上下回流人工湿地预处理微污染水库水的研究

采用上下回流潜流人工湿地对微污染水库水进行预处理试验。根据试验数据,构建了上下回流潜流人工湿地系统CODCr、TN、TP的一级动力学模拟方程。结果表明:在水力负荷为0.4m3/(m2.d)条件下,CODCr、TN、NH3-N、TP的平均去除率均分别达到56.06%、58.97%、55.91%和50.56%。湿地系统夏季处理效果明显好于其他季节。使用周期按20年考虑,日均进水量3.6m3/d,湿地建设成本为2100元,水的处理成本为0.13元/m3,这表明采用人工湿地预处理微污染水库水是经济可行的。     

Enhanced leachability of gold and silver in cyanide media: Effect of alkaline pre-treatment of jarosite minerals

Composite samples of tailings containing gold (1.35 g/t) and significant amounts of silver (155 g/t) were subjected to batchwise cyanide leaching to assess the feasibility of extracting gold and silver. The tailings are waste solids arising from flotation and leaching operations whereby the flotation product (sphalerite concentrate) is calcined and then solubilised into dilute sulphuric acid solution and eventually sequestered from the electrolyte by electrowinning. Silver and gold are part of the zinc refinery residue, flotation tailings and to a limited extent the calcine leach tailings. Mineralogical results showed that composite tailings are refractory in nature (44% quartz, 17% silico aluminates and 12% jarosites).The concept of enhancing gold and silver recovery from the tailings focused on firstly decomposing the jarosite minerals by alkaline pre-treatment and then secondly leaching with cyanide solution. These two steps ensured that free gold and silver found in the zinc refinery residue and in the jarosite minerals could be leached simultaneously. The composite tailings were treated with Ca(OH)₂ solutions and then heated to 90 °C for 2 h to decompose the silver-bearing mineral (Ag,PbFe₃(SO₄)₂(OH)₆). The alkaline pre-treated tailings were then subjected to cyanide leach tests at different NaCN dosages (2.5–10 kg/t) and particle size (96–200 μm). Without an alkaline pre-treatment stage, leach efficiencies achieved were 41% and 25% for gold and silver, respectively at 40 °C and 8 h mixing time. But, better leach efficiencies (55% for Au, 81% for Ag) were achieved after the feed was pre-treated with Ca(OH)₂. The leaching mechanism of gold was explained by the shrinking sphere model denoted by surface chemical reaction.     

消除20钢无缝管冷弯成型角裂的预处理工艺试验

对两批20钢无缝矩形管冷弯成型时角部出现裂纹的现象进行了组织观察分析,认为原料管热轧工艺不当而形成的魏氏组织是裂纹形成的主要原因。提出了冷弯成型前对原料管进行预处理的工艺方案;研究分析了正火温度、保温时间和冷却方式对原料管组织和力学性能的影响规律;确定了20钢原料管的常规正火工艺:加热温度(890±10)℃,保温6min后散置空冷。本常规正火工艺可完全消除20钢原料管的魏氏组织,使其屈服强度和抗拉强度的匹配更加合理,屈强比σS/bσ≤0.78,延伸率5δ≥30%,冷成型性能大幅度提高并避免出现冷弯开裂现象。     

Mechanical,thermal and morphological properties of durian skin fibre reinforced PLA biocomposites

Durian skin waste generated by durian fruit or Durio zibethinus Murray show potential as a new reinforcement based-natural fibre. Similar to other lignocellulosic fibre, durian skin fibre (DSF) is capable in reinforcing polylactic acid (PLA) through extrusion and injection moulding processes for various applications. In current study, the effects of fibre content and pre-treatment using 4% sodium hydroxide (NaOH) on DSF were investigated on impact and thermal properties of PLA biocomposites. Treated DSF significantly enhanced the properties of PLA biocomposites as compared to untreated biocomposite. PLA can be replaced by 30 wt% DSF for similar impact performance. Thermogravimetry analysis (TGA) demonstrated that pre-treated DSF improved the thermal stability of PLA biocomposite. Differential scanning calorimetry (DSC) showed the presence of pre-treated DSF minimally enhanced the glass transition temperature (T_g), crystallization temperature (T_c) and melting temperature (T_m) relative to untreated DSF which suggests on better reinforcement with NaOH pre-treatment.     

