Assessment of different carbon and salinity level on growth kinetics,lipid, and starch composition of Chlorella vulgaris SAG 211-12

ABSTRACT

The quality of microalgal biofuel depends on the fatty acid (FA) distribution. A high ratio of saturated fatty acids (SFAs) favors better biofuel characteristics. Palmitic acid (C16:0) and stearic acid (C18:0) are essential FAs for required biodiesel quality. In this study, combined effects of growth medium concentrations of NaCl, glucose and glycerol on cell composition and FA profile of the Chlorella vulgaris SAG 211–12 were investigated. A central composite design (CCD) based design of experiments (DoE) was used for experimental setup. According to experimental results, the maximum mass fraction for palmitic acid (C16:0), 40.67% of total fatty acids, was obtained in the medium supplemented with 0.9% (w/v) NaCl, 0.3% (w/v) glucose, and 0.3% (w/v) glycerol, whereas stearic acid (C18:0) percentage reached the highest value of 22.16% of total fatty acids in the presence of 2.5% NaCl, 0.6% glucose, and 0.6% glycerol. According to the same set of designed experiments, best starch content was found as 22.08% of dry cell weight in a medium containing 2.0% NaCl, 0.3% glucose, and 0.3% glycerol. C16:0 mass fraction as a function of three medium ingredient concentrations was modeled using a Kriging model. Optimum concentrations of NaCl, glucose and glycerol to reach maximum C16:0 fraction were predicted as 0.5, 1, and 1%, respectively.     

Biodiesel synthesis and characterization using welted thistle plant (Carduus acanthoides) as source of new non-edible seed oil

In this work we applied base catalyzed transesterification to convert non-edible welted thistle oil (Carduus acanthoides) as new non-edible feedstock into biodiesel (Fatty acid methyl esters). The highest biodiesel yield of 88% was obtained using optimized reaction conditions of 70°C and 5:1 molar ratio (methanol:oil). The synthesized esters were characterize and confirmed by the application of NMR and FT-IR techniques. Gas chromatography and mass spectroscopy identified different fatty acids as palmatic acid (C16:0), oleic acid (C18:1), linoleic acid (18:2), arachidic acid (C20:0), eicosanic acid (C20:1), and erucic acid (C22:1) in the oil of welted thistle. Six corresponding methyl esters reported in welted thistle oil biodiesel includes 9-hexadecenoic acid, hexadecanoic acid, 9-octadecadienoic acid, 11-eicosanoic acid, eicosanoic acid and 13-docosenoicacid. Fuel properties, such as density @40°C Kg/L (0.8470), kinematic viscosity @ 40°C c St (4.37), flash point (95°C), cloud point (+4°C), pour point (?5°C), and sulfur contents (0.0112% wt) of the biodiesel produced were compatible with American Society for Testing and Materials D 6751 specifications.     

Comparison of Four <Emphasis Type="Italic">Sesbania</Emphasis> Species to Remediate Pb/Zn and Cu Mine Tailings

A 6-month greenhouse pot trial was performed, aimed at screening appropriate Sesbania species for remediation of Pb/Zn and Cu mine tailings. Performances of young seedlings of four Sesbania species (S. cannabina, S. grandiflora, S. rostrata, and S. sesban) were compared with and without inoculation of rhizobia. Seedlings were planted in two types of tailings amended with garden soil or garden soil mixed with river sediment. The results indicated that inoculated plants generally produced a higher biomass than samples without inoculation. Pb/Zn mine tailings containing rather high concentrations of total and water-soluble Cu, Pb, and Zn were toxic to plant growth compared with Cu mine tailings, according to the growth performance of the four species. Sesbania sesban and S. rostrata showed superior growth performance, compared to the other two species. Thus, they can serve as pioneer species to modify the barren environment, by providing organic matter and essential nutrients such as nitrogen, upon decomposition, in a relatively short period of time. This is especially true for S. rostrata, which is an annual plant that forms both stem and root nodules. However, a longer-term field trial should be conducted to investigate if superior species can beneficially modify the habitat for the growth of subsequent plant communities.     

