Bioelectrochemical systems (BESs) have been shown to be useful in removing individual metals from solutions, but effective treatment of electroplating and mining wastewaters requires simultaneous removal of several metals in a single system. To develop multiple-reactor BESs for metals removal, biocathodes were first individually acclimated to three different metals using microbial fuel cells with Cr(VI) or Cu(II) as these metals have relatively high redox potentials, and microbial electrolysis cells for reducing Cd(II) as this metal has a more negative redox potential. The BESs were then acclimated to low concentrations of a mixture of metals, followed by more elevated concentrations. This procedure resulted in complete and selective metal reduction at rates of 1.24 ± 0.01 mg/L-h for Cr(VI), 1.07 ± 0.01 mg/L-h for Cu(II), and 0.98 ± 0.01 mg/L-h for Cd(II). These reduction rates were larger than the no adaptive controls by factors of 2.5 for Cr(VI), 2.9 for Cu(II), and 3.6 for Cd(II). This adaptive procedure produced less diverse microbial communities and changes in the microbial communities at the phylum and genus levels. These results demonstrated that bacterial communities can adaptively evolve to utilize solutions containing mixtures of metals, providing a strategy for remediating wastewaters containing Cr(VI), Cu(II), and Cd(II).

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The solubility of trehalose in a water + ethanol solvent system was measured with the mole fraction of water ranging from 0.000 to 1.000 at temperatures from (288.15 to 318.15) K using the gravimetric method. There was a minimum point on each solubility curve at the mole fraction of water ranging from 0.040 to 0.050. The differential scanning calorimetry measurement results show that anhydrous trehalose (a white flocculent precipitate) appeared in the suspension at water content lower than the critical point. While higher than that point, the crystals in the slurry were still hydrous polymorph which is apparently different from the anhydrous one. The solubility data at water content lower and higher than the critical points were nonlinear surface fitted separately using the combination version of the Jouyban-Acree and van't Hoff models which is a three-dimensional (3D) model. The average relative deviation (ARD) values for trehalose solubility at water content lower and higher than the critical point were 25.71 % and 11.62 %, respectively, which shows the model fitted the data well especially for the latter.

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The solubility of trehalose in the water + methanol solvent system was measured with the mole fraction of water ranging from 0.000 to 0.700, at temperatures from (293.15 to 313.15) K, using the gravimetric method. Two kinds of crystals were collected and measured by differential scanning calorimetry and X-ray diffraction to prove the change of crystal habit for dihydrate trehalose from granular to powderlike at low water content. The turning points of every solubility curve were the critical points of crystal habit transition from the granular dihydrate trehalose (higher than the critical points) to the powderlike dihydrate trehalose (lower than the critical points). The mole fraction of the critical water content ranged from 0.160 to 0.250. The combination version of the Jouyban−Acree and van't Hoff models was used to separately correlate the solubility data lower and higher than the critical points by nonlinear surface fit. The root-mean-square deviation (rmsd) values for the powderlike and the granular dihydrate trehalose solubility data were 1.4900·10 −4 and 3.5919·10 −4 , respectively, which shows the model correlated the data well. ■ INTRODUCTIONTrehalose, a nonreducing disaccharide which is widespread in plants, animals and microbes, is formed by two glucose units linked in an α,α-1,1-glycosidic linkage. 1 Depending on the given thermodynamic conditions, trehalose mainly has two kinds of polymorphs: dihydrate and anhydrous forms. 2 The dihydrate trehalose can be easily obtained by crystallization from supersaturated solutions and is the most stable one. There are four different forms of anhydrous trehalose reported until now. 3 The β-form which is stable at room temperature and less hydroscopic has been obtained when keeping the dihydrate trehalose under vacuum at 130°C for 4 h, 4 or from the transformation of dihydrate trehalose to anhydrous trehalose using ethanol. 3,5,6 The α-form which could be easily rehydrated back to dihydrate trehalose has been observed when keeping the dihydrate trehalose under vacuum at 85°C for 4 h. 4 The γ-form, the mixture of dihydrate and β-form trehalose, has been shown by the shape of the calorimetric curve for the dihydrate trehalose at 5 K·min −1 to 20 K·min −1 . 4 The ε-form has been obtained still by thermal treatment according to Sussich's report. 7 The importance of observing polymorphic forms and solvated varieties has been recognized by most academic and industrial research groups. 8 In our previous work, we determined the solubility of trehalose in a water + ethanol solvent system, and a white flocculent suspension which is the anhydrous form was observed in low water content. Most researches simply involve water + methanol solvents and water + ethanol solvents to determine the solubility results. 9 So it is necessary to determine the solubility of trehalose in the water + methanol solvent system.In this work, the solubility of trehalose in the water + methanol solvent system was measured with the mole fraction of water ranging from 0.000 to 0.700, at temperatures ...