气相分子吸收光谱法测定垃圾填埋场渗滤液中的氨氮研究

垃圾填埋场渗滤液成分复杂,其氨氮的测定干扰物质多,测定难度大.气相分子吸收光谱法是一种较为新兴的方法,通过对气相分子吸收光谱法和传统纳氏试剂分光光度法系统的比较,研究气相分子吸收光谱法测定垃圾填埋场渗滤液中氨氮的分析方法.结果表明,气相分子吸收光谱法测定垃圾填埋场渗滤液中氨氮操作便捷、干扰小、精密度好,中浓度与高浓度废水测定结果能较好的与纳氏试剂光度法测定结果法吻合,超低浓度废水的测定结果低于纳氏试剂分光光度法.为监测工作者分析方法的选择提供依据.     

Anaerobic digestion in mesophilic and room temperature conditions: Digestion performance and soil-borne pathogen survival

Tomato plant waste(TPW) was used as the feedstock of a batch anaerobic reactor to evaluate the effect of anaerobic digestion on Ralstonia solanacearum and Phytophthora capsici survival. Batch experiments were carried out for TS(total solid) concentrations of 2%, 4% and 6% respectively, at mesophilic(37 ± 1°C) and room(20–25°C) temperatures. Results showed that higher digestion performance was achieved under mesophilic digestion temperature and lower TS concentration conditions. The biogas production ranged from 71 to 416 L/kg VS(volatile solids). The inactivation of anaerobic digestion tended to increase as digestion performance improved. The maximum log copies reduction of R. solanacearum and P. capsici detected by quantitative PCR(polymerase chain reaction) were 3.80 and 4.08 respectively in reactors with 4% TS concentration at mesophilic temperatures. However, both in mesophilic and room temperature conditions, the lowest reduction of R. solanacearum was found in the reactors with 6% TS concentration, which possessed the highest VFA(volatile fatty acid) concentration. These findings indicated that simple accumulation of VFAs failed to restrain R. solanacearum effectively, although the VFAs were considered poisonous. P. capsici was nearly completely dead under all conditions. Based on the digestion performance and the pathogen survival rate, a model was established to evaluate the digestate biosafety.     

pH-dependent release characteristics of antimony and arsenic from typical antimony-bearing ores

The pH-dependent leaching of antimony (Sb) and arsenic (As) from three typical Sb-bearing ores (Banxi, Muli and Tongkeng Antimony Mine) in China was assessed using a pH-static leaching experiment. The pH changes of the leached solutions and pH-dependent leaching of Sb and As occurred in different ways. For the Banxi and Muli Sb ores, alkaline conditions were more favorable for the release of Sb compared to neutral and acidic conditions, but the reverse was true for the pH-dependent release of As. For the Tongkeng Sb ore, unlike the previous two Sb-bearing ores, acidic conditions were more favorable for Sb release than neutral and alkaline conditions. The ores with lower Sb and As contents released higher percentages of their Sb and As after 16 day leaching, suggesting that they are the largest potential sources of pollution. This work may provide key information on the geochemistry of Sb and As in the weathering zone.     

标准气溶胶发生系统的建立与性能评估

针对气溶胶测量仪器校准和实验室气溶胶光学特性研究的需求,搭建了一套标准气溶胶发生系统,并对其性能开展了测试研究.系统采用恒定流量的雾化器产生气溶胶,经过扩散干燥管干燥以及电荷中和器带电中和后,产生标准气溶胶粒子.利用氯化钠样品对系统的性能进行了测试,结果表明,当样品溶液浓度增加时,系统雾化产生粒子的数浓度和粒径均随之增加;当载气气压增加,系统雾化产生粒子的数浓度随之增加,而粒径随之减小.在测试时间内,系统发生的多分散气溶胶粒子的几何平均粒径波动小于1%,总粒子数浓度波动小于2%,单分散气溶胶粒子数浓度的稳定性好于4%.     

Effect of algal flocculation on dissolved organic matters using cationic starch modified soils

Modified soils(MSs) are being increasingly used as geo-engineering materials for the sedimentation removal of cyanobacterial blooms. Cationic starch(CS) has been tested as an effective soil modifier, but little is known about its potential impacts on the treated water.This study investigated dissolved organic matters in the bloom water after algal removal using cationic starch modified soils(CS-MSs). Results showed that the dissolved organic carbon(DOC) could be decreased by CS-MS flocculation and the use of higher charge density CS yielded a greater DOC reduction. When CS with the charge density of 0.052, 0.102 and0.293 meq/g were used, DOC was decreased from 3.4 to 3.0, 2.3 and 1.7 mg/L, respectively.The excitation–emission matrix fluorescence spectroscopy and UV254 analysis indicated that CS-MS exhibits an ability to remove some soluble organics, which contributed to the DOC reduction. However, the use of low charge density CS posed a potential risk of DOC increase due to the high CS loading for effective algal removal. When CS with the charge density of 0.044 meq/g was used, DOC was increased from 3.4 to 3.9 mg/L. This study suggested, when CS-MS is used for cyanobacterial bloom removal, the content of dissolved organic matters in the treated water can be controlled by optimizing the charge density of CS. For the settled organic matters, other measures(e.g., capping treatments using oxygen loaded materials) should be jointly applied after algal flocculation.     

Inducing pollution prevention adoption: effectiveness of the 33/50 voluntary environmental program

The Environmental Protection Agency has encouraged voluntary efforts at pollution prevention by facilities through participation in voluntary environmental programs (VEPs) such as the 33/50 program to reduce toxic releases. This paper examines the effectiveness of the 33/50 program in the adoption of pollution prevention practices and disentangles the effect of adoption from that of program participation on releases of 33/50 chemicals. Using facility-specific panel data and controlling for the endogeneity of program participation and pollution prevention adoption