Assessment of biomass and lipid productivity and biodiesel quality of an indigenous microalga Chlorella sorokiniana MIC-G5

Generation of biodiesel from microalgae has been extensively investigated; however, its quality is often not suitable for use as fuel. Our investigation involved the evaluation of biodiesel quality using a native isolate Chlorella sorokiniana MIC-G5, as specified by American Society for Testing and Materials (ASTM), after transesterification of lipids with methanol, in the presence of sodium methoxide. Total quantity of lipids extracted from dry biomass, of approximately 410–450 mg g^?1 was characterized using FTIR and ¹H NMR. After transesterification, the total saturated and unsaturated fatty acid methyl esters (FAMEs) were 43% and 57%, respectively. The major FAMEs present in the biodiesel were methyl palmitate (C16:0), methyl oleate (C18:1), and methyl linoleate (C18:2), and the ¹H NMR spectra matched with criteria prescribed for high-quality biodiesel. The biodiesel exhibited a density of 0.873 g cm^–3, viscosity of 3.418 mm² s^?1, cetane number (CN) of 57.85, high heating value (HHV) of 40.25, iodine value of 71.823 g I₂ 100 g^?1, degree of unsaturation (DU) of 58%, and a cold filter plugging point (CFPP) of –5.22°C. Critical fuel parameters, including oxidation stability, CN, HHV, iodine value, flash point, cloud point, pour point, density, and viscosity were in accordance with the methyl ester composition and structural configuration. Hence, C. sorokiniana can be a promising feedstock for biodiesel generation.     

INACTIVATION OF GIARDIA MURIS CYSTS BY CHLORAMINES1

ABSTRACT: In a study to measure the efficacy of chioramines at inactivating Giardia cysts, the ability of cysts to excyst was measured after exposure to different concentrations of chloramines, for different times, and at different temperatures and pH. The chloramines were generated by mixing ammonium sulfate and sodium hypochlorate in water to approximate a 7:1 chlorine:ammonia ratio by weight. Times of 40, 80, 180, and 270 minutes; temperatures of 3, 10, and 18°C; target chioramine concentrations of 0.4, 1.4, 2.0, and 2.6 mg/L; and pH of 7.0 and 8.5 were the actual values tested. The combinations of these variables that were able to inactivate >99.8 percent of the cysts were a minimum chloramine concentration of 2.26 mg/L applied for 270 minutes at a water temperature of 10°C; and at 18°C, averaged minimum chloramine concentrations of 2.14 and 1.55 mg/L applied for 180 and 270 minutes, respectively. The minimum CT values corresponding to these combinations capable of >99.8 percent cyst inactivation, are 610 at 10°C and 385 at 18°C. Temperature was noted to exert a major effect on the ability of chloramines to inactivate cysts. Modifications of the methods used to generate chloramines may have an effect on the capacity of this disinfectant to inactivate cysts.     

CHLOROPHYLL,PHOSPHORUS, SECCHI DISK,AND TROPHIC STATE1

ABSTRACT: The relationship between chlorophyll u, total phosphorus, secchi disk depth, and trophic state were examined using data on U.S. lakes collected by U.S. EPA's National Eutrophication Survey. By comparing predicted secchi disk depths with observed summer secchi disk depths in 757 lakes, it was determined that in many lakes non-chlorophyll related light attenuation is important in controlling the amount of chlorophyll u produced per unit of total phosphorus. Ranking of 44 lakes by 18 different trophic state measurements and single and multivariable indices were compared with rankings provided by mean summer ambient total phosphorus and chlorophyll u. The trophic state measurements and indices were much more successful in ranking the lakes against total phosphorus than chlorophyll u, indicating that there are differences in the relative trophic rankings of many of the lakes depending upon whether primary nutrients or biological manifestations are used as the ranking mechanism. If the manifestations of nutrients rather than their absolute levels are the primary criteria for beneficial use of lakes, the use of many of the commonly employed trophic state measurements, which assume or imply that there is a constant relationship between total phosphorus or secchi disk and chlorophyll, can lead to erroneous conclusions and unnecessary costly management controls. Secchi disk measurements may be more useful as a predictor of ambient lake total phosphorus concentrations than of chlorophyll.     

