Xuebin Lu

Optimization of H2SO4-catalyzed hydrothermal pretreatment of rapeseed straw for bioconversion to ethanol: focusing on pretreatment at high solids content.

A central composite design of response surface method was used to optimize H(2)SO(4)-catalyzed hydrothermal pretreatment of rapeseed straw, in respect to acid concentration (0.5-2%), treatment time (5-20 min) and solid content (10-20%) at 180 degrees C. Enzymatic hydrolysis and fermentation were also measured to evaluate the optimal pretreatment conditions for maximizing ethanol production. The results showed that acid concentration and treatment time were more significant than solid content for optimization of xylose release and cellulose recovery. Pretreatment with 1% sulfuric acid and 20% solid content for 10 min at 180 degrees C was found to be the most optimal condition for pretreatment of rapeseed straw for ethanol production. After pretreatment at the optimal condition and enzymatic hydrolysis, 75.12% total xylan and 63.17% total glucan were converted to xylose and glucose, respectively. Finally, 66.79% of theoretical ethanol yielded after fermentation.

Microwave pretreatment of rape straw for bioethanol production: focus on energy efficiency.

The energy efficiency of microwave-assisted dilute sulfuric acid pretreatment of rape straw for the production of ethanol was investigated. Different microwave energy inputs and solid loadings were tested to find economic pretreatment conditions. The lowest energy consumption was observed when solid loading and energy input were fixed at 50% (w/w) and 54 kJ (900 W for 1 min), respectively, and amounted to 5.5 and 10.9 kJ to produce 1g of glucose after enzymatic hydrolysis and 1g ethanol after fermentation, respectively. In general, 1g ethanol can produce about 30 kJ of energy, and therefore, the energy input for the pretreatment was only 35% of the energy output. The approach developed in this study resulted in 92.9% higher energy savings for producing 1g ethanol when compared with the results of microwave pretreatments previously reported.

Excess sludge reduction using pilot-scale lysis-cryptic growth system integrated ultrasonic/alkaline disintegration and hydrolysis/acidogenesis pretreatment

A pilot-scale lysis-cryptic growth system was built and operated continuously for excess sludge reduction. Combined ultrasonic/alkaline disintegration and hydrolysis/acidogenesis were integrated into its sludge pretreatment system. Continuous operation showed that the observed biomass yield and the sludge reduction efficiency of the lysis-cryptic growth system were 0.27 kg VSS/kg COD consumed and 56.5%, respectively. The water quality of its effluent was satisfactory. The sludge pretreatment system performed well and its TCOD removal efficiency was 7.9% which contributed a sludge reduction efficiency of 2.1%. The SCOD, VFA, TN, NH(4)(+)-N, TP and pH in the supernatant of pretreated sludge were 1790 mg/L, 1530 mg COD/L, 261.1mg/L, 114.0mg/L, 93.1mg/L and 8.69, respectively. The total operation cost of the lysis-cryptic growth system was

Enhanced bio-decolorization of azo dyes by co-immobilized quinone-reducing consortium and anthraquinone

0.186/m(3) wastewater, which was 11.4% less than that of conventional activated sludge (CAS) system without excess sludge pretreatment.

Kinetic study for Fe(NO3)3 catalyzed hemicellulose hydrolysis of different corn stover silages

In the present study, the accelerating effect of co-immobilized anthraquinone and quinone-reducing consortium was investigated in the bio-decolorization process. The anthraquinone and quinone-reducing consortium were co-immobilized by entrapment in calcium alginate. The co-immobilized beads exhibited good catalytic activity and increased the decolorization rate for many kinds of azo dyes. The reusability of the co-immobilized beads was evaluated with repeated-batch decolorization experiments. After ten repeated experiments, the decolorization rate of co-immobilized beads retained over 92.8% of their original value. Furthermore, acclimatized quinone-reducing consortium was analyzed by denaturing gradient gel electrophoresis (DGGE) and 16S rDNA gene sequencing to get the complete picture of its diversity. This study explored a great improvement of conventional treatment system and the new bio-treatment concept.

