Key Laboratory for Solid Waste Management and Environment Safety

of China, China

Key Laboratory for Solid Waste Management and Environment Safety

of China, China
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Sikarwar V.S.,Tsinghua University | Zhao M.,Tsinghua University | Zhao M.,Key Laboratory for Solid Waste Management and Environment Safety | Fennell P.S.,Imperial College London | And 2 more authors.
Progress in Energy and Combustion Science | Year: 2017

Biofuels from biomass gasification are reviewed here, and demonstrated to be an attractive option. Recent progress in gasification techniques and key generation pathways for biofuels production, process design and integration and socio-environmental impacts of biofuel generation are discussed, with the goal of investigating gasification-to-biofuels’ credentials as a sustainable and eco-friendly technology. The synthesis of important biofuels such as bio-methanol, bio-ethanol and higher alcohols, bio-dimethyl ether, Fischer Tropsch fuels, bio-methane, bio-hydrogen and algae-based fuels is reviewed, together with recent technologies, catalysts and reactors. Significant thermodynamic studies for each biofuel are also examined. Syngas cleaning is demonstrated to be a critical issue for biofuel production, and innovative pathways such as those employed by Choren Industrietechnik, Germany, and BioMCN, the Netherlands, are shown to allow efficient methanol generation. The conversion of syngas to FT transportation fuels such as gasoline and diesel over Co or Fe catalysts is reviewed and demonstrated to be a promising option for the future of biofuels. Bio-methane has emerged as a lucrative alternative for conventional transportation fuel with all the advantages of natural gas including a dense distribution, trade and supply network. Routes to produce H2 are discussed, though critical issues such as storage, expensive production routes with low efficiencies remain. Algae-based fuels are in the research and development stage, but are shown to have immense potential to become commercially important because of their capability to fix large amounts of CO2, to rapidly grow in many environments and versatile end uses. However, suitable process configurations resulting in optimal plant designs are crucial, so detailed process integration is a powerful tool to optimize current and develop new processes. LCA and ethical issues are also discussed in brief. It is clear that the use of food crops, as opposed to food wastes represents an area fraught with challenges, which must be resolved on a case by case basis. © 2017

Chen X.,Tsinghua University | Jiang J.,Tsinghua University | Jiang J.,Key Laboratory for Solid Waste Management and Environment Safety | Jiang J.,Collaborative Innovation Center for Regional Environmental Quality | And 2 more authors.
Catalysis Science and Technology | Year: 2015

SiO2 synthesized from photovoltaic waste by a vapor-phase hydrolysis method was applied as a support for a nickel catalyst in a biogas dry reforming process for the first time. The catalytic performance was compared with those of commercial precipitated SiO2 and ordered mesoporous SiO2. Nickel supported on waste-derived SiO2 exhibited high CH4 conversion (92.3%) and high CO2 conversion (95.8%) at 800°C, and there was no deactivation after a 40 h-on-stream test. Catalyst characterization results revealed that the SBET values and pore properties of catalysts affected the catalytic performance. A higher pore volume/SBET ratio led to a smaller crystal metal size and higher metal dispersion, thus the catalyst was less prone to deactivation. This discovery will help improve catalyst design. The use of nickel supported on waste-derived SiO2, which is competitive with commercial and mesoporous catalysts, shows the use of photovoltaic waste as a high value-added product; it can also deliver a cheap and environmentally benign support for catalysts in the biogas dry reforming process. © The Royal Society of Chemistry 2015.

Xiao Y.,Tsinghua University | Jiang J.,Tsinghua University | Jiang J.,Key Laboratory for Solid Waste Management and Environment Safety | Huang H.,Tsinghua University
Scientific Reports | Year: 2014

Persistent organic pollutants (POPs) originating from POP waste are playing an increasingly important role in the elevation of regional POP levels. In this study we realized the complete dechlorination of high concentration hexachlorobenzene (HCB) waste in the presence of polyethylene glycol and hydroxide, rather than using conventional high temperature incineration. Here, we demonstrate the dominant effect of temperature and hydroxide on HCB dechlorination in this process. Complete dechlorination of HCB was only observed at temperature about 2006C or above within 4 h reaction, and the apparent activation energy of this process was 43.1 kJ/mol. The alkalinity of hydroxides had notable effects on HCBdechlorination, and there was a considerable linear relationship between the natural logarithm of the HCB dechlorination rate constant and square root of the ionic potential of metal cation (R2 = 0.9997, p = 0.0081, n = 3). This study highlights a promising technology to realize complete dechlorination of POP waste, especially at high concentrations, in the presence of PEG in conjunction with hydroxide.

