珠江三角洲典型过程VOCs的平均浓度与化学反应活性

分析了珠江三角洲秋季VOCs在相对污染与清洁情况下的日变化特征.污染情况下的VOCs质量浓度可达清洁情况下的2.2倍,污染富集的是甲苯、二甲苯、乙苯、正丁烷、戊烷、丙烷、乙炔、乙烯等物种.自然排放的异戊二烯具有早晚浓度低而白天浓度高的日变化规律,体现植物的光合作用特征;而人类活动污染排放的甲苯其日变化规律基本反映了气象条件与污染源排放日变化的影响,在相对污染情况下早上出现明显的污染富集,午后出现污染低值.反应活性较强的物质主要是烯烃(反式-2-丁烯、异戊二烯、顺2-戊烯)与芳香烃(间对-二甲苯、甲苯);烯烃的质量百分比最低,却占最高的化学反应活性百分比.     

基于2.4G无线通讯的绝缘子喷涂清洁设备控制系统

为了更好地满足电网的安全可靠运营,提高并改善喷涂与清洁效果,亟需开发自动化程度高的绝缘子喷涂、清洗设备及其控制系统。本文结合2.4 G无线通讯短距离通讯技术,提供绝缘子喷涂与清洁机械臂的应用方案,其中电气电子控制系统包括无线组网控制、机械臂定位控制及喷涂过程控制,由主控制中心集中控制平台升降、机械臂动作、物料车动作,实现清洗、风干、喷涂、散料回收的过程控制,在电网系统中的绝缘子喷涂清洁领域具有广阔的市场应用前景。     

换热器不锈钢换热管束开裂原因分析

一台换热器换热管束发生了开裂泄漏.采取全面检验的方式,通过宏观检查、化学成分分析、断口微观形貌和能谱分析、金相分析等方法,对换热管开裂原因进行了分析.结果表明:该换热管开裂为氯化物应力腐蚀开裂.壳程介质循环冷却水中CI元素含量是应力腐蚀开裂的主要因素,结构缺陷、敏感的工作温度区间、水中溶解氧和含S杂质导致了应力腐蚀的快速发展.     

成都市降水对大气颗粒物湿清除作用的观测研究

为研究成都市降水对大气颗粒物(以下简称颗粒物)的湿清除作用,对2014—2016年成都市的颗粒物(PM_(2.5)、PM_(10))和气象观测数据进行分析。结果表明:月、季尺度下,降水对PM_(2.5)、PM_(10)均有削减作用。降水时段的PM_(2.5)、PM_(10)浓度较非降水时段分别降低17.1%和15.8%,且冬季降幅最为明显。考察472次降水过程对颗粒物的湿清除作用,发现单次降水过程后PM_(2.5)、PM_(10)浓度增长频次(243、234次)和削减频次(229、238次)接近,但颗粒物浓度总体呈削减趋势。对于单次降水过程,颗粒物的初始浓度与降水对颗粒物的湿清除作用关系密切,特别是降水持续时间超过8h后,颗粒物初始浓度越高,削减效果越好。     

The coupling of sand with ZVI/oxidants achieved proportional and highly efficient removal of arsenic

• Simply doping sands with ZVI achieved an even activation of ZVI by oxidants. • Sand doping facilitated proportional As trapping along the ZVI/oxidants column. • ZVI/sand/oxidants are highly efficient for arsenic removal. • ZVI/sand/oxidants reduced significantly the Fe²⁺ leaching and effluent turbidity. • More than 54% of arsenic was reduced to As(III) in ZVI/sand/oxidants system. The coupling of zero-valent iron (ZVI) with common oxidants has recently achieved very rapid and highly efficient removal of Heavy metals from wastewater. However, the uniform activation of ZVI throughout the column and the proportional removal of target contaminants are urgently required for the prevention of premature filter clogging and the extension of the effective column operational time. In this study, we successfully achieved this objective by simply doping granular sand with ZVI at appropriate weight ratios. When pure ZVI packed column was spiked with oxidants, the majority of As trapping occurred between the column inlet and the first sampling point. In a packed column with a 1:20 mixture of ZVI and sand, the average As removal efficiency was 36 (1st), 13.1 (2nd), 18.5 (3rd), 19.2 (4th) and 5.9% (5th outlet). The overall arsenic removal performance of the composite filling system of ZVI/sand was equally as efficient as that of the previous pure ZVI-packed system. Moreover, the leaching of Fe was significantly reduced with an increased sand ratio, resulting in clearer water with less turbidity. The results of X-ray photoelectron spectroscopy (XPS) demonstrated that more than 54% of the arsenic was reduced to As(III). X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the extensive corrosion of the ZVI surface, which resulted in various species of iron oxyhydroxides responsible for the highly efficient sequester of arsenic through reduction, adsorption, and coprecipitation.     

