Qiuzhuo Zhang

The enhanced adsorption of dibenzothiophene onto cerium/nickel-exchanged zeolite Y

The investigations for selective adsorption of dibenzothiophene (DBT) over Ce/Ni-loaded Y zeolites with the emphasis on the effect of Ce as a cocation in the Ni-loaded Y zeolite are carried out in an attempt to produce more effective adsorbents for the desulfurization from transportation fuels. The promotional effects of Ce and coexisting toluene in the model fuel as well as contact time and adsorbent dose on the adsorptive performance were examined. The sulfur uptake strongly depends on the amount of Ce in the zeolite structure. The sorption data is varied according to both Langmuir and Freundlich isotherm models. The maximum sorption capacity by theoretically calculation is 22.2mg/g at 25 degrees C. The Langmuir constants b=5.82 mL/mg and the Freundlich constants K=1.042 L/mg and 1/n=0.4 are evaluated. Ni/Ce-loaded Y zeolites (NiCeY) and NiY, CeY, NaY zeolites were used as adsorbents for the removal of DBT from model fuel containing 500 mg/L sulfur with 5 vol% of toluene by a batch method under ambient conditions. NiCeY exhibits higher adsorptive selectivity for DBT than NiY and CeY, indicating that NiCeY is a more effective adsorbent to remove sulfur compounds from transportation fuels.

Bio-grout based on microbially induced sand solidification by means of asparaginase activity

Bio-grout, a new ground improvement method, has been recently developed to improve the mechanical properties, decrease the permeability of porous materials, reinforce or repair cementitious materials and modify the properties of soil or sand. Bio-grout production depends on microbially induced calcite precipitation (MICP), which is driven mainly by an enzyme, urease. However, urease-based MICP process produces excessive ammonia, in addition to secondary pollution generated by urea that is used as substrate in it. In the present study, we reported asparaginase-based MICP process for sand bio-grout development using Bacillus megaterium, and results were also compared with urease-based bio-grouts. The asparaginase activity led to significantly less ammonia production compared to urease without compromising with desired properties of a novel grout. The UCS of bio-grout was obtained at 980 kPa, while the permeability was decreased substantially. The mineralogical composition of precipitated substance was identified as calcite using XRD and the crystal morphology was observed under SEM. The mass percentage of calcite in bio-grout was calculated by thermogravimetric analysis and XCT verified calcite precipitation in it. The results confirmed that biocalcification by means of bacterial asparaginase is a potential solution for geotechnical problems. The asparaginase-based MICP process could be of wider acceptance in future.

Stimulatory effects of biosurfactant produced by Pseudomonas aeruginosa BSZ-07 on rice straw decomposing.

Biosurfactant, produced by Pseudomonas aeruginosa BSZ-07, was added to the rice straw decomposing process to enhance the production of reducing sugars. Observed by Fourier Transform InfraRed (FT-IR) and Nuclear Magnetic Resonance (NMR) analysis, the purified biosurfactant was considered as a mixture of RL1 and RL2, which are two different types of rhamnolipids. Two different adding methods, adding the purified rhamnolipid and the on-site production of it were compared. The results showed that 0.5 g/L was the optimum concentration for adding purified rhamnolipid and the optimum temperature for on-site production was 30 degrees C for the first 48 h and 34 degrees C for the next 48 h. Under the optimum conditions, these two adding methods could improve the production of reducing sugar to 2.730 and 2.504 g/L, which was 22.30% and 12.20% higher than that of the rhamnolipid-free sample, respectively, which indicated that both of them were more effective than any other kind of surfactant discussed in this article. As the on-site production of rhamnolipid could omit the purification process, thus reducing the production cost effectively, it seemed to be a prospective adding method of the biosurfactant for enhancing rice straw decomposing.

Stimulatory effect and adsorption behavior of rhamnolipids on lignocelluloses degradation system

Di-rhamnolipid and mixed rhamnolipid were added to rice straw degrading system to investigate their mechanism of stimulatory effect. By batch adsorption experiments, it was shown that the equilibrium adsorption time of rhamnolipids on rice straw single system was the shortest (50min). The adsorption capacity of Trichoderma reesei single system was the strongest, whose Qe,exp for di-rhamnolipid and mixed rhamnolipid was 10.57×10-2mg·g-1 and 8.13×10-2mg·g-1, respectively. The adsorption of rhamnolipids on consortia system was not the simple adduct of the two single systems. The adsorption of rhamnolipids on the three different systems might belong to chemisorptions. SEM and FTIR analyses were used to observe the morphology and to analyze the chemical functions in lignocellulosic biomass degradation with rhamnolipid. It was shown that after addition of rhamnolipids, the basic tissue in rice straw was severely destroyed and hydrogen bond was formed between biosurfactant and bacteria in lignocellulose degrading system.

Isolation and characterization of diesel degrading bacteria, Sphingomonas sp. and Acinetobacter junii from petroleum contaminated soil

Two indigenous bacteria of petroleum contaminated soil were characterized to utilize diesel fuel as the sole carbon and energy sources in this work. 16S rRNA gene sequence analysis identified these bacteria as Sphingomonas sp. and Acinetobacter junii. The ability to degrade diesel fuel has been demonstrated for the first time by these isolates. The results of IR analyses showed that Sphingomonas sp. VA1 and A. junii VA2 degraded up to 82.6% and 75.8% of applied diesel over 15 days, respectively. In addition, Sphingomonas sp. VA1 possessed the higher cellular hydrophobicities of 94% for diesel compared to 81% by A. junii VA2. The isolates Sphingomonas sp. VA1 and A. junii VA2 exhibited 24% and 18%, respectively emulsification activity. This study reports two new diesel degrading bacterial species, which can be effectively used for bioremediation of petroleum contaminated sites.

