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A rotating-perforated-tubes biofilm reactor was used for treatment of synthetic wastewater at different operating conditions. The biofilm reactor consisted of two sections each having 25 perforated tubes mounted on three perforated discs. The battery of the tubes was rotated with the aid of a shaft and a motor. Effects of major process variables such as feed wastewater flow rate and COD concentration on the system performance were investigated. Kinetics of COD removal was investigated and kinetic constants determined by using the experimental data. An empirical design equation was developed to quantify the system's performance as a function of major process variables.

Diluted cheese whey (CW) solutions with different initial COD contents (4,800-25,000 mg l) were electro-hydrolyzed by application of constant DC voltage (3 V) for hydrogen gas production and COD removal. The highest cumulative hydrogen production (3,923 ml), hydrogen yield (1,719 ml H g COD), hydrogen formation rate (699 ml d), and percent hydrogen (99.2 %) in the gas phase were obtained with the highest initial COD of 25,025 g COD l with an energy conversion efficiency of 90.3 %. Hydrogen gas production in water and cheese whey controls were negligible indicating no significant H gas production by electrolysis of water and fermentation of cheese whey. Percent COD removals were between 18 and 20 % for initial CODs above 11,500 mg l. Major COD removal mechanism was anaerobic fermentation of carbohydrates producing volatile fatty acids (VFA) and CO. Hydrogen gas was produced by reaction of (H+) ions released from VFAs and electrons provided by DC current. Electro-hydrolysis of CW solution was proven to be an effective method of H gas production with simultaneous COD removal. [ABSTRACT FROM AUTHOR]

Dark fermentative hydrogen gas production from cheese whey powder solution was realized at 55°C. Experiments were performed at different initial biomass concentrations varying between 0.48 and 2.86 g L−1 with a constant initial substrate concentration of 26 ± 2 g total sugar (TS) per liter. The highest cumulative hydrogen evolution (633 mL, 30°C), hydrogen yield (1.56 mol H2 mol−1 glucose), and H2 formation rate (3.45 mL h−1) were obtained with 1.92 g L−1 biomass concentration. The specific H2 production rate decreased with increasing biomasss concentration from the highest value (47.7 mL g−1 h−1) at 0.48 g L−1 biomass concentration. Total volatile fatty acid concentration varied beetween 10 and 14 g L−1 with the highest level of 14.2 g L−1 at biomass concentration of 0.48 g L−1 and initial TS content of 28.4 g L−1. The experimental data were correlated with the Gompertz equation and the constants were determined. The most suitable initial biomass to substrate ratio yielding the highest H2 yield and formation rate was 0.082 g biomass per gram of TS. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 931-936, 2012 [ABSTRACT FROM AUTHOR]

Abstract: Waste ground wheat was subjected to acid hydrolysis (pH = 3.0) at 90 °C for 15 min using an autoclave. The sugar solution obtained from acid hydrolysis was subjected to dark fermentation for hydrogen gas production after neutralization. In the first set of experiments, initial total sugar concentration was varied between 3.9 and 27.5 g L−1 at constant biomass (cell) concentration of 1.3 g L−1. Biomass concentration was varied between 0.28 g L−1 and 1.38 g L−1 at initial total sugar concentration of 7.2 ± 0.2 g L−1 in the second set of experiments. The highest hydrogen yield (1.46 mol H2 mol−1 glucose) and the specific formation rate (83.6 ml H2 g−1 cell h−1) were obtained with 10 g L−1 initial total sugar concentration. Biomass (cell) concentration affected the specific hydrogen production rate yielding the highest rate (1221 ml H2 g−1 cell h−1) and the yield at the lowest (0.28 g L−1) initial biomass concentration. The most suitable Xo /So ratio, maximizing the yield and specific rate of hydrogen gas formation was Xo /So  = 0.037. Dark fermentation of acid hydrolyzed ground wheat was found to be more beneficial as compared to simultaneous bacterial hydrolysis and fermentation. [Copyright &y& Elsevier]

Abstract: Batch dark fermentation experiments were performed to investigate the effects of biomass and substrate concentration on bio-hydrogen production from acid hydrolyzed ground wheat at 55 °C. In the first set of experiments, the substrate concentration was constant at 20 g total sugar L−1 and biomass concentration was varied between 0.52 and 2.58 g L−1. Total sugar concentration was varied between 4.2 and 23.7 g L−1 in the second set of experiments with a 1.5 g L−1 constant biomass concentration. The highest cumulative hydrogen formation (582 mL, 30 °C, 1 atm), formation rate (5.43 mL h−1) and final total volatile fatty acid (TVFA) concentration (6.54 g L−1) were obtained with 1.32 g L−1 biomass concentration. In variable substrate concentration experiments, the highest cumulative hydrogen (365 mL) and TVFA concentration (4.8 g L−1) were obtained with 19.25 g L−1 initial total sugar concentration while hydrogen gas formation rate (12.95 mL h−1) and the yield (200 mL H2 g−1 total sugar) were the highest with 4.2 g L−1 total sugar concentration. [Copyright &y& Elsevier]

