Effects of alkalinity on interaction between EPS and hydroxy-aluminum with different speciation in wastewater sludge conditioning with aluminum based inorganic polymer flocculant

Extracellular polymeric substances (EPS) form a stable gel-like structure to combine with water molecules through steric hindrance, making the mechanical dewatering of wastewater sludge considerably difficult. Coagulation/flocculation has been widely applied in improving the sludge dewatering performance, while sludge properties (organic fraction and solution chemistry conditions) are highly changeable and have important effects on sludge flocculation process. In this work, the alkalinity effects on sludge conditioning with hydroxy-aluminum were comprehensively investigated, and the interaction mechanisms between EPS and hydroxy-aluminum with different speciation were unraveled. The results showed that the effectiveness of hydroxy-aluminum conditioning gradually deteriorated with increase in alkalinity. Meanwhile, the polymeric hydroxy-aluminum (Al₁₃) and highly polymerized hydroxy-aluminum (Al₃₀) were hydrolysed and converted into amorphous aluminum hydroxide (Al(OH)₃), which changed the flocculation mechanism from charge neutralization and complexing adsorption to hydrogen bond interaction. Additionally, both Al₁₃ and Al₃₀ showed higher binding capacity for proteins and polysaccharides in EPS than monomeric aluminum and Al(OH)₃. Al₁₃ and Al₃₀ coagulation changed the secondary structure of proteins in EPS, which caused a gelation reaction to increase molecular hydrophobicity of proteins and consequently sludge dewaterability. This study provided a guidance for optimizing the hydroxy-aluminum flocculation conditioning of sludge with high solution alkalinity.     

Optimizing food waste hydrothermal parameters to reduce Maillard reaction and increase volatile fatty acid production

The occurrence of the Maillard reaction and melanoidins formation during the hydrothermal treatment of food waste can reduce the yield of volatile fatty acids (VFA); however, few studies have investigated the adverse effects of the Maillard reaction. This study identified the impact of hydrothermal treatment parameters on hydrolysis and melanoidins formation and optimized the hydrothermal treatment conditions to enhance VFA production by minimizing the impact of the Maillard reaction. A response surface methodology was employed to optimize the hydrothermal treatment parameters and VFA production was evaluated. Results showed that temperature, reaction time, and pH were significant interacting factors with respect to hydrolysis and melanoidins formation while the C/N ratio and moisture content of food waste had little impact. The optimal conditions for hydrothermal treatment (temperature of 132 °C, reaction time of 27 min, and a pH of 5.6) enhanced VFA production by 22.1%. Under optimal hydrothermal treatment conditions, a higher initial C/N ratio further increased VFA production.     

金川矿区表土金属空间污染特征及磁学响应

采集金川铜镍矿区及周边表层土壤样品26个,基于环境磁学方法对样品开展了金属元素（Cu、Ni、Cr、Fe、Sr、Ti、Pb和Mn）的含量分析及相关分析,采用单因子污染指数和内梅罗污染指数评价方法对研究区域表土金属污染状况进行评价.研究区域表土磁学特征与金属元素含量呈明显空间分布差异,体现为：矿区源地 > 加工区域 > 繁忙路段 > 门岗区域 > 其他区域;受Cu和Ni元素污染的土壤样品为重度污染,Cr、Pb、Ti、Sr等金属为轻度污染和中度污染;χ_lf、SIRM、χ_ARM和HIRM数值相对较高,表明研究区域亚铁磁性矿物含量较高;研究区表层土壤样品磁晶粒度特征以较粗的假单畴（PSD）和多畴（MD）颗粒为主导;相关分析结果表明Cu、Ni、Cr、Fe、Pb和Mn元素之间皆存在较好的相关性,其中Cu、Ni显著（R=0.91）;χ_lf和SIRM、χ_ARM与各金属的相关性较为突出（0.52≤R≤0.78）,表明磁参数可有效监测城市表土重金属污染状况,快速圈定重金属污染的区域与范围,为城市表土污染监测工作提供快速有效的数据支持.     

Human milk survey for dioxins in the general population in Japan

BACKGROUND: Much attention has been paid to the level of dioxins in breast milk in Japan but few large-scale studies have been conducted on the subject. METHODS: From 1997 to 2002, we collected 839 samples of breast milk from primiparas residing throughout Japan. Starting in 1999, breast milk was also collected from secundiparas. Seven isomers of polychlorinated dibenzo-p-dioxins (PCDDs), 10 of polychlorinated dibenzofurans (PCDFs), 4 of coplanar polychlorinated biphenyls (Co-PCBs) and 8 of mono-orthochlorinated polychlorinated biphenyls (mono-ortho PCBs) were analyzed by employing gas chromatography and mass spectrometry. A correlation between the level of dioxins in human milk and the age of the mothers was noted for the primiparas and the secundiparas; and the levels were compared between the first and the second deliveries. Grouped by parity and prefecture in each year, observations were also made on the trends in these levels. Dioxin levels are shown by using geometric means because their distributions were skewed to the left. RESULTS: The sum of PCDDs and PCDFs, Co-PCBs, mono-ortho PCBs, and total dioxins in the breast milk of primiparas were 13.9, 5.4, 3.4, and 22.7 pg TEQ/g fat, respectively. In the samples obtained from secundiparas, these levels were 63-68 percents of those taken from the primiparas. The correlation coefficients between the PCDDs/DFs, Co-PCBs, mono-ortho PCBs, and total dioxins and the age of the primiparas were 0.19, 0.17, 0.36, and 0.24, respectively. All these correlations were statistically significant (p < 0.001). The positive correlations between these contaminants and the age of the secundiparas were also examined. The total dioxins as well as PCDDs/DFs, Co-PCBs, and mono-ortho PCBs in the breast milk of the primiparas declined significantly between 1998 and 2002 (regression coefficients: -0.04, -0.05, -0.03, and -0.03, respectively). However, no significant decline in these levels was observed when sorted by prefectures. CONCLUSIONS: Much attention should be paid to the age and parity of nursing mothers when investigating the relationship between the level of dioxins in breast milk and the body burden of infants.     

