Monday, July 11, 2005
Manure Has Promise as Filter
A little-known and unpleasant fact from the Department of Agriculture: Food animals in the United States produce 350 billion tons of manure each year. A lot of it returns to the fields as fertilizer, but not all -- not by a long shot.
Last week, USDA's Agricultural Research Service reported that research chemist Isabel Lima has devised a way to turn chicken manure into porous activated carbon with the ability to leach heavy metals from wastewater.
"Animals leave behind incredible amounts of manure," Lima said in a telephone interview from her office at USDA's Southern Regional Research Center in New Orleans. "We wanted to see if there was any way to transform it and add value."
Lima's team first "charred" the manure -- heated it in an oxygen-free environment to boil off volatiles and pollutants, leaving a carbon-rich, charcoallike residue. Then the team bombarded the residue with steam, imparting porosity to give it a large amount of surface with which to catch impurities.
Lima said that most activated carbons are made from coal, wood or plant "residuals" such as peanut shells, soybean hulls or coconut husks, and are best used in removing odor and organic materials from drinking water.
Unlike these products, chicken manure turns out to have an unusual ability to extract from industrial wastewater positively charged metal particles such as zinc, copper and cadmium, many of which are carcinogens.
Lima's team is conducting further tests to find out how this happens.
The team is also trying to reduce the cost of making manure carbon, but in the targeted industrial market, where coal is currently the predominant raw material, manure has an advantage: "Coal is expensive and nonrenewable," Lima said. "With manure, the raw material is free."
-- Guy Gugliotta
Kids' TV Exposure Studied
Three new studies provide fresh evidence that children who watch a lot of television do more poorly in school.
In the first study, researchers at the University of Washington at Seattle analyzed data from a national survey of 1,797 children and found the more television children watched before age 3, the more poorly they performed in school when they were 6 or 7. TV viewing from ages 3 to 5, however, appeared to have a beneficial effect on reading and short-term memory, the researchers found.
In the second study, researchers at the University of Otago in New Zealand examined 1,000 children born in Dunedin, New Zealand, and found those who watched the most television during childhood and adolescence were the least likely to finish school or go on to earn a university degree.
In the third study, researchers at the Johns Hopkins Bloomberg School of Public Health in Baltimore and Stanford University studied 348 third-graders and found those with a TV in their bedrooms tended to score lower on standardized tests while those with a home computer scored higher.
Other researchers said that although the studies were valuable, they failed to differentiate between commercial and educational television.
"Research examining the short- and long-term effects of exposure to educational TV has consistently pointed to positive cognitive outcomes," Ariel R. Chernin and Deborah L. Linebarger of the University of Pennsylvania wrote in an editorial accompanying the studies in the July issue of the Archives of Pediatrics & Adolescent Medicine. "As a result, parents should be encouraged to incorporate well-produced, age-appropriate educational TV into their children's lives. Such programming represents a valuable tool for stimulating children's cognitive development."
-- Rob Stein
Methods Devised to Grow Meat
Would you like your meat well-done, rare or cultured in a lab dish? While the last option might not taste as good, it may be higher in nutrients, produced without any messy waste and pollution, and guaranteed to be free of mad cow disease or other food-borne diseases.
"Cultured meat" production is not a reality now, but researchers have concluded that because animal cells can be endlessly multiplied in a lab dish, it could be possible and economically feasible. In a review and analysis of existing and potential meat-creating technologies in the journal Tissue Engineering, University of Maryland doctoral student Jason Matheny and his colleagues identified two techniques for creating products that taste like beef, chicken, pork and fish with the nutrients and texture of meat.
One process involves growing animal muscle and fat cells on thin membranes stretched over large flat sheets and then removing the meatlike material and stacking it together to create a thicker "cut" of meat.
The other method would involve growing the cells on small three-dimensional beads that stretch as the temperature changes and harvesting them to make processed meat similar to nuggets or hamburgers.
"The challenge is getting the texture right," Matheny said in a news release. "We have to figure out how to 'exercise' the muscle cells. For the right texture, you have to stretch the tissue, like a live animal would."
Some cultured tissue has already been created. Matheny said that NASA succeeded in growing small amounts of fish tissue as part of research into how to feed astronauts during long-term space travel. What he foresees, however, is much grander. "With a single cell, you could theoretically produce the world's annual meat supply," he said. "And you could do it in a way that's better for the environment and human health."
-- Marc Kaufman