Advanced Materials Research Vols. 724-725

Abstract: In this paper, the possibility and potential of biohydrogen production by co-fermentation of starch wastewater (SW) and WAS under thermophilic temperature was studied in batch fermentation tests. WAS was first pretreated by thermophilic enzyme together with low intensity ultrasound (LIU) to improve the biochemical degradability. Then After 8 h pretreatment, all soluble substances were much higher than raw sludge without pretreatment. In addition, the SCOD, carbohydrate and protein of the tests which were accelerated by low-frequency ultrasound were 11.5% 18.4%, 17.8% higher than the control, respectively. Results from the co-fermentation further demonstrated that the sludge had high pH buffering capacity. A mixing ratio of 1:1 was found to be the best among of all co-fermentation tests. Moreover it was proved in this study that hydrogen production by co-fermentation of starch wastewater and sludge was a promising technology to recovery energy from the waste.

Abstract: 5-hydroxymethylfurfural (HMF) was produced from glucose using WO₃-MoO₃ mixed metal oxides as the catalyst in a biphasic system (H₂O-NaCl/THF), comprised of reactive aqueous phase saturated with NaCl, and containing AlCl₃^.6H₂O, combined with an organic extracting phase consisting of tetrahydrofuran (THF). The influences of different catalysts, initial concentrations of glucose and reaction time on preparation of HMF were investigated. As a result, A HMF yield of 61% could be obtained at 170 °C in 40 min. Recycle of the aqueous phase and WO₃-MoO₃ demonstrated constant activity after 4 cycles of use.

Abstract: Hydrolysis of the aquatic vegetables waste would lead to the generation of some toxic components and by-products, such as weak acids, aldehydes and phenols. They might do harm to sequent fermentation process to some extent. The toxic effect of acetic acid on ethanol fermentation by ethanologenic Escherichia coli SZ470 was investigated. The growth curves of Escherichia coli SZ470, specific growth rate (μ), the ethanol yield and consumption of glucose were compared with different concentrations of acetic acid addition in the fermentation medium. When concentrations of acetic acid exceed 0.8 g/L, the exponential growth phase of Escherichia coli SZ470 was significantly expanded from 10 h to above 12 h, moreover, the ethanol yield and consumption of glucose drastically decreased. Specific growth rate increased as acetic acid concentrations below 0.6 g/L, but fell as acetic acid concentrations exceeded 0.6 g/L, the result indicated that minor amount of acetic acid might be helpful with growth of Escherichia coli SZ470.

Abstract: The article proved the effects of urea treatment on the structure and properties of wheat straw, using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), contact angle analyze (CAA) and thermal gravimetric analysis (TGA) other methods. The results show that the urea treatment of wheat straw epidermis and lignin chemical structure has undergone significant changes, most of the inorganic components of wheat straw has dissolved, making the cellulose from the lignin parcels released while the lignin from hard degradable mesh macromolecules into small molecules of a straight chain of easily biodegradable, so that the anaerobic microorganisms to the degradation of cellulose and lignin can be more easily.

Abstract: Anaerobic fermentation experiment was carried out with manure wastewater to produce biogas by using six parallel glass digesters system. Basic process conditions were chosen reference to previous studies. Based on the theory of methane fermentation, a prediction model was deduced, which can be used to forecast methane production according to a few of process parameters. In the experiment, two pivotal parameters involved in model were calculated, the sludge yield coefficient (Y_H) is 2.829×10^-2 and the sludge digestion coefficient (K_d) is 0.0215. The certain parameters, such as the oxygen equivalent (λ), the difference of COD between influent and effluent (D), the volume of fermentation broth (V), Y_H and K_d were substituted into prediction model, and then got the methanogenesis dynamics model in the process of methane fermentation by manure wastewater.

