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The curing stress can significantly improve the engineering properties of cement-treated dredged soil (CDS). Based on the large-scale consolidation tests, this study investigated the settlement pattern of CDS under the curing stress of 0–100 kPa, and the pressure dissipation and chemical properties of pore water were also explored. The results showed that the application of curing stress greatly accelerated the settlement of CDS and significantly reduced its void ratio, however, the consolidation efficiency gradually weakened with the increase of cement content. With the curing stress increasing, the completion time of primary settlement of CDS was prolonged, and the pH and EC values of the pore water both gradually increased. The void-ratio reduction of CDS during stress curing arises from the combined effect of mechanical compression and chemical filling, and the two effects have different contributions to the reduction of void ratio at different consolidation stages. Moreover, the effects of curing stress on the microstructure of CDS were also investigated by the scanning electron microscopy (SEM) and mercury intrusion porosimeter (MIP) tests. The results show that with the curing stress applied, the volume of large pore in CDS significantly decreased and the structure became denser.
Xingxing He; Yijun Chen; Yuan Li; Dongdong Guo; Qiang Xue; Shiquan Wang; Ping Wang; Yong Wan; Lei Liu. Consolidation behavior and microstructure properties of cement-treated dredged soil during the stress curing. Marine Georesources & Geotechnology 2021, 1 -30.
AMA StyleXingxing He, Yijun Chen, Yuan Li, Dongdong Guo, Qiang Xue, Shiquan Wang, Ping Wang, Yong Wan, Lei Liu. Consolidation behavior and microstructure properties of cement-treated dredged soil during the stress curing. Marine Georesources & Geotechnology. 2021; ():1-30.
Chicago/Turabian StyleXingxing He; Yijun Chen; Yuan Li; Dongdong Guo; Qiang Xue; Shiquan Wang; Ping Wang; Yong Wan; Lei Liu. 2021. "Consolidation behavior and microstructure properties of cement-treated dredged soil during the stress curing." Marine Georesources & Geotechnology , no. : 1-30.
The unsaturated hydraulic characteristics of waste soil are an essential basis for predicting and evaluating leachate migration and distribution in landfills. The saturated water content and permeability coefficient were measured, and a multi-step drainage monitoring experiment was conducted indoors at different dry densities, particle sizes, and degradation ages. Single and dual permeability models were adopted to determine the unsaturated hydraulic characteristic parameters of waste. Results show that dry density and particle size are the key factors affecting the saturated water content and permeability of waste. A single degradation age has little effect on it. Respectively, the saturated water content has a linear relationship with dry density, and permeability has an exponential relationship with dry density under limited experimental data. The overflow numerical inversion method can accurately obtain the unsaturated hydraulic characteristic parameters of wastes and summarizes the values of the unsaturated hydraulic characteristic parameters of wastes with different attributes in the literature and the results of this study. The dual-permeability model performed significantly better than the single-permeability model for water movement, suggesting that a dual-domain description is required for water flow in landfills.
Chai Zhang; Bing Liang; Lei Liu; Yong Wan; Qichen Zhu. Determination of Unsaturated Hydraulic Properties of Seepage Flow Process in Municipal Solid Waste. Water 2021, 13, 1059 .
AMA StyleChai Zhang, Bing Liang, Lei Liu, Yong Wan, Qichen Zhu. Determination of Unsaturated Hydraulic Properties of Seepage Flow Process in Municipal Solid Waste. Water. 2021; 13 (8):1059.
Chicago/Turabian StyleChai Zhang; Bing Liang; Lei Liu; Yong Wan; Qichen Zhu. 2021. "Determination of Unsaturated Hydraulic Properties of Seepage Flow Process in Municipal Solid Waste." Water 13, no. 8: 1059.
Modified calcium bentonite (Ca-bentonite) is extensively used in engineered barrier systems (EBSs) for municipal and industrial disposal sites due to its high swelling potential and low hydraulic conductivity. However, few studies have focused on the micromechanism of hydration and swelling under the effect of inorganic chemical solution. In this study, free swell index (FSI) and the type and content of modified Ca-bentonite bound water under the inorganic chemical solution were quantitatively studied by using the free swell test and nuclear magnetic resonance (NMR). According to the results, modification of sodium and polymer significantly increases the FSI of Ca-bentonite, bringing it close to that of natural sodium bentonite. In addition, the chemical stability of polymer-modified bentonite is significantly higher than that of sodium-modified bentonite but less than that of natural Na-bentonite. The FSI of modified Ca-bentonite decreases with the increase of cation valence and ionic strength. T2 distribution curves of the two types of modified bentonite are three-peak curves. With the increase of ionic strength, the content of total water and permeated hydrated water (accounting for 69%–95%) in bentonite decreases gradually, whereas the surface hydration water (accounting for 2%–31%) and free water content (accounting for 0–15%) increase. A uniform linear relationship exists between the FSI and corresponding total peak area of NMR (independent of ion valence, concentration, and bentonite type). Furthermore, a linear relationship exists between the FSI of the same type of bentonite and the T2 relaxation time. Research results can provide data and theoretical basis for quantitative analysis and mechanism of the hydration swelling of bentonite.
