requires not only more energy for pumping, but also additional chemicals for treatment. Not here! The digester centrate comes to the former sludge incinerator building where a special process removes phosphorus and ammonia and creates a long-lasting, slow-release, pelletized fertilizer that is being used in agriculture, on golf courses, and in other applications.

See what I mean? Nothing is wasted. By recovering resources like phosphorus and energy from wastewater, this treatment plant has joined a new breed of facilities that are extracting beneficial products from what most people consider waste. The dedicated management and staff at the York Wastewater Treatment Plant are making a difference to the communities that they serve. Pursuing sustainable technologies like the ones that York has adopted not only solve problems for today, but for tomorrow, as well.

Dr. Jennie Saxe joined EPA in 2003 and is currently a Water Policy Analyst in the Water Protection Division of EPA Region 3 in Philadelphia. When not in the office, Jennie enjoys spending time tending to a vegetable garden.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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