Day: November 27, 2021

#Aurora and other #Colorado communities push past ‘toilet-to-tap’ reluctancy — The Aurora Sentinel

Prairie Waters schematic via Aurora Water.

From The Associated Press (Brittany Peterson and Sam Metz):

hen Aurora buys one bucket of water, it’s really buying multiple buckets of water. Each drop of water will likely be used over and over again.

The growing city approaching 400,000 residents isn’t interested so much in acquiring single-use water anymore, said Greg Baker, spokesperson for Aurora Water. With its Prairie Waters potable reuse system, Aurora can recapture and reuse about 95% of the city’s water, so having multiple uses written into water rights agreements has become a top priority as water rights are likened to gold in the West — expensive and often hard to come by.

Aurora’s method — sterilizing wastewater from toilets, sinks and factories and then piping it back into homes and businesses as tap water — is catching on across the U.S.

In the Los Angeles area, plans to recycle wastewater for drinking are moving along with little fanfare just two decades after similar efforts in the city sparked such a backlash they had to be abandoned. The practice, which must meet federal drinking water standards, has been adopted in several places around the country, including nearby Orange County…

The shifting attitudes around a concept once dismissively dubbed “toilet to tap” come as dry regions scramble for ways to increase water supplies as their populations boom and climate change intensifies droughts. Other strategies gaining traction include collecting runoff from streams and roads after storms, and stripping seawater of salt and other minerals, a process that’s still relatively rare and expensive.

Though there are still only about two dozen communities in the U.S. using some form of recycled water for drinking, that number is projected to more than double in the next 15 years, according to WateReuse, a group that helps cities adopt such conservation practices.

In most places that do it, the sterilized water is usually mixed back into a lake, river or other natural source before being reused — a step that helps make the idea of drinking treated sewage go down easier for some.

In Aurora, the process is thanks to the Prairie Waters system, which was opened in 2010. It starts south of Weld County along the Platte River, where Aurora holds water rights that can be used “to extinction,” meaning nearly endlessly.

“Essentially, this means that the water residents use for washing, laundry, showering, as well as some of the water from lawn watering, stays in the South Platte River Basin,” Aurora Water explains…

A few dozen wells on the basin pull water through hundreds of feet of sand and gravel to purify the water. Next, the water is pumped into basins of more sand and gravel where filtration continues. Finally, pipes take the water to three different pump stations, which lift the water 1,000 feet over a ridge and back to the Peter D. Binney Purification Facility, near Aurora Reservoir.

From there the water is treated and pumped back out to the city’s thousands of homes and businesses, where the cycle begins all over again…

Currently, the facility treats about 50 million gallons of water each day…

Funding for more wastewater recycling projects is on the way. The bipartisan infrastructure bill passed by Congress has $1 billion for water reuse projects in the West, including the $3.4 billion project in Southern California.

And tucked into the federal budget reconciliation package being debated is $125 million in grants for alternative water sources nationwide that could include reuse technologies.

Plans for expansion of the Aurora Prairie Waters project are ever-evolving and so there isn’t a build out budget attached, Baker said.

New breakthrough in surface-based groundwater measurement — Aarhus University

Credit: CC0 Public Domain

From Aarhus University via Phys.org:

Based on recent breakthroughs in instruments and data modeling, researchers from the Department of Geoscience and the Department of Electrical and Computer Engineering at Aarhus University have collaborated to develop an effective technology to measure groundwater accurately from the surface.

The new technology sends very much cleaner signals than have so far been possible using NMR-based (nuclear magnetic resonance) measurements, and this enables the researchers to make a detailed map of the hydrogeological and geological structure of the subsurface, even in inaccessible areas.

The research has just been published in Geophysical Research Letters.

“Using this new technology, NMR measurements are now a cheap, fast and, above all, very accurate tool for mapping and characterizing groundwater systems. There are problems with groundwater all over the world, and the really good news is that, using this tool, we can better map the groundwater and thereby take better care of it,” says Assistant Professor Denys Grombacher from the Department of Geoscience.

