Integrated production of second generation ethanol and lactic acid from steam-exploded elephant grass.

Elephant grass was subjected to steam explosion to enhance cellulose accessibility and convert it into ethanol. After catalyzed pretreatment at 190 °C for 5 min, enzymatic hydrolysis was carried out using high rate of solid loading combined with different enzyme dosages. Assays employing 20% (w/v) solids loading and an enzyme dosage of 20 FPU g-1 substrate led to a yield of 86.02 g glucose released per 100 g potential glucose in the water insoluble solids. This condition was selected to carry out the simultaneous saccharification and fermentation procedure through S. cerevisiae CAT-1, producing 42.25 g L-1 ethanol with a yield of 74.57% regard to the maximum theoretical. The liquor containing C5 and C6-sugars was successfully converted into lactic acid using L. buchneri NRRL B-30929, resulting in 13.35 g L-1 with a yield of 68.21% in relation to the maximum theoretical.

Degradation of ß-blockers in hospital wastewater by means of ozonation and Fe2+/ozonation.

This study investigates the degradation of the ß-blockers in hospital wastewater by direct ozonation and Fe2+/ozonation with a focus on measurements at different initial pHs and Fe2+ concentrations, and the determination of kinetic constants. The results showed that these 'emerging contaminants' were completely degraded, when the removal rate of organic matter reached 30.6% and 49.1% for ozonation and Fe2+/ozonation, respectively. Likewise, the aromaticity removal rates were 63.4% and 77.9% for ozonation and Fe2+/ozonation, respectively. The experimental design showed that pH was the variable which had the greatest effect on the Fe2+/ozonation. The kinetic constants of atenolol, metoprolol and propranolol degradation by direct ozonation complied with pseudo-first-order conditions, while Fe2+/ozonation was suited to a biphasic degradation model. The k obs tended to rise when the pH increases; propranolol showed high k obs, which can be attributed to the naphthalene group (an electron-rich moiety). The identification of degradation products was carried out in aqueous solution using HPLC-MS2, followed by a suggestion of degradation pathways by means of ozonation. The degradation products proved to be dependent on the initial pH, and followed pathways that are based on direct ozonolysis and free radicals.

PDMS extraction bars for the determination of volatile aromatic hydrocarbons in water and wastewater.

In this study, the preparation and application of extraction bars of PDMS were investigated to preconcentrate and determine benzene, toluene, ethylbenzene, and xylene in water and wastewater by means of HPLC with fluorescence detection. Aliquot samples from hospital wastewater were used as the model effluent. The independent variables for the sorptive extraction were as follows: ionic strength (added amounts of NaCl); pH; temperature and time of absorption; temperature and time of desorption. Under optimized conditions, by using a factorial design, the suspended extraction bars could allow the determination of benzene, toluene, ethylbenzene, and xylene (1.20 ± 0.05 µg/L; 10.40 ± 0.02 µg/L; 1.80 ± 0.04 µg/L; 15.9 ± 0.04 µg/L, respectively) in hospital effluent (fortified samples), by recoveries of 71.9 ± 4.9 to 74.8 ± 5.6%. This procedure represents an innovation that eliminates the time-consuming stage of vacuum microfiltration, and allows the determination of volatile organic compounds by HPLC. As far as we know, this procedure is original and represents an important contribution to the field.