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How
useful is it to make diesel fuel from soybeans?
Erika Felix's net energy analysis study of soybean bio-diesel showed that
production of the fuel from soybean feedstock used over twice as much total
energy as it produced, which included the energy embodied in gasoline,
diesel, coal-electricity, natural gas, fertilizer, water and soil. This
indicates that bio-diesel cannot be a PRIMARY SOURCE of energy. However, it
may be a worthwhile process for converting non-petroleum fossil fuels to
liquid fuel. One of the largest inputs to the complete process was
electricity used at the processing plant. Stay tuned for further information
on soybean-to-fuel and other crop-to-fuel conversions that used switchgrass,
hybrid poplar, castorbean in Erika's master's thesis in the Spring of 2006.
A Better Tool for
Monitoring Nitrogen Pollution in Wetlands is under Development.
Emily Poynter is determining whether hyperspectral reflectance of marsh
plants can be interpreted to infer plant nitrogen concentrations and
distinguish among different types of marsh plant communities in tidal
freshwater marshes. Hyperspectral reflectance is the fraction of solar energy
reflected from plants in hundreds of small (1 nanometer) spectral
bands. In her research project, she applied various amounts of nitrogen
to natural wetlands, and then monitored their reflectance throughout
the growing season with a spectroradiometer. Early indications are that her
Master's thesis will show that the technology could be used to monitor the
health of wetlands, which is something that needs improvement. Look for
Emily's thesis in early summer 2006.
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Soil Eats Engine Exhaust Poisons!
Jeff Mentzer found that native soil ecosystems could remove the poisonous gas
carbon monoxide from the exhaust of an engine running on gasoline. He
directly loaded soil microcosms with engine exhaust. Microcosms with soil and
plants performed better than soils by themselves. The uptake rate of CO was
found to be higher when there was more CO in the exhaust. Jeff noted that
these type of free ecosystem services should be better valued by the public
and suggested that ecological engineers should consider how this beneficial
characteristic of soil can be better integrated into our urban highways. Look
for Jeff's article, co-authored with Dr. Tilley, in Tilley, D.R., J. Mentzer,
2006. Soil uptake of carbon monoxide emitted in the exhaust of a gasoline
powered engine. J. Air & Waste Management Association 56: 115-120 Journal of the Air & Waste Management
Association. 
How can Shrimp Farming
be made Sustainable? With Ecological Engineering Principles of Course.
Listen to the audio (1.5 MB MP3) segments produced by Voices of Innovation.
Audio1
Audio2
Audio3
Audio4
Abstract from Tilley, D.R., Badrinarayanan, H., R. Rosati and J. Son,
2002. Constructed wetlands as recirculation filters in large-scale
shrimp aquaculture. Aquacultural Engineering vol. 26 no. 2 pp.81-109
Effluent waters from shrimp aquaculture, which can contain elevated levels of
phosphorus, ammonia, nitrate, and organics, must be managed properly if
shrimp aquaculture is to achieve sustainability. Constructed wetlands are
ecologically beneficial, low cost treatment alternatives proven capable of
reducing suspended solids, biochemical oxygen demand, nitrogen, phosphorus
and heavy metals from wastewater of many sources. The goal of this study was
to determine how well a constructed wetland performed as a filter in a
full-scale shrimp aquaculture operation. A 7.7 ha (19 ac) mesohaline (3
– 8 ppt) constructed wetland treating 13,600 m3 d-1 (3.6 MGD) of
effluent from 8.1 ha (20 ac) of intensively farmed shrimp ponds at the Loma
Alta Shrimp Aquaculture Facility (LASAF), located along the coast of the Gulf
of Mexico in semi-arid South Texas, was found to reduce concentrations of
total phosphorus (TP), total suspended solids (TSS) and inorganic suspended
solids (ISS) by 31%, 65% and 76%, respectively, during recirculation, and
maintained consistently low levels of mean biochemical oxygen demand (< 9
mg L-1), total ammonia (< 1.8 mg-N L-1) and nitrate (<0.42 mg-N
L-1). Determination of parameter values for the k-C* wetland design model
for ISS or TP showed that mean target levels could be achieved, given
expected influent concentrations, when the ratio of pond surface to wetland
surface was 12. Constructed wetlands can perform satisfactorily as
recirculation filters in large-scale shrimp aquaculture operations, reducing
the impact of effluent on local water bodies, conserving large quantities of
water and providing valuable ecological habitat. |