Nutrient status and pollution levels in five areas around a manganese mine in southern China

• The soil TP level was high or extremely high in all areas. • TN, OM and available Cu were insufficient in EA, TA and RA. • All areas reached the heavily polluted level and had high ecological risk levels. • Mn and Cd were the dominant pollutants. Nutrient status and pollution levels are the main factors affecting soil restoration. The nutrient status and pollution levels in five areas, an unexplored mine area (UA), an explored mine area (EA), a tailings area (TA), a reclamation area (RA) and an agricultural area (AA), around the Pingle manganese mine in Guangxi, China, were assessed in this study. The results showed that the average total phosphorus in these five areas ranged from 1.05 to 1.57 mg/kg, corresponding to grades of extremely high and high. The average total nitrogen values were 0.19, 0.69, 0.93, 1.24 and 1.67 mg/kg in EA, TA, RA, UA and AA, corresponding to grades of very low, low, medium-low, medium-high and medium-high, respectively. The average organic matter values were 12.78, 8.92, 22.77, 21.29 and 29.11 mg/kg in EA, TA, RA, UA and AA, which corresponded to grades of medium-low, low, medium-high, medium-high and medium-high, respectively. All these results indicated that the total phosphorus was sufficient in these areas, while the total nitrogen and organic matter were insufficient in EA, TA and RA. The available concentrations of Mn and Zn corresponded to the intermediate grade, while the values for Cu corresponded to the very low grade; these might be another factor restricting ecological reclamation. Contamination and ecological risk assessments based on the single contamination index, Nemerow multi-factor index and potential ecological risk index showed that the five tested areas around the Mn mine were considered heavily polluted and presented high ecological risk. Mn and Cd were the dominant pollutants.     

Dibutyl phthalate adsorption characteristics using three common substrates in aqueous solutions

• DBP adsorption was tested using three kinds of substrates in constructed wetlands. • The DBP adsorption capacity followed the order: steel slag>gravel>shell sand. • High temperatures increased the DBP adsorption capacity in the substrates. • DOM consistently inhibited the DBP adsorption onto steel slag and gravel. In recent years, the presence and adverse impacts of phthalic acid esters in aquatic environments have gained increasing attention. This work investigated the adsorption behavior of a typical phthalic acid ester, dibutyl phthalate (DBP), onto steel slag, gravel, and shell sand (substrates commonly used in constructed wetlands). The influence of dissolved organic matter (DOM) on DBP adsorption was investigated using humic acid as a proxy for DOM. The results demonstrated that the adsorption of DBP to three substrates reached equilibrium within 96 h, and the adsorption kinetics were well fitted by a pseudo-second-order model. The DBP adsorption isotherms were best fitted by the Langmuir adsorption model. The DBP adsorption capacity decreased in the order of steel slag>gravel>shell sand, with values of 656 mg/kg, 598 mg/kg, and 6.62 mg/kg at 25°C, respectively. DBP adsorbed to the surface of all substrates in a monolayer via an endothermic process. The DBP adsorption capacities of steel slag and gravel decreased as the DOM content increased. The DBP adsorption mechanisms to steel slag and gravel mainly involved the surface coordination of DBP with –OH or –COOH groups and electrostatic interactions. The results of this work suggest that steel slag and gravel may be ideal substrates for use in constructed wetlands to treat wastewater polluted with DBP.     

单组分垃圾厌氧降解初期的产气规律及恶臭特征

研究了垃圾单组分(蛋白类和糖类)厌氧降解初期的产气动态规律和恶臭特征。结果表明,糖类物料厌氧降解的累积产气量大于蛋白类物料,各物料的气体排放动态曲线不同,酪蛋白和淀粉物料呈现Monod型曲线,而纤维素物料呈现2次Monod型曲线;蛋白类物料降解产生的恶臭气体成分更丰富,且动态变化曲线有多种形式:硫化氢、磷化氢和硫8的浓度变化曲线呈单峰型,聚硫醚浓度曲线呈S型,挥发性脂肪酸(VFAs)呈Monod型曲线;臭气强度分析结果表明,蛋白类物料产生的臭气强度高于糖类物料。单组分垃圾产气规律和恶臭特征的研究结果为开发高效恶臭原位控制技术提供了理论基础。