Hexbyte Glen Cove Nutrient-rich human waste poised to sustain agriculture, improve economies thumbnail

Hexbyte Glen Cove Nutrient-rich human waste poised to sustain agriculture, improve economies

Hexbyte Glen Cove

A new study from the University of Illinois Urbana-Champaign helps define the global relationship between sustainable agriculture and sanitation technology. Credit: L. Brian Stauffer

The future connection between human waste, sanitation technology and sustainable agriculture is becoming more evident. According to research directed by University of Illinois Urbana-Champaign civil and environmental engineering professor Jeremy Guest, countries could be moving closer to using human waste as fertilizer, closing the loop to more circular, sustainable economies.

A new study characterizes the spatial distribution of human urine-derived nutrients—nitrogen, phosphorus and potassium—and agricultural fertilizer demand to define supply-demand location typologies, their prevalence across the globe and the implications for resource recovery. The findings are published in the journal Environmental Science and Technology.

“The total amount of nitrogen, phosphorus and potassium largely remains constant in our bodies, once we stop growing,” said Guest, who also serves as the acting associate director for research at the Institute for Sustainability, Energy, and Environment at the U. of I. “Whatever comes in through food and drink must come out in our urine, feces and sweat. Knowing that, we can estimate how much of each of these nutrients is in a population’s bodily waste if we know their diet.”

Previous studies by Guest and others have assessed the potential for recovering the nutrients from human waste across the globe and identified locations with a surplus of human waste-derived nutrients relative to the for agricultural fertilizers.

“The new study is the first to describe human waste-derived nutrient supply-demand location relationships using a single mathematical equation,” Guest said. “The quality of sanitation infrastructure varies greatly across the globe, as do people’s diets and the availability of land suitable for agriculture. Having the means to characterize and quantitatively compare a location’s nutrient-recovery potential can go a long way to better inform decision-makers when it comes to future sanitation and agriculture policy.”

The team performed extensive numerical and geographic analyses of dietary, population, sanitation and agricultural data from 107 countries to accomplish this quantitative characterization at the global scale. The investigation revealed three distinct supply-demand typologies: countries with a co-located supply-demand; countries with a dislocated supply-demand; and countries with diverse supply-demand proximities.

The United States and Australia, for example, fall under the dislocated supply-demand typology. They have intensive agriculture in areas far from large cities, thus the human waste-derived nutrient supply is far away from where it is needed, Guest said. Even with advanced sanitation infrastructure in place, this means that nutrients would need to be transported over large distances, either as heavy fluids or converted into concentrated crystalline products. Economically speaking, Guest said, it would make sense to work with a concentrated product to implement a human waste-derived fertilizer in these countries.

The study reports that in countries with co-located supply-demand typologies like India, Nigeria and Uganda, human populations are more substantively in the proximity of agricultural areas, making local reuse possible. In many communities with co-located supply-demand, however, there is a need for improved sanitation infrastructure. Guest said implementing a human waste-derived fertilizer program could be highly beneficial to sanitation and agriculture in these places.

Countries like Brazil, Mexico, China and Russia exhibit a continuum of co-location to dislocation of nutrient supply and demand. The study reports that policymakers would need to approach -derived nutrient use with more regionalized strategies and a range of local reuse and transport approaches. “Higher income countries in this group may have the infrastructure and economic support for various technologies, but those with limited financial resources would require prioritization of resource-recovery technology in some areas,” Guest said.

The team was surprised to find the typologies corresponded closely to the United Nations Human Development Index.

“Higher HDI-scoring countries like the U.S., Western Europe and Australia tend to fall in the dislocated supply-demand typology and lower HDI-scoring countries tend to fit the co-located supply-demand typology. Of course, there are exceptions, but we did not expect to find such a strong correlation,” Guest said.

The team hopes this research will help clarify the salient economic, sanitation and agricultural characteristics of countries across the globe so that can prioritize investment, policies and technologies that will advance goals for a circular economy and the provision of to all, Guest said.

More information:
Desarae Echevarria et al, Defining Nutrient Colocation Typologies for Human-Derived Supply and Crop Demand To Advance Resource Recovery, Environmental Science & Technology (2021). DOI: 10.1021/acs.est.1c01389

Nutrient-rich human waste poised to sustain agriculture, improve economies (2021, August 19)

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Hexbyte Glen Cove Team improves polar direct drive fusion neutron sources for use in laser experiments thumbnail

Hexbyte Glen Cove Team improves polar direct drive fusion neutron sources for use in laser experiments

Hexbyte Glen Cove

This is representative of the capsules used in the Orange and Cutie designs. Credit: Lane Carlsen/General Atomics.

