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Gao X.,Chinese Research Academy of Environmental Sciences | Liu X.,China Urban Construction Design and Research Institute | Wang W.,Tsinghua University
Renewable Energy | Year: 2016

Biodegradation of particulate organics is considered to be as an essential factor in the anaerobic co-digestion performance and biogas recovery of biowaste. To determine the rate-limiting step of particulate organics hydrolysis during co-digestion of municipal biowaste and waste activated sludge (WAS), the particle size distribution of organic compounds before and after digestion was examined for a mesophilic co-digestion system. As organic load rate increased and hydraulic retention time decreased, the removal rate of big-size particulate organics did not change significantly, indicating that the disintegration of big particles is not the rate-limiting step, while soluble organics accumulated in the digestate. This implies that the enzymatic hydrolysis of soluble organics is the rate-limiting step in the hydrolysis process. Addition of WAS to substrate did not significantly change the removal rate of particulate organics >420 μm, while the residual content of particulate organics 0.45-74 μm in size increased because the non-biodegradable organics in WAS were in this size range. After biodegradability enhancement of WAS by hydrothermal pretreatment, the removal rate of particulate organics increased significantly. Thus, biodegradability enhancement is more effective than particle size reduction in optimizing the co-digestion process with WAS in practice. © 2016 Elsevier Ltd. All rights reserved.


Liu X.,China Urban Construction Design and Research Institute | Liu X.,Tsinghua University | Wang W.,Tsinghua University | Shen R.,University of Science and Technology Beijing
Chinese Journal of Environmental Engineering | Year: 2013

A pilot-scale one-stage mesophilic anaerobic digestion research is presented to elucidate the feasibility of developing anaerobic digestion as an effective disposal method for municipal biomass waste (MBW) in China, focusing on performance stability, biogas production and organic reduction. The reactor was operated stably for 410 d with an organic loading rate increase from 2.4 to 6.0 kg VS/(m3·d). A high biogas production rate of 4.25 m3/(m3·d) and a high organic reduction rate of 63.2% were achieved at organic loading rate of 6.0 kg VS/(m3·d). Protein, fat, cellulose and polysaccharide showed different reduction rates during anaerobic digestion, while fat can achieve 98.2% removal which is responsible for 38.8% of biogas production. The research achieved the stable operation under high OLR and high conversion rate which is of crucial importance to the development of large-scale treatment projects of municipal biomass waste in China.


Chen T.,Tsinghua University | Jin Y.,Tsinghua University | Qiu X.,China Urban Construction Design and Research Institute | Chen X.,Tsinghua University
Journal of the Air and Waste Management Association | Year: 2015

Using laboratory experiments, the authors investigated the impact of dry-heat and moist-heat treatment processes on hazardous trace elements (As, Hg, Cd, Cr, and Pb) in food waste and explored their distribution patterns for three waste components: oil, aqueous, and solid components. The results indicated that an insignificant reduction of hazardous trace elements in heat-treated waste—0.61–14.29% after moist-heat treatment and 4.53–12.25% after dry-heat treatment—and a significant reduction in hazardous trace elements (except for Hg without external addition) after centrifugal dehydration (P < 0.5). Moreover, after heat treatment, over 90% of the hazardous trace elements in the waste were detected in the aqueous and solid components, whereas only a trace amount of hazardous trace elements was detected in the oil component (<0.01%). In addition, results indicated that heat treatment process did not significantly reduce the concentration of hazardous trace elements in food waste, but the separation process for solid and aqueous components, such as centrifugal dehydration, could reduce the risk considerably. Finally, combined with the separation technology for solid and liquid components, dry-heat treatment is superior to moist-heat treatment on the removal of external water-soluble ionic hazardous trace elements. Implications: An insignificant reduction of hazardous trace elements in heat-treated waste showed that heat treatment does not reduce trace elements contamination in food waste considerably, whereas the separation process for solid and aqueous components, such as centrifugal dehydration, could reduce the risk significantly. Moreover, combined with the separation technology for solid and liquid components, dry-heat treatment is superior to moist-heat treatment for the removal of external water-soluble ionic hazardous trace elements, by exploring distribution patterns of trace elements in three waste components: oil, aqueous, and solid components. © 2015 A&WMA.