Yong Wan; Dongdong Guo; Xinminnan Hui; Lei Liu; Yuan Yao. Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite. Advances in Polymer Technology 2020, 2020, 1 -11.
AMA StyleYong Wan, Dongdong Guo, Xinminnan Hui, Lei Liu, Yuan Yao. Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite. Advances in Polymer Technology. 2020; 2020 ():1-11.
Chicago/Turabian StyleYong Wan; Dongdong Guo; Xinminnan Hui; Lei Liu; Yuan Yao. 2020. "Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite." Advances in Polymer Technology 2020, no. : 1-11.
Aeration is one mainstream technique to accelerate municipal solid waste (MSW) degradation in landfills. The determination of an appropriate aeration rate is critical to the design and operation of a landfill aeration system. In this study, we analyze 132 waste degradation tests reported in forty one studies in the literature. We use L min-1 kg-1 dry organic matter (L min-1 kg-1 DOM) as the uniform unit to quantify the aeration rates in all tests. The first order rate coefficient for chemical oxygen demand removal in leachate (kCOD) is selected as the parameter to characterize MSW degradation process. We further divide aerobic tests into five aerobic groups base on the respective aeration rates, 1 L min-1 kg-1 DOM. With an increase in the aeration rate, the kCOD increases first and then decreases. The aeration rate between 0.1-0.3 L min-1 kg-1 DOM has the best enhancement on the kCOD. The kCOD values are not much improved than the anaerobic and semi-aerobic tests when the aeration rates are 0.3 L min-1 kg-1 DOM reduces the kCOD likely due to excess water evaporation and ventilation cooling. The aeration rate is the most related to the kCOD in principal component analysis than the other factors, including liquid recirculation, special liquid addition, waste total density, waste degradation level, and waste initial temperature.
Jun Ma; Lei Liu; Qiang Xue; Yong Yang; Yi Zhang; Xunchang Fei. A systematic assessment of aeration rate effect on aerobic degradation of municipal solid waste based on leachate chemical oxygen demand removal. Chemosphere 2020, 263, 128218 .
AMA StyleJun Ma, Lei Liu, Qiang Xue, Yong Yang, Yi Zhang, Xunchang Fei. A systematic assessment of aeration rate effect on aerobic degradation of municipal solid waste based on leachate chemical oxygen demand removal. Chemosphere. 2020; 263 ():128218.
Chicago/Turabian StyleJun Ma; Lei Liu; Qiang Xue; Yong Yang; Yi Zhang; Xunchang Fei. 2020. "A systematic assessment of aeration rate effect on aerobic degradation of municipal solid waste based on leachate chemical oxygen demand removal." Chemosphere 263, no. : 128218.
In this work, the impact of exogenous aerobic bacteria mixture (EABM) on municipal solid waste (MSW) is well evaluated in the following aspects: biogas production, leachate analysis, organic waste degradation, EABM population, and the composition of microbial communities. The study was designed and performed as follows: the control bioreactor (R1) was filled up with MSW and the culture medium of EABM and the experimental bioreactor (R2) was filled up with MSW and EABM. The data suggests that the composition of microbial communities (bacterial and methanogenic) in R1 and R2 were similar at day 0, while the addition of EABM in R2 led to a differential abundance of Bacillus cereus, Bacillus subtilis, Staphylococcus saprophyticus, Staphlyoccus xylosus, and Pantoea agglomerans in two bioreactors. The population of exogenous aerobic bacteria in R2 greatly increased during hydrolysis and acidogenesis stages, and subsequently increased the degradation of volatile solid (VS), protein, lipid, and lignin by 59.25%, 25.68%, 60.47%, and 197.62%, respectively, compared to R1. The duration of hydrolysis and acidogenesis in R2 was 33.33% shorter than that in R1. At the end of the study, the accumulative methane yield in R2 (494.4 L) was almost three times more than that in R1 (187.4 L). In addition, the abundance of acetoclasic methanogens increased at acetogenesis and methanogenesis stages in both bioreactors, which indicates that acetoclasic methanogens (especially Methanoseata) could contribute to methane production. This study demonstrates that EABM can accelerate organic waste degradation to promote MSW biodegradation and methane production. Moreover, the operational parameters helped EABM to generate 20.85% more in accumulative methane yield. With a better understanding of how EABM affects MSW and the composition of bacterial community, this study offers a potential practical approach to MSW disposal and cleaner energy generation worldwide.
Sai Ge; Jun Ma; Lei Liu; Zhiming Yuan. The Impact of Exogenous Aerobic Bacteria on Sustainable Methane Production Associated with Municipal Solid Waste Biodegradation: Revealed by High-Throughput Sequencing. Sustainability 2020, 12, 1815 .