Germination,Growth, and Nodulation of Sesbania rostrata Grown in Pb/Zn Mine Tailings

Sesbania rostrata in pure and amended Pb/Zn tailings. About 90% of seeds of S. rostrata germinated in pure Pb/Zn tailings, which contained high concentrations of Pb, Zn, Cu, and Cd. Although seedling growth suffered from the adverse environment of Pb/Zn tailings, they became established on tailings stands, in the greenhouse, as well as on the actual tailings dam, and completed their life cycle in 4 months. Dry matter production and nitrogen accumulation was 3200 kg/ha and 69.4 kg/ha, respectively in the actual tailings dam. Applying inorganic fertilizer to Pb/Zn tailings led to no obvious improvement in growth and nodulation of S. rostrata, while tailings amended by river sediment or domestic refuse rich in organic matter improved the growth and nodulation of the species. Azorhizobium caulinodans survived and formed N-fixing stem and root nodules in S. rostrata grown in pure Pb/Zn tailings with a nodule biomass exceeding 300 mg fresh matter per plant.     

Effects of wood bark and fertilizer amendment on trace element mobility in mine soils, Broken Hill, Australia: implications for mined land reclamation

Soil amendments can immobilize metals in soils, reducing the risks of metal exposure and associated impacts to flora, fauna and human health. In this study, soil amendments were compared, based on "closed system" water extracts, for reducing metal mobility in metal-contaminated soil from the Broken Hill mining center, Australia. Phosphatefertilizer (bovine bone meal, superphosphate, triple superphosphate, potassium orthophosphate) and pine bark (Pinus radiata) were applied to two soils (BH1, BH2) contaminated with mining waste. Both soils had near neutral to alkaline pH values, were sulfide- or sulfate-rich, and contained metal and metalloid at concentrations that pose high environmental risks (e.g., Pb = 1.25 wt% and 0.55 wt%, Zn = 0.71 wt% and 0.47 wt% for BH1 and BH2, respectively). The addition of fertilizers and/or pine bark to both soil types increased water extractable metals and metalloids concentrations (As, Cd, Cu, Fe, Mn, Pb, Sb, Zn) compared with nonamended soils. One or more of the elements As, Cd, Cu, Mn, Pb, and Zn increased significantly in extracts of a range of different soil+pine bark and soil+fertilizer+piner+pine bark tests in response to increased pine bark doses. By contrast, Fe and Sb concentrations in extracts did not change significantly with pine bark addition. Solution pH was decreased by phosphate fertilizers (except for bovine bone meal) and pine bark, and pine bark enhanced dissolved organic carbon. At least in the short-term, the application of phosphate fertilizers and pine bark proved to be an ineffective method for controlling metal and metalloid mobility in soils that contain admixtures of polymetallic, polymineralic mine wastes.     

Transesterification of Caesalpinia eriostachys seed oil using heterogeneous and homogeneous basic catalysts

Caesalpinea eriostachys seed oil, as a source of triglycerides with potential application for biodiesel production in Mexico is introduced. Its lipid profile obtained by Gas Chromatography-Mass Spectrometry (GC-MS) revealed saturated and unsaturated glycerol esters as the constituents. Therefore, heterogeneous and homogeneous catalyzed transesterification reactions were assayed employing ZnAl hydrotalcites and KOH, as the catalysts, respectively. The transesterification reactions yielded 59% for Zn/Al(2), 79% for Zn/Al(4), and 90% for KOH, depicting typical behavior, as in biodiesel production data from literature, where Zn-Al hydrotalcites or KOH were assayed. The caloric, density, viscosity values, and fatty acid methyl esters profile from reaction products were concordant to EN 14214, suggesting C. eriostachys as a promising feedstock for biodiesel production.     

Homogeneous catalysed biodiesel synthesis from Alexandrian Laurel (Calophyllum inophyllum L.) kernel oil using ortho-phosphoric acid as a pretreatment catalyst

In this study, a non-edible seed oil of Alexandrian Laurel (Calophyllum inophyllum L.) with higher free fatty acid content has been harnessed to produce biodiesel by transesterification process. The 20.2% free fatty acid (FFA) content was first reduced to 12.9% by using TOP degumming process. Ortho-phosphoric acid was used to esterify the refined kernel oil. Transesterification reaction was performed with NaOH as an alkaline catalyst and methanol as an analytical solvent. The effects of methanol to oil molar ratio (MR), catalyst concentration (CC), reaction temperature (TP), reaction time (TM), and stirrer speed (SS) on biodiesel conversion were studied to optimize the transesterification conditions using DOE- approach. The experimental study revealed that 9:1 MR, 0.8 wt.% CC, 60°C TP, 75 min TM and 1000 rpm SS were the optimal process control variables. The study indicated that CC was the most important control parameter in optimal methyl ester production. The optimal treatment combination yielded 97.14% of biodiesel. The profile of biodiesel was determined using gas chromatography-mass spectrometry. ¹H NMR spectrum of Calophyllum inophyllum methyl ester (CIME) has been reported. The properties of the biodiesel have been found within specifications of the ASTM D6751 and EN 14214 standards and hence could be considered as a suitable alternative to diesel fuel for sustainable circulation of carbon.     

