Applied Mechanics and Materials Vol. 737

Abstract: A novel Mg/Fe/Ce layered double hydroxide (LDHs) and its calcined product (CLDH) were synthesized and CLDH was used as adsorbents for the removal of chlorate ions. Results showed that the initial solution pH was an important factor influencing the chlorate adsorption. The adsorption behavior of chlorate followed the Langmuir adsorption isotherm with a maximum adsorption capacity of 18.2 mg/g. The adsorption kinetics of chlorate on CLDH can be described by the pseudo-second-order kinetic model. It was concluded that the CLDH material is a potential adsorbent for the purification of polluted water with chlorate.

Abstract: Mechanical soil aeration is an easy, effective, and low-cost soil remediation technology; in particular, it is suitable for large sites contaminated by volatile chlorinated hydrocarbons (VCHs). Mechanical soil aeration encourages the volatilization of soil contaminants, but soil moisture, which reduces the amount of open pores, may hinder this process. The present study examined the remediation of silty soil containing 1,2-dichloroethane (1,2-DCA), chloroform (TCM), trichloroethylene (TCE), and tetrachloroethylene (PCE) using mechanical soil aeration and evaluated the influence of soil water content on the efficiency of the process. For artificially contaminated soil, the following conclusions were reached: (i) moisture undermines the volatilization of contaminants. When the soil water content increased from 5% to 20%, the residual concentrations of 1,2-DCA, TCM, TCE, and PCE in the soil increased from 0.08, 0.10, 0.09, and 0.48 mg/kg to 1.43, 0.81, 1.16, and 1.43 mg/kg, respectively. The effective diffusion coefficients also decreased from 1.88×10-2, 1.43×10-2, 1.88×10-2, and 1.30×10-2 cm2/s to 1.71×10-6, 1.30×10-6, 1.71×10-6, and 1.18×10-6 cm2/s, respectively. (ii) Residual contaminants are related to the octanol-water partition coefficient. The soil-water distribution coefficient of PCE was highest among the hydrocarbons (3.72), and the residual contaminants were mainly adsorbed on soil particles. The soil-water distribution coefficient of DCA was lowest (0.42), and the residual contaminants were mainly dissolved in the soil water.

Abstract: In this study, we illustrated enhanced biodegradation enzyme activity and the strains growth using the plants residues as carriers during the biodegradation of phenol in petrochemical wastewater. The three phenol-degrading strains named as A1, A2 and A3 were selected for an immobilized microorganism technique. A1, A2 and A3 were identified as Penicillium oxalicum, Aspergillus sp. and Sphingobacterium sp. using detailed morphological, biochemical and molecular characterization. The growth and degradation rate of phenol in wastewater by strains A1, A2 and A3 pre-grown in the agricultural residues (peanut shell) were higher than the free strains. Compared with the free strains,the enzyme activity of strains A1,A2 and A3, using the residues for pre-grown, increased 29.01 U/L, 30.30 U/L and 38.07 U/L, respectively. Hence, the immobilized microorganism technique is conducive to the phenol degradation.

Abstract: This study used coagulation - ultrafiltration technology for domestic sewage treatment, which was used widely in water supply and secondary treatment with sewage, in order to achieve high efficiency, low-cost, integrated treatment of domestic sewage treatment. This article chooses fly ash coagulant is not only simple preparation process, low cost, and with the traditional aluminum chloride and ferric chloride coagulation effect. The research results show that the coagulation can make the organic particles size distribution to move to larger particles area and significantly reduce colloidal substance. Ultrafiltration membrane system can further remove the coagulation treatment failed to completely remove polymer and part in the process of low molecular substances, to achieve high organic matter removal efficiency. The backwash of ultrafiltration membrane can make membrane flux recovery by about 80%. This system of SS can remove more than 95%, COD removal rate can reach 60% ~ 70%.

