residue

A substantial amount of corn is grown in this country for the purpose of producing ethanol. The value of doing so is debatable for many reasons. Nevertheless, the majority of the corn crop is grown for food. But along with all that corn, there is corn stover. Stover is the dried stalks, leaves, and other plant parts that remain in the field after the corn itself has been harvested. Corn stover is the largest quantity of biomass residue in the United States. Around 250 million tons of it is produced annually and the majority of it is left unused. Some is used for animal feed and other purposes and has monetary value, but much of it goes to waste.

Scientists at Washington State University have developed a way to produce low-cost sugar from stover that can be used to make biofuels and other bioproducts.

Corn stover is an abundant and cheap source of biomass, which holds great potential as a source of energy and valuable chemicals. The challenge is to overcome the high cost of processing stover whose complex structural molecules like cellulose and lignin need to be broken down.

The new process uses potassium hydroxide and ammonium sulfite to convert stover into a sugar. It is a mild-temperature process that allows enzymes to break down the cellulosic polymers in stover into sugar, which can then be fermented into biofuels. The resulting sugar from the process would be cost-competitive with low-cost imported sugars. The researchers estimate that their patent-pending process could produce sugar that could be sold for as low as 28 cents per pound.

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Scientists discover a new way to convert corn waste into low-cost sugar for biofuel

Photo, posted August 30, 2012, courtesy of Idaho National Laboratory Bioenergy Program via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

According to a new study published in the journal Environmental Research Letters, concentrations of pharmaceuticals in rivers and lakes have dramatically increased across the globe over the past 20 years.

Traces of medicines get passed into waterways through the excretion of active drugs in human waste, the disposal of unused medicines down drains, and runoff from livestock farms.

The study looked in detail at two specific drugs: carbamazepine, an anti-epileptic drug, and ciprofloxacin, an antibiotic. The study found that the risk of ecological damage from the residue from these two drugs was 10 to 20 times higher in 2015 than in 1995.

Chronic exposure to carbamazepine, for example, has been shown to alter feeding behavior and reduce egg viability in zebrafish, as well as reduce reproductive success in crustaceans. Antibiotics can alter major nutrient cycles and decrease the effectiveness of bacteria-based wastewater treatment systems.

The study, led by researchers from the Netherlands, created a new model estimating concentrations of the two drugs over a 20-year period in 449 aquatic systems around the globe. The model predicts a relatively high environmental risk in densely populated and dry areas such as the Middle East.

When the researchers compared the model’s results to samples from four river systems in various locations, they found that the actual drug concentrations were even higher than model results, in some cases by a factor of 10 to 100.

The new model should act as a guide for a more thorough investigation into pharmaceutical residues in waterways, which pose significant environmental risks all over the world.

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Concentrations of Pharmaceuticals in Freshwater Increasingly Globally

Photo, posted March 22, 2012, courtesy of Rajeev Rajagopalan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Fuel from Corn Waste

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Drugs In The Water

According to a new study published in the journal Environmental Research Letters, concentrations of pharmaceuticals in rivers and lakes have dramatically increased across the globe over the past 20 years.

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