Chen T.,Tsinghua University | Jin Y.,Tsinghua University | Qiu X.,China Urban Construction Design and Research Institute | Chen X.,Tsinghua University
Expert Systems with Applications | Year: 2014

The product safety of food-waste feed is the key factor limiting the development of its industrial chain. In this paper, we construct a method based on data from the testing of food-waste feed with comprehensive evaluation of its product safety by integrating fuzzy mathematics effectively, i.e.; the entropy method (EM), and the model of the analytic hierarchy (AHP) process. Furthermore, a hierarchical three-level evaluation-index system including biological-safety and chemical-safety considerations is first established via data analysis, data surveys and expert experiential investigation as well, with an actual case in China being fully applied. In addition, we apply the EM and AHP process to calculate the weights of the individual evaluation indices. Finally, through the dimensionless treatment of test data from samples, we determine the degree of membership of each test value relative to the different levels of safety using a trapezoidal membership function. By adopting the developed three-level model of fuzzy mathematics for comprehensive evaluation, we derive the safety grades of tested samples. The comprehensive evaluation method developed in this paper can effectively overcome the shortcomings of traditional single-factor evaluation and offer the qualitative and quantitative advantages of expert survey and basic data research as well. As a result, it is considerably applicable for the product-safety analysis and production control of animal feed generated from food waste. © 2014 Elsevier Ltd. All rights reserved.


Liu P.,Beijing Jiaotong University | Guo M.,Beijing Jiaotong University | Guo M.,China Academy of Building Research | Li T.,Beijing Jiaotong University | And 2 more authors.
Gongcheng Lixue/Engineering Mechanics | Year: 2012

Similar to the multi-grid composite wall reinforced by steel bars, an improved multi-grid composite wall reinforced by light steels is proposed, where the steel bars in grid beams and columns are replaced by light steels. To apply the improved composite in large-bay high-rise buildings, its seismic performance should be examined. 1/2 scale multi-grid composite walls reinforced by light steels, as well as by steel bars, were tested under reversed cyclic loading. Damage procedures, load-bearing capacity and ductility were compared. It is found that both kinds of walls fail in shear, and the damage propagates from the filling blocks to grids made up of grid beams and columns, and finally to the edged frame. Compared with using steel bars, using light steels to reinforce composite walls, with a 17% increase of steel, generated a yielding capacity of 54.3% larger and an ultimate capacity of 53.1% larger. The stiffness behavior and energy dissipation capacity of the improved composite wall were better too, while the ductility capacity of the two composite walls was almost the same.


Xing L.,China University of Geosciences | Xing L.,Water Resources University | Xing L.,China Urban Construction Design and Research Institute | Guo H.,China University of Geosciences | And 3 more authors.
Journal of Asian Earth Sciences | Year: 2013

The North China Plain is one of the biggest plains in China, where municipal, agricultural and industrial water supplies are highly dependent on groundwater resources. It is crucial to investigate water chemistry and hydrogeochemical processes related to hydrogeologic settings for sustainable utilization of groundwater resources. Two hydrochemical profiles proximately along the groundwater flow paths were selected for hydrogeochemical study. Major components and 2H and 18O isotopes were analyzed in groundwater samples from the profiles. The study area was divided into three zones, including strong runoff-alluvial/pluvial fans in the piedmont area (Zone I), slow runoff-alluvial/lacustrine plain in the central area (Zone II), and discharge-alluvial/marine plain in the coastal area (Zone III). Major components of groundwater samples showed obvious zonation patterns from Zone I to Zone III. Total dissolved solid (TDS) concentrations gradually increased, and the hydrochemical type changed from HCO3-SO4-Ca- Mg and HCO3-Cl-Ca-Mg types to HCO3-SO4-Na-Ca, SO4-Cl-Na-Ca and SO4-Cl-Na types from Zone I to Zone III. Abrupt increases in concentrations of Na+, Cl and SO2 4 in deep groundwater were observed around the depression cones, which indicated that overexploitation resulted in water quality deterioration. Calcite and dolomite precipitation occurred in Zone I of deep groundwater systems and shallow groundwater systems. Cation exchange was believed to take place along the entire flow paths. Gypsum tended to dissolve in groundwater systems. The depletion in D and 18O isotopes in deep groundwater was related to the recharge from precipitation in paleo-climate conditions in glacial or interglacial periods, indicating that renewal groundwater was very limited. Efficient strategies must be taken to preserve the valued water resources for sustainable development. © 2013 Elsevier Ltd. All rights reserved.