Abstract: The toluene being removed by dielectric barrier discharge (DBD) combined with modified photocatalyst was studied in the paper. Transition metal manganese was doped into crystal lattice of TiO₂ in order to improve the activity of photocatalyst, and the optimal doping ratio was confirmed in the study. As one of main factors, the influence on toluene removal efficiency of gas flow rate, initial concentration and electric field intensity was analyzed in the study. Furthermore, the energy efficiency was another important index which had been compared amongγ-Al₂O₃, TiO₂/γ-Al₂O₃ and Mn-TiO₂/γ-Al₂O₃. The result of study showed that DBD combined with Mn-TiO₂/γ-Al₂O₃ had the best buffer action against increasing of gas flow rate and initial concentration, the energy efficiency had the tendency as Mn-TiO₂/γ-Al₂O₃ > TiO₂/γ-Al₂O₃>γ-Al₂O₃, and the optimal doping ratio of manganese was 0.01.

Abstract: For the study on microbial contamination of reclaimed water from reverse osmosis process during storage, multiple controlled experiments were designed to simulate actual storage conditions and three influencing factors (storage materials, time and concentration of organic acids) which had an effect on the growth of microorganisms were investigated. The results showed that the stainless steel material was superior to PVC and glass material, but different materials of storage containers didn’t make a big difference in microorganism growth. In 30 days, all the total numbers of bacteria in three container materials were under 100cfu/mL which reached the Chinese Pharmacopoeia standards for purified water and also there is no clear law between organic acids concentration and microbial growth. Analyzed by DNA sequencing and checked by microscopic and electron microscopy, the pollution bacteria was identified as Bacillus. Bacteriostatic test results showed that the concentration 0-1000 mg/L of acetic acid had no significant inhibitory effect on the growth of Bacillus.

Abstract: Mercury is one of harmful pollutants during the coal-burning process that can not be ignored. The Ontario-Hydro method, Method 30B and Method 29 are mainly used for sampling the mercury in the flue gas from the coal-fired industrial boilers. This article studied the control ability of the mercury by the electrostatic precipitator (ESP), wet flue gas device (WFGD) and the dust removal and desulfurization integration at home and abroad.

Abstract: Discuss the corrosion factors of generator stator cooling water system (SCWs) in detail. Summarize the development and application status of generator stator cooling water control technology at home and abroad.

Abstract: Fe-containing compound clinoptilolite media (Fe-M), prepared with natural clinoptilolite, was applied to be the filter media of BAF, and then the treating performance of sewage by BAFs with Fe-M and ceramsite were investigated. Because Fe-M had relatively larger surface area, better pore connectivity, higher biofilm microbial biomass, and the ion-exchanging and adsorption effect, a higher ammonia nitrogen removal efficiency was obtained in BAF with Fe-M than ceramsite; and higher phosphorus removal in BAF with Fe-M was also realized by the adsorption and precipitation effect of the leaching ferric ions. Fe-M is more suitable to be used as the filter of BAF to treat sewage wastewater than ceramsite, which has a high value of broad application prospects and engineering popularization value.

Abstract: Pulverized coal combustion is one of the main NOx emission sources. The existing low NOx combustion technology can not meet the requirements of environment conservation. In this paper, a new low NOx combustion technology, the NOx inhibition method based on water-gas reaction, is presented, in which steam is injected into the anoxic flame of pulverized coal to bring water-gas reaction and produce CO and H₂ which will inhibit the production of NOx. The produced H₂ is especially very active. Water-gas reaction is endothermic, which has an effect of reducing the peak temperature of the flame and is very propitious to the inhibition of thermal type NOx. As the water-gas reaction is also an interim process, the heat absorbed in it will be released when burning with oxygen so that the whole amount of heat inside the furnace is not affected. The principle of the method is proved correct by experiments and industrial scale of 420 t/h boiler tests in which the effect of NOx reduction is obvious. The technology is consistent with that of air-staged combustion.