Metric Tons (metric + ton)

Distribution by Scientific Domains
Distribution within Chemistry

Selected Abstracts

Causes for the decline of suspended-sediment discharge in the Mississippi River system, 1940,2007,

Robert H. Meade
Abstract Before 1900, the Missouri,Mississippi River system transported an estimated 400 million metric tons per year of sediment from the interior of the United States to coastal Louisiana. During the last two decades (1987,2006), this transport has averaged 145 million metric tons per year. The cause for this substantial decrease in sediment has been attributed to the trapping characteristics of dams constructed on the muddy part of the Missouri River during the 1950s. However, reexamination of more than 60 years of water- and sediment-discharge data indicates that the dams alone are not the sole cause. These dams trap about 100,150 million metric tons per year, which represent about half the decrease in sediment discharge near the mouth of the Mississippi. Changes in relations between water discharge and suspended-sediment concentration suggest that the Missouri,Mississippi has been transformed from a transport-limited to a supply-limited system. Thus, other engineering activities such as meander cutoffs, river-training structures, and bank revetments as well as soil erosion controls have trapped sediment, eliminated sediment sources, or protected sediment that was once available for transport episodically throughout the year. Removing major engineering structures such as dams probably would not restore sediment discharges to pre-1900 state, mainly because of the numerous smaller engineering structures and other soil-retention works throughout the Missouri,Mississippi system. Published in 2009 by John Wiley & Sons, Ltd. [source]

Determination of membrane areas for ultrafiltration processes

Changsheng Liu
Abstract For batch mode ultrafiltration processes a numerical method for calculating membrane area has been devised with flux predicted from Flemmer's model. Erythromycin broth filtrate was used as a model fluid. Experiments at a 20,dm3 scale were used to estimate the parameters involved in Flemmer's equation, from which membrane areas appropriate for operations of 80 metric tons were calculated. Factors such as rejection, concentration ratio, etc, which affect the membrane size for batch operation, are discussed. The calculated results were consistent with experimental data at the 100,dm3 scale. For continuous operation equations for calculating membrane areas have also been established. The minimum membrane area was calculated at the optimum concentration ratios of each stage, usually their values were different at each stages. Comparison between batch and continuous mode in the context of the membrane area required is also discussed. The method could be applicable to other ultrafiltration operations. © 2001 Society of Chemical Industry [source]

Whey Protein Isolate and ,-Lactalbumin Recovery from Lactic Acid Whey Using Cation-Exchange Chromatography

K. N. Turhan
ABSTRACT: The objective of this work was to develop a process to fractionate proteins from lactic acid whey, which is underused compared with sweet whey, using food-grade buffers and cation-exchange chromatography. Bound proteins were desorbed either all at once to make whey protein isolate (WPI), or in 2 steps to 1st make ,-lactalbumin (ALA) and then WPI depleted in ALA. Recovery and purity using lactic acid whey were comparable to previously reported processes using sweet whey. Capacity and throughput were slightly lower using lactic acid whey. This research provides a basis for adding value to the 6 million metric tons of lactic acid whey produced annually in the United States. [source]

