The effects of selected parameters on the nitric oxide removal by biofilter

A bench-scale biofilter was used to demonstrate the treatability of off-gas containing nitric oxide (NO) by examining selected operational parameters. After 6 days of operation, the biofilter reached to a steady state and NO reduction was significant, reducing from 200 ppm to 95 and 40 ppm after 6 and 40 days of continuous operation. The oxygen concentrations in the inlet would affect NO removal performance significantly; as oxygen content decreasing from 6% to 0%, the NO removal efficiency increased from 55% to 99%, indicating that oxygen inhibited the progress of denitrification. NO removal was inversely proportional to inlet NO concentration, removal efficiency decreased from 88% to 40 % as NO concentration increasing from 60 to 500 ppm. Column height would significant effect on the NO removal efficiency, under column height=6.5m and O(2)=6% conditions, 90% of removal efficiency was achievable. The effect of glucose added into biofilter would significantly enhance the NO removal efficiencies for both anaerobic and aerobic conditions of which 99% and 55%, respectively.     

Efficient removal of formaldehyde by diatomite decorated with BiOCl/TiO2 under visible-light irradiation: Effects of key preparation parameters

The diatomite decorated with BiOCl/TiO₂ (BiOCl/TiO₂@diatomite) composites were prepared by supporting BiOCl/TiO₂ heterogeneous junction on the surface of diatomite with precipitation-calcination method. This work systematically studied the effects of terminal pH, calcination temperature, and TiO₂/BiOCl ratio. Furthermore, the relationship between structure and photocatalytic performance of the composite was investigated. The results demonstrated that composite with optimized performance (84.1% formaldehyde degradation rate of 1.0 g photocatalyst) can be obtained at terminal pH of 6, calcination temperature of 500 °C, and TiO₂/BiOCl ratio of 55/45. It is indicated that the phase structure, grain size, and porous structure can be significantly affected by the above preparation parameters. In conclusion, the formaldehyde adsorption and degradation properties can be enhanced by the construction of porous structure and heterogeneous junction of composites. Overall, BiOCl/TiO₂@diatomite composites exhibited excellent formaldehyde degradation performance under visible light due to the multi-layer structure and the combination of TiO₂ and BiOCl on the surface of diatomite.     

从煤制甲醇合成气中回收LNG技术的开发

煤制甲醇工艺气化炉出来的合成气中含有甲烷,使后续工艺的能耗大大增加。研制的甲醇合成气分离回收LNG装置,不仅降低了合成气中甲烷含量,而且将合成气中甲烷分离液化成LNG供商业销售,创造较好的经济效益和社会效益。介绍甲烷深冷分离回收LNG技术的工艺流程特点和应用实例。     

Effects of pollutant concentration ratio on the simultaneous removal of NH3, H2S and toluene gases using rock wool-compost biofilter

The biological treatment of a tri-component mixed waste gas system in BRC1 and BRC2 biofilters packed with rock wool-compost media was studied. The model gases were NH(3), H(2)S and toluene. The gases were fed initially at about 50-55 ppm each. H(2)S was found to have the shortest start-up while toluene had the longest. Under two different NH(3):H(2)S:toluene concentration ratios of 250:120:55 and 120:220:55 (in ppm) for BRC1 and BRC2, the removal efficiencies of NH(3), H(2)S and toluene were found to be affected by their respective loading rate. On the other hand, toluene removal was observed to be inhibited at H(2)S concentration of 220 ppm as well. Almost complete removal of NH(3) and H(2)S was achieved when loading rate was applied up to 16.14 g-NH(3)/(m(3) bed h) and 36.09 g-H(2)S/(m(3) bed h), respectively. The maximum elimination capacity for NH(3) was determined to be 23.67 g-NH(3)/(m(3) bed h) at 78.6% removal efficiency and for H(2)S, 38.50 g-H(2)S/(m(3) bed h) at 68.1% removal efficiency. The maximum toluene elimination capacity was 30.75 g-toluene/(m(3) bed h) at 87.9% removal efficiency when the concentration of NH(3):H(2)S:toluene was 250:120:55 in BRC1, and was 16.60 g-toluene/(m(3) bed h) at 45.5% removal efficiency when the concentration of NH(3):H(2)S:toluene was 120:220:55 in BRC2. The pressure drops along both columns were low and the ratio of bed compactions over biofilter height was observed to be less than 0.02.     