Biohydrogen production by Clostridium butyricum and Rhodopseudomonas palustris in Co-cultures

This study evaluated biohydrogen production by co-culture of Clostridium butyricum and Rhodopseudomonas palustris. C. butyricum and R. palustris were grown separately and together as batch cultures. Hydrogen production, growth, NH₄-N, total volatile fatty acid production, and sucrose degradation were monitored. The hydrogen production of the co-culture produced 562 ml, R. palustris 426 ml, and C. butyricum 333 ml. The co-culture produced 2.16 mol H₂/mol sucrose, C. butyricum and R. palustris produced 1.77 and 1.64 mol H₂/mol sucrose, respectively. The co-culture was more efficient in the hydrogen production. Therefore, the co-culture is a good method for biohydrogen fermentation.     

Influence of Landfill Gas on the Microdistribution of Grass Establishment Through Natural Colonization

Many revegetated landfills have poor cover including bare areas where plants do not grow. This study, on the Bisasar Road Landfill site in South Africa, assessed grass species preferences to microhabitat conditions in a mosaic of patches of well-established grassed areas and bare, nonvegetated areas. Factors, including soil CO₂, CH₄, O₂, nutrients, and other general soil conditions, were measured in relation to species distribution and grass biomass in the field. Cynodon dactylon was the dominant grass in the established grass areas but was less abundant in the areas bordering the bare areas where Paspalum paspalodes and Sporobolus africanus were common. A number of soil factors measured were significantly correlated with grass biomass and these included Mg, Ca, Zn, Mn, K, temperature, moisture, and CO₂. However, a laboratory bioassay using the growth of C. dactylon with soils removed from the landfill indicated that there were no differences in the soils from the bare areas and those that supported high plant biomass. Thus, no nutrient deficiency or chemical toxicity was inherent in the soil in the laboratory. The results of the field investigation and bioassay indicated that soil CO₂ as a result of landfill gas infiltration into the root zone was probably the main factor causing bare areas on the landfill where no grass species could colonize and grow and that C. dactylon was more sensitive to elevated soil CO₂ than other grass species such as P. paspalodes and S. africanus.     

Some Physical Properties of CdO Thin Films Used as Window Material in Photovoltaic Solar Cells

Abstract

CdO thin films which can be used in photovoltaic solar cells as window material were obtained on glass substrates at 250°C and 300°C substrate temperatures using Ultrasonic Spray Pyrolysis (USP) technique. The electrical, optical, structural, and surface properties of the films were investigated for two different substrate temperatures. After all investigations, it is concluded that, the CdO thin films can be used in photovoltaic solar cells as window materials and cell efficiencies can be increased using different growth parameters.     

Evaluation of Biogas Yield of Selected Ratios of Cattle,Swine, and Poultry Wastes

Production of biogas from animal wastes could lessen the problems of energy shortage and indiscriminate animal waste disposal. A study of anaerobic digestion of selected ratios of cattle, swine, and poultry wastes was carried out to evaluate their biogas yields. Cattle (C), swine (S), and poultry (P) wastes were mixed as C:S:P in the following ratios: 1:0:0 (control), 1:0:1, 4:1:3, 2:1:1, 4:3:1, and 1:1:0 by mass to obtain six samples of of 0.4 kg each, referred to as samples 1 to 6 respectively. A quantity (0.1 kg) of inoculum (obtained by pre-fermenting equal masses of poultry waste and water for 50 days under anaerobic condition) and 0.5 kg of water were added to each of the samples. The resulting slurries were digested in triplicates for 30 days in 1.3 L laboratory-scale anaerobic digesters. The volume of biogas produced was obtained by downward displacement of water in a measuring cylinder. The cumulative biogas yields of samples 1 to 6 were 332.5, 497.5, 487.5, 467.5, 457.5, and 430.0 cm³/kg slurry respectively. The cumulative biogas yields of samples 2 and 3 were significantly (p < 0.05) higher than those of the other samples but not significantly (p > 0.05) different from each other. However, the cumulative biogas yield of sample 1 was significantly (p < 0.05) lower than those of the other samples. The study revealed that a blend of equal masses of cattle and poultry wastes is optimum for biogas production.     

