Advanced Materials Research Vols. 518-523

Abstract: Using granular activated carbon (GAC) as electric particle electrode and heterogeneous catalyst loaded metal oxide to replace insulated particle in bipolar packing bed cell (BPBC), the electro-heterogeneous catalytic oxidation system was constructed. Adopting impregnation method to prepare γ-Al₂O₃ supported catalysts containing Cu and Ce, it was evenly mixed with GAC to construct packing materials. Using stainless steel as anode, porous graphite as cathode and packing materials between them, landfill leachate was treated by an electro-catalytic oxidation process and COD removal efficiency was studied. The activity of catalysts was explored, and using scanning electron microscope (SEM) and X-ray diffraction (XRD), the microstructure and morphology were characterized. The operating parameters such as cell voltage, initial pH, airflow and inter-electrode distance were also investigated. The results showed that when the metal ion concentration in soaking solution was 2% for Cu, 9% for Ce, the activity of prepared catalyst was the highest. Under the conditions of an applied voltage of 15.0 V, pH of 7.0, airflow of 0.08 m³/h, and an inter-electrode distance of 3.0 cm, the removal efficiencies of COD reached 92.9%. Qualitative analysis of the interim products was carried out, adopting ultraviolet-visible spectrum, and the mechanism of electro-heterogeneous catalytic oxidation reaction was discussed. The whole degradation involves two main processes: electro-oxidation and electro-coagulation.

Abstract: This paper is devoted to studying the desulfurization and structural transformation behavior of lead sulfate in alkaline medium. The effects of roasting temperature, roasting time, and raw material ratio on the desulfurization and phase transition behavior of lead sulfate in sodium hydroxide molten salt was systematically investigated through a series of experiments and analyses. The results show that lead sulfate is gradually transformed to Pb₅O₄SO₄, α-PbO, β-PbO, and finally to Pb₃O₄ during roasting in sodium hydroxide molten salt at temperatures of 250°C to 550°C. At the conditions of roasting temperature 450°C, roasting time 40 minutes, molar ratio of lead sulfate to sodium hydroxide 1 : 2.6, lead sulfate can be completely converted to near-pure phase β-PbO powder. This paper provides a simple and efficient method for the recycling of waste lead acid battery, which consists mainly of lead sulfate.

Abstract: To find a suitable and affordable technology for the composting of human faeces in the Ger Areas of Ulaanbaatar, Mongolia, new composting system was developed and several trials have been conducted. Under controlled conditions with pH, temperature and moisture, three different mixtures were tested: human faeces plus sawdust, human faeces plus straw and human faeces plus wood chips. Based on the experimental results it can be concluded that the composting process, if started under controlled and appropriate conditions, could start and last about 32 days. Meanwhile, when ambient temperature drops sharply, the reactor temperature correspondingly drops sharply, but shows different results in the different temperature ranges. For stable and high efficient composting under such condition, further improvement measures and more trials should be done in next stages.

Abstract: The usefulness of chlorella pyrenoidosa were investigated for the removel of U(Ⅵ) from aqueous solution. Employing monofactorial and orthogonal experiment method for evaluating the biosorption of U(Ⅵ) onto chlorella pyrenoidosa, respectively, the influence of U(Ⅵ) concentration、pH、N/P and temperature on the biosorption of U(Ⅵ) by chlorella pyrenoidosa were studied.The results showed that the pH and U(Ⅵ) concentration were significant to remove U(Ⅵ) and that the increases of pH as well as U(Ⅵ) concentration was beneficial to the U(Ⅵ) absorption. However, the U(Ⅵ) absorption was affected less by the N/P and the temperature. Confirmed through orthogonal experiment, the optimum condition composition to attenuate U(Ⅵ) was 3.4mg/L U(Ⅵ) concentration at pH 6.0 with temperature 293K,and 3/1 of N/P. It was also proved that fresh cell of 1g/L(in dry weight) was able to attenuate U(Ⅵ) in wastewater from 3.4mg/L to 0.72 mg/L after batch experiments under the optimum conditions, which indicated good prospect in its future application.

Abstract: Experiments of desulfurization of limestone during sewage sludge combustion with different phosphorus contents were conducted in a 15 kW circulating fluidized bed test rig to investigate the effect of phosphorus on desulfurization. Chemical thermodynamic analysis was performed to compare with the experimental results. Chemical thermodynamic analysis indicates that relatively high content of phosphorus in sewage sludge will affect desulfurization because calcium will first react with phosphorus and then the rest is available for reaction with sulfur, which agrees well with the experimental results. The experimental results also show that relatively high content of phosphorus in sewage sludge affects self-desulfurization of calcium in sewage sludge and desulfurization of limestone. The effect of phosphorus on desulfurization must be taken into account during sewage sludge combustion.

