Preparation and reactivation of magnetic biochar by molten salt method: Relevant performance for chlorine-containing pesticides abatement.

Molten salt has been regarded as a versatile and environmental-friendly method for the material preparation and waste destruction. In this work, molten FeCl3 was utilized for the generation of magnetic biochar (MBC) derived from simultaneous activation and magnetization of biomass. The sample characterization indicated that MBC had a rough surface with BET surface area of 404 m2/g and total pore volume of 0.35cm3/g. Highly dispersed Fe3O4 and nitrogen could be deposited on the surface, leading to an excellent magnetization property. The MBC exhibited a great 2,4-Dichlorophenol (2.4-DCP) and atrazine removal performance in solution with the maximum adsorption capacity achieved 298.12 mg/g and 102.17 mg/g. Kinetics results demonstrated that MBC adsorption met the Pseudo-first-order model better. Molten NaOH-Na2CO3 was provided for the re-activation of exhausted MBC. 2,4-DCP was firstly desorbed from the MBC and subsequently destructed by the active species in the melt medium. Chlorine can be captured in the molten alkaline medium from the XRD pattern of residues.The MBC could be easily recovered with a yield of 98.2% and fixed carbon content of 61.0% after the molten salt regeneration process. With no 2,4-DCP detected, 65.5% and 31.69% of initial Cl was found in washing water and residues with the molten NaOH-Na2CO3, respectively. After 4 cycles of regeneration and adsorption, 60.55%-72.22% of initial adsorption capacity can be kept. This preparation and regeneration method can be an effective way to reduce the risk of secondary pollution of chlorinated organic compounds during adsorbent regeneration.Implications: Molten salt (MS) is a salt or multiple salts with a low melting point, and has been applied in many sectors and is regarded as a crucial role in terms of energy, environmental, and resource sustainability. In our paper, magnetic biochar was prepared by one-step activation and magnetization of fir dust using molten FeCl3∙6H2O. Meanwhile, a regeneration method using molten alkaline salt was provided. Magnetic biochar generated in our study performed well in the 2,4-dichlorophenol and atrazine adsorption. After four cycles of regeneration and adsorption, 72.2% of initial 2,4-DCP adsorption capacity can be kept.

[Ecological demonstration activity and eco-civilization construction mode: review and prospects].

Ecological civilization is to normalize human development behaviors to harmonize the relationships between social and ecological development and eco-environment protection. In this paper, a comparative analysis was made on the ecological demonstration activities of ecological demonstration areas led by the Ministry of Environmental Protection, exemplar cities of national environmental protection, and ecological provinces, cities, and counties. It was considered that all the ecological demonstration activities had the problems of lacking pertinence of construction goals, disordered construction subjects, inefficient construction processes, and lacking continuous incentive mechanisms of assessment. In the meantime, through the analysis of the connotations of eco-civilization, the relationships between eco-civilization and eco-demonstration constructions were approached, and the eco-civilization construction mode was put forward in terms of construction goal, construction subject, and construction processes and assessment. The construction mode included the construction goal based on regional characteristics; the synergistic cooperation of construction subjects, the expanding ways of public participation, and the establishment of evaluation system for comprehensively measuring the 'actions and results'.

Greenhouse gases emissions accounting for typical sewage sludge digestion with energy utilization and residue land application in China.

About 20 million tonnes of sludge (with 80% moisture content) is discharged by the sewage treatment plants per year in China, which, if not treated properly, can be a significant source of greenhouse gases (GHGs) emissions. Anaerobic digestion is a conventional sewage sludge treatment method and will continue to be one of the main technologies in the following years. This research has taken into consideration GHGs emissions from typical processes of sludge thickening+anaerobic digestion+dewatering+residue land application in China. Fossil CO(2), biogenic CO(2), CH(4,) and avoided CO(2) as the main objects is discussed respectively. The results show that the total CO(2)-eq is about 1133 kg/t DM (including the biogenic CO(2)), while the net CO(2)-eq is about 372 kg/t DM (excluding the biogenic CO(2)). An anaerobic digestion unit as the main GHGs emission source occupies more than 91% CO(2)-eq of the whole process. The use of biogas is important for achieving carbon dioxide emission reductions, which could reach about 24% of the total CO(2)-eq reduction.

[Evolution and discrimination of ecological planning and its related conceptions].

Ecological planning is one of the most important tools in realizing city's sustainable development. The ecological planning in China was started in the 1980s, and on the basis of assimilating the existing theoretical and practical experiences from western countries, basically formed a theoretical system in accordance with the Chinese characteristics and acquired a series of practical results. This paper reviewed the research and development processes of China' s ecological planning. It is considered that the study of our ecological planning was derived from the geographical principles of land resources ecological utilization, the ecological principles of complex ecological system theory, and the combination of these two principles. The ecological planning has experienced three research stages, i. e., single-disciplinary exploration, multi-disciplinary and multi-perspective study (including landscape ecology, ecology and urban planning), and interdisciplinary and multidisciplinary collaboration research. The ecological planning and the related conceptions, primary principles, main academic points, and representatives at each research stage were summarized, and through the discrimination of the basic conceptions of ecological planning and other related plans, it was pointed out that ecological planning is an general conception which includes land ecological planning, urban ecological planning, and eco-city planning, and the principles and theories of ecological planning should be integrated into, led and restricted the present planning system to promote the city's and regional sustainable development.