Estimation of Suspended‐Sediment Concentration From Total Suspended Solids and Turbidity Data for Kentucky, 1978‐19951

Williamson, Tanja N. and Charles G. Crawford, 2011. Estimation of Suspended‐Sediment Concentration From Total Suspended Solids and Turbidity Data for Kentucky, 1978‐1995. Journal of the American Water Resources Association (JAWRA) 47(4):739‐749. DOI: 10.1111/j.1752‐1688.2011.00538.x Abstract: Suspended sediment is a constituent of water quality that is monitored because of concerns about accelerated erosion, nonpoint contamination of water resources, and degradation of aquatic environments. In order to quantify the relationship among different sediment parameters for Kentucky streams, long‐term records were obtained from the National Water Information System of the U.S. Geological Survey. Suspended‐sediment concentration (SSC), the parameter traditionally measured and reported by the U.S. Geological Survey, was statistically compared to turbidity and total suspended solids (TSS), two parameters that are considered surrogate data. A linear regression of log‐transformed observations was used to estimate SSC from TSS; 72% of TSS observations were less than coincident SSC observations; however, the estimated SSC values were almost as likely to be overestimated as underestimated. The SSC‐turbidity relationship also used log‐transformed observations, but required a nonlinear, breakpoint regression that separated turbidity observations ≤6 nephelometric turbidity units. The slope for these low turbidity values was not significantly different than zero, indicating that low turbidity observations provide no real information about SSC; in the case of the Kentucky sediment record, this accounts for 30% of the turbidity observations.     

Chromosomal genes conferring tolerance to heavy metal (Ag) toxicity

Bacterial strains were isolated from sediment samples from the Thames River. Successive transfer growth of the various strains on nutrient agar containing increasing concentrations of AgNO₃ revealed that three of the bacterial isolates were found to be capable of tolerating high concentrations of AgNO₃ ranging from 20 to 80 mM on a solid medium and up to 10 mM AgNO₃ in liquid medium. Molecular characterization and identification based on 16S rDNA gene sequencing of three strains of bacteria that are tolerant to silver nitrate showed that the major tolerant strains include the superbug, Shewanella oneidensis, Pseudomonas sp. and Bacillus sp. Protein extraction and two-dimensional (2D) sodium dodecyl sulfate SDS-polyacrylamide gel electrophoresis (PAGE) of the protein extracts in bacteria exposed to very high concentrations of AgNO₃ revealed a general reduction in the number of expressed proteins, although two protein spots were conspicuously over expressed in the exposed bacteria compared to control. The N-terminal amino acid sequence analysis of the protein spots identified the major up-regulated proteins as the outer membrane protein To1C (45.2 kDa) and the structural protein of the flagellar filament, flagellin (28.34 kDa), encoded for by the to1C and fliC genes, respectively. The roles of these genes in a number of multi-drug resistant pathogen and potentials for biotechnological applications in toxic metal control for treatment of contaminated ecosystems and biomining were discussed.     

Evaluation of heavy metals accumulation by two emergent macrophytes from the polluted soil: an experimental study

The concentrations of copper (Cu) and lead (Pb) in, and the biomass of, the different parts of Persicaria glabra (Willd.) Gamez and Juncellus alopecuroides (Rottb.) C.B.Cl. were evaluated while grown in pots under laboratory conditions. Cu and Pb were added as sulphates (50, 100, 200, 400 mg/kg) to the pots. Heavy metal concentrations in the plants were measured by atomic absorption spectrometry. Results reveal that the biomass of J. alopecuroides (particularly roots) was higher than P. glabra, and that the growth tendency of macrophytes decreased with increasing heavy metal concentration in the soil, while in P. glabra, biomass went on increasing with the increase in copper concentration. Heavy metal accumulation in the roots was more than in aerial parts, and, therefore, barring two exceptions, the transfer factor of heavy metals from roots to aerial parts showed as less than 1, suggesting less transfer of heavy metals from roots to aerial parts. Thus, these macrophytes are efficient accumulators of trace elements, particularly J. alopecuroides, which can be recommended for biofiltration of heavy metals from contaminated soils.     