Investigations into the application of a combination of bioventing and biotrickling filter technologies for soil decontamination processes—A transition regime between bioventing and soil vapour extraction

Bioventing has emerged as one of the most cost-effective in situ technologies available to address petroleum light-hydrocarbon spills, one of the most common sources of soil pollution. However, the major drawback associated with this technology is the extended treatment time often required. The present study aimed to illustrate how an intended air-injection bioventing technology can be transformed into a soil vapour extraction effort when the air flow rates are pushed to a stripping mode, thus leading to the treatment of the off-gas resulting from volatilisation. As such, a combination of an air-injection bioventing system and a biotrickling filter was applied for the treatment of contaminated soil, the latter aiming at the treatment of the emissions resulting from the bioventing process. With a moisture content of 10%, soil contaminated with toluene at two different concentrations, namely 2 and 14 mg g soil⁻¹, were treated successfully using an air-injection bioventing system at a constant air flow rate of ca. 0.13 dm³ min⁻¹, which led to the removal of ca. 99% toluene, after a period of ca. 5 days of treatment. A biotrickling filter was simultaneously used to treat the outlet gas emissions, which presented average removal efficiencies of ca. 86%. The proposed combination of biotechnologies proved to be an efficient solution for the decontamination process, when an excessive air flow rate was applied, reducing both the soil contamination and the outlet gas emissions, whilst being able to reduce the treatment time required by bioventing only.     

Effect of water removal on the textural properties of resorcinol/formaldehyde gels by azeotropic distillation

The resorcinol/formaldehyde gels containing 5% (w/v) of reactants have been prepared. After curing for seven days, the gel is treated with trifluoroacetic acid to initiate the condensation of hydroxymethyl groups. Drying of the prepared gels is done by removing water with the help of vacuum heterogeneous azeotropic distillation using amyl acetate and n-butanol. The textural properties of the gels thus obtained are compared with the properties of the gel obtained from exchange of water by acetone (control experiment). The pore volume and average pore diameter of the gel obtained from the azeotropic distillation of water with amyl acetate are 0.7663 × 10–3 m3/kg and 0.0145 m, respectively. These values are 1.5 times higher than the values obtained by vacuum heterogeneous azeotropic distillation with n-butanol and about twice than the values obtained in the control experiment. The surface areas in all the three gels are almost constant.     

Effect of sorption-desorption of water and methanol on the surface area and textural parameters of zirconia gels

Sorption-desorption of water on two hydrated zirconia gels with specific surface areas of about 300 m²g^?1 (as determined by nitrogen adsorption) did not change significantly the textural parameters. However, a similar treatment with methanol resulted in a surface area decrease of about 15–20%. Simultaneously, the C_BET parameter was found to decrease to approximately one half of its original value.It is shown that the t-plot method for surface area determination can only be applied when the isotherm under study and the standard isotherm have nearly the same value of the C_BET parameter.     

Biofiltration and kinetic aspects of a biotrickling filter for the removal of paint solvent mixture laden air stream

In the present study, removal of methyl ethyl ketone (MEK), toluene, n-butyl acetate and o-xylene (MTBX) emitted from the paint industry was carried out in a coal based biotrickling filter. When the influent MTBX loadings were less than 120 gm(-3)h(-1), nearly 100% removal could be achieved. A maximum elimination capacity of 184.86 gm(-3)h(-1) was obtained at a MTBX load of 278.27 gm(-3)h(-1) with an empty bed residence time of 42.4s in phase V. Results showed that the condition was the most favorable for n-butyl acetate degradation followed by MEK, toluene and then o-xylene. The corresponding maximum removal rate, r(max) values of MTBX were calculated as 0.085, 0.033, 0.16 and 0.024 gm(-3)h(-1), respectively. Standard deviation of error in prediction of MEK, toluene and o-xylene removal were within limit of 10%, while in the case of n-butyl acetate this was approximately 60%. The MTBX concentration profiles along the depth were also determined by using convection-diffusion reaction (CDR) model. It was observed that at low concentration and low flow rate, the model is in good agreement with the experimental values for MEK, toluene and n-butyl acetate, but for o-xylene the model results deviated from the experimental.     

Effect of fibre conditioning on the interfacial shear strength of glass-fibre composites

A study of the interaction of water-sized E glass fibres, supplied with and without an aminopropylsilane coupling agent, with vinyl and epoxy resins is reported. Interfacial shear strength measurements, made by means of the multifragmentation technique, have demonstrated that molecularly thin layers are effective adhesion promoters, as indicated by (a) the silane contamination on the nominally non-coupled fibres and (b) the aqueous extraction of the coupled fibres. Epoxy resins adhere through amino coupling reactions, but for the vinyl ester resin the maximum adhesion probably occurs through aluminium hydroxide sites exposed through extractive hydrolysis, and acidic residues in the resin.     

