Wednesday, November 9, 2005

Bacteria Eat Human Sewage, Produce Rocket Fuel


Brian Handwerk
for National Geographic News

The high cost of treating human wastewater may one day tank thanks to a bacterium that eats ammonia and produces rocket fuel. Standard water treatment plants use oxygen-hungry bacteria to break down human waste. To feed the microbes, plants must aerate sewage sludge with costly, power-hogging equipment.

But Brocadia anammoxidans, or anammox bacteria, survive without oxygen, producing energy from nitrite and ammonia, which is found naturally in human waste.

"Conventional [bacteria] treatments do a good job, so the big benefit is doing this much more efficiently and cheaply," said Marc Strous, a microbiologist at the University of Nijmegen in the Netherlands.

Strous says savings could be enormous, up to 90 percent versus standard sewage treatment plants. A prototype facility in Rotterdam is already earning praise.

Rocket Fuel

Scientists first discovered anammox bacteria in yeast and later in the open ocean in the late 1990s.

The unusual microbes consume ammonia, producing hydrazine�better known as rocket fuel�in the process. The ability still puzzles scientists.

"They are the only organism on Earth that produces hydrazine, so until their discovery, [hydrazine] was thought to be a man-made substance," Strous said.

The bacteria safely store the toxic fuel in an organelle, or specialized cell structure, similar to mitochondria, a type of biological power plant found in human cells.

The anammox organelle binds hydrazine with a fatty-acid membrane that could itself have intriguing scientific applications, including the design of optoelectronic equipment.

But don't expect the bacteria to supply NASA with rocket fuel to launch a spacecraft.

"It costs [the bacteria] a lot of energy, and they get return on their investment by consuming it again," Strous explained. "They are dependent on it, so it can't be removed."

Prototype Plant

Instead, researchers are harnessing the bacteria for more down-to-Earth applications, such as sewage treatment.

Strous says it took two or three years to scale up the anammox process from the lab to a waste treatment facility.

The prototype plant in Rotterdam is performing at a high level, he says, and others will soon follow. "The next one is already starting up much more quickly," Strous said.

The researcher, who advises sewage treatment projects in the Netherlands, notes that conventional sewage treatment facilities can be easily retrofitted to use the anammox reaction.

The low operating costs might allow such systems to provide much needed waste water treatment in regions where adequate facilities are lacking or nonexistent.

More sewage treatment plants could benefit human health. They could also reduce global amounts of ammonia from untreated waste.

Excessive ammonia can wreak havoc with freshwater ecosystems by reacting with oxygen, tying up the gas, which many species need for respiration.


Thursday, April 14, 2005

Red LEDs to Grow Lettuce


Apparently red LEDs are 60% more efficient than fluorescent light when growing vegetables hydroponically.

According to IEEE Spectrum Online: Of all the colors of the rainbow, red is lettuce’s favorite. Chlorophyll, the electrochemical engine of photosynthesis, runs on red photons. So if you are growing the vegetable indoors in a factory, why waste energy on colors you don’t need?

Using a red LED-based growth process developed by Cosmo Plant Co., in Fukuroi, Japan, instead of a fluorescent lighting based one, cuts a factory’s electric bill by 60 percent, the company told Agence France Press.

Cosmo’s customers uses the technology to produce 7000 heads of lettuce per day all year round in a 10-floor building on just 1000 square meters of space. The lettuce matures more than three times as fast under the LEDs than outdoors. While growing lettuce in an open field is still less costly, growing it inside under LEDs means you don’t have to worry about crop-decimating typhoons and other nasty weather.

Effect of LED-light Stimulation at Specific Frequencies on Lettuce Growth

Accession number;03A0621435
Title;Effect of LED-light Stimulation at Specific Frequencies on Lettuce Growth
Author;NAKABAYASHI KAZUSHIGE(Meiji Univ., Sch. of Agric.) SUZUKI TAKANORI(Meiji Univ., Sch. of Agric.)
Journal Title;Journal of Society of High Technology in Agriculture (J. SHITA)
Journal Code:L1430A
Figure&Table&Reference;FIG.3, TBL.4, REF.13
Pub. Country;Japan
Abstract;Plant growth rate can be controlled by adjusting both the light quality and during light and dark transition. Light intensity and time also have an effect on growth rate. We investigated the effects of low-intensity light irradiation of specific frequency on the growth and inorganic contents of lettuce in the field. Lettuce was cultivated using three types of nutrient solution (complete nutrition, NO3-N-excessive, NO3-N-deficient). Light sources were red and yellow LEDs, which are low-cost artificial light sources used in plant production. Leaves were irradiated by pulsed LED-light for several hours each day. Red and yellow LED-light stimulation of specific frequency (20Hz,50Hz) increased the lettuce yield in nutrient solutions with lower NO3-N concentrations, despite of the fact that the chlorophyll in lettuce does not response much yellow light. Changes in light stimulation frequency affected NO3-N concentrations in lettuce sap. These results suggest that stimulation by red or yellow LED-ligh in the field has a positive effect on photosynthetic activity. (author abst.)