Jiang J.,Tsinghua University | Jiang J.,Key Laboratory for Solid Waste Management and Environment Safety | Zhang Y.,Tsinghua University | Li K.,Tsinghua University | And 3 more authors.
Bioresource Technology | Year: 2013

The effects of pH, temperature, and organic loading rate (OLR) on the acidogenesis of food waste have been determined. The present study investigated their effects on soluble chemical oxygen demand (SCOD), volatile fatty acids (VFAs), volatile solids (VS), and ammonia nitrogen (NH4+-N). Both the concentration and yield of VFAs were highest at pH 6.0, acetate and butyrate accounted for 77% of total VFAs. VFAs concentration and the VFA/SCOD ratio were highest, and VS levels were lowest, at 45°C, but the differences compared to the values at 35°C were slight. The concentrations of VFAs, SCOD, and NH4+-N increased as OLR increased, whereas the yield of VFAs decreased from 0.504 at 5. g/L. d to 0.306 at 16. g/L. d. Acetate and butyrate accounted for 60% of total VFAs. The percentage of acetate and valerate increased as OLR increased, whereas a high OLR produced a lower percentage of propionate and butyrate. © 2013 Elsevier Ltd.

Sicong T.,Tsinghua University | Jianguo J.,Tsinghua University | Jianguo J.,Key Laboratory for Solid Waste Management and Environment Safety | Chang Z.,Tsinghua University
Journal of Hazardous Materials | Year: 2011

The influence of CO 2 content and SO 2 presence on the leaching toxicity of heavy metals in municipal solid waste incinerator (MSWI) fly ash was studied by examining the carbonation reaction of MSWI fly ash with different combinations of simulated incineration flue gases. Compared with raw ash, the leaching solution pH of carbonated ash decreased by almost 1 unit and the leaching concentrations of heavy metals were generally lower, with that of Pb decreasing from 19.45mg/L (raw ash) to 4.08mg/L (1# carbonated ash). The presence of SO 2 in the incineration flue gas increased the leaching concentrations of heavy metals from the fly ash to different extents after the carbonation stabilization reaction. The pH of the leaching solution was the main factor influencing the leaching concentrations of heavy metals. The increase in buffer capacity with the pH of carbonated ash caused an increase in heavy metal stability after the carbonation reaction. Accelerated carbonation stabilization of MSWI fly ash could reduce its long-term leaching concentrations (toxicity) of Cu, Pb, Se, and Zn. The leaching concentrations of heavy metals from carbonated ash also likely had better long-term stability than those from raw ash. The presence of SO 2 in the incineration flue gas increased the proportion of exchangeable state species of heavy metals; slightly increased the long-term leaching toxicity of Cu, Pb, Se, and Zn; and reduced the long-term stability of these metals in the fly ash after the carbonation reaction. © 2011 Elsevier B.V.

Li K.-M.,Tsinghua University | Jiang J.-G.,Tsinghua University | Jiang J.-G.,Key Laboratory for Solid Waste Management and Environment Safety | Tian S.-C.,Tsinghua University | And 2 more authors.
Journal of Physical Chemistry C | Year: 2014

Amine-silica hybrid materials have been investigated extensively in terms of their suitability for postcombustion CO2 capture. However, research on how the silica types affects the synthesis and performance of amine-silica hybrid materials is scarce. In this study, four types of commonly used and representative silica including precipitated silica, fumed silica, MCM-41, and silica gel are used to synthesize a series of comparable materials by grafting a silane onto them. We undertake a porosity analysis of plain silica and the amine-silica hybrid materials and determined the CO2 adsorption performance of amine-silica hybrid materials. The results suggest that precipitated silica is a superior and promising support material for amine-silica hybrid materials synthesis by grafting. The amine-silica hybrid material supporting with precipitated silica possesses relatively high amine content, exhibits good porosity, and obtains the highest CO2 adsorption capacity and amine efficiency compared to those of three other amine-silica hybrid materials. © 2014 American Chemical Society.

Jiang J.,Tsinghua University | Jiang J.,Key Laboratory for Solid Waste Management and Environment Safety | Gong C.,Tsinghua University | Wang J.,Tsinghua University | And 2 more authors.
Bioresource Technology | Year: 2014

This paper describes a series of studies on the effects of food waste disintegration using an ultrasonic generator and the production of volatile fatty acids (VFAs) by anaerobic hydrolysis. The results suggest that ultrasound treatment can significantly increase COD [chemical oxygen demand], proteins and reducing sugars, but decrease that of lipids in food waste supernatant. Ultrasound pre-treatment boosted the production of VFAs dramatically during the fermentation of food waste. At an ultrasonic energy density of 480. W/L, we treated two kinds of food waste (total solids (TS): 40 and 100. g/L, respectively) with ultrasound for 15. min. The amount of COD dissolved from the waste increased by 1.6-1.7-fold, proteins increased by 3.8-4.3-fold, and reducing sugars increased by 4.4-3.6-fold, whereas the lipid content decreased from 2 to 0.1. g/L. Additionally, a higher VFA yield was observed following ultrasonic pre-treatment. © 2013 Elsevier Ltd.