Abstract: Nutritive salts and complex anaerobic cellulose decomposing bacteria (CACDB) were added for anaerobic digestion process in order to improve biogas production and biodegradability of acid hydrolytic cotton stalk. The results showed that addition of CACDB, nutritive salt I and nutritive salt II could effectively enhance daily biogas production, cumulative biogas and methane yields, in this treatment, the total gas production, daily average gas production, TS gas production rate, VS gas production rate and average yield of methane were all highest and reached 5908.90 mL, 196.96 ± 7.97 mL·d^-1, 143.07 ± 5.79 mL·g^-1, 156.32 ± 6.33 mL·g^-1, 102.58 ± 3.34 mL·d^-1, separately. The addition of CACDB and nutritive salts could improve the biodegradability of acid hydrolytic cotton stalk, in all addition treatments, the degradation rates of cellulose and lignin, VS reduction rates were higher and C/N ratios were lower than control treatment. The SEM analysis showed that the microstructure changes of digestion residues were helpful for biogas production.

Abstract: Steam-exploded cotton stalk was used as raw material in ethanol production through simultaneous saccharification and fermentation by Penicillium Q59 and Saccharomyces cerevisiae P1. The fermentative conditions were firstly examined by single factor experiments to determine the central point in Box-Behnken design, which was explored with expectation to get optimized fermentative conditions for enhancement of ethanol production. The results of optimized fermentative conditions were determined as follows: fermentation time was 10.5 days, bran added percent was 15%, initial pH value was 5.5. Under the optimal conditions, the experimental yield of ethanol was 99.85 ± 4.21 g·kg^-1SECS (steam-exploded cotton stalk), which was close to the theoretical predicting value, it showed the model was feasible. The research results will provide technical reference for further exploitation of cotton stalk.

Abstract: Green liquor, a process liquor of alkali recovery in pulp and papermaking industry, pretreatment used in poplar kraft pulping process and the influences of pretreatment conditions on pentosan extraction have been studied. The results show that the influence of green liquor dosage on pentosan extraction is the most remarkable, with temperature taking the second place and time the third. Under the conditions of liquor ratio 1:4, green liquor dosage 1.5 L/kg (based on oven dried material), temperature 100 °C, time 90 min, higher pentosan extraction ratio of 13.81% (based on the pentosan content of raw material) is achieved. The wood was pulped under normal KP conditions after pretreated by the optimal pentosan extraction conditions. Comparing two kinds of pulp with and without pretreatment at similar stock yield level, the results show that the former has a little lower viscosity, significantly decreased Kappa number and excellent paper physical properties.

Abstract: To address the twin problems of fast depletion of fossil fuels and environmental degradation, there is an urgent need to reduce dependence on petroleum derived fuels for better economy and environment. Adaptation of bio-origin alternative fuels can address both these issues. Liquid bio-origin fuels are renewable fuels coming from biological sources and have proved to be a good substitute for petroleum derived oil and environmentally-sustainable solution. To sustain agricultural and agro-engineering needs blends of linseed oil with diesel is a better solution. Present study shows the comparative assessment of physical and chemical analysis of Linseed oil and its blends asa potential fuel for internal combustion diesel engine. To understand diesel engines fuel properties of vegetable oils and comparable physico-chemical properties such as calorific value, kinematic viscosity and density were measured for different fuel blends to predict its suitability as replacement or extender of mineral diesel. The fatty acid composition was measured by using a chromatograph. From the results, it is clear that the physico-chemical properties of linseed oil lies in close resemblance with lower calorific value high viscosity. When blended in the v/v ratio of 5%, 10%, 15%, 20% its calorific value decreases with increase of percentage blends, whereas viscosity and density increases with increase of blend ratio. Linseed oil hence can be recommended as a potential fuel for Diesel engine in neat or blended form without any major change in present design, in the hour of energy need.

Abstract: A kind of small molecular hemicellulose was prepared from coconut shell by ultrasound-assisted and alkaline hydrogen peroxide extraction. Unlike the common hemicelluloses and celluloses, it is similar to liquid for the hemicelluloses in ethanol solution, but insoluble in it. Through the gel permeation chromatography (GPC) analysis, it was found that its molecular weight is much lower than that of the traditional hemicelluloses, indicting the lower polymerization degree. But from the infrared spectroscopy spectra analysis, this type of small molecular hemicelluloses has the similar infrared spectrum characteristic peaks to that hemicellulose.