上转换发光剂掺杂纳米TiO2的制备及可见光降解乙基紫的研究

合成了一种新型含有稀土金属Er的上转换发光剂40CdF₂·60BaF₂·1.6Er₂O₃,此上转换发光剂在488 nm可见光的激发下,产生了5个波长均小于387 nm的上转换紫外光发射峰.采用超声波分散的方法制备出了上转换发光剂掺杂的纳米TiO₂可见光光催化剂.利用X-射线衍射(XRD)及透射电镜(TEM)对催化剂进行了表征.以乙基紫染料为研究对象,研究了在(三基色灯下发出的)可见光的照射下该可见光光催化剂的催化降解性能,并与未掺杂的纳米TiO₂粉末的催化性能进行了对比.结果表明,作为掺杂成分的上转换发光剂可有效地将可见光转化为紫外光并被纳米TiO₂粉末吸收利用,在可见光照射12.0 h后乙基紫降解率达到了99.68%,大大高于未掺杂纳米TiO2时的降解率.     

哈得油田污水循环利用技术的研究应用

针对哈得油田生产过程中存在的注水水量不够和蒸发池负荷过大的问题,哈得油田对蒸发池污水循环利用技术开展了论证和实践。通过对清洁生产技术的应用,哈得油田将外排污水回收循环利用,减少了清水用量,实现了哈得油田作业区污水零排放,为同行业开展污水循环利用提供参考和借鉴。     

基于热减量法2/1樟发射药安全贮存寿命预估

目的 预估2/1樟发射药的安全贮存寿命,建立一种基于加速热减量试验,利用热减量曲线和贝瑟洛特(Berthelot)方程预估其安全贮存寿命的方法。方法 首先对2/1樟发射药分别进行85、95、105、115 ℃下的加速热减量试验,获得样品在各个温度下不同加速时间的热减量数据。然后基于热减量曲线,得到2/1樟发射药在各个温度下的延滞期。最后利用各个温度下的半延滞期,根据Berthelot方程拟合得到2/1樟发射药安全贮存寿命预估模型。结果 根据其安全贮存寿命预估模型计算得到2/1樟发射药在30 ℃下的安全贮存寿命约为50.9 a。结论 预测结果与文献值接近,且试验时间比文献减少了近1/2,验证了该方法的有效性,可为2/1樟发射药或其他发射药的安全贮存寿命预估提供一种可行的技术途径。     

聚合氯化铁-腐殖酸(PFC-HA)絮体的粒度和分形维数的动态变化

通过采集PFC-HA絮体的单个样品和拍摄它们的二维图像,研究了在不同混凝条件下絮体的粒度和分形维数的变化.结果表明,原水pH的下降滞后了PFC-HA絮体的出现.原水pH≥7.0时,随着投药量的增加,PFC-HA絮体的分形维数D2(lgA-lgdL)和D3(lgV1-lgdL)随之降低,表明絮体的结构越来越疏松;而原水pH=5.0时,PFC-HA絮体的分形维数存在波动.在PFC的最佳投药量时,水力条件的优化可以提高HA的去除效果,但随着原水pH的下降,HA去除效果的提高程度也随之减小.在最佳水力条件下,PFC-HA絮体的粒度为数百微米,其分形维数值较大,表明絮体的结构较为密实.此外,PFC-HA絮体的粒度分布具有(类)分形特征,最佳水力条件下正的D.值表明絮体的粒度分布趋向平稳.在整个混凝搅拌过程中,PFC-HA絮体的分形维数的变化是与混凝的溶液化学条件、搅拌时间和分形维数类型有关,其D2具有先上升后下降的趋势,这一过程中絮体结构先趋向密实,然后趋向疏松.而且慢速搅拌过程中絮体的尺度也是先增加后下降.     

絮体性状实时图像检测系统的开发与应用

概述了水处理絮体性状(包括絮体粒度、分形维数及表观强度)在线图像检测系统的开发,结合实验室条件下的混凝实验考查了该实时图像检测系统的应用情况.结果表明,利用该图像检测系统获取的数据符合一般混凝实验的结果,且对混凝慢速搅拌时间、原水浊度及混凝剂投加量有不同程度的敏感性.在进一步研究的基础上,该图像检测系统可在水处理混凝过程的自动控制中加以应用.     

兰州市街道尘埃粒度空间变化特征

采用Mastersizer2000激光粒度仪对2006年3月采集的兰州市街道尘埃进行了粒度分析。结果表明,兰州市街道尘埃中颗粒物平均粒径范围在46．83μm-266．59μm,平均值为118．73μm;其中〉2μm的颗粒占总量的92％-99．5％,〈2μm的颗粒占10％以下。受地形因素影响,兰州市西部和东部地区粒径较粗,中间地段粒径相对较细;进一步分析发现在风动能大的区域,尘埃主要以较粗物质为主;在风动能相对较弱区域,细颗粒和粗颗粒含量差别不大,而在风动能小的区域,街道尘埃主要以细颗粒物为主。由此可见,兰州市街道尘埃中的颗粒物的主要来源是由于风力和人为活动产生的土壤尘和人为排放的污染物所共同贡献的;粒度分布特征受到风动力条件和物源（污染源）两方面因素的控制。