AMA StyleSai Ge, Jun Ma, Lei Liu, Zhiming Yuan. The Impact of Exogenous Aerobic Bacteria on Sustainable Methane Production Associated with Municipal Solid Waste Biodegradation: Revealed by High-Throughput Sequencing. Sustainability. 2020; 12 (5):1815.
Chicago/Turabian StyleSai Ge; Jun Ma; Lei Liu; Zhiming Yuan. 2020. "The Impact of Exogenous Aerobic Bacteria on Sustainable Methane Production Associated with Municipal Solid Waste Biodegradation: Revealed by High-Throughput Sequencing." Sustainability 12, no. 5: 1815.
VOCs are the major harmful pollutants released from MSW landfills, which are toxicity to human health. In order to in-situ biodegradation of VOCs released from landfill, two novel laboratory-scale biocovers, including waste-char obtained from MSW pyrolysis (WC), and sewage sludge modified the WC (SWC), are used to degradate VOCs. The removal performances of VOCs as well as the bacterial community in the WC and SWC are investigated in a simulated landfill systems with the contrast experiment of a landfill cover soil (LCS) for 60 days. Meanwhile, the adsorption-biodegradation of VOCs model compounds over the LCS, WC, and SWC are also tested in fixed-bed adsorption reactor and in-situ FTIR. The VOCs removal efficiencies by the SWC are maintained above 85% for a long-term, much higher than that of the LCS and WC. The higher removal efficiencies and long-term stability for VOCs degradation in SWC are attributed to a strongly positive synergistic between adsorption and biodegradation that the gaseous VOCs released from MSW is effectively adsorbed by the SWC due to its higher VOCs adsorption capacity, and then the adsorbed-VOCs is converted into CO2 and H2O by the microorganisms that consuming the adsorbed-VOCs as energy and carbon sources. Subsequently, the decrease of the adsorbed-VOCs in SWC would also promote the transformation of the gaseous VOCs into the adsorbed VOCs and accelerate the growth of microorganisms by taking the adsorbed-VOCs as the energy and carbon source, resulted in a higher adsorption rate and degradation rate for VOCs.
Linbo Qin; Zhe Xu; Lei Liu; Haijun Lu; Yong Wan; Qiang Xue. In-situ biodegradation of volatile organic compounds in landfill by sewage sludge modified waste-char. Waste Management 2020, 105, 317 -327.
AMA StyleLinbo Qin, Zhe Xu, Lei Liu, Haijun Lu, Yong Wan, Qiang Xue. In-situ biodegradation of volatile organic compounds in landfill by sewage sludge modified waste-char. Waste Management. 2020; 105 ():317-327.
Chicago/Turabian StyleLinbo Qin; Zhe Xu; Lei Liu; Haijun Lu; Yong Wan; Qiang Xue. 2020. "In-situ biodegradation of volatile organic compounds in landfill by sewage sludge modified waste-char." Waste Management 105, no. : 317-327.
Carbonation of reactive magnesia (MgO) has recently received increasing attention in the area of soil stabilization and ground improvement. However, as a critical parameter in terms of long-term seepage behavior in the geotechnical analysis, the hydraulic conductivity of carbonated reactive MgO-stabilized silt has not been fully studied. In this context, the effect of water-MgO ratio (ratio of initial water content to MgO content, w0/c) and carbonation time on hydraulic conductivity (or permeability) characteristics was systematically investigated. Serial microstructural tests including mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analyses were applied to elucidate the intrinsic mechanisms. The obtained results indicate that as the initial water-MgO ratio decreases, the void ratio gradually decreases and the reduction of hydraulic conductivity becomes less prominent because of the little presence of flow paths. The hydraulic conductivity of carbonated MgO-admixed silt similar to that of PC-treated silt is mainly governed by the porosity, and its correlation with void ratio is proposed in the article. The variations of permeability with void ratio are consistent with those of the cumulative pore volume from MIP results in general, and the medium pores (3–30 μm) are substantiated to be the primary contributor in controlling the permeability. SEM and DSC analyses reveal that the cementation of soil particles and filling of hydrated magnesium carbonates marginally reduce the voids and permeability. The reasons for changes of permeability behaviors have been confirmed by the pore-size distribution and microstructure characteristics.
Guang-Hua Cai; Song-Yu Liu; Guang-Yin Du; Liang Wang; Jiang-Shan Li; Lei Liu. Hydraulic conductivity characteristics of carbonated reactive magnesia-treated silt. Bulletin of Engineering Geology and the Environment 2020, 79, 3033 -3047.
AMA StyleGuang-Hua Cai, Song-Yu Liu, Guang-Yin Du, Liang Wang, Jiang-Shan Li, Lei Liu. Hydraulic conductivity characteristics of carbonated reactive magnesia-treated silt. Bulletin of Engineering Geology and the Environment. 2020; 79 (6):3033-3047.