Groundwater is a critical source of freshwater for many billions of people, but climate change, pollution and over-exploitation are making it more difficult to find suitable areas as a groundwater source.

NMR measurements are the only technique available today that enable direct non-invasive measurements of the water content and pore properties of the soil.

NMR is short for Nuclear Magnetic Resonance and in short it means that we influence the hydrogen atoms in water molecules in the subsurface using a man-made magnetic field on the surface.

Hydrogen atoms have a nuclear spin which, in principle, aligns with the magnetic field of the earth, either with or against the field—just like small magnets. A pulse from the artificially created magnetic field changes the spin direction of the hydrogen atoms, and when the pulse fades out, the atoms return to the direction they had before. This realignment emits an electromagnetic field that can be measured.

NMR measurements have a disadvantage, however, in that background noise from the electricity grid, for example, can interfere with the signals, and this can make it exceedingly difficult to measure the very weak electromagnetic field in the realignment.

Roughly speaking, the researchers are looking for a whisper-like voice among the audience at a Motörhead rock concert, and this is where the new technologies in the field of data transmission and modeling come into play.

“We can sort of direct the microphone towards the specific sound source we want to hear, and through a number of identical pulses almost ‘force’ a clear signal from the hydrogen atoms in the soil. The computer can piece together the signal we receive to an accurate reproduction of the original signal using data modeling,” says Associate Professor Jakob Juul Larsen from the Department of Electrical and Computer Engineering.

The research team sees the new technology as a breakthrough in groundwater modeling, and as a quick, stable, reliable and inexpensive alternative for mapping groundwater throughout the world.

The research is being headed by Associate Professor Jakob Juul Larsen from the Department of Electrical and Computer Engineering and support is from a grant from the Independent Research Fund Denmark of DKK 5.9 million.

Top #climate scientists are sceptical that nations will rein in #globalwarming — Nature

From Nature (Jeff Tollefson):

A Nature survey reveals that many authors of the latest IPCC climate-science report are anxious about the future and expect to see catastrophic changes in their lifetimes.

As a leading climate scientist, Paola Arias doesn’t need to look far to see the world changing. Shifting rain patterns threaten water supplies in her home city of Medellín, Colombia, while rising sea levels endanger the country’s coastline. She isn’t confident that international leaders will slow global warming or that her own government can handle the expected fallout, such as mass migrations and civil unrest over rising inequality. With such an uncertain future, she thought hard several years ago about whether to have children.

“My answer was no,” says Arias, a researcher at the University of Antioquia in Medellín, who was one of the 234 scientists who wrote a climate-science report published by the Intergovernmental Panel on Climate Change (IPCC) in August (see go.nature.com/3pjupro). That assessment, which makes clear that the world is running out of time to avoid the most severe impacts of climate change, will figure prominently in climate negotiations over the next two weeks at the COP26 meeting in Glasgow, UK.

Many other leading climate researchers share Arias’s concerns about the future. Nature conducted an anonymous survey of the 233 living IPCC authors last month and received responses from 92 scientists — about 40% of the group. Their answers suggest strong scepticism that governments will markedly slow the pace of global warming, despite political promises made by international leaders as part of the 2015 Paris climate agreement.

Six in ten of the respondents said that they expect the world to warm by at least 3 °C by the end of the century, compared with what conditions were like before the Industrial Revolution. That is far beyond the Paris agreement’s goal to limit warming to 1.5–2 °C.

Source: Nature analysis

Most of the survey’s respondents — 88% — said they think global warming constitutes a ‘crisis’, and nearly as many said they expect to see catastrophic impacts of climate change in their lifetimes. Just under half said that global warming has caused them to reconsider major life decisions, such as where to live and whether to have children. More than 60% said that they experience anxiety, grief or other distress because of concerns over climate change.