Tan X.,CAS Institute of Policy and Management | Xu J.,China Urban Construction Design and Research Institute | Wang S.,Chongqing Academy of Social Science
Procedia Environmental Sciences | Year: 2011

With the research on some critical technology going deeply, the problem of technology route and project approach for the saving energy & reducing consumption have become the focus of municipal wastewater treatment process. In this article, LCA (Life Cycle Analysis) is applied to identify and compare the energy consumption of each stage of different technologies in municipal wastewater treatment from the view of whole process. This is carried out after reviewing the condition of energy utilizing of typical technologies in China. And some measures are brought forward to improve the efficiency of energy utilizing. Integrated Oxidation Ditch (IOD) is taken as an example and the energy consumption from its raw and processed materials exploitation, construction, treatment and running, rebuilding to its discarding and removing is identified and quantified, which is also compared with traditional treatment process of wastewater and waste sludge in China. This study shows that application of the high-energy-efficiency aeration device and optimizing control operation are essential paths to improve the energy consumption of IOD during its life cycle. And LCA is an important foundation of improving products quality and a main measure of sales promotion for manufacturers in recent years. © 2011 Published by Elsevier Ltd.


Zhuang K.,Tongji University | Quanmei G.,Tongji University | Yang W.,China Urban Construction Design and Research Institute
WIT Transactions on the Built Environment | Year: 2014

Calculating accumulated soil deformation caused by millions of cyclic loadings with finite element simulating calculation is usually limited by storage space and physical error accumulation. The implicit method with which the constitutive relation of soil can be well described in fact cannot satisfy the finite element calculation on millions of times of cyclic loadings. With the research on the long-term deformation of soil under cyclic loadings, it is evident that this process has a similar character with the process of creep deformation of materials. In addition, the two experience expressions describing the two deformation process are also analogues. Based on these, a new idea to forecast soil deformation under high accumulated cyclic loadings is proposed in this paper. With this idea, the time-wasting and space-wasting problems in finite element calculation implementation is solved. Comparing the finite element calculation results and the dynamic triaxial experiment results, the accuracy of the idea is proved. With the comparison between the practical measured results of detection on highspeed railway section and finite element calculation results, the idea is further proved that it can represent the regularity and tendency of soil deformation under long-term cyclic loadings on a high-speed railway. © 2014 WIT Press.


Yu H.,Narvik University College | Solvang W.D.,Narvik University College | Yuan S.,China Urban Construction Design and Research Institute
3rd IEEE International Conference on Cognitive Infocommunications, CogInfoCom 2012 - Proceedings | Year: 2012

Dealing with municipal solid waste (MSW) is a worldwide challenge. When planning a MSW management system, conflicting objectives, i.e., the minimization of system operating costs and environmental risks, the maximization of resource utilization and equity, have to be simultaneously considered. The optimum solution for one objective is always not a good choice for another. This paper presents a decision support system (DSS) for optimum waste management solution based upon a multi-objective dynamic logistics model. The DSS consists of a conceptual framework and the corresponding mathematical formulation. These have been further illustrated through a fictional example presented in the end of the paper. © 2012 IEEE.


Zhao C.,China Urban Construction Design and Research Institute | Fu G.,CAS Institute of Geographical Sciences and Natural Resources Research | Fu G.,CSIRO | Liu X.,Beijing Forestry University | Fu F.,North China University of Technology
Building and Environment | Year: 2011

Eleven sites, representing different urban morphologies across central Beijing, are used to simulate urban heat island effects and explore the relationship between urban planning indicators and climate indicators such as daily maximum and minimum surface temperatures. The results indicate that mesoscale urban planning indicators can explain the majority of the urban climate differences among the sites. For example, green cover ratio and floor area ratio can explain 94.47-98.57% of the variance for daily maximum surface temperature, green cover ratio and building height can explain 98.94-99.12% of the variance for daily minimum surface temperature, and floor area ratio, green cover ratio and building density together can explain 99.49-99.69% of the variance for time of peak surface temperature. Furthermore, green cover ratio is identified as the most significant urban planning indicator affecting the urban thermal environment. © 2010 Elsevier Ltd.

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