Archives
February 2012
Secret Weapon Against the Smell of Sludge? Sludge
http://www.nytimes.com/2005/02/21/science/21sludge.html?pagewanted=1&_r=0
Published: February 21, 2005
Ruby Washington/The New York Times – Teresa J. Bandosz is New York’s unofficial odor warden, monitoring how treatment plants keep odors from getting out and figuring out new ways to reduce the smell.
By ANTHONY DePALMA
Every city is saddled with aspects of urban life that are as undesirable as they are unavoidable – things, for instance, like sludge, and the stink that goes with it. Most people do not want to even think about how a city the size of New York gets rid of 1.2 billion gallons of everything that goes down the toilet, drain or gutter every day, and they certainly do not want to smell it.
And on most days, at most times, they do not, because sewage treatment plants are buttoned up tighter than a walk-in cigar humidor and people like Teresa J. Bandosz are there to make sure that what goes on inside stays inside.
Dr. Bandosz, a research scientist and professor of chemistry at City College, is New York’s unofficial odor warden. With a small team of student researchers and a technician, she monitors how well carbon filters at the treatment plants keep foul odors from spewing into the air.
Dr. Bandosz has also been trying to figure out how to make the smell-scrubbing process more efficient. Like a modern-day Edison, she has experimented with an odd assortment of materials to make the best filter. She has tried scrap paper and recycled plastic, then moved on to coal before going out on a limb and trying the pits from olives and peaches after she and her assistants ate around them.
Now she thinks she has come up with just about the perfect material for taking the stink out of sludge – sludge itself. She starts with fertilizer pellets that the New York Organic Fertilizer Company in the Bronx makes from the city’s treated sludge.
In an oxygen-free container, she heats the tiny pellets to more than 1,700 degrees, which helps them filter out offending compounds, primarily hydrogen sulfide, more efficiently. Each piece of treated sludge becomes like a microscopic sponge, filled with cavities that absorb the stuff that gives sludge its awful smell. “We ran the tests and we’ve had fantastic results,” said Dr. Bandosz, 44, who came to the United States from Poland in 1991. She said she has wanted to be a chemist since a teacher showed her the invisible world of compounds and molecules when she was 12.
“You had to use your imagination to link what you knew with what you couldn’t see,” she said.
continued………. read more: http://tbandosz.com/?page_id=530
Sewage’s Toxic Smell, Smothered by Coffee
http://www.nytimes.com/2012/02/21/science/sewages-toxic-smell-smothered-by-coffee.html?_r=0
Published: February 21,2012
By SINDYA N. BHANOO
Coffee lovers around the world can rejoice: The piles of grounds they discard could help rid the world of the toxic smell of sewage. Writing in The Journal of Hazardous Materials, researchers at the City University of New York report thatcoffee grounds can absorb hydrogen sulfide gas, a big part of what makes sewage smell so terrible.
Today, activated carbons or porous coals are used in treatment facilities to draw hydrogen sulfide from sewage. But when coffee grounds are transformed into activated carbon, the researchers found that they sop up sulfur particularly well. That’s because of a key ingredient in coffee: caffeine.
Caffeine contains nitrogen, which increases carbon’s ability to eliminate sulfur from the air, said Teresa J. Bandosz, a chemist and chemical engineer at CUNY and an author of the report. To carbonize the coffee grounds, she and her colleagues mixed the grounds with water and zinc, and then dried the mixture in an oven. Dr. Bandosz hopes that entrepreneurs might take the research and turn it into a business.
A coffee drinker herself, Dr. Bandosz came up with the idea because she throws out piles of coffee grounds. “Fresh coffee would work even better — it has more caffeine,” she said. “But it is not economical.”
read more: http://www.nytimes.com/2012/02/21/science/sewages-toxic-smell-smothered-by-coffee.html?_r=0
Carbonized coffee grounds remove foul smells
http://www.rdmag.com/news/2012/02/carbonized-coffee-grounds-remove-foul-smells
Published: February 22, 2012
For coffee lovers, the first cup of the morning is one of life’s best aromas. But did you know that the leftover grounds could eliminate one of the worst smells around—sewer gas?
In research to develop a novel, eco-friendly filter to remove toxic gases from the air, scientists at The City College of New York (CCNY) found that a material made from used coffee grounds can sop up hydrogen sulfide gas, the chemical that makes raw sewage stinky.
Teresa Bandosz, PhD, CCNY professor of chemistry and chemical engineering, develops and tests materials that scrub toxic gases like hydrogen sulfide from air in industrial facilities and pollution control plants. Much like the grains of charcoal packed into the filter of a tabletop water pitcher, her filters use a form of charcoal called “activated carbon.”
Carbon producers already use materials like coal, wood, peat, fruit pits, and coconut shells to make filters. Bandosz realized that our modern coffee culture could supply an abundant source of eco-friendly organic waste. But coffee grounds also come equipped with a special ingredient that boosts their smell-fighting power.
Caffeine, the stimulant that gives coffee its energy jolt, contains nitrogen. This element cranks up carbon’s ability to clean sulfur from the air, a process called adsorption. “We should not neglect the natural biomass that is rich in this element,” she and colleagues assert in the Journal of Hazardous Materials. The National Science Foundation (NSF) and the Army Research Office funded the research.
Usually, making carbon adsorbents more reactive to toxins requires treating the original with a nitrogen-rich chemical such as ammonia, melamine, or urea, the main nitrogen-containing substance in mammal urine. “All of these,” the researchers note, “significantly increase the cost of adsorbents.”
To make their new filter, Bandosz and her colleagues carbonized old coffee grounds, essentially turning them into charcoal.
To do so, they prepared a slurry of coffee grounds, water and zinc chloride, a chemical “activator.” The team then dried and baked the mixture at temperatures of up to 800 C. The process of activation fills the carbon with scores of minute holes about 10 to 30 A in diameter, roughly equivalent to 10 to 30 hydrogen atom-widths across. These densely packed pores are blanketed with nitrogen, perfect to capture hydrogen sulfide molecules passing through.
Hydrogen sulfide gas isn’t just a smelly nuisance for sewage plant neighbors; it can be deadly. Human noses are so sensitive to the rotten-egg scent of this toxin that it can overwhelm the sense of smell, Bandosz explained. “When someone is exposed to high concentrations of hydrogen sulfide, the nose will stop detecting it,” she said. “There have been cases in which workers died of hydrogen sulfide exposure in sewer systems.” Bandosz suspects that the coffee-based carbon could also separate out other pollutants from the air and water.
With the ubiquitous motto to “Reduce, Reuse, Recycle,” and coffee-ground carbon’s special affinity for a toxic gas, Bandosz hopes coffee grounds can be commercially developed into the next green waste filter. For now, however, she recycles them on her own: “I put them outside under the plants in my garden, especially those that like acidic soil,” she said. They are a great fertilizer, of course, packed as they are with nitrogen-rich caffeine.
read more: http://www.rdmag.com/news/2012/02/carbonized-coffee-grounds-remove-foul-smells
