From Pig to Fuel - Anaerobic digester generates energy, reduces odors

 Teng Lim is operating a small-scale anaerobic digester at the MU swine farm in Columbia. The system generates energy and can mitigate hog odor. Courtesy Jon Lamb.

The University of Missouri has unveiled a prototype small-scale anaerobic digestion system that produces biogas from pig manure. The biogas can be used to heat a farm and create electricity. The device also reduces odor from swine operations.

“What we want to do is improve and fully utilize all the biogas for energy production,” said Teng Lim, Extension Ag Systems Management associate professor.

Funded by the MU College of Agriculture, Food and Natural Resources, the anaerobic digester consists of three tanks. Manure from the hog barn pit is pumped into one tank where the manure is stored and mixed. The anaerobic digestion takes place in the other two tanks, where bacteria break down the manure in these warm and oxygen-free tanks.

The biogas from the manure can be used for electricity and hot water production. With some further treatment it can also be stored as a compressed natural gas, for heating or even vehicle fuel.

PigsLim says a larger scale digester could supply a farm’s energy needs and also be sold to the grid to provide electricity to the community.

There are other benefits to anaerobic digestion in addition to energy generation. The digested manure retains the nutrients to be good fertilizer while becoming a more consistent product. Also, the digester can reduce odor emissions.

“When the manure is treated by the digester process the odor concentration is significantly reduced,” Lim said. “There is still going to be odor, but it’s going to be much lower and less fluctuation than the raw manure.”

A Lot of Pork

The swine industry is big in the United States – there are 73,150 pork farms in America with 120 million pigs marketed each year.

Before the 1960s, most pork in the U.S. was raised in outside lots or on pasture systems. With the development of slotted floors and liquid manure handling equipment, it became possible for producers to more easily care for larger numbers of animals. Enclosed buildings overcame most weather problems and predators, and minimized the potential pollution from outside lot runoff.

Typically, pig odor is a localized air quality problem, with low concentrations of odorous gases such as p-cresol. Odor problems are often a starting point for litigation. Many farmers can go out of business just fighting a lawsuit.

An Important Part of Future Farms?

There are challenges to anaerobic digestion, the biggest being cost and management. In a commercial setting the digester would be 100 times larger than the one at MU’s swine research facility.

Lim pointed out that industry leaders and scientists believe anaerobic digesters will be an important piece of future farms, both to mitigate odor and for generating renewable energy.  The cost is a major obstacle now. The team is working closely with industry experts from Martin Machinery, a Missouri company who specializes in biogas generators and control systems.

MU researchers are using the scaled down digester to find ways to make digesters more affordable and easier to manage. They are also using it as an education tool to show producers the potentials, what it takes to process the manure, and to train people how to properly run a system like this.

Source: Cafnr

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Stanford scientists team with indigenous people to produce detailed carbon calculations of Amazon rainforest

The late Dr. Kye Epps teaches Wapichana field researchers how to measure tree diameter, information that can then be used to calculate a tree's biomass and carbon storage.

When it comes to measuring the carbon storage potential of the Amazon forest, indigenous people might outperform sophisticated satellites.

The results from a long-term collaboration between Stanford scientists and indigenous people in Guyana suggests that traditional remote sensing techniques might be undervaluing the region's carbon storage potential by as much as 40 percent. The work could influence how indigenous people in Guyana and elsewhere manage their forests and lead to greater opportunities for these communities to engage in carbon offset programs.

The project, led by Jose Fragoso, a senior scientist in the Department of Biology at Stanford, grew out of his earlier efforts to engage indigenous peoples to gain a better understanding of ecosystems relatively undisturbed by modern civilization.

What is carbon?

The first challenge was teaching people with little to no exposure to the outside world just what carbon is. Co-author Kimberly "Kye" Epps, a postdoctoral scholar in Stanford School of Earth Sciences (who passed away during the project,) developed lesson plans for explaining that all life is based on carbon.

Epps pointed out that the black charcoal from a burnt twig is primarily carbon, and how the carbon-laden smoke enters the atmosphere and ultimately affects the global climate. The plants and trees suck carbon from the atmosphere, she explained, and store it in their trunks and leaves.

"Kye's innovative lessons helped get them to where they not only understand what carbon is, but also understand its global implications and how much they actually hold themselves on their land," said Fragoso, the senior author on the paper. "When they realized its importance, they became very invested in the work."