Production of bio-ethanol from an innovative mixture of surgical waste cotton and waste card board after ammonia pre-treatment

Ethanol production from waste biomass using a slightly modified bio-refinery approach was performed in this work to cater to the increasing need of alternate fuels and fuel additives globally. A surgical waste cotton and waste packaging cardboard mixture after a 15% v/v ammonia pre-treatment showed 70% lignin removal. An optimized saccharification using In-house Cellulases produced from Trichoderma harzanium ATCC 20846 had a percentage saccharification of 45% and percentage yield saccharification of 94.6%. An optimized fermentation using Saccharomyces cereviseae strain RW143 resulted in the yield of 0.4 g ethanol/g glucose from the 15% (v/v) glucose in the enzymatically saccharified hydrolysate loaded. The distilled ethanol had 90% (v/v) concentration and180 proof (twice the amount of concentration percentage in v/v) purity. 1 kg biomass mixture when processed as mentioned would yield 120 mL ethanol. Two diesel-ethanol blends (E-10 and E-20) and a commercial Diesel control were used to rate an IC engine’s brake power.     

Viability of ultrasonication of food waste for hydrogen production

Batch anaerobic studies were conducted to study the effect of ultrasonication as a pre-treatment method for pulp waste prior to anaerobic hydrogen production. Pre-treatment was conducted by sonicating a 100 mL of pulp waste at different sonication times varying from 0.5 min to 30 min. The ultimate hydrogen production increased with increasing sonication time. The highest ultimate hydrogen production was achieved at a sonication time of 30 min and reflected an 88% increase over the unsonicated food waste, of 80 mL/g VS_added. The highest final VFAs concentration after fermentation (corresponding to 70% increase over the unsonicated food waste) was also achieved at a sonication time of 30 min. There were no significant differences between the acetate-to-butyrate ratios (HAc/HBu) for the all sonication times. The maximum hydrogen production rate at sonication time of 30 min was about 145% higher than that the unsonicated food waste.     

Effect of pre-treatment and biofouling of proton exchange membrane on microbial fuel cell performance

Nafion^® 117, as the most popular proton exchange membrane, has been studied with regards to the effect of pre-treatment and biofouling for bioelectricity production and wastewater treatment, in dual chamber microbial fuel cells. The obtained results showed that maximum generated power was obtained using pre-treated Nafion^® 117, at approximately 100 mW/m². However, maximum generated power for untreated Nafion^® 117 and biofouled Nafion^® 117 were 52.8 mW/m² and 20.9 mW/m², respectively. Furthermore, the columbic efficiency of pre-treated Nafion^® 117 was 2.32 and 4.15 times higher than untreated and biofouled Nafion^® 117, respectively. Obtained results demonstrated that the pre-treatment of the proton exchange membrane is necessary to reach higher powers, and biofouling is a major obstacle for proton exchange membranes in dual chamber MFCs.     

Pre-treatment study on two-stage biohydrogen and biomethane productions in a continuous co-digestion process from a mixture of swine manure and pineapple waste

This study involves continuous co-digestion of swine manure and pineapple waste mixture using two-stage anaerobic reactors and examines hydraulic retention time (HRT) and substrate heat pre-treatment. The maximum hydrogen and methane production rates of 1488.62 and 991.57 mL/L/d, respectively, reached optimal HRTs of 4.5 h in the hydrogen production fermenter (HPF) and 9 d in the methane production fermenter (MPF) using heat pre-treatment. Acetic acid is a dominant volatile fatty acid of the soluble metabolites with values 70%–73% under all the tested conditions and increased values under heat pre-treatment and high HRT. Firmicutes and Euryarchaeota are the main bacteria species detected in HPF and MPF, respectively. The optimal total energy of 196.47 kJ/L/d and chemical oxygen demand (COD) removal efficiency of 90% were obtained by a complete anaerobic co-digestion process at a high substrate concentration of 105 g COD/L and low HRT of 4.5 h. This shows that the two-stage co-digestion process could increase the COD removal efficiency, hydrogen production rate, and net energy gains and produce high quality biogas and significantly reduce fermentation time.     

SHRINKAGE CHARACTERISTICS OF STRAWBERRIES OSMOTICALLY DEHYDRATED IN COMBINATION WITH MICROWAVE DRYING

The subject of this paper is to study the shrinkage of strawberries as a function of the moisture ratio during microwave-convective drying. Strawberries were pre-treated and osmotically dehydrated and dried at power levels 0.1 and 0.2W/g, based on initial mass. The main results showed that the shrinkage has a linear relation with moisture ratio; the equivalent diameter of the strawberry has a reciprocal logarithmic function with moisture ratio; the change in volume was bigger for the fruits osmotically dehydrated than for the not osmotically dehydrated ones, power level exerts influence on shrinkage and equivalent diameter for pre-treated and osmotically dehydrated samples.     

常压等离子体在涤/锦双组分复合纤维前处理工艺中的应用研究

利用大气压射频辉光放电装置所产生的低温等离子体对涤/锦双组分复合纤维进行表面处理,可明显改善前处理效果,对涤/锦双组分复合纤维的裂解开纤,有明显促进作用。