Applied Mechanics and Materials Vols. 260-261

Abstract: Construction and demolition waste has in its composition gypsum plaster which is a soil and groundwater contaminating material. Some works have been developed to recyle this gypsum waste. The aim of this work is to show a thermal analysis of recycled plaster. The recycled plaster was produced through a recycling process consisting of grinding and burnig the gypsum waste. Physical and thermal properties (TGA/DTA) from both commercial and recycled gypsum plaster were analysed. The results show a recycled plaster with similarities with commercial plaster, showing the possibility to reuse this waste in construction works.

Abstract: IBIS (Integrated Biosphere Simulator) model is an ecosystem process model, which represents the research direction of a global carbon cycle simulation. Based on the existing research achievements, the regional ecological carbon sink potential is simulated from point to surface with a long time serie of meteorological data (1954-2010), data on different ecosystem vegetation types, soil texture data, terrain data and remote sensing data. The results are listed as follows: there is no significant variation of potential carbon sink of Shenzhen vegetation over the past 30 years, carbon sequestration caapcity ranges within 43.52-55.82×10⁴ Mg C/a, and the potential carbon sink intensity value within 0-624 C/m²/a. Precipitation is a main factor which influnces the ecosystem carbon sink intensity in Shenzhen City. The carbon sink intensity of ecosystem is increased with more annual precipitation.

Abstract: Based on the target of ecological province, the meaning of ecological province is analyzed, the assessment objects and content of building an ecological province are elaborated, the structural model and the principle of selecting indicators are discussed. Taking the ecological province building plan of Guangxi Province as a case to be studied.

Abstract: In this paper the change of CO₂ concentration in an office of a university is continuously monitored, using test multifunction measuring instrument. The result shows that the CO₂ concentration present a different trends which is affected by the time, the number of person and the ventilation. In closed conditions, the longer the time, the more the number, the higher the CO₂ concentration will be. Ventilation playes a crucial role in controlling the indoor CO₂ concentration.

Abstract: By the leaching experiment of soil column, e researched speciation analysis and bioavailability of Cr in soil before and after fixing. The contents of Cr in fixed soil including exchangeable chromium, carbonate bound chromium, iron manganese oxide bound chromium, organic matter bound chromium, all lower than the soil before fixing, but residues chromium is higher than the soil before fixing. There is obvious difference bioavailability in soil before and after fixing. Soil heavy metal pollution which brings a threat to agricultural product quality could cause surface water and groundwater contamination, and cause the food chain poisoning[1-2]. Compared with the organic pollutants, heavy metal pollutants does not produce decoration in environmental media, through the soil-plant system enter the food chain therefore affecting the safety of agricultural produces and harm to human health. Therefore, it is essential to begin management of the heavy metal contaminated soil. Currently，heavy metal pollution mainly come from the following fields: chromium compounds used as electroplating, leather tanning, pigments, paints, alloys, dyeing and printing, offset printing. Cr contaminated soil repair method include: biology, agricultural engineering, physico-chemical treatment. By max fixatives into the soil adjusted or changed physical and chemical properties of Cr and produce precipitation adsorption ion-exchange humification and oxidation-reduction series reaction ,situ stabilization is one of treatment methods for physical-chemical, consequently reducing mobility and bioavailability in the soil environment , thereby decreasing the toxicity hazards of Cr elements on plants and animals[5]. Since the 1950s, zeolites have a wide range of applications in various fields. Zeolite is a frame-like structure, moisture content of aluminum silicate minerals, with a porous structure, adsorption and ion exchange[6]. In this paper, not only curing effect of fixatives on the metal has been emphasized, but also fixative for friend of environment has been taken into consideration. Natural Zeolite magnesium oxide and FeSO4 have been chosen as fixative and leaching solvent select demonized water. Provide some theoretical basis and technical support for farmland Cr contaminated soil immobilized system.

Abstract: In many arid and semiarid lands, dry lake beds (saline playa) represent a tremendous source of unconsolidated salt-rich sediments that are available for aeolian transport. Severe salt-dust storms caused by the erosion of such landforms have become very harmful natural phenomena. Base on texture and appearance characteristic, five principal undisturbed playa surfaces for sampling to investigate the deflation rate and the vertical distribution of material abraded using a wind-tunnel experiment in this study. Two additional field deflation monitoring transect were aslo established to examine vertical deflation by wind from measurements of erosion pins at the Ebinur (dry) Lake. The results indicate that winds greater than 8 m/s is the main factor for inducing the erosion of the playa sediments. Soft salt, aeloian sediment and alluvial deposit are the main sources of the saline dust storms in Ebinur region. The near-surface vertical distribution of material abraded concentrated in 0 -10 cm height. The annual wind erosion rate ranged from 0.48 cm to 5.6 cm in the northwest portion of the lake and from 0.24 cm to 0.96 cm in the southeast portion.

Abstract: The article discussed mainly 3R principles of circular economy, and how to take use of 3R principles to manage construction waste. At last, gave some suggestions of managing construction waste, in order to exhort people to focus on reducing, reusing and recycling of construction waste.So,heighten people awareness of saving resources and protecting environment. On the other side, hope that these suggestions can provide scientific reference to government in managing construction waste.

Abstract: Based on the research of municipal solid waste leachate treatment technology in China, aiming at several typical leachate treatment technologies in the Guangxi area, this paper has made analyses and studies. It has made comprehensive investigation of materials, and has obtained the final leachate treatment technology scheme applicable in the Guangxi area.

Abstract: Escherichia coli and Bacillus subtilis as objects of the study, ultrasonic fragmentation acted on the bacterial cells in different growth stages, results showed that, it’s similar to the crushing effect of ultrasound on E. coli and B. subtilis cells of different growth stages, the highest crushing rate in the logarithmic phase, reached to 95.8% and 94.3% respectively, the crushing rate of adjustment phase is lowest, maintained at around 60%, the crushing rate stability cell was centered, which can be achieved 90%. The structure of the bacterial cell wall didn’t the main factor to decide the ultrasonic fragmentation effect, but different growth periods of bacterial cells did the determinant.

Abstract: Three-dimensional flow field of flocculating reactor is simulated. Numerical results were applied to analyze and explain influence of flow field under different flocculation conditions. The results indicate that k, ε can reasonably explain flocculation effect, and meanwhile verify the better applicability as the CFD numerical simulation evaluation indexes of flocculation effect. The results can be extended to find an effective way to optimize the design and operation, to improve the efficiency of flocculation.