Applied Mechanics and Materials Vols. 295-298

Abstract: In order to concentrate vanadium in converter slag bearing vanadium, the effect of SiO2 on behavior of vanadium in the process of enriching was studied. Experimental results show that, during cooling, dicalcium silicate containing vanadium and phosphorus precipitate first from original slag. For original with 7% SiO2, most of vanadium dissolves in calcium silicate phase. However, the proportion of dicalcium silicate is big. For slag modified by 12% SiO2, during cooling, two vanadium-rich minerals precipitate firstly, i.e. Ca3(V,P)2O8(30-33%V2O5) and Ca3(V,P)2O8•nCa2SiO4 (14-31%V2O5), then 3CaO•2SiO2 (2-4%V2O5) generates. With addition amount of SiO2 increasing, the proportion of 3CaO•2SiO2 decreases gradually, and the content of vanadium in vanadium-rich phase increases gradually. So appropriate SiO2 addition can suppress the precipitation of Ca2SiO4 and Ca3•Si2O7, and promote the generation of vanadium-rich phase.

Abstract: The main objectives of this research were to determine the effect of leachate refluence on biogas production for dry mesophilic co-fermentation of chicken manure and corn straw. The biogas production, the ratio of biogas production, methane content and pH were analyzed. The results showed that the leachate refluence has a significant impact on biogas production of dry co-fermentation. The cumulative biogas yield of the once in 48h has an increase by 10% and 5% for no reflux and once in 24h, respectively. The leachate refluence has little influence on the methane content, but it has good effect to keep pH in the optimum rang.

Abstract: This paper studied on the energy efficiency of the sludge anaerobic digestion after the pretreatment of ultrasonic wave. Adding ratio of the sludge after the ultrasonic pretreatment was 30 %，50 %，70 % respectively, the retention time of the digested sludge was 27 d，20 d，16 d. The experiment results show that to treat the sludge by ultrasonic wave in 50-90s is considered to be suitable and the Energy Consumption is relatively less. The ultrasonic disruption rate is 3 %-4.2 % which met the requirement of the sludge anaerobic digestion technique. When the adding ratio of the sludge by the ultrasonic pretreatment was 70 % and the retention time of the digested sludge was 20 d, the gas production of the unit sludge is the highest. When the adding ratio of the sludge by the ultrasonic pretreatment was 30 % and the retention time of the digested sludge was 20 d, the effect is better than others.

Abstract: Kitchen waste recycling is an environmental friendly measure. Two identical samples of kitchen waste were conducted for composting by the barrel-type of method in this study. Compost produced from these two experiments was analyzed for their physical and chemical properties. No significant difference was found between the compositions of the two kitchen waste samples. The major components of the two kitchen waste samples of this study were water content (averaged 72.7%), followed by combustible constituent (about 25.6%). The carbon-to-nitrogen (C/N) ratio was between 15 and 25. Compost by the simple barrel method had the average C/N ratio of 12. For the simple barrel method, because its enzyme fermentation lasted longer, the maturity of the compost was better. The compost samples had the average germination rate of 95%, indicating the simple barrel composting method definitely has better maturity. When comparing the compost samples produced in this study to the standards given by the Council of Agriculture, Taiwan, the simple barrel compost qualified all the criteria. The simple barrel composting method is a convenient and easy method for recycling and processing organic waste, especially kitchen. The compost products, both solid and liquid, can be used for agricultural purposes.

Abstract: The present environmental regulations in China require sludge to be disposed of in a safe and environmentally sound manner. This paper presented an investigation on methods to stabilize wastewater sludge and stability evaluation of stabilized sludge landfill. Laboratory studies were conducted to determine the feasibility of solidifying and stabilizing sludge using fly ash, lime, and clay at varied mixing ratios. Geotechnical properties of stabilized sludge were studied. The test results revealed that the strength of stabilized sludge increased with curing time and the decrease of moisture content. Significant increases in strength were achieved to math suitability for disposal in landfills and a stabilization method was selected based on cost and availability of material. The stability of landfill slope was studied and an optimum slope ratio balancing the safety and economy was presented.