Abstract: The composting experiment was conducted to study the dynamics of indices (temperature, Moisture content，seed germination index) during composing process, which lasted 50 days, used duck manure mixed with corn straw or (and) reed skin, with biological agents in the compost. The results showed that it was feasible to compost with duck manure. During the composting, treatment DCI and DRI which add biological agent, temperature increased rapidly to 50°C on the 4d and 6d, the high temperature stage could maintain for 15 and 13 days. In addition, germination index of Cabbage seeds in compostwas up to 86.28% and 81.38% respectively, after composting for 35 days, one or two weeks early than the normal treatment DC and treatment DR. The treatment group of nutrient content are present the increasing trend, the highest nutrient groupwas treatment DCI, the increased proportions of N, P, K ,available phosphorus and available potassium accounted for 20.24%, 6.74%, 21.00%, 20.41% and 20.66% respectively. Comprehensive nutrition quality and efficiency of compost, duck manure mixed with corn straw compost effect was better than that with reed skin caboodle corruption. That duck manure as raw material to produce organic fertilizer fermented, is useful to solve regional livestock solid waste, and may have great significance on change Bai-yangdian regional environment.

Abstract: A field experiment was conducted to investigate the effects of composted sewage sludge’s application on the dynamics change of enzyme activities in aeolian sandy soil. The composted sewage sludge was applied to the soil at 0,2,5,10,15,20 and 25 t·ha-1 respectively. The effects of various sewage sludge dosages on the soil’s enzyme activities were evaluated by measuring urease,sucrase,neutral phosphatase and catalase at different time intervals of 15,50,80,110 and 150 days after the addition of sewage sludge to the soil.The results showed that the urease,sucrase,neutral phosphatase and catalase activities increased to varying degrees as the sewage sludge dosages added to the soil increased. And the four enzyme activities were affected by the sampling time significantly,the urease and sucrase activities reached their maximum values in 50 days,and neutral phosphatase and catalase activities reached their maximum values in 80 days.The results also showed that the application of sewage sludge had positive effects on improving the aeolian sandy soil’s fertility.

Abstract: To study the effects of inoculating microorganism on aerobic composting of chicken manure, this paper utilized microorganism agents screened by ourselves to do research on the effect of compost producing organic fertilizer by chicken manure. The temperature, total carbon, Kjeldahl nitrogen, and seeds germination index were measured during the fermentation. The results showed that, compared with CK, the disposal inoculated with microorganism agents could obviously raise the temperature with the highest reaching 63.5°C and accelerate the organic matter decomposing with lower 4 % than control on the 16 d. The contents of Kjeldahl nitrogen declined from 2.44 % to 1.47 %. Furthermore, the seeds germination index achieved 80 % on the 22 d, higher 9 % than the control. The research described the factors in composting process for discussing the relativity of microorganism and chicken manure composting, which could provide the theoretical basis for the harmlessly efficient decomposition and rapid fermentation of poultry manure.

Abstract: Just like other paper/plastic/aluminum (PPA) composites, Tetra Pak-package-material (Tetra Paks) has excellent water and vapor barrier abilities, and is widely used in food and beverage packaging industry. However, serious environmental problem follows due to its long service life. In this paper, a novel electromagnetic shielding composite board was developed with recycled Tetra Paks and copper-iron mixed fibers. The influence of Cu/Fe ratio and mat configuration on board shielding effectiveness (SE), volume resistivity (VR) and mechanical properties were investigated. The results showed that the boards with copper-iron mixed fiber layers showed better electromagnetic shielding performance than those with only iron or copper fiber layer. The SE of the boards was improved with higher copper fiber content. The location of the metal fiber layers in the mat had a significant influence on board electromagnetic shielding performance. A symmetrical sandwich structure was found beneficial to better shielding performance, and in the same condition of wave frequency and shielding material thickness, the shielding system with a Fe core exhibited better shielding performance than that with a Cu core. The ratio of Cu/Fe and the configuration of mat both had significant influences on mechanical properties of the boards. It can be concluded that qualified electromagnetic shielding composite board could be produced with Tetra Paks wastes and copper-iron mixed fibers. Showing both environmental and economic values, this type of board could be considered as an alternative material used in packaging, interior finish, furniture, and other applications.

Abstract: The effect of sulfate radical(SO4−•) pretreatment on mesophilic anaerobic digestion of sewage sludge was investigated and compared with a control group. The results showed that pretreatment can effectively improve sludge anaerobic digestion performance. After sulfate radical pretreatment, the removal rate of TCOD during the digestion was increased by 11.5% , the cumulative gas production was increased by 44.9%.The VFA concentration increased in the supernatant after pretreatment, but the alkalinity was also increased at the same time, so as to ensure the stability of whole system. The highest methane yield under pretreatment condition was 0.27m3 CH4/kgVSremoval, 180.0% of the control. The results indicated that persulfate /K2S2O8 pretreatment could be an effective method for improving methane yield.