Next came lessons on establishing survey plots, cataloging plant species and learning how to measure plant trunk circumferences, which is a standard measurement used to calculate biomass and thus how much carbon is contained in the plot.

"The people know the trails really well, and some of them will walk two days to get to their plot and make measurements," Fragoso said. "They can make really good measurements in really isolated areas, where government workers would never get to. Generally, professional scientists will not travel these distances on foot to verify carbon estimates."

Biomass specifics

Whereas satellite observations would most likely have identified each of these plots as "forest" and assigned them a standardized value for carbon storage, Fragoso said that the field workers identified 11 habitat types with trees, each of which requires a different set of calculations for determining its carbon storage potential. Because the researchers could be more specific about the biomass of each vegetation type making up a plot, they were able to calculate that forests in Guyana contain 20 to 40 percent more carbon than previously estimated.

This difference can affect a number of different areas. For one, it means that climate models that include blanket estimations of carbon storage in lands governed by indigenous people might be missing significant data – indigenous people govern about half of all remaining undeveloped land on the planet.

Indigenous lands probably play a much larger role in the global climate than previously assumed, Fragoso said, and indigenous people need to be better represented at global climate talks. These land-owners have more carbon storage at their disposal to sell as carbon credits to governments and corporations looking to offset their greenhouse gas-producing activities.

"Having a good measurement of carbon storage really helps them to enter into discussions with the national government and surrounding communities," Fragoso said. "This helps them to both prevent global climate change while also benefiting, and that is something that the people we worked with were very interested in."

This is the first model for turning indigenous people into field researchers capable of producing scientifically rigorous calculations for carbon, said Fragoso, who is now planning to share the concept with other indigenous nations around the world.

The paper was published recently in the journal Forest Ecology and Management. The work was co-authored by Nathalie Butt of the University of Queensland, Australia, who completed Epps' work; Stanford postdoctoral fellow Takuya Iwamura; and Han Overman, a postdoc at State University of New York. While not official co-authors, Stanford professors Peter Vitousek and Pamela Matson were instrumental in providing guidance for Epps' work.

Source: Stanford

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Smelly discovery challenges effectiveness of antimicrobial textiles

University of Alberta textiles scientist Rachel McQueen has found that anti-odor clothing may not be living up to its promise. Credit: University of Alberta

Anti-odour clothing may not be living up to its promise, and an ALES researcher is saying it could all be a matter of how the product was tested.

In two separate experiments, Human Ecology researcher Rachel McQueen and her team found that some antimicrobial textiles were far more effective at performing their advertised tasks in the lab than in testing on humans. In one experiment, the fabrics were designed to help lower the risk of infection; in the second, the fabric was treated with a silver compound, which can be marketed preventing odour in clothing.

"We aren't necessarily seeing the same results in the lab about antimicrobial activity translating into antimicrobial activity when we're wearing them next to our bodies in real life," she said.

The first experiment analyzed the effectiveness of three different textiles coated in antimicrobials triclosan, a zinc pyrithione derivative and a silver chloride-titanium dioxide compound. After putting the fabric on people's arms under plastic film for 24 hours, the silver-chloride titanium dioxide compound hardly eliminated any bacteria. Overall, they found the in vivo -- tested on humans -- results were not comparable with in vitro -- tested in the lab -- results in how they prevented microorganisms from surviving in the textile.

The second test had similar results, and tested whether polyester textiles treated with bioactive concentrations of an antimicrobial silver chloride compound reduced armpit odour and bacterial populations. Although lab testing showed antimicrobial activity, the treated fabrics did not lower odour or bacterial intensity in in vivo testing.

McQueen said that anything from sweat to the proteins in the human body can disrupt the antimicrobial properties of a fabric.

"In reality, when it goes to the point that it gets put on a textile... it may not have the same level of effectiveness as the ones they studied," she said.

McQueen said these findings highlight the importance of in vivo testing, which is less common than in vitro testing, in textile product development. But, because the textiles appear to be effective at reducing bacteria in the lab, she said they may be advertised as being anti-odourous, although they may not necessarily be so when actually worn.

So, for now, McQueen suggests thinking twice before trusting textile's advertised claims.

"It's just a real spectrum to how effective they may truly be. So I'd probably say, from a consumer's point of view, if you're actually buying something that says it's antimicrobial, it may not be," she said. "I think that's important to consider in relation to a lot of claims made about textiles, that is, to be skeptical about the claims marketers make."

McQueen's research was recently published in the International Journal of Clothing Science and Technology.

Source: University of Alberta

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