The Wastewater Technology Leap: What's In Store for Us Now?

Innovation no longer means incremental advances. It means whole new ways of doing things. It’s happening in the water and wastewater sectors.

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In 1995, Nicholas Negroponte’s book, Being Digital, explored what back then was the emerging power of technology.

In many ways it was prophetic. My analog brain fixated on the idea in the book that the world was no longer driven by, or especially interested in, incremental changes. In other words, progress wasn’t about a car engine 2 percent more efficient, or a computer processor 5 percent faster.

No, in the digital world, progress was about revolutionary change — entirely new ways to do things. And look at what we have today versus 20 years ago. Instead of postal service trucks we talk of drones delivering packages. Instead of hailing a cab, we can hire a ride with a smartphone app. Instead of going to a video store, we stream movies online. We can use a website to turn our homes into bed and breakfast inns. Driverless cars seem to be on the horizon.

What about water?

Are revolutionary things happening in the water and wastewater sector? Yes, they are. For one thing, on the wastewater side, the entire mindset is changing. What we have long called wastewater treatment plants are now becoming water resource recovery facilities. The Water Environment Federation officially endorses that terminology.

So it’s no longer simply about getting the water clean. It’s about taking in wastewater and extracting the resources it contains: clean water, nutrients (mainly as biosolids) and energy (biogas). At the same time, there are big advances in the processes involved.

There’s no digital magic here. It still takes gravity to settle waste material out of the water. It still takes microorganisms, properly fed and aerated, to consume the suspended organic matter. It still takes bacteria to digest and stabilize the solids stream. None of that will change. But consider a few of the big innovations announced in recent months.

Air efficiency

Traditionally, the secondary treatment (aeration) process is about more energy-efficient blowers and finer air bubbles to increase the surface area for oxygen exchange. But of course, whatever their size, those bubbles ultimately rise to the surface and escape. So up to 70 percent of the energy to pump air into the aeration basins essentially goes to waste.

Enter ZeeLung technology from GE Water & Process Technologies. Instead of relying on bubbles to carry oxygen to microorganisms suspended in water, this technology transfers oxygen by diffusion through a membrane to a biofilm that grows on the outside membrane surface. Air is pushed through bundles of membrane fibers and oxygen diffuses from the inside of the membrane through to the biofilm on the outside. Thus the bacteria are in direct contact with the medium that provides the oxygen they need.

GE says the process uses one-fourth the energy required for fine-bubble aeration, which typically accounts for about 60 percent of a treatment facility’s electricity usage. The technology can be retrofitted to existing basins.

The solids side

There have been leaps forward in biosolids digestion, too. The PONDUS thermochemical hydrolysis process, distributed in North America by CNP and deployed in the city of Kenosha, Wisconsin, in partnership with Centrisys, claims a 25 to 35 percent increase in biogas production versus conventional anaerobic digestion.

The process uses heat and the addition of sodium hydroxide to break down the cell walls of organisms in waste activated sludge. This, according to the companies, makes the material more digestible. The technology also reduces polymer costs, reduces solids handling costs (because final solids volume is lower), and increases digester capacity.

On the way

There’s even a big improvement in how wastewater is delivered to the treatment plant, and it’s highlighted in the Technology Deep Dive article in this issue of TPO. Called the DIP System (for direct inline pumping), it replaces the traditional lift station configuration of a wet well with submersible pumps controlled by float mechanisms.

Instead, wastewater is piped directly into a variable-speed grinder pump that chews up trash and sends the flow on its way. The pumps run continuously, automatically adjusting their speed to fit the incoming flow volume. The article describes the advantages.

These technologies aren’t solely the result of the digital revolution, although digital technology surely helped in their development and helps enable their control when installed. The point is that if you operate a treatment plant (or water resource recovery facility), it doesn’t have to be business as usual. These and other technologies are available to be explored as ways to make big strides toward better and more cost-effective operations.


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