Jiang J.,Tsinghua University | Jiang J.,Key Laboratory for Solid Waste Management and Environment Safety | Du X.,Tsinghua University | Yang S.,Tsinghua University
Waste Management | Year: 2010

The treatment and disposal of sewage sludge are significant environmental problems in China. The reuse of sewage sludge for fuel could be an effective solution. The aim of this study was to characterize the behavior of sludge-derived fuel during combustion by a thermogravimetric method. The combustion profiles obtained showed four obvious weight loss regions. The results of dynamics analysis showed that first-order reactions together with Arrhenius' law explained reasonably well the different stages of weight loss in the samples. Three temperature regions (162-327 °C, 367-445 °C, and 559-653 °C for sawdust and 162-286 °C, 343-532 °C, and 609-653 °C for coal) in each derivative thermogravimetry (DTG) curve corresponded well with the Arrhenius equation. The reactivity of sludge was lower than that of samples containing sawdust, but higher than that of coal-containing samples. These data demonstrate that sludge-derived fuel has better combustion characteristics than sludge, sawdust, or coal. © 2010 Elsevier Ltd.

Li K.,Tsinghua University | Jiang J.,Tsinghua University | Jiang J.,Key Laboratory for Solid Waste Management and Environment Safety | Yan F.,Tsinghua University | And 2 more authors.
Applied Energy | Year: 2014

Amine-silica adsorbents are considered alternatives to aqueous solutions of amines, which have been traditionally used to capture carbon dioxide (CO2) from flue gas. Among amine-silica adsorbents, polyethyleneimine (PEI)-silica is particularly effective at capturing CO2 from flue gas due to its high thermal stability. In this study, we investigated the influence of PEI type (i.e. branched vs. linear) and molecular weight on the CO2 capture performance of PEI-silica adsorbents. PEI molecular weight influenced the thermal stability of PEI-silica adsorbents; however, when the molecular weight was ≥1200Da the increase in stability was negligible in the temperature range of 25-160°C. Branched PEIs (BPEIs) achieved higher CO2 saturated sorption capacities compared to linear PEIs (LPEIs); however, LPEIs were more stable than BPEIs during CO2 sorption-desorption cycling. PEI molecular weight also influenced the CO2 saturated sorption capacity; CO2 saturated sorption capacity decreased as PEI molecular weight increased, and among the adsorbents tested in this study BPEI/800-silica had the highest CO2 saturated sorption capacity (202mg CO2/g adsorbent). Both PEI type and molecular weight exhibited influence on the sorption or desorption heat of PEI-silica adsorbents. The CO2 regeneration heat was much lower than that of MEA solution for all PEI-silica adsorbents tested in this study. © 2014 Elsevier Ltd.

Li K.,Tsinghua University | Jiang J.,Tsinghua University | Jiang J.,Key Laboratory for Solid Waste Management and Environment Safety | Tian S.,Tsinghua University | And 2 more authors.
Journal of Materials Chemistry A | Year: 2015

Adsorbents for CO2 captured with nano silica as support were synthesized by impregnating polyethyleneimine (PEI) into nano silica. For impregnation of PEI into nano silica, the 2-40 nm pore of silica support plays an important role in the synthesis process of adsorbents. The PEI loading content, adsorption temperature and CO2 partial pressure influenced CO2 adsorption capacity and PEI utilization efficiency. At 105°C and under 1 atm CO2 partial pressure, the adsorbent with 60% PEI loading content obtained a CO2 adsorption capacity of 186 mg g-1 adsorbent and a PEI utilization efficiency of 304 mg g-1 PEI. The CO2 cycling adsorption-desorption was tested under the condition as follows: adsorption at 90 or 105°C under pure CO2 and desorption at 120°C under pure N2 showed relatively good adsorption-desorption stability, and no evident deactivation of amines was observed under this condition. However, for adsorption at 90 or 105°C under pure CO2 and desorption at 135 or 150°C under pure CO2, evident deactivation of amines occurred, and the formation of linear or cyclic urea is one reason which led to the decrease of CO2 adsorption capacity. © The Royal Society of Chemistry 2015.

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