Abstract: Para-chlorophenol (4-chlorophenol, 4-CP) containing synthetic wastewater was treated using a rotating perforated tubes biofilm reactor (RTBR). Box–Wilson statistical experiment design and response surface methodology (RSM) were used to investigate the effects of the feed COD, 4-CP contents and the A/Q (biofilm surface/flow rate) ratio on percent COD, 4-CP and toxicity removals. Increases in A/Q ratio and the feed COD contents improved COD, 4-CP and toxicity removals. High feed 4-CP contents adversely affected the system performance due to toxic effects of 4-CP on microorganisms. High A/Q ratio and feed COD contents were required for effective 4-CP and toxicity removals at high feed 4-CP contents. More than 95% 4-CP and toxicity removals were obtained with an A/Q ratio of 186m2 d m−3, and feed COD of 6000mg L−1 with the feed 4-CP content of 1000mg L−1. The RTBR was proven to be more efficient than the RBBR used for the same purpose in our previous studies. [ABSTRACT FROM AUTHOR]

Abstract: Advanced oxidation of amoxicillin was realized in aqueous solution by using Fenton''s reagent treatment. Box–Behnken statistical experiment design was used to determine the effects of reagent concentrations on amoxicillin degradation and mineralization. Amoxicillin (10–200mgL−1), hydrogen peroxide (10–500mgL−1) and Fe(II) (0–50mgL−1) concentrations were considered as independent variables in batch oxidation experiments. Percent amoxicillin and total organic carbon (TOC) removals (mineralization) were considered as the objective functions to be maximized. Required reaction times were 2.5min and 15min, respectively for degradation and mineralization of amoxicillin. Both peroxide and amoxicillin concentrations affected the extent of amoxicillin degradation and mineralization. Complete amoxicillin degradation was obtained within 2.5min while 37% mineralization took place within 15min. The optimum peroxide/Fe/amoxicillin ratio resulting in complete amoxicillin degradation and 37% mineralization was 255/25/105mgL−1. [Copyright &y& Elsevier]

Abstract: Bio-hydrogen production by combined dark and light fermentation of ground wheat starch was investigated using fed-batch operation. Serum bottles containing heat-treated anaerobic sludge and a mixture of Rhodobacter sp. was fed with a medium containing 20gdm−3 wheat powder (WP) at a constant flow rate. The system was operated at different initial dark/light biomass ratios (D/L). The optimum D/L ratio was 1/2 yielding the highest cumulative hydrogen (1548cm3), yield (65.2cm3 g−1 starch), and specific hydrogen production rate (5.18cm3 g−1 h−1). Light fermentation alone yielded higher hydrogen production than dark fermentation due to fermentation of volatile fatty acids (VFAs) to H2 and CO2. The lowest hydrogen formation was obtained with D/L ratio of 1/1 due to accumulation of VFAs in the medium. [Copyright &y& Elsevier]

Composition of the mixed culture was varied in combined dark-light fermentation of wheat powder starch in order to improve hydrogen gas formation rate and yield. Heat-treated anaerobic sludge and pure culture of Clostridium beijerinckii ( DSMZ 791 T) were combined with two different light fermentation bacteria of Rhodobacter sphaeroides (RS-NRRL and RS-RV) in order to select a more suitable mixture resulting in high hydrogen yield and formation rate. A combination of the anaerobic sludge and RS-NRRL yielded the highest cumulative hydrogen (CHF = 140 ml), the highest yield (0.36 mol H2 mol−1 glucose) and specific hydrogen formation rate (2.5 ml H2 g−1 biomass h−1). During dark fermentation (70 h) hydrogen was produced simultaneously by the dark and light fermentation bacteria using glucose from hydrolyzed starch. However, only light fermentation bacteria produced hydrogen from VFA’s derived from dark fermentation after a long adaptation period. [ABSTRACT FROM AUTHOR]

Advanced oxidation of simazine in aqueous solution by the peroxone (hydrogen peroxide/ozone) treatment was investigated using Box-Behnken statistical experiment design and response surface methodology. Effects of pH, simazine and H2O2 concentrations on percent simazine and total organic carbon (TOC) removals were investigated. Ozone concentration was kept constant at 45 mg L-1. The optimum conditions yielding the highest simazine and TOC removals were also determined. Both simazine and peroxide doses affected simazine removal while pH and pesticide dose had more pronounced effect on mineralization (TOC removal) of simazine. Nearly 95% removal of simazine was achieved within 5 min for simazine and peroxide concentrations of 2.0 and 75 mg L-1, respectively at pH=7. However, mineralization of simazine was not completed even after 60 min at simazine doses above 2 mg L-1 indicating formation of some intermediate compounds. The optimum H2O2/pH/Simazine ratio resulting in maximum pesticide (94%) and TOC removal (82%) was found to be 75/11/0.5(mg L-1). [ABSTRACT FROM AUTHOR]

Abstract: Removal of simazine from aqueous solution by Fenton''s reagent oxidation was investigated. Box–Behnken statistical experiment design and the response surface methods were used to investigate the effects of simazine, H2O2 and Fe (II) concentrations on simazine degradation and mineralization. Total organic carbon (TOC) and simazine removals were investigated at different reagent doses to determine the experimental conditions yielding the highest removal of simazine and TOC. Fe (II) concentration had more profound effect than H2O2 for simazine removal while all parameters affected mineralization (TOC removal). Complete disappearance of simazine was achieved within 6min reaction period. However, only 32% of simazine was mineralized after 15min indicating formation of some intermediate products. The optimal H2O2/Fe (II)/simazine ratio resulting in the maximum pesticide (100%) and TOC removal (32%) was found to be 55/15/3 (mgL−1). The initial rate of simazine degradation was found to be first-order with respect to the initial simazine concentration. [Copyright &y& Elsevier]