Chicago/Turabian StyleGuang-Hua Cai; Song-Yu Liu; Guang-Yin Du; Liang Wang; Jiang-Shan Li; Lei Liu. 2020. "Hydraulic conductivity characteristics of carbonated reactive magnesia-treated silt." Bulletin of Engineering Geology and the Environment 79, no. 6: 3033-3047.
Old landfills require pre‐aeration before excavation to reduce the emissions of volatile organic compounds and methane. Variation and distribution of gas species during landfill aeration is important in designing an aeration system and evaluating aeration progress. Limited research is conducted on the variation of gas concentration in aerobic landfills considering methane oxidation and aerobic waste degradation. In this study, a numerical model is developed considering reactions to simulate the changes in methane, oxygen, and carbon dioxide concentrations in landfills during air injection and extraction. Parameter sensitivity analyses are conducted to evaluate the effects of permeability, dispersion coefficient, maximum methane oxidation rate, and oxygen consumption rate on simulation results. Results show that the model is sensitive to oxygen consumption rate. Overall, the application of this model in aerobic landfills provides a practical method to predict gas concentration variation. This model can be used in the optimal design of in‐situ aeration system.
Jun Ma; Lei Liu; Xiao Yu; Xunchang Fei; Xiong Zhang; Gang Zeng; Yuzhang Bi. Simulation of gas concentration during the process of air injection and extraction in a landfill. Environmental Progress & Sustainable Energy 2020, 39, 1 .
AMA StyleJun Ma, Lei Liu, Xiao Yu, Xunchang Fei, Xiong Zhang, Gang Zeng, Yuzhang Bi. Simulation of gas concentration during the process of air injection and extraction in a landfill. Environmental Progress & Sustainable Energy. 2020; 39 (5):1.
Chicago/Turabian StyleJun Ma; Lei Liu; Xiao Yu; Xunchang Fei; Xiong Zhang; Gang Zeng; Yuzhang Bi. 2020. "Simulation of gas concentration during the process of air injection and extraction in a landfill." Environmental Progress & Sustainable Energy 39, no. 5: 1.
MSW landfill releases a lot of harmful pollutants such as H2S, NH3, and VOCs. In this study, two laboratory-scale biocovers such as biochar (BC) derived from agricultural & forestry wastes (AFW) pyrolysis, and sludge modified the biochar (SBC) were designed and used to remove the harmful pollutants. In order to understand in-situ biodegradation mechanism of the harmful pollutants by the SBC, the removal performances of the harmful pollutants together with the bacterial community in the BC and SBC were investigated in simulated landfill systems for 60 days comparing with the contrast experiment of a landfill cover soil (LCS). Meanwhile, the adsorption capacities of representative harmful pollutants (hydrogen sulfide, toluene, acetone and chlorobenzene) in the LCS, BC, and SBC were also tested in a fixed bed reactor. The removal efficiencies of the harmful pollutants by the SBC ranged from 95.43% to 100.00%, which was much higher than that of the LCS. The adsorption capacities of the harmful pollutants in the SBC were 4 times higher than that of the LCS since the SBC exhibited higher BET surface and N-containing functional groups. Meanwhile, the biodegradation rates of the harmful pollutants in the SBC were also much higher than that of the LCS since the populations of the bacterial community in the SBC were more abundant due to its facilitating the growth and activity of microorganisms in the porous structure of the SBC. In addition, a synergistic combination of adsorption and biodegradation in the SBC that enhanced the reproduction rate of microorganisms by consuming the absorbed-pollutants as carbon sources, which also contributed to enhance the biodegradation rates of the harmful pollutants.
Linbo Qin; Xinming Huang; Qiang Xue; Lei Liu; Yong Wan. In-situ biodegradation of harmful pollutants in landfill by sludge modified biochar used as biocover. Environmental Pollution 2019, 258, 113710 .
AMA StyleLinbo Qin, Xinming Huang, Qiang Xue, Lei Liu, Yong Wan. In-situ biodegradation of harmful pollutants in landfill by sludge modified biochar used as biocover. Environmental Pollution. 2019; 258 ():113710.
Chicago/Turabian StyleLinbo Qin; Xinming Huang; Qiang Xue; Lei Liu; Yong Wan. 2019. "In-situ biodegradation of harmful pollutants in landfill by sludge modified biochar used as biocover." Environmental Pollution 258, no. : 113710.