Abstract: To protect the marine environment, a kind of new composite curing agent was used to solidify dredged soil. The compression test and direct shear test were conducted to make experimental study on solidified soil of 2 curing time and 4 curing agent content, and to analyze the effects made by curing time and curing agent upon soil shear strength and soil compression modulus. The results show the increase of curing time raises compression modulus and soil cohesion to some extent but affects soil internal friction angle slightly. The rise of curing agent content makes a significant growth of compression modulus and cohesion. The compression modulus and cohesion of 7%-curing-agent solidified soil are respectively 1.57 and 15.8 times those of plain soil. But curing agent impacts slightly on the increase of internal friction angle. The maximum growing rate of internal friction angle is just 18.2%.

Abstract: Waste management of several typical construction projects was investigated in Hunan area; the project differences were analyzed on the waste amount and components, the increasing environmental impact of construction wastes was discussed. The disposal advices were given on the aspects of reducing, resources and eco-friendship of construction wastes. The environmental impact of construction wastes is permanent and accumulated, and the components are increasing diversified, so, the secondary contaminations are also increasing severe.

Abstract: Waste distiller's grains (WDG),a co-product of brewing industry, was an abundant source of biomass that could be hydrolyzed to yield fermentation sugar for the production of fuel ethanol. In this study, hydrolysis of WDG using mixed acid as catalysts was examined with the indices of the concentration of reducing sugar and furfural. The structural characteristics of WDG before and after acid treatment were also discussed by means of SEM, FTIR and XRD. The results indicate that there are 59.32gL-1 reducing sugar under the conditions of 100°C, solid-liquid ratio of 1:12 gmL-1, acid concentrations of 2.0% and time of 120 min, with the conversions rate of 77.38% and 62.50% for hemicelluloses and cellulose, respectively. SEM photographs show that the structural modifications after acid treatment are pronounced in comparison to that of WDG, which present a rigid and compact morphology. A lot of large irregular pores with different sizes and shapes are formed and the structures are also severely distorted resulting in the increasing surface exposure and porosity. Instrumental analyses with FTIR and XRD indicate that the strength of characteristic peaks for corresponding typical functional groups of each component are changed compared with the feedstock, and there is an increase of the crystallinity index when WDG is subjected to the MACH treatment.

Abstract: Large amounts of chromite ore processing residues (COPR) containing hexavalent chromium (Cr(VI)) discharged from the production processes of sodium chromate and dichromate need to be treated since Cr(VI) has been recognized as a carcinogen internationally and has posed a great threat to the environment and human health. Remediation of COPR containing Cr(VI) with bacteria, biomass and ferrous sulfate was studied in this work. A strain of Cr(VI)-reducing bacteria (CRB), a strain of sulfate-reducing bacteria (SRB), orange peels and ferrous sulfate were used as antidotes to reduce Cr(VI) to Cr(III). The experimental design methodologies — Uniform Design and Orthogonal Experimental Design were adopted to investigate the effects of the reductants on the reduction of the Cr(VI) in COPR. The results show that orange peels and CRB can reduce Cr(VI) in COPR over 95% in 30 days. Together using the four stuff can reduce Cr(VI) over 97% in 12 days. However, it seems that presence of the SRB is not beneficial to Cr(VI) reduction because it might refrains the action of CRB. Therefore, it is not surely beneficial to apply multiple microorganisms simultaneously to the reduction of Cr(VI) in COPR.

Abstract: Circular consumption play an important role in saving resources and reducing waste emissions ,it can also realize optimization of waste resources .Only through circular consumption, can we achieve the circle of economic and social, can we achieve the coordinated development of resources and the environment. Community shop is a noticeable pattern in circular consumption. Through the rational management and operation of community shop, more people can vintage be recycled and transferred to the people who need them, and circular consumption and the harmonious development of society can be realized.