Fabrication of two-dimensional superposed microstructure by interference lithography.

In this paper, we report the basic theory and method of single exposure interference lithography (IL) to fabricate two-dimensional (2D) superposed microstructures. Distribution of six-beam interference intensities with different azimuth angle is discussed, and 2D superposed microstructures with different periodic constants are obtained by computer simulations. The experiment results using CHP-C positive photoresist show a 2D superposed photonic crystal composed of a periodically repeated hexagonal pattern of hexagonal lattice cells, which is in close agreement with the computer simulation. Fabrication of a superposed structure by single exposure IL paves the way for studying 2D photonic crystal fabrication, surface lasing, optical waveguides, and so on.

[Experimental study on stabilization of sewage sludge by MOC].

Magnesium oxychloride cement (MOC) was used for the stability agent in the stabilization experiments of sewage sludge. It is found that MgCl2 in MOC is a kind of water-absorbent, water absorption of MgCl2 can be achieved at 1.55 mL/g (per 100 g sludge). Meanwhile, some water in sludge can be combined with MOC in the hydration reaction and sludge moisture content can be reduced efficaciously. The crystal structure of 3 phase and 5 phase, which occurred in the hydration process, makes the sludge compressive strength as high as 85.14 kg/cm2. The best ratio of MOC/sludge is 3/100, and MgO/MgCl2 is 3/1. Mg-Si-Al gel system is formed with Si2+, Al3+, Cu2+ in the sludge under alkaline condition, and it plays an important role in the stabilization of the heavy metals in sludge. Leaching experiments of sludge show that heavy metal concentrations of Cu, Zn, Cd, Cr, As in lixivium from sludge are lower than leachability standard.

[Effects of initial pH on hydrogen production from acid pretreated municipal sludge].

A series of batch tests were conducted to investigate the effects of initial pH on bio-hydrogen production from acid pretreated municipal sludge. The pH of sludge was first adjusted to 2.0, 3.0, 4.0 and 5.0, stood by for 24 h in a refrigerator at 4 degrees C, then adjusted to pH 2.0-12.0 respectively before using as the substrates for batch experiments. The results showed that the acid pretreated sludge with initial pH 11.0 gave the highest hydrogen production, and the corresponding accumulative hydrogen for sludge (dry basis) pretreated at pH 2.0, 3.0, 4.0 and 5.0 were 0.59, 1.83, 0.50 and 0.56 mL/g respectively. Hence, it could be seen that the initial pH 11.0 for the acid pretreated sludge should be the optimum pH range for promoting the growth of dominant hydrogen-producing anaerobes, while inhibiting hydrogen-consuming anaerobes. Meanwhile it also could be concluded that both hydrogenogen and methanogen were inhibited at the initial pH 2.0 to 4.0 and 12.0, which resulted in a low hydrogen production. Although the hydrogenogen and methanogen could be promoted at the initial pH 5.0 to 9.0, the corresponding hydrogen production was still quite low.

Optimization of methane fermentation from effluent of bio-hydrogen fermentation process using response surface methodology.

The individual effects and interactive effects of substrate concentration, ratio of inoculum to substrate, Ca(2+) concentration on the methane yield from the effluent of bio-hydrogen fermentation of food waste were investigated in this study. A central composite design (CCD) and response methodology (RSM) were employed in designing the experiments, in order to determine the optimum conditions for methane fermentation. The experiment results showed that the effects of substrate concentration, ratio of inoculum to substrate, Ca(2+) concentration were statistically significant at 5% level. The interactive effect of substrate concentration and ratio of inoculum to substrate was significant, however the interactive effect of substrate concentration and Ca(2+) concentration, ratio of inoculum to substrate and Ca(2+) concentration were found to be insignificant at 5% level. A maximum yield of 565.76 ml CH(4)/g VS(added) was estimated under the optimum conditions for substrate concentration 7.77 g of VS/l, inoculum to substrate ratio of 2.81 and calcium concentration of 380.82 mg/l. Verification experiment of the estimated optimum conditions confirmed that the RSM was useful for optimizing the methane yield from effluent of bio-hydrogen fermentation of food waste.

[Contrasting experiment of two types of MSW aerobic bioreactor landfill].

Bioreactor landfill is an emerging landfilling method, which represents the newest developing aspect of Municipal Solid Wastes (MSW) treatment. On basis of analyzing the merits and defects of present bioreactor landfilling methods, the paper improves these methods and combines organically aeration and leachate recirculation into a new reactor (called reactor A), which is contrasted with bare aerobic landfill (called reactor B). During the course of experiment, NH3, CH4, CO2, pH, temperature and electric conductivity in the two bioreactors were controlled and detected, meanwhile, COD, Fe3+, NH4(+) in the leachate were detected and analyzed. The paper researches on the wastes degradation and the COD, Fe3+ and NH4(+) removal of the two bioreactors, probes into the mechanics of wastes and leachate degradation. Finally the paper draws a conclusion that the effect of degrading wastes and leachate of bioreactor A is better than that of bioreactor B.