Ferrous sulfate (FeSO4) is widely used to effectively stabilize hexavalent chromium (Cr(VI))‐contaminated soil. The leaching behavior, Cr(VI) content, and chromium speciation distribution in the stabilized soil are the most important indexes for determining the effectiveness of reduction treatment. Numerous factors, such as reductant dosage and soil particle size, affect the stabilization process; these factors are relatively important. This study investigated the influence of FeSO4 dosage and soil particle size on leachability and speciation distribution of chromium in contaminated soil. Results showed that the increase in FeSO4 significantly reduced the leachability and Cr(VI) content in the soil given the increased reducible species that stem from an acid soluble fraction of chromium. The small particle size of the soil that contains a large surface area facilitated the reaction between Cr(VI) and FeSO4, thereby resulting in low leachability and high reducible species of Cr(VI) in the stabilized soil. The leached Cr(VI) concentration was exponentially correlated to Cr(VI) content in the stabilized soil, and the leachability of Cr from the stabilized soil was linearly correlated to the exchangeable phase of Cr. In addition, the leached Cr(VI) concentration from the stabilized soil conform to the US Environmental Protection Agency and China regulatory limits; meanwhile, considerable Cr(VI) remained in a few stabilized soil and exceeded the environmental quality standards for soil in China. These results illustrated the importance of a comprehensive assessment of Cr(VI)‐contaminated soil, which is treated by reductants for enabling flexible future land use. © 2018 American Institute of Chemical Engineers Environ Prog, 00: 000–000, 2018
Ting‐Ting Zhang; Qiang Xue; Jiang‐Shan Li; Ming‐Li Wei; Ping Wang; Lei‐ Liu; Yong Wan. Effect of ferrous sulfate dosage and soil particle size on leachability and species distribution of chromium in hexavalent chromium‐contaminated soil stabilized by ferrous sulfate. Environmental Progress & Sustainable Energy 2018, 38, 500 -507.
AMA StyleTing‐Ting Zhang, Qiang Xue, Jiang‐Shan Li, Ming‐Li Wei, Ping Wang, Lei‐ Liu, Yong Wan. Effect of ferrous sulfate dosage and soil particle size on leachability and species distribution of chromium in hexavalent chromium‐contaminated soil stabilized by ferrous sulfate. Environmental Progress & Sustainable Energy. 2018; 38 (2):500-507.
Chicago/Turabian StyleTing‐Ting Zhang; Qiang Xue; Jiang‐Shan Li; Ming‐Li Wei; Ping Wang; Lei‐ Liu; Yong Wan. 2018. "Effect of ferrous sulfate dosage and soil particle size on leachability and species distribution of chromium in hexavalent chromium‐contaminated soil stabilized by ferrous sulfate." Environmental Progress & Sustainable Energy 38, no. 2: 500-507.
Leachate recirculation has the better effect to the biogas production in landfill. A pilot scale test of leachate recirculation considered the gas and liquid well was conducted in a landfill. The long term record of the leachate recirculation volume and gas production was preserved. The variation of the methane production was addressed under different recirculation schemes. The recirculation loading was the key parameter in recirculation scheme, especially considering the special condition in landfill. The recycling program and collection method implemented in the sites have an important effect on the evaluation of leachate recirculation for methane generation enhancement. It will be provided useful evidence for assessing the gas production by Leachate recirculation and collection well design in landfill.
Lei Liu; Jun Ma; Xin Min Nan Hui; Yi Dong; Sai Ge. The Acceleration of Methane Production by Leachate Recirculation in Pilot Scale in a Landfill. Soil and Recycling Management in the Anthropocene Era 2018, 498 -503.
AMA StyleLei Liu, Jun Ma, Xin Min Nan Hui, Yi Dong, Sai Ge. The Acceleration of Methane Production by Leachate Recirculation in Pilot Scale in a Landfill. Soil and Recycling Management in the Anthropocene Era. 2018; ():498-503.
Chicago/Turabian StyleLei Liu; Jun Ma; Xin Min Nan Hui; Yi Dong; Sai Ge. 2018. "The Acceleration of Methane Production by Leachate Recirculation in Pilot Scale in a Landfill." Soil and Recycling Management in the Anthropocene Era , no. : 498-503.
Leachate recirculation is a critical element in the evaluation of the availability of methane production enhancement in bioreactor landfills. Field experiments in leachate injection were conducted in horizontal wells at a landfill in Hubei Province in China. The experiments included the long-term test of methane concentration and production in three cells; the test was operated with nonrecirculation (NR), continued recirculation (CR), and descending recirculation (DR). The average methane concentration in CR is 54.8%, which is higher than that in the NR and DR sites. The average biogas flow rate in the CR site was 2.2 times that in the NR site. The recirculation loading should be determined with the specific conditions, to effectively improve the methane production in field site. The position of the gas collection well was also very important, coordinating with the distribution of the leachate injection well and influence area of the liquid injection. The long-term monitoring of injection volume and gas production is essential to determine the reliability of recirculation for methane reuse.
Lei Liu; Huan Xiong; Jun Ma; Sai Ge; Xiao Yu; Gang Zeng. Leachate Recirculation for Enhancing Methane Generation within Field Site in China. Journal of Chemistry 2018, 2018, 1 -7.