Scientists from Lawrence Livermore National Laboratory (LLNL) and the Laboratory for Laser Energetics (LLE) are working to improve polar direct drive (PDD) neutron sources on the National Ignition Facility (NIF), the world’s most energetic laser.

PDD neutron sources are capsules filled with deuterium-tritium (DT) gas at ambient temperature and shot with robust laser pulses that do not require stringent laser power contrast control or power accuracy. These sources are more time and resource efficient to field on NIF than conventional indirect drive sources that require high-quality cryogenic layers of DT ice. In addition, a lower generated target debris load allows neutron radiation effects experiments to position much closer to the target, creating a stronger neutron radiation field for testing.

The team substantially enhanced the total fusion output and laser-to-fusion energy conversion efficiency for PDD. The team also developed a PDD exploding pusher, or PDXP, platform that has enabled radiation effects testing of recoverable samples at record 14 MeV (Mega electron-volt) neutron fluence levels.

“For over a year and a half after the initial experimental success, this design of PDD was the most efficient way in existence to convert laser energy input into fusion output,” said Charles Yeamans, team lead and first author of a paper that appears in Nuclear Fusion. Co-authors include Elijah Kemp, Zach Walters, Heather Whitley and Brent Blue from LLNL, and Steve Craxton, Patrick McKenty, Emma Garcia and Yujia Yang from LLE.

“Shooting really big lasers at stuff can stimulate fusion reactions like what happens in the sun and other stars and terrestrially in the core of a nuclear detonation,” Yeamans said. “We want to study how the intense radiation fields generated from fusion affect materials, electronics and engineered systems like satellites and airplanes. At NIF we are able to control and position our test objects close to that source.”

Additionally, similar direct drive capsule platforms have many applications on the NIF. With different gas fills they can be used for studies of nuclear reactions of interest to astrophysics and as a source of protons for point backlighting. They also have been used to produce short pulses of high-brightness continuum X-rays for extended X-ray absorption fine structure (EXAFS) studies and for opacity measurements. Additionally, they have been used to make large compressed plasmas for studies of electron-ion energy transfer.

“Overall, a better NIF neutron source design allows us to conduct better radiation effects tests in greater numbers than if we were to rely solely on the mainstream NIF experiments,” he said.

Yeamans said the work developed a valuable addition to the overall radiation effects experimental test capability for the Lab. “It also developed the modeling and simulation capability to understand and improve the neutron source design,” he said. “With this work, we are better able to fulfill this responsibility now and in the future.”

Team success

The work was conducted by a team of designers—scientists who run computer codes that do complicated physics calculations—and experimentalists—engineers who understand and operate the world’s biggest laser, and who determine the best way to test in practice what works in the simulation.

Several of the team members work in both roles, and others specialize as either designer or experimentalist based on what the research team needs. Sixteen days of NIF experimental time spread over more than five years were included in the source development effort, with the three best-performing designs, each conducted during a shot day in 2019, selected for detailed discussion in the publication, said Yeamans.

Heather Whitley, associate program director for High Energy Density Science at LLNL, developed the initial design for a large diameter polar direct drive capsule with Craxton and Garcia from LLE and Warren Garbett from the U.K. Atomic Weapons Establishment.

“This platform is important because it provides high neutron fluences and enables the close positioning of samples near the source for survivability experiments,” Whitley said. “The polar direct drive configuration also provides excellent diagnostic access for other high temperature plasma physics experiments.”

Craxton from LLE helped lead the work of undergraduate students Garcia and Yang and said that the participation of the students has been important to this work. Each student was responsible for calculating the optimized laser beam pointing to achieve uniform implosion of a specific diameter of capsule. This optimization is complicated by the NIF beam entry angles being optimized to drive a cylindrical hohlraum target. McKenty worked closely with Craxton and the rest of the team to determine the ideal pulse shape.

“We went through a whole series of experiments over many years, first to produce neutrons to test NIF neutron diagnostics while NIF was being commissioned,” Craxton said. “These experiments evolved to meet the needs of a wide variety of applications, with the largest targets producing the high yields required for the effects experiments.”

Critical to the success of this effort was the fabrication and developing the proper testing protocols to obtain key data for prescribing safe fielding pressures of these large (2-5 millimeters in diameter), thin wall (approximately 10-30 micrometers) capsules, which are more susceptible to bursting. This was done by target fabrication team mainly at General Atomics (GA) in San Diego, working closely with LLNL’s target fabrication team as well as the above mentioned physics team. Claudia Shuldberg and her team led the work at GA, while Bill Saied and Kelly Youngblood led the target fabrication engineering effort at LLNL.

More information:
C.B. Yeamans et al. High yield polar direct drive fusion neutron sources at the National Ignition Facility, Nuclear Fusion (2021). DOI: 10.1088/1741-4326/abe4e6

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