Mathematical modeling for the evaluation of zinc removal efficiency on clay sorbent

The adsorption characteristics of zinc ion from aqueous solution on the lateritic clay were investigated through batch and column mode of operation. The system variables were optimized to evaluate the maximum extent of zinc adsorption as well as for the purpose of modeling. A model equation correlating zinc adsorption with input concentration was described. The adsorption behavior can well be described by Freundlich isotherm model rather than Langmuir isotherm model. The favorable and spontaneous nature of adsorption was indicated from the thermodynamical parameters. The capacity was determined from isotherm parameters in batch mode and breakthrough parameters in column mode. The bed depth service time (BDST) model was utilized to predict column efficiency corresponding to different bed heights. Elution performance of retained zinc, using HNO(3) of definite composition, was examined from elution profile. Efficiency of the process was determined through repetitive operation cycles of retention and elution. Effectiveness of the process was judged through estimation of efficiency versus the cost of operation.     

三个国标中甲醛测定方法的比较和探讨

对GB 18582-2001、GB 18583-2001、GB/T 15516-1995三个国家标准中甲醛含量测定方法进行了比较,指出了其异同点,并提出了笔者对标准的一些理解和看法。     

Influence of leaks in surface filters on particulate emissions

Compliance with severe limit values of dust emissions is a main characteristic of surface filters. This characteristic is due to the high particle collection efficiency of surface filters. Beside regular operation it is necessary to consider phenomena such as a "pinhole" bypass through leaks in surface filters to ensure the above mentioned compliance with the limit values at all times. Experimental research has been carried out to observe and understand the "pinhole" bypass through leaks and the behaviour of pinholes over filtration time. To work out the influence of different filtration conditions the parameters pinhole diameter, filter face velocity and dust cake thickness were varied. The results can be explained by formulas usually used to calculate volumetric flow rates of orifice gauges. The experiments and the calculations lead to the conclusions that bigger pinholes decrease the collection efficiency and higher filter face velocities increase the collection efficiency of pinholed filter media.     

膨胀石墨的表面修饰及其对甲醛吸附性能研究

以氧化插层法制备的膨胀石墨(expanded graphite,EG)为吸附剂,采用十六烷基三甲基溴化铵(cetyltrimethylammonium btomide,CTAB)对EG进行表面修饰(改性).研究改性和吸附工艺对EG吸附甲醛气体性能的影响.结果表明:改性荆的浓度对EG吸附甲醛气体有较大影响,当CTAB的浓度为0.04 mol/L时,改性EG对甲醛的吸附效果较好.随着改性温度和时间的增加,改性EG对甲醛的吸附量先增加后减少,最佳改性温度和时间分别为70℃和90min.在室温(25℃)下,改性EG对甲醛气体的吸附效果较好.最佳工艺条件下,改性EG对甲醛气体的吸附量高达840mg/g.     

Effect of key parameters on the morphology transformation of three-dimensional TiO2 solid microspheres

Three-dimensional (3D) TiO₂ solid microspheres with different morphologies have been synthesized on a large scale by a simple hydrothermal method using titanium tetrachloride (TiCl₄) as the titanium source and ammonium fluoride (NH₄F) as the etchant. X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) studies show that the 3D solid microspheres, with an average diameter from hundreds of nanometers to several micrometers, are composed of numerous anatase TiO₂ particles. In addition, the morphologies of the as-prepared 3D solid microspheres can be controlled by adjusting the dosage of NH₄F and the reaction temperatures. The present study has enlarged the family of 3D solid microspheres, and offers a possible route for the synthesis of other inorganic hierarchical structures.     

Identification of the optimal product configuration and parameters based on individual customer requirements on performance and costs in one-of-a-kind production

One-of-a-kind production (OKP) aims at manufacturing products based on the requirements from individual customers while maintaining the high quality and efficiency of mass production. This research addresses the issues in identifying the optimal product configuration and its parameters based on individual customer requirements on performance and costs of products. In this work, variations of product configurations and parameters in an OKP product family are modeled by an AND-OR tree and parameters of the nodes in this tree. Different product configurations with different parameters are evaluated by performance and cost measures. These evaluation measures are converted into comparable customer satisfaction indices using the non-linear relations between the evaluation measures and the customer satisfaction indices. The optimal product configuration and its parameters with the maximum overall customer satisfaction index are identified by genetic programming and constrained optimization. A case study to identify the optimal configuration and its parameters of window products in an industrial company is used to demonstrate the effectiveness of the introduced approach.     