AMA StyleLei Liu, Huan Xiong, Jun Ma, Sai Ge, Xiao Yu, Gang Zeng. Leachate Recirculation for Enhancing Methane Generation within Field Site in China. Journal of Chemistry. 2018; 2018 ():1-7.
Chicago/Turabian StyleLei Liu; Huan Xiong; Jun Ma; Sai Ge; Xiao Yu; Gang Zeng. 2018. "Leachate Recirculation for Enhancing Methane Generation within Field Site in China." Journal of Chemistry 2018, no. : 1-7.
The optimization design of well spacing (WS) and aeration rate (AR) is crucial to the in situ aeration system operation in under long-term and high-efficiency conditions. This optimization design aims to transport additional air into landfills and to develop an improved oxygen environment for enhancing aerobic degradation. Given the specific pore structure distribution within landfills, providing sufficient oxygen in all waste bodies in field sites through gas wells is difficult. The design of well distribution also lacks adequate criteria. In this work, the multi-well optimization aeration method (MWOAM) was proposed to select the WS and AR from prediction results that consider gas transport properties by maximizing oxygen storage ratio (OSR) as the key objective threshold. This method was applied to the aeration restoration engineering in Jinkou landfill, which represents the first full-scale application of an aeration project in China, to optimize the operation scheme of the aeration system. Results of the gas concentration monitoring show that the trend of the OSR with aeration time based on the measurement agrees with the prediction. The oxygen and methane contents remain high and low within the landfill during the aeration process, respectively. Moreover, the temperature in the waste body did not exceed the upper limit value. These results suggested that the MWOAM is an effective means of supplying sufficient oxygen content across the landfill body and extend the aeration system operation for the long term. Therefore, this work provides reliable evidence to support the design and operation management of the aeration systems in full-scale landfills.
Lei Liu; Jun Ma; Qiang Xue; Jingbang Shao; Yijun Chen; Gang Zeng. The in situ aeration in an old landfill in China: Multi-wells optimization method and application. Waste Management 2018, 76, 614 -620.
AMA StyleLei Liu, Jun Ma, Qiang Xue, Jingbang Shao, Yijun Chen, Gang Zeng. The in situ aeration in an old landfill in China: Multi-wells optimization method and application. Waste Management. 2018; 76 ():614-620.
Chicago/Turabian StyleLei Liu; Jun Ma; Qiang Xue; Jingbang Shao; Yijun Chen; Gang Zeng. 2018. "The in situ aeration in an old landfill in China: Multi-wells optimization method and application." Waste Management 76, no. : 614-620.
Evaluation of oxygen distribution during aeration in landfill is significantly important to determine the design parameters of an injection well. A coupling model describing gas preferential transport in a landfill was developed, which linked the effect of advection–diffusion and oxidation reaction and mass exchange between the fracture and the matrix system. The quantitative simulation of the variation in gas distribution during vertical well aeration in short term was presented, combined with the typical cases in field site. The parameter sensitivity in the coupling model to gas transport was addressed. Simulation result of the oxygen and methane concentrations by using the dual advective–diffusive (DAD) model, which considered the immobile zone effect, was closer to the monitoring data than that by using single advective–diffusive model. The variation of the AR under aeration was presented with the key parameters to provide the theory evidence for gas well design in landfill. This study provided reference for the design of the gas injection well distribution in aerobic landfill.
Lei Liu; Jun Ma; Qiang Xue; Yong Wan; Xiao Yu. Modeling the oxygen transport process under preferential flow effect in landfill. Environmental Science and Pollution Research 2018, 25, 18559 -18569.
AMA StyleLei Liu, Jun Ma, Qiang Xue, Yong Wan, Xiao Yu. Modeling the oxygen transport process under preferential flow effect in landfill. Environmental Science and Pollution Research. 2018; 25 (19):18559-18569.
Chicago/Turabian StyleLei Liu; Jun Ma; Qiang Xue; Yong Wan; Xiao Yu. 2018. "Modeling the oxygen transport process under preferential flow effect in landfill." Environmental Science and Pollution Research 25, no. 19: 18559-18569.
Permeability is a very important parameter to evaluate the landfill gas (LFG) transport properties of municipal solid waste (MSW). Waste permeability is largely dependent on pore structure, which is affected directly by compression stress and degradation. In this article, laboratory tests were conducted to determine the permeability of MSW under different stresses and degradation phases. Test results showed that porosity and permeability values were in the range of 0.11–0.65 and 8.7 × 10−14–7.29 × 10−12 m2, respectively. The porosity of waste samples declined exponentially with the increase of compacted density and linearly with the increase in water content. Permeability decreased significantly with stress and degradation because of the increase in compacted density and finer particles of the waste, which led to low porosity of the samples. The influence of stress on permeability was in the scope of 1.6 × 10−12–3.7 × 10−12 m2, whereas porosity was 0.23–0.34. However, the effect of coupled stress and degradation on permeability was reduced to more than an order of magnitude. The power model was found to be suitable for fresh and degradation wastes, whereas Kozeny–Carman model was only suitable for old wastes. This study provides theoretical and practical significance for environmental pollution control and resource utilization of LFG in landfills. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1694–1699, 2017
Gang Zeng; Lei Liu; Qiang Xue; Yong Wan; Jun Ma; Ying Zhao. Experimental study of the porosity and permeability of municipal solid waste. Environmental Progress & Sustainable Energy 2017, 36, 1694 -1699.
