Applied Mechanics and Materials Vols. 448-453

Abstract: The decision-making and control system of a burner-type diesel particulate filter (DPF) regeneration was designed. Through the online simulation and the application research, it showed that the regeneration system had good response performances on prediction, decision-making, support and control. The DPF regeneration could be rapidly completed in 5-10 minutes and the regeneration efficiency be more than 87%, and the peak temperature and its maximum average grads were in the safe range. The system can realize the efficient, reliable and safe regeneration.

Abstract: By Series of comparative experiments, Factors of influencing the yield of biurea which is prepared from the condensation reaction between hydrazine hydrate and urea are studied, such as pH value, ratio of urea to hydrazine hydrate, temperature of reaction solution, reaction time and acid addition order. Under the optimum process conditions, the yield of biurea can reach over 97%, the biurea produced by hydrochloric acid method avoids large amounts of complex salt wastewater in condensation reaction of sulfuric acid method, and make the production process of biurea tends to be more environmentally friendly.

Abstract: Two Gravel-less Perforated Pipe Leach Fields systems with naturally ventilated or not were tested to treat domestic sewage under the hydraulic loading of 3.3 cm/d, and the differences of the two systems decontamination effect were also investigated by using T test. The results showed that the average removal rates of COD_Cr, TP, TN and turbidity were 86.1%, 58.0%, 61.1% and 93.6% in the naturally ventilated system, which was 2.0%, 5.4%, 10.2% and 3.2% higher than the normal GPPLF system under the same operating condition. T test indicated that the system of natural ventilation had little effect on removal of COD_Cr and TP, but could significantly improve the treatment effect of TN and turbidity.

Abstract: this paper reviewed the progress of flow field distribution in subsurface flow constructed wetlands (SSF), generalized the theoretical basis for numerical simulation of flow field distribution and the application of computer software in subsurface flow constructed wetlands. At the same time, analysed the relationship of flow field distribution with the bed body of aspect ratio, substrate thickness, material properties of matrix and the way of filling, found that the appropriate aspect ratio, substrate thickness and scientific way of filling could improve the flow field distribution, which was an effective way to improve the utilization rate of substrate. In addition, summarized the plant roots system and microbe growth effect on the flow field distribution. Therefore, the flow field distribution was directly effected of utilization ratio of matrix material, and living environmental condition of microbe, thus the flow field distribution as a parameter for design would be a kind of scientific method. Finally, proposed the corresponding research methods, and discussed how to improve the flow field distribution uniform, for improving the design level of subsurface flow constructed wetlands.

Abstract: The Sequencing Inclined Dynamic Membrane Biological Reactor (SIDMBR) was investigated on a pilot scale for 60 days of emulsified oil wastewater treatment at zero excess sludge discharge. Results indicate that at hydraulic retention time of 24 h, the average removals of chemical oxygen demand (COD), ammonia nitrogen and oil are 66.83, 64.2 and 70.8% in 1~60 days, respectively. The membrane flux, biofilm quantity, and extracellular polymeric substances (EPS) content begin to change after 20th, which indicate that membrane fouling has occurred.

Abstract: Through this pot experiment of corns, the paper studied the effect of the use of FGD gypsum into the alkalization soil to improve corn output and soil property in the alkalization soil of the west of Jilin Province. The study indicated that FGD gypsum reduced effectively the PH value of the alkalization soil and improved the corn output. When the amount of FGD gypsum was 3t/667m², the growth index of planting corn, such as the plant height, root length, plant fresh weight, was the best. But when the amount of FGD gypsum was 2t/667m², the difference was not obvious. The results indicated that considering the factors of soil PH value and salt-resistance, when the amount of FGD gypsum was 2t/667m², the effect of the use of FGD gypsum of the alkalization soil in the west of Jilin Province to improve soil property was the best.

Abstract: Phosphorus leakage from phosphorus-enriched soils (PES) is a major cause of water degradation worldwide, and phytoextraction is known to be an effective method of remediation. However, it is unclear whether phytoextraction is equally efficient in mountainous regions. We investigated the potential of P accumulation of major plant species in the Lake Dianchi Watershed of Southwestern China. Most of the plants living in PES of this region have high P contents; some have been identified as P-hyperaccumulators, such as Polygonum pubescens, which has the highest leaf P content of 16.88 mg/g. Although the dominate species have relatively low P contents than the P-hyperaccumulators, they still have a higher P uptake potential due to their greater biomass, for example, the P uptake potentials of Alnus nepalensis, Coriaria nepalensis, and Erianthus rufipilus are 46.98, 16.91, and 22.78 kg/ha, respectively. While these plants can decrease the total P of rhizospheric soil and topsoil, the effects on the total P-pool was not significant. Our results suggest that just phytoextraction may be less efficient in remediating PES in mountainous regions, and it requires further studies about P cycling and native plants to design more effective measures for P immobilization.

Abstract: For investigating the competitive ability of denitrifying bacteria and sulfate reducing bacteria on the substrate in the anaerobic environment, denitrification and sulfate reduction experiments were conducted under the conditions of different carbon content and different nitrate/sulfate ratio, and the kinetic difference of denitrification and sulfate reduction was also analyzed. The experimental results showed that denitrification could essentially be completed in 7~9 h at the same condition of carbon source content, but sulfate reduction was completed after 12 h. Denitrification rate constant of the microbes was over one time larger than that of sulfate reduction. When the carbon source was enough (C/N ratio and C/S ratio more than 3), denitrification efficiencies all surpassed 98%, while that of sulfate reduction only reached 84%. Under the same condition, the nitrate reduction ability of microbes was stronger than that of sulfate reduction, and the process of nitrate reduction had much more superiority.

Abstract: A static aeration biopile process was used to bioremediate polycyclic aromatic hydrocarbon (PAH)-contaminated soil using four different approaches for treating about 30 m³ of soil at a former oil-producing site. The four treatments investigated were as follows: (i) fertilizer plus bulking agent (FB); (ii) fertilizer, bulking agent, plus Tween 80 (FBT); (iii) fertilizer, bulking agent, Tween 80, plus fungi agent (FBTF); and (iv) fertilizer, bulking agent, bacterial inoculum, plus fungi agent (FBBF). After bioremediation for 320 days, the total amount of 16 PAHs ranged from 4.14 to 5.31 mg/kg in the final soil, removal rates ranging from 75.5% to 81.5%. The sum concentration of seven carcinogenic PAHs decreased down to 0.15 mg/kg. The values of the total toxicity equivalence concentrations for 16 PAHs ranged from 0.014 to 0.068 mg/kg. The removal rates of the 16 PAHs in these four different treatments decreased in order FBBF > FBT > FBTF > FB.

Abstract: Phosphorus removal by substrates in constructed wetland has been widely accepted as the most important way. However, as the substrates of constructed wetland will be saturated with phosphorus adsorption after the long-term treatment of sewage, the effect of phosphorus removal and adsorption by substrates is limited. To improve phosphorus retention ability of substrates and extend the lifetime of full-scale constructed wetland system, this paper systematically summarized the researches of P-saturated substrates regeneration in constructed wetland. And the concern with future research directions encompasses several major topics were also prospected in this paper.