More Clean-Water Plants Fulfill Their Potential As Resource Recovery Centers

The more you look around, the more you see clean-water plants looking to fulfill their whole potential as centers for water reclamation and resource recovery.

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Not long ago, a couple of TPO colleagues and I toured the clean-water plant in Stevens Point, Wis. What we saw there was impressive (you read about it in the September issue), and yet in various ways it was not at all unusual.

The team at Stevens Point is going all out to save energy, produce energy (with combined heat and power), reuse effluent and, perhaps in the not-too-distant future, harvest nutrients from wastewater to create a marketable fertilizer, something fully separate from the Class B biosolids the plant already supplies to farmers.

And speaking of biosolids, the plant feeds its anaerobic digesters with wastes from local brewers, food processors and dairies, increasing the volume of biosolids and of methane gas, which fuels the generator that supplies nearly all the plant’s energy. A plan is in the works to pipe waste from a fast-growing brewery directly to one of the digesters. That will give gas production another boost and enable the plant to land solidly in energy-positive territory.

It’s an interesting story about a great plant team, but the most interesting thing is how mainstream it all now appears. Look around the industry today and you see fewer and fewer “sewage plants” and more and more of what the Water Environment Federation calls “water resource recovery facilities.”

Huge possibilities

Using the resources inherent in wastewater makes incredible sense. Take biogas for just one example. The 2014 Biogas Market Snapshot from XPRT Media says the United States contains the world’s greatest untapped potential to use that fuel.

The report says that although more than 1,500 of the nation’s clean-water plants have anaerobic digesters, only about 250 use the biogas; the other 1,250 flare it. All told, between clean-water plants, farms and various sources of urban organic waste, the report says the U.S. could produce nearly 70 million megawatt-hours of renewable electricity per year from biogas.

By my dinner-napkin calculation, that’s the amount produced by eight large coal-fired power plants. That alone won’t resolve all the country’s energy challenges, but in a time of concern over climate change, a clean and renewable fuel like biogas has to be looked at seriously.

More in the stream

And biogas is only one part of the picture. There’s all kinds of progress toward better-quality biosolids — not the Class B kind used only for animal feed crops and trees and mine reclamation, but the Class A material people can use right on their lawns and gardens. One increasingly attractive option is solar biosolids drying, a highly sustainable practice.

That’s to say nothing about the nutrients — nitrogen and phosphorus — carried in the wastewater. Processes now available can capture those nutrients in the form of a granular, slow-release, marketable fertilizer. The purveyor of one such process says it can remove up to 90 percent of the phosphorus and 40 percent of the ammonia from centrate or filtrate from biosolids dewatering.

Then of course comes the resource that is the plants’ reason for being: the water. As drought paralyzes California and other states, we see more communities studying the full reclamation of wastewater, not just for landscape irrigation but for drinking or, at the minimum, recharging groundwater aquifers.

It’s about the people

And who are the people doing all this? They’re the folks often perceived by the public as the guys and gals in dirty jeans at that smelly place on the dead-end road outside town. In other words, clean-water operators. The more progress they make toward energy production and resource recovery, the more the public will see them for who they really are.

That is, men and women often with two-year associate, four-year college or advanced degrees. People who, whatever their formal education, have become experts in microbiology, chemistry, mechanics and other disciplines, while effectively deploying, operating and maintaining a host of sophisticated machines and systems.

They’re dedicated not just to meeting their discharge permits but to getting the absolute most from their facilities, in ways that safeguard the environment and treat ratepayers fairly. Thanks to them, and their initiative, we’re on the way toward a time when fully optimized, truly outstanding facilities are the rule, not the exception.



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