AMA StyleGang Zeng, Lei Liu, Qiang Xue, Yong Wan, Jun Ma, Ying Zhao. Experimental study of the porosity and permeability of municipal solid waste. Environmental Progress & Sustainable Energy. 2017; 36 (6):1694-1699.
Chicago/Turabian StyleGang Zeng; Lei Liu; Qiang Xue; Yong Wan; Jun Ma; Ying Zhao. 2017. "Experimental study of the porosity and permeability of municipal solid waste." Environmental Progress & Sustainable Energy 36, no. 6: 1694-1699.
The rationality of air injection well for operation parameter design is important for effective repair and safety of aeration systems in landfills. On the basis of the literature, the operating results of the air injection systems used in field sites were summarized, and the key design parameters were addressed. The operation and assessment of aeration systems were presented. First, the behavior of oxygen transport was caused by the characteristics of the pore media in the waste body. A mathematical model was needed to address the spatial–temporal evolutions of oxygen concentration in landfill. The optimum design method of gas injection well should be developed to elevate the oxygen content at maximum level across the field site, applying to most landfills. Second, an effective leachate exchange and recirculation plan should be developed to ensure sustained aerobic reaction in full scale. Some experiences of leachate discharge in field sites were presented. Third, the relationship between oxygen consumption and stability indicators should be determined to create an effective aeration plan. This function will help evaluate the reliability of aeration systems. This study provides evidence for the design, construction, operation, and effectiveness assessment of air injection well in repair engineering of landfills. © 2016 American Institute of Chemical Engineers Environ Prog, 2016
Lei Liu; Jun Ma; Qiang Xue; Gang Zeng; Ying Zhao. The viability of design and operation of the air injection well for improvementIn Siturepair capacity in landfill. Environmental Progress & Sustainable Energy 2016, 36, 412 -419.
AMA StyleLei Liu, Jun Ma, Qiang Xue, Gang Zeng, Ying Zhao. The viability of design and operation of the air injection well for improvementIn Siturepair capacity in landfill. Environmental Progress & Sustainable Energy. 2016; 36 (2):412-419.
Chicago/Turabian StyleLei Liu; Jun Ma; Qiang Xue; Gang Zeng; Ying Zhao. 2016. "The viability of design and operation of the air injection well for improvementIn Siturepair capacity in landfill." Environmental Progress & Sustainable Energy 36, no. 2: 412-419.
The dual permeability model (DPM) is used to describe the gas flow in landfills under the preferential flow effect. A steady-state radial DPM was developed in this study to predict gas distribution at extraction well operations. Two typical cases of a short-term pumping field test from a single extraction well were also studied. The sensitivity of kf/km and mass transfer coefficient in the DPM was simulated. The mechanism of higher deviation between the simulation result and the test could be explained by the gas flux and influence radius, as determined by the single permeability model based on gas pressure distribution in the radial direction. The reliability of the DPM in the prediction of gas flux and influence radius in extraction wells was initially verified. The study provides evidence of the improvement of the design and operation parameters of extraction wells in landfills using the proposed method. © 2016 American Institute of Chemical Engineers Environ Prog, 2016
Lei Liu; Jun Ma; Qiang Xue; Gang Zeng; Ying Zhao. Evaluation of dual permeability of gas flow in municipal solid waste: Extraction well operation. Environmental Progress & Sustainable Energy 2016, 35, 1381 -1386.
AMA StyleLei Liu, Jun Ma, Qiang Xue, Gang Zeng, Ying Zhao. Evaluation of dual permeability of gas flow in municipal solid waste: Extraction well operation. Environmental Progress & Sustainable Energy. 2016; 35 (5):1381-1386.
Chicago/Turabian StyleLei Liu; Jun Ma; Qiang Xue; Gang Zeng; Ying Zhao. 2016. "Evaluation of dual permeability of gas flow in municipal solid waste: Extraction well operation." Environmental Progress & Sustainable Energy 35, no. 5: 1381-1386.