Levels, sources and probabilistic health risks of polycyclic aromatic hydrocarbons in the agricultural soils from sites neighboring suburban industries in Shanghai

The levels, sources and quantitative probabilistic health risks for polycyclic aromatic hydrocarbons (PAHs) in agricultural soils in the vicinity of power, steel and petrochemical plants in the suburbs of Shanghai are discussed. The total concentration of 16 PAHs in the soils ranges from 223 to 8214ng g-1. The sources of PAHs were analyzed by both isomeric ratios and a principal component analysis-multiple linear regression method. The results indicate that PAHs mainly originated from the incomplete combustion of coal and oil. The probabilistic risk assessments for both carcinogenic and non-carcinogenic risks posed by PAHs in soils with adult farmers as concerned receptors were quantitatively calculated by Monte Carlo simulation. The estimated total carcinogenic risks (TCR) for the agricultural soils has a 45% possibility of exceeding the acceptable threshold value (10-6), indicating potential adverse health effects. However, all non-carcinogenic risks are below the threshold value. Oral intake is the dominant exposure pathway, accounting for 77.7% of TCR, while inhalation intake is negligible. The three PAHs with the highest contribution for TCR are BaP (64.35%), DBA (17.56%) and InP (9.06%). Sensitivity analyses indicate that exposure frequency has the greatest impact on the total risk uncertainty, followed by the exposure dose through oral intake and exposure duration. These results indicate that it is essential to manage the health risks of PAH-contaminated agricultural soils in the vicinity of typical industries in megacities.

Optimization of Bioethanol Production Using Whole Plant of Water Hyacinth as Substrate in Simultaneous Saccharification and Fermentation Process

Water hyacinth was used as substrate for bioethanol production in the present study. Combination of acid pretreatment and enzymatic hydrolysis was the most effective process for sugar production that resulted in the production of 402.93 mg reducing sugar at optimal condition. A regression model was built to optimize the fermentation factors according to response surface method in saccharification and fermentation (SSF) process. The optimized condition for ethanol production by SSF process was fermented at 38.87°C in 81.87 h when inoculated with 6.11 ml yeast, where 1.291 g/L bioethanol was produced. Meanwhile, 1.289 g/L ethanol was produced during experimentation, which showed reliability of presented regression model in this research. The optimization method discussed in the present study leading to relatively high bioethanol production could provide a promising way for Alien Invasive Species with high cellulose content.

Enhancing bioethanol production from water hyacinth by new combined pretreatment methods

This study investigated the possibility of enhancing bioethanol production by combined pretreatment methods for water hyacinth. Three different kinds of pretreatment methods, including microbial pretreatment, microbial combined dilute acid pretreatment, and microbial combined dilute alkaline pretreatment, were investigated for water hyacinth degradation. The results showed that microbial combined dilute acid pretreatment is the most effective method, resulting in the highest cellulose content (39.4 ± 2.8%) and reducing sugars production (430.66 mg·g-1). Scanning Electron Microscopy and Fourier Transform Infrared Spectrometer analysis indicated that the basic tissue of water hyacinth was significantly destroyed. Compared to the other previously reported pretreatment methods for water hyacinth, which did not append additional cellulase and microbes for hydrolysis process, the microbial combined dilute acid pretreatment of our research could achieve the highest reducing sugars. Moreover, the production of bioethanol could achieve 1.40 g·L-1 after fermentation, which could provide an extremely promising way for utilization of water hyacinth.

Green stormwater infrastructure eco-planning and development on the regional scale: a case study of Shanghai Lingang New City, East China

Urban underlying surface has been greatly changed with rapid urbanization, considered to be one of the major causes for the destruction of urban natural hydrological processes. This has imposed a huge challenge for stormwater management in cities. There has been a shift from gray water management to green stormwater management thinking. The green stormwater infrastructure (GSI) is regarded as an effective and cost-efficient stormwater management eco-landscape approach. China’s GSI practice and the development of its theoretical framework are still in the initial stage. This paper presents an innovative framework for stormwater management, integrating green stormwater infrastructure and landscape security patterns on a regional scale based on an urban master plan. The core concept of green stormwater infrastructure eco-planning is to form an interconnected GSI network (i.e., stormwater management landscape security pattern) which consists of the location, portion, size, layout, and structure of GSI so as to efficiently safeguard natural hydrological processes. Shanghai Lingang New City, a satellite new town of Shanghai, China was selected as a case study for GSI studies. Simulation analyses of hydrological processes were carried out to identify the critical significant landscape nodes in the highpriority watersheds for stormwater management. GSI should be planned and implemented in these identified landscape nodes. The comprehensive stormwater management landscape security pattern of Shanghai Lingang New City is designed with consideration of flood control, stormwater control, runoff reduction, water quality protection, and rainwater utilization objectives which could provide guidelines for smart growth and sustainable development of this city.

A study of cadmium remediation and mechanisms: Improvements in the stability of walnut shell-derived biochar

Biochar has been recognized as an efficient soil amendment for cadmium remediation in recent years. In the present study, biochar was prepared using walnut shell, and it was incubated in Cd(NO3)2 and kaolin for 15 days. Different chemical forms of cadmium in kaolin and biochar were determined, and the stability of biochar was evaluated by R50 using TGA analysis. It was found that walnut shell derived biochar could reduce the mobility of cadmium. After incubation, the R50, biochar value increased from 61.31% to 69.57%-72.24%, indicating that the stability of biochar was improved. The mechanisms that initiated improvements in biochar stability were investigated by XPS, XRD and SEM-EDS analysis. The result showed that the enhanced biochar stability is likely due to physical isolation and the formation of precipitates and complexes, formed on the surface or interior of the biochar. The results suggested that walnut shell-derived biochar can be used as a cadmium sorbent for soil remediation.