INUNDATION TOLERANCES OF RIPARIAN WILLOWS AND COTTONWOODS1

ABSTRACT: Throughout western North America, willows and cottonwoods are dominant woody plants in riparian zones, streamside areas that are periodically flooded. This study compared tolerances of willows‐Salix discolor, S. exigua, and S. lutea‐and cottonwoods‐Populus angustifolia, P balsamifera, and P deltoides‐to water inundation, one component of stream flooding. Rooted cuttings were grown for 152 days in 10 cm tall pots in water depths from 2.5 to 10 cm (inundated). Shoot and root elongation growth of the inundated cottonwoods were reduced 23 and 45 percent, while S. lutea was relatively unaffected and the inundated sandbar willow, S. exigua, displayed 72 and 43 percent increases in shoot and root elongation. The inundation reduced transpiration in P deltoides and for mature P balsamifera trees that were flooded by a small reservoir on Willow Creek, Alberta. Those flooded trees died in their second year of inundation. The greater inundation tolerance of willows versus cottonwoods is consistent with observations along Midvale Creek, Montana, where beaver dams created a pond in which P trichocarpa died while willows thrived after five years. These patterns of inundation tolerance are consistent with elevational zones of occurrence as willows‐and particularly the sandbar willow—occur at low elevations close to the stream. The understanding of inundation tolerances should assist in the provision of hydrologic patterns that will conserve and restore these shrubs and trees along streams and could permit their establishment along artificial reservoirs.     

Biomass from phytopathogens and culture conditions improve Penicillium chrysogenum antimicrobial activity and antifungal compounds production

The present study evaluated the effect of culture conditions and phytopathogenic strain co-culture on the production of antimicrobial metabolites and antifungal activity of Penicillium chrysogenum R1, which PCR identified. Antimicrobial activity was determined using the Hunter-Hunter experimental design with three factors (pH, incubation temperature, and inoculum, at two levels each). The antifungal metabolites, β 1-3 glucanase and chitinase, produced in the presence of live and inactivated Fusarium oxysporum Fsox C11 biomass, were evaluated using HPLC-MS and GC-MS. Results showed that P. chrysogenum inhibited the growth of five phytopathogenic fungal strains, and the most significant inhibition was observed for F. oxysporum Fsox C11. The best conditions to achieve the highest antifungal activity of the cell-free extract were pH 7, 28°C, 1 × 10⁶ spores/mL, and 144 h of fermentation, observing 86% inhibition of F. oxysporum Fsox C11 growth. Production of antifungal metabolites such as 1,4-benzoquinone imine, viridicatic acid, phenol-5-methyl-2-(1-methyl ethyl), and hydrolytic enzymes β 1-3 glucanase and chitinase was detected. The results define the perspective in designing new processes and products for biocontrol phytopathogens.     

Projected Freshwater Withdrawals Under Efficiency Scenarios for Electricity Generation and Municipal Use in the United States for 20301

Chen, Limin, Sujoy B. Roy, and Robert A. Goldstein, 2012. Projected Freshwater Withdrawals Under Efficiency Scenarios for Electricity Generation and Municipal Use in the United States for 2030. Journal of the American Water Resources Association (JAWRA) 1‐16. DOI: 10.1111/jawr.12013 Abstract: Water withdrawals in the United States (U.S.) have been relatively uniform over the past two decades on a nationally aggregated basis, although on a more highly resolved geographical basis, increases have occurred, largely associated with growth in population and the cooling needs for new electricity generation. Using recent county‐level water use data, we develop projections for five different scenarios, bracketing a range of future conditions, and representing different levels of efficiency in the municipal and electricity generation sectors, where the municipal sector includes public and self‐supplied domestic withdrawals. Starting with the 2005 estimate of 347 billion gallons per day (bgd) of freshwater withdrawal in the continental U.S., our analysis shows that under a business‐as‐usual scenario of growth, there will be a need for additional water over current levels: 11 bgd in the municipal sector, with a smaller requirement for new electricity generation (1 bgd). However, we also estimate that withdrawals could be reduced significantly over current levels, through increased water use efficiencies in the electric power and municipal sectors. The study shows that if water withdrawals are to be held at their current levels for the thermoelectric and municipal sectors individually at a county level over the next 25 years, large improvements in efficiency will be needed in many parts of the Southeast and Southwest.