The field‐scale test of aeration to accelerate biodegradation of the waste was conducted, which was selected in an old landfill in Hubei province in China. The long‐term monitoring was presented, lasted for 11 months, to estimate the degradation stability of the landfill. The monitoring parameters included the temperature, COD and BOD of leachate, gas concentration, water level, settlement, and cellulose/lignin. The results show that the waste degradation rate was increased under the aeration condition, while there was a trend of the stability in the whole waste body. The water level within the landfill was adjusted by discharge measurements, contributing to the buildup of the oxygen environment in landfill. The C/L could be used to assess the stability of the full‐scale waste during the degradation process. But, there was obviously discrete by means of drilled sampling. The field‐scale test was needed to provide the evidence for aeration engineering operation. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 380–385, 2016
Lei Liu; Qiang Xue; Gang Zeng; Jun Ma; Bing Liang. Field-scale monitoring test of aeration for enhancing biodegradation in an old landfill in China. Environmental Progress & Sustainable Energy 2015, 35, 380 -385.
AMA StyleLei Liu, Qiang Xue, Gang Zeng, Jun Ma, Bing Liang. Field-scale monitoring test of aeration for enhancing biodegradation in an old landfill in China. Environmental Progress & Sustainable Energy. 2015; 35 (2):380-385.
Chicago/Turabian StyleLei Liu; Qiang Xue; Gang Zeng; Jun Ma; Bing Liang. 2015. "Field-scale monitoring test of aeration for enhancing biodegradation in an old landfill in China." Environmental Progress & Sustainable Energy 35, no. 2: 380-385.
Non-homogeneity of permeability largely depends on heterogeneity of the pore structure of waste in a landfill, which contributes to variation in gas flow state. Gas pressure dropping test (GPDT) was one of the most effective methods to describe the gas preferential flow, was used to investigate the gas breakthrough curves in initial pressures, moisture contents and degradation phases in lab test. Dual-permeability model was developed to quantify the gas preferential flow in waste column. The reliability of the model was verified by a good agreement from the gas flow rate between the simulation results and experimental results. The simulation results show the biodegradation of the waste produced an obviously decrease in the permeability in fracture system due to the variation of the particle distribution. The porosity and mass transfer in fracture system has largely decreased with the continued biodegradation and moisture content increasing. It will be provided useful evidence for assessing the gas preferential flow during the well operation in landfill. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 41–47, 2016
Lei Liu; Qiang Xue; Yong Wan; Yu Tian. Evaluation of dual permeability of gas flow in municipal solid waste: Experiment and modeling. Environmental Progress & Sustainable Energy 2015, 35, 41 -47.
AMA StyleLei Liu, Qiang Xue, Yong Wan, Yu Tian. Evaluation of dual permeability of gas flow in municipal solid waste: Experiment and modeling. Environmental Progress & Sustainable Energy. 2015; 35 (1):41-47.
Chicago/Turabian StyleLei Liu; Qiang Xue; Yong Wan; Yu Tian. 2015. "Evaluation of dual permeability of gas flow in municipal solid waste: Experiment and modeling." Environmental Progress & Sustainable Energy 35, no. 1: 41-47.
This study focuses on the impact of landfill high concentration solutions erosion on geosynthetic clay liner (GCL) materials permeability. The permeation tests on the GCL, submerged using different kinds of solutions with different concentrations, were carried out systematically by taking these chemical solutions as permeant liquids. Based on seasonal variations of ion concentrations in Chenjiachong landfill leachate (Wuhan Province), CaCl2, MgCl2, NaCl, and KCl were selected as chemical attack solutions to carry out experimental investigations under three concentrations (50 mM, 100 mM, 200 mM) and soak times (5, 10, and 20 days). The variation law of the GCL hydraulic conductivity under different operating conditions was analyzed. The relationship between GCL hydraulic conductivity, chemical solutions categories, concentrations, and soak times were further discussed. The GCL hydraulic conductivity, when soaked and permeated with high concentration chemical solutions, increases several times or exceeds two orders of magnitude, as compared with the permeation test under normal conditions that used water as the permeant liquid. This reveals that GCL is very susceptible to chemical attack. For four chemical solutions, the chemical attack effect on GCL hydraulic conductivity is CaCl2 > MgCl2 > KCl > NaCl. The impact of soak times on GCL hydraulic conductivity is the cooperative contribution of the liner chemical attack reaction and hydration swelling. A longer soak time results in a more advantageous hydration swelling effect. The chemical attack reaction restrains the hydration swelling of the GCL. Moreover, the GCL hydraulic conductivity exponentially decreases with the increased amplitude of thickness.
Qiang Xue; Qian Zhang; Lei Liu. Impact of High Concentration Solutions on Hydraulic Properties of Geosynthetic Clay Liner Materials. Materials 2012, 5, 2326 -2341.
AMA StyleQiang Xue, Qian Zhang, Lei Liu. Impact of High Concentration Solutions on Hydraulic Properties of Geosynthetic Clay Liner Materials. Materials. 2012; 5 (11):2326-2341.
Chicago/Turabian StyleQiang Xue; Qian Zhang; Lei Liu. 2012. "Impact of High Concentration Solutions on Hydraulic Properties of Geosynthetic Clay Liner Materials." Materials 5, no. 11: 2326-2341.