Framework, method and case study for the calculation of end of life for HWL and parameter sensitivity analysis.

Mass construction and operation of hazardous waste landfill infrastructure has greatly improved China's waste management and environmental safety. However, the deterioration of engineering materials and the failure of landfill may lead to the release of untreated leachate rich in persistent toxic pollutants to the soil and shallow groundwater. Accordingly, we develop the framework and process model to predict landfill life by coupling the landfill hydrological performance model and material degradation model. We found that the decrease rate of the concentration of persistent pollutants in leachate was significantly slower than the deterioration rate of the landfill engineering materials. As a result, when the materials failed, the leachate with high concentrations of persistent pollutants continued to leak, resulting in the pollutants concentration in surrounding groundwater exceeding the acceptable concentration at around 385 a, which is the average life of a landfill. Further simulation indicated that hydrogeological conditions and the initial concentration of leachate will affect landfill lifespan. The correlation coefficients of concentration, the thickness of vadose zone and the thickness of aquifer are - 0.79, 0.99 and 0.72 respectively, so the thickness of vadose zone having the greatest impact on the life of a landfill. The results presented herein indicate hazardous waste landfill infrastructure reinvestment should be directed toward long-term monitoring and maintenance, waste second-disposal, and site restoration.

Isolation distance between municipal solid waste landfills and drinking water wells for bacteria attenuation and safe drinking.

Groundwater pollution and human health risks caused by leachate leakage have become a worldwide environmental problem, and the harm and influence of bacteria in leachate have received increased attention. Setting the isolation distance between landfill sites and groundwater isolation targets is particularly important. Firstly, the intensity model of pollutant leakage source and solute transport model were established for the isolation of pathogenic Escherichia coli. Then, the migration, removal and reduction of bacteria in the aerated zone and ground were simulated. Finally, the isolation distance was calculated based on the acceptable water quality limits, and the influence of hydrogeological arameters was analyzed based on the parameter uncertainty. The results of this study suggest that the isolation distances vary widely ranging from 106 m-5.46 km in sand aquifers, 292 m-13.5 km in gravel aquifers and 2.4-58.7 km in coarse gravel aquifers. The gradient change of groundwater from 0.001 to 0.05 resulted in the isolation distance at the highest gradient position being 2-30 times greater than that at the lowest gradient position. There was a difference in the influence of the thickness of the vadose zone. For example, under the same conditions, with the increase of the thickness of the aeration zone, the isolation distance will be reduced by 1.5-5 times, or under the same thickness of the aeration zone, the isolation distance will be significantly shortened. Accordingly, this needs to be determined based on specific safety isolation requirements. In conclusion, this research has important guiding significance for the environmental safety assessment technology of municipal solid waste landfill.

[Heavy Metal Content of Rural Living Solid Waste and Related Source and Distribution Analysis].

Living solid waste of 72 typical villages and towns in 12 provinces was investigated, and related heavy metal pollution characteristics, source, and distribution were analyzed. Results showed that heavy metal content of As, Hg, Pb, Cd, Cr, Cu, Zn, and Ni in living solid waste of typical northern villages of China was (7.51±8.89), (0.64±0.42), (21.91±12.29), (4.82±8.37), (86.36±59.99), (36.43±15.98), (62.19±36.61), and (46.07±25.22) mg·kg-1, respectively. Content of As, Hg, Pb, Cd, Cr, Cu, Zn, and Ni in living solid waste of typical southern towns was (7.43±8.82), (0.83±0.74), (21.62±13.76), (1.84±4.55), (131.06±74.96), (37.20±16.80), (98.04±63.71), and (46.75±25.75) mg·kg-1, respectively. Cd and Hg exceeded the standards for urban garbage agricultural control and soil environmental quality. Sources of heavy metals in domestic waste were explored by Pearson correlation analysis, cluster analysis, and principal component analysis. Results showed that Pb and Cd were mainly derived from kitchen waste, dust, paper, rubber, and plastic. Hg was mainly from kitchen waste and dust. Zn and Cr were mainly from dust. Cu was mainly from dust, paper, rubber, plastic, battery, and electronic waste. Ni was mainly from battery and electronic wastes. As was mainly derived from pesticides and fertilizers.

[Basic Features of Combustible Rural Garbage Component and Its Spatial-temporal Difference in China].

In order to realize the disposal feasibility of rural garbage by incineration, 72 rural garbage sampling points of 12 provinces in China were chosen to analyse mass fraction of full component and combustible component, moisture content of full component and low heating value of rural garbage in spring, summer, autumn and winter of 2015. The results revealed that the mass fraction of combustible rural garbage components in wet basis followed the order of kitchen residual(13%-53%) > the rubber(10%-18%) > the paper(10%-15%) > the wood(0-10%) > the fabric(0-8%). The compositional difference of rural garbage was not apparent between villages and towns within the same administrative region. The average moisture content of full component in southern rural garbage was higher than that in northern area, and the average moisture content of national rural garbage was about 40.1%. The low heating value of rural garbage in full composition which surpassed 3500 kJ·kg-1 was more than 81% in the north China, but in the south China, it was 44%, 50%, 61% and 72% in spring, summer, autumn and winter, respectively. After sorting, the low heating value increased greatly, but the low heating value of southern rural garbage in spring was still less than 3500 kJ·kg-1, more than 56% towns and villages of southern rural garbage in summer, autumn and winter and annual northern rural garbage heating value met the heating value requirement of incineration disposal. Therefore, after sorting, the rural garbage by incineration disposal method was feasible to the north China rural garbage, but the south China rural garbage requires strengthened pretreatment process.