Effect of oxy-hydrogen blending with gasoline on vehicle performance parameters and optimization using response surface methodology

ABSTRACT

Rapid decline in fossil fuel reservoirs has attracted researchers to use a variety of fuel blends in Spark ignition (SI) and Compression ignition (CI) engines demonstrating similar performance and lower emissions. Oxy-hydrogen gas obtained through electrolysis has been successfully tested for this use. This paper presents a two wheeler chassis dynamometer based study of a two wheeler loaded with newly developed single cylinder variable compression ratio (VCR) engine utilizing different blends of gasoline and oxy-hydrogen gas. Variation in fuel average performance (FAP), wheel power (WP) and acceleration performance (AP) due to oxy-hydrogen blending with gasoline is studied and compared with neat gasoline at five different gears. Further multi objective optimization of FAP and WP is carried out using response surface methodology (RSM). Regression models are postulated for predicting FAP and WP at different levels of compression ratio (CR) and oxy-hydrogen gasoline blends. Interaction between CR and oxy-hydrogen-gasoline blending is also studied and discussed. Modification carried out on an engine improves vehicle performance parameters and oxy-hydrogen gasoline blending further enhances the improvements. Maximum FAP and WP in top gear is obtained at highest CR of 11.57:1 and a oxy-hydrogen gasoline blend with 112.558 ml/min flow rate of oxy-hydrogen gas.     

Effect of process parameters and talc ratio on hot plate welding of polypropylene

This study analyzes the influence of different talc ratios on weld strength of polypropylene joined with hot plate welding process. It further determines the optimum welding parameter settings to achieve the optimum weld strength and observes the effect of process parameters, namely plate temperature and heating time on the joint quality. Process parameters were considered as variables and their effect, interactions and relative significance were investigated by utilizing design of experiment. Simultaneously, a mathematical predictive model of the weld strength was developed in terms of welding parameters. The model can predict effectively weld strength with a 95% confidence level.     

Effect of waste plastic bottles on the stiffness and fatigue properties of modified asphalt mixes

Nowadays, the use of recycled waste materials as modifier additives in asphalt mixes could have several economic and environmental benefits. The main purpose of this research was to investigate the effect of waste plastic bottles (Polyethylene Terephthalate (PET)) on the stiffness and specially fatigue properties of asphalt mixes at two different temperatures of 5 and 20 °C. Likewise, the effect of PET was compared to styrene butadiene styrene (SBS) which is a conventional polymer additive which has been vastly used to modify asphalt mixes. Different PET contents (2–10% by weight of bitumen) were added directly to mixture as the method of dry process. Then the resilient modulus and fatigue tests were performed on cylindrical specimens with indirect tensile loading procedure. Overall, the mix stiffness reduced by increasing the PET content. Although stiffness of asphalt mix initially increased by adding lower amount of PET. Based on the results of resilient modulus test, the stiffness of PET modified mix was acceptable and warranted the proper deformation characteristics of these mixes at heavy loading conditions. At both temperatures, PET improved the fatigue behavior of studied mixes. PET modified mixes revealed comparable stiffness and fatigue behavior to SBS at 20 °C. However, at 5 °C the fatigue life of SBS modified mixes was to some extent higher than that of PET modified ones especially at higher strain levels of 200 microstrain.     

Effect of operating parameters on color and COD removal performance of SBR: sludge age and initial dyestuff concentration

Effect of sludge and initial dyestuff concentration on color and COD removal performance of anaerobic-aerobic sequential batch reactor was investigated. Remazol Red RR a vinylsulphonyl (VS) and monochlortriazine (MCT), reactive azo dye was used in the study. Sludge age was varied between thetaC=12 days and thetaC=30 days and dyestuff concentration was between D0=50 and D0=500 mg l(-1). The maximum color and COD removal was obtained as 95% and 70% for D0=60 mg l(-1) and COD0=800 mg l(-1) at 15 days sludge retention time, respectively, and no further improvement was observed when sludge age was increased to 30 days. The main color removal phase in this operation system was the anaerobic phase. Because, the color removal efficiency was already above 95% under anaerobic condition and therefore, the contribution of aerobic phase to color removal was negligible. Increasing dyestuff concentration did not significantly affect the decolorization. It was possible to obtain over 90% dyestuff removal even at D0=500 mg l(-1). SBR system reduces 1000 mg l(-1) initial COD concentrations to about 400 mg l(-1) for dyestuff concentration up to 150 mg l(-1). COD removal efficiency decreased from 70% to 60% by increasing initial dyestuff concentration from 100 to 500 mg l(-1). The results indicated that dyestuff and COD are mainly used by anaerobic organisms and aeration does not improve the performance of SBR system.     

Influence of key cement chemical parameters on the properties of metakaolin blended cements

The use of metakaolin (MK) as a mineral admixture for cement and concrete is a well-documented practice. The properties of cement pastes and mortars containing MK have been investigated as a function of key cement chemical parameters recognized as potential activators of the MK. Rheological behavior, initial setting time and compressive strength development have been compared by varying the total sulfate content, the nature of the added calcium sulfate and the free lime content (in the form of portlandite) in the cement. The results obtained indicate that it exists a compromise for the ratio performance/consistency in term of sulfate content and nature. Concurrently, a small addition of portlandite improves the consistency of the properties investigated.