Prymnesium parvum: The Norwegian Experience,

Torbjørn M. Johnsen
Johnsen, Torbjørn M., Wenche Eikrem, Christine D. Olseng, Knut E. Tollefsen, and Vilhelm Bjerknes, 2010. Prymnesium parvum: The Norwegian Experience. Journal of the American Water Resources Association (JAWRA) 46(1):6-13. DOI: 10.1111/j.1752-1688.2009.00386.x Abstract:, In Norwegian waters, Prymnesium parvum has been reported from Oslofjorden in the south to Spitzbergen in the north. However, blooms of P. parvum have only been reported from the Sandsfjorden system in Ryfylke, Western Norway where the salinity of the permanent brackish layer (2-5 m) typically is in the range of 4-7 psu during the summer months. The first bloom on record occurred in 1989, and it killed 750 metric tons of caged salmon and trout which was a significant economic loss to the fish farming industry. Toxic blooms occurred as well in subsequent years and the number of fish farms in the area decreased considerably as did the occurrence of P. parvum. In 2005, fish farming was reintroduced to the area and again, in 2007 a toxic bloom of P. parvum killed 135 metric tons of caged fish. The Norwegian Institute for Water Research has, in collaboration with "Erfjord Stamfisk" fish farm, set up a monitoring program that includes light microscopy cell counts of Prymnesium, water quality measurements, and observation of the caged fish. A submergible fish net was mounted over the fish pens and during the toxic outbreak of P. parvum in July-August 2007, which was as previous years confined to the upper brackish water layer, the fish nets were lowered to 10 m depths below the surface and fish feeding was temporarily stopped. Despite substantial weight loss, the fish survived the toxic bloom and the economic loss was minimal. Monitoring of P. parvum bloom dynamics in 2007 revealed that populations were initially dominated by the nonmotile forms which were gradually replaced by the flagellated forms. Toxicity was observed when the flagellated cells dominated populations in the summer. Chrysochromulina, solitary small Chaetoceros species, and small centric diatoms co-existed with P. parvum during the monitoring period (June-October). [source]


Kent D. Becher
ABSTRACT: The introduction of nutrients from chemical fertilizer, animal manure, wastewater, and atmospheric deposition to the eastern Iowa environment creates a large potential for nutrient transport in watersheds. Agriculture constitutes 93 percent of all land use in eastern Iowa. As part of the U.S. Geological Survey National Water Quality Assessment Program, water samples were collected (typically monthly) from six small and six large watersheds in eastern Iowa between March 1996 and September 1997. A Geographic Information System (GIS) was used to determine land use and quantify inputs of nitrogen and phosphorus within the study area. Streamliow from the watersheds is to the Mississippi River. Chemical fertilizer and animal manure account for 92 percent of the estimated total nitrogen and 99.9 percent of the estimated total phosphorus input in the study area. Total nitrogen and total phosphorus loads for 1996 were estimated for nine of the 12 rivers and creeks using a minimum variance unbiased estimator model. A seasonal pattern of concentrations and loads was observed. The greatest concentrations and loads occur in the late spring to early summer in conjunction with row-crop fertilizer applications and spring nmoff and again in the late fall to early winter as vegetation goes into dormancy and additional fertilizer is applied to row-crop fields. The three largest rivers in eastern Iowa transported an estimated total of 79,000 metric tons of total nitrogen and 6,800 metric tons of total phosphorus to the Mississippi River in 1996. The estimated mass of total nitrogen and total phosphorus transported to the Mississippi River represents about 19 percent of all estimated nitrogen and 9 percent of all estimated phosphorus input to the study area. [source]

Cumin seed meal with enzyme and polyethylene glycol as an alternative to wheat bran in broiler diets

Behzad Mansoori
Abstract Iran produces about 7000 metric tons of cumin seed meal (CSM) as a by-product of cumin oil extraction factories, annually. To evaluate the nutritional significance of cumin seed meal as a broiler feedstuff, an experiment was conducted using 288 male broiler chicks (14 days old) receiving diets containing 0, 25 and 50 g kg,1 of CSM with and without polyethylene glycol (PEG) and enzyme (GrindazymeÔ GP 15000) for 28 days. Total body weight (BW), body weight gain (WG), feed intake (FI), feed conversion ratio (FCR), weight of carcass and percentage of legs, breast and edible parts of carcass were measured. The results showed that, inclusion of CSM in broiler diets had no negative influence on parameters evaluated compared to the control diet containing wheat bran (P > 0.05). PEG and enzyme had no influence on the bird performance (P > 0.05). There was an increase in relative weight of gizzard when the amount of CSM in the diet was increased (P < 0.01). An increase in relative weight of gizzard in birds that received the CSM diet was likely to be due to the increase in fibre content of CSM diets. In respect of the low price of CSM, it could be concluded that inclusion of CSM at levels used in this experiment has no negative effect on broiler performance and reduces the overall cost of broiler production. Copyright © 2006 Society of Chemical Industry [source]