[Physical and chemical properties of land-filling pile and aged refuse in 5-year-old semi-aerobic and anaerobic landfills].

This paper studied the surface settlement, temperature, and gas production of land-filling pile, and the physical and chemical properties of aged refuse in 5-year-old semi-aerobic and anaerobic landfills. The pile's surface settlement and its volume reduction rate were significantly higher in semi-aerobic than in anaerobic landfill; and the treatment with leachate recycling brought larger uneven settlement than the treatment with water recycling. The temperature of anaerobic landfill pile (25.6 degrees C) was slightly higher than that of semi-aerobic landfill file (24.8 degrees C), but the difference was not significant. During land-filling period, the O2 concentration in semi-aerobic landfill pile was significantly higher than that in anaerobic one, while the CH4 concentration was in reverse. After 5 years land-filling, the contents of easily degradable organic matters in aged refuse, such as kitchen refuses and papers, decreased dramatically, while the contents of plastics, glasses, bricks, and woods increased. In addition, the contents of organic matters and nutrients in aged refuse were higher than those in typical southern China soils, and the concentrations of heavy metals except chromium in anaerobic landfill aged refuse were not beyond the grade three of Environmental Quality Standards for Soils (GB 15618-1995).

[Release amount of heavy metals in cement product from co-processing waste in cement kiln].

Clinker was produced by Simulating cement calcination test, and concrete samples were also prepared according to national standard GB/T 17671-1999. Long-term cumulative release amount of heavy metals in cement product from co-processing waste in cement kiln was researched through leaching test which refers to EA NEN 7371 and EA NEN 7375, and one-dimensional diffusion model which is on the base of Fick diffusion law. The results show that availabilities of heavy metals are lower than the total amounts in concrete. The diffusion coefficients of heavy metals are different (Cr > As > Ni > Cd). During 30 years service, the cumulative release amounts of Cr, As, Ni and Cd are 4.43 mg/kg, 0.46 mg/kg, 1.50 mg/kg and 0.02 mg/kg, respectively, and the ratios of release which is the division of cumulative release amount and availability are 27.0%, 18.0%, 3.0% and 0.2%, respectively. The most important influence factor of cumulative release amount of heavy metal is the diffusion coefficient, and it is correlative to cumulative release amount. The diffusion coefficient of Cr and As should be controlled exactly in the processing of input the cement-kiln.

Simultaneous removals of NOx, HC and PM from diesel exhaust emissions by dielectric barrier discharges.

The main target of this work is to characterize the abatements of particulate matter (PM), hydrocarbons (HC) and nitrogen oxides (NO(x)) from an actual diesel exhaust using dielectric barrier discharge technology (DBD). The effects of several parameters, such as peak voltage, frequency and engine load, on the contaminant removals have been investigated intensively. The present study shows that for a given frequency, the removals of PM and HC are enhanced with the increase of peak voltage and level off at higher voltage, while in the range of higher voltages a decline of NO(x) removal efficiency is observed. For a given voltage, the maximums of specific energy density (SED) and removal efficiency are attained at resonance point. The increase of peak voltage will result in a significant decrease of energy utilization efficiency of DBD at most engine loads. Alkanes in soluble organic fraction (SOF) are more readily subjected to removals than polycyclic aromatic hydrocarbons (PAHs).

Influence of ethanol-diesel blended fuels on diesel exhaust emissions and mutagenic and genotoxic activities of particulate extracts.

This study was aimed at evaluating the influence of ethanol addition on diesel exhaust emissions and the toxicity of particulate extracts. The experiments were conducted on a heavy-duty diesel engine and five fuels were used, namely: E0 (base diesel fuel), E5 (5%), E10 (10%), E15 (15%) and E20 (20%), respectively. The regulated emissions (THC, CO, NOx, PM) and polycyclic aromatic hydrocarbon (PAH) emissions were measured, and Ames test and Comet assay, respectively, were used to investigate the mutagenicity and genotoxicity of particulate extracts. From the point of exhaust emissions, the introduction of ethanol to diesel fuel could result in higher brake specific THC (BSTHC) and CO (BSCO) emissions and lower smoke emissions, while the effects on the brake specific NOx (BSNOx) and particulate matters (BSPM) were not obvious. The PAH emissions showed an increasing trend with a growth of ethanol content in the ethanol-diesel blends. As to the biotoxicity, E20 always had the highest brake specific revertants (BSR) in both TA98 and TA100 with or without metabolizing enzymes (S9), while the lowest BSR were found in E5 except that of TA98-S9. DNA damage data showed a lower genotoxic potency of E10 and E15 as a whole.

Ambient air temperature effects on the temperature of sewage sludge composting process.

Using data obtained with a full-scale sewage sludge composting facility, this paper studied the effects of ambient air temperature on the composting temperature with varying volume ratios of sewage sludge and recycled compost to bulking agent. Two volume ratios were examined experimentally, 1: 0: 1 and 3: 1: 2. The results show that composting temperature was influenced by ambient air temperature and the influence was more significant when composting was in the temperature rising process: composting temperature changed 2.4-6.5 degrees C when ambient air temperature changed 13 degrees C. On the other hand, the influence was not significant when composting was in the high-temperature and/or temperature falling process: composting temperature changed 0.75-1.3 degrees C when ambient air temperature changed 8-15 degrees C. Hysteresis effect was observed in composting temperature's responses to ambient air temperature. When the ventilation capability of pile was excellent (at a volume ratio of 1:0:1), the hysteresis time was short and ranging 1.1-1.2 h. On the contrary, when the proportion of added bulking agent was low, therefore less porosity in the substrate (at a volume ratio of 3:1:2), the hysteresis time was long and ranging 1.9-3.1 h.