Influence of NaOH and thermal pretreatment on dewatered activated sludge solubilisation and subsequent anaerobic digestion: Focused on high-solid state

Five inorganic salts, ZnCl(2), FeSO(4), Fe(2)(SO(4))(3), FeCl(3) and Fe(NO(3))(3) were chosen as catalysts to determine their effects on hemicellulose hydrolysis in control silage (no silage additive), and the results indicated that Fe(NO(3))(3) was the most efficient catalyst for hemicellulose hydrolysis. The kinetics of Fe(NO(3))(3) catalyzed hydrolysis for control silage and acid silage (treatment with HNO(3)) were investigated at various pretreatment conditions. The results demonstrated that Saeman model was well consistent with Fe(NO(3))(3) catalyzed hydrolysis reaction for corn stover silage, and kinetic parameters for this model were developed by the Arrhenius equation. Optimum pretreatment conditions were 0.05 M Fe(NO(3))(3) at 150°C for 21.2 min for control silage and 12.7 min for acid silage, which obtained the maximum xylose yields 81.66% and 93.36% of initial xylan, respectively. The activation energies for hemicellulose hydrolysis in control and acid silage ranged from 44.35 to 86.14 kJ/mol and from 3.11 to 34.11 kJ/mol, respectively.

Study on the waste liquid crystal display treatment: focus on the resource recovery.

In this study, the influence of NaOH and thermal pretreatment of dewatered activated sludge (DAS) on the high-solid solubilisation and anaerobic digestion was separately investigated by monitoring common parameters. The results indicated that COD, proteins and carbohydrates were efficiently solubilised in both NaOH and thermal pretreated DAS samples. For NaOH pretreatment, the concentrations of volatile fatty acids (VFAs) and total ammonium nitrogen (TAN) firstly increased followed by decreasing with NaOH dose increasing. However, they decreased with the severity of thermal pretreatment. During the batch digestion experiments (at 37°C), for 80mg NaOHg(-1) total solid (TS) DAS pretreatment it resulted in a 6.99% decrease in cumulative methane yield (CMY) compared to untreated DAS. While for 80, 100, 120°C and 20mg NaOH pretreatment, CMY increased by 15%, 42%, 71% and 35%, respectively, in comparison to untreated DAS.

Pretreatment of corn stover with diluted acetic acid for enhancement of acidogenic fermentation

A process combined pyrolysis and acid immersion was proposed in this study to dispose the hazardous liquid crystal display (LCD) waste for recovering valuable resources. The thermogravimetric (TG) analysis and fixed bed pyrolysis were investigated for the polarizing film that was separated from LCD. The results suggested the liquid product mainly contained acids, esters and aromatics should be upgraded such as hydrotreating process before used as industrial feedstock or fuel source. The gaseous product mainly consisted of H(2), CO, CO(2) and CH(4) can be used as a valuable fuel. The sulfuric acid immersion experiments were studied for recovering indium from the LCD glass after stripping the polarizing film. Central composite design (CCD) under response surface methodology (RSM) was used to optimize the acid immersion process and the results indicated the indium recovery can be fitted based on the actual value to a polynomial quadratic equation and the temperature was more essential factor than time and acid concentration in the studied ranges. The optimum processing condition was obtained with time 42.2 min, temperature 65.6 °C and acid concentration 0.6 mol/L. Under the optimal conditions, the indium recovery was close to 100%.

Two-step pretreatment of corn stalk silage for increasing sugars production and decreasing the amount of catalyst.

A Box-Behnken design of response surface method was used to optimize acetic acid-catalyzed hydrothermal pretreatment of corn stover, in respect to acid concentration (0.05-0.25%), treatment time (5-15 min) and reaction temperature (180-210°C). Acidogenic fermentations with different initial pH and hydrolyzates were also measured to evaluate the optimal pretreatment conditions for maximizing acid production. The results showed that pretreatment with 0.25% acetic acid at 191°C for 7.74 min was found to be the most optimal condition for pretreatment of corn stover under which the production of acids can reach the highest level. Acidogenic fermentation with the hydrolyzate of pretreatment at the optimal condition at the initial pH=5 was shown to be butyric acid type fermentation, producing 21.84 g acetic acid, 7.246 g propionic acid, 9.170 butyric acid and 1.035 g isovaleric acid from 100g of corn stover in 900 g of water containing 2.25 g acetic acid.

Sewage sludge drying method combining pressurized electro-osmotic dewatering with subsequent bio-drying

The study investigated the effects of two-step pretreatment on fermentable sugar production from corn stalk silage. In the first step, the corn stalk silage was extracted by tepid water and then the solid was pretreated using Fe(NO(3))(3) as catalyst. The results showed that 45.8 g/100g DM total sugars was obtained and the surface of remaining solid was seriously damaged after two-step pretreatment. Compared with one-step pretreatment, the production of total sugars increased by 23.8% and the amount of the catalyst of Fe(NO(3))(3) decreased by 28.8%. This research provides a new effective, suitable and economical pretreatment method for biogas production from corn stalk.