The three-step of MSWI fly ash washing process, to remove chloride from fly ash as much as possible, were investigated. The results show that with the increase of L/S, the release of chloride and sulphate both increased at the first step, but the effect of second and third washing step decreased for chloride, while the effect for sulphate increased. The suitable washing condition happened with a L/S ratio of 5 and 2 minutes of washing, considering the two economic factors (water consumption and economical factor).
With a growing demand for crop products in China, a great deal of local resources and industrial inputs are consumed including agricultural machineries, chemical fertilizers, pesticides, and energies, which results in many environmental issues such as resource depletion, water pollution, soil erosion and contamination, and CO2 emissions. Thus, this study evaluated the trend of sustainability of China’s crop production from 1997 to 2016 in terms of emergy and further explored the driving forces using decomposition analysis methods. The results showed that the total emergy used (U) increased by 50% from 7.82 × 1023 in 1997 to 1.17 × 1024 solar emergy Joule (sej) in 2016. Meanwhile, the values of the emergy sustainability index (ESI) were all smaller than one with a declining trend year by year, indicating that China’s crop production system is undergoing an unsustainable development pattern. From the results of the ESI decomposition, the renewable resource factor (R/GDP) and land use factor (L/A) are two key factors impeding the sustainable development of the crop production system. Therefore, the increased capacity of renewable resources and enough labor forces engaged in crop production will be the key strategies for its sustainable development.
The high-solids anaerobic digestion of biological municipal waste (BMW) produces both a valuable fuel production (methane) and an anaerobic digestion residue. Compost technology was chosen to treat with anaerobic digestion residue and the conclusion was. 1) The anaerobic digestion of the bio-waste as a whole worked fine during the stabilization stage, the maximum daily gas production happened on the 125th day, the maximum was 91.86L/d and TS concentration in the digestive juice was14.78%, methane concentration was about 50-55%, HRT was 20 days and the biodegradation rate was 65.28%;2) The temperature of AD residue compost entered the thermophilic phase(55°C) on day 3 of composting, lasted at least 3days, the changes in pH followed the same trend with a rise from 6.18 to 7.26 on the 14th day, he final mass loss was 30.12%, which resulted in the compost quality higher than innocuity criteria.
Collection efficiency is a key indicator for the design and evaluation of municipal solid waste (MSW) landfill gas (LFG) collection and utilization system. Although most Chinese sanitary landfills have been equipped with LFG collection systems, there are no accurate data on collection efficiencies, lack of which always result in huge loss of LFG or investment. The fates of methane generated in a landfill include collection through LFG pipes, fugitive emission from the surface, and oxidation by methanotrophs. Field campaigns for measuring methane emission and oxidation were conducted at one landfill located in Beijing. Methane samples were collected by means of static flux chambers. The measurements were carried out at soil covered road and operating and slope surfaces. Two methods, i.e. landGEM model based and field measurement based estimation were used for calculating the collection efficiency in this research. The methane emission amount were 262.1 and 53222.4 m3 in July 2013 for the working and slope surfaces, respectively. The collection efficiency was 94.3% according to field measurement. Calculated with the LandGEM model, the collection efficiencies for 2011 and 2012 were 48.5 and 47.7% (k=0.09 yr-1) and 20.9 and 22.2% (k=0.3 yr-1), respectively. The estimation based on field measurement was more credible than the other, although the lateral migration and the storage insitu were naglected. The model method did not perform well probably due to the inapplicability of the landGEM model on this landfill, where the MSW was packed into small-subcells, and inaccurate parameter, k.
Large amount of emissions from industrial waste residue to the environment has caused serious pollutions. Utilization way to using industrial waste residue preparing sulfoaluminate cement (SAC) is got much attention of scholars both at home and abroad. It summarized the present researches for preparation of SAC from industrial waste residue (IWR). Sintering temperature, mineral composition, physical properties (fineness, standard viscosity, setting time), mechanical properties (compressive strength, flexural strength) and corrosion resistance of cement clinker were analyzed. Preparation of SAC clinker using IWR is a very promising environmental technology.
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