High-temperature sequestration of elemental mercury by noncarbon based sorbents

Sung Jun Lee
Abstract This work is concerned with sequestration of elemental Hg at high temperatures (900,1100 °C) on a sorbent that is mineral based, rather than carbon based. This sorbent consists of an intimate mixture of CaO, CaCO3, and Al2O3,2SiO2, and is manufactured in industrially relevant quantities (metric tons) from residues produced in paper recycling processes. In contrast to activated carbon (AC), this noncarbon based sorbent has special advantages in that, it can actually enhance fly ash utilization for cement manufacture, rather than diminish it, as is the case for AC. Disperse phase experiments have been conducted, using an externally heated quartz tube reactor, with sorbent feeding rates ranging from 1 to 6 g/h. Preliminary results indicate that Hg removal efficiency is sensitive to sorbent feed rates and to furnace temperature. The Hg removal percentage increased with both these variables. Two mechanisms come into play: an in-flight Hg sorption mechanism, and an Hg sorption mechanism related to sorbent deposits on the reactor wall. A maximum total (in-flight plus deposit-related) Hg removal efficiency of 83,90% was obtained at temperatures of 900,1100 °C. There was negligible sorption by either mechanism at temperatures below 600 °C. Results for the in-flight mechanism alone showed a maximum sorption efficiency at ,900 °C, whereas that on the reactor surface increased monotonically with temperature. This suggests that sorbent deactivation can occur in-flight at high temperatures, which is in agreement with other fixed bed results obtained in this laboratory. Deactivation was not apparent for the sorbent-related substance formed on the reactor wall. Raw and spent sorbents were analyzed by X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive spectrophotometer (SEM-EDS) to identify the sorbent mineral transitions that seem to activate the process. The in-flight mechanisms appear to involve (1) activation of the sorbent, caused most probably by an internal solid,solid reaction, followed by (2) Hg sorption, and (3) possible deactivation, if the temperatures are too high for longer period. Reactor surface mechanisms still remain to be elucidated. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Protein feeds coproduction in biomass conversion to fuels and chemicals

Bruce E. Dale
Abstract Agriculture has changed greatly in the past in response to changing human needs. Now agriculture is being called on to provide raw materials for very large-scale fuel and chemical production. Agriculture will change again in response to this demand and all producers and users of agricultural feedstocks will be affected by this change. For example, livestock feeding practices have already changed in response to the availability of distillers' grains from corn ethanol production. A fuels industry based on herbaceous biomass energy crops will be many-fold larger than the existing corn ethanol industry and will produce its own set of impacts on livestock feeding. We explore here one of these impacts: the availability of large new sources of feed protein from biomass energy crops. In addition to structural carbohydrates, such as cellulose and hemicellulose, herbaceous biomass energy crops can easily be produced with approximately 10% protein, called ,leaf protein'. This leaf protein, as exemplified by alfalfa leaf protein, is superior to soybean meal (SBM) protein in its biological value. Leaf protein recovery and processing fit well into many process flow diagrams for biomass fuels. When leaf protein is properly processed to concentrate it and remove antinutritional factors, as we have learned over the years to do with soybean meal protein, protein in leaf protein concentrate (LPC) will probably be at least as valuable in livestock diets as SBM protein. If LPC is used to meet 20% of total animal protein requirements (i.e., market penetration of 20%) then the potential utilization of leaf protein concentrate could reach as much as 24 million metric tons annually. This leaf protein will replace protein from SBM and other sources. This much leaf protein will reduce by approximately 16 million hectares the amount of land required to provide protein for livestock. Likewise the amount of land required to meet fuel needs will effectively be reduced by 8 million hectares because this land will effectively do ,double duty' by producing needed animal protein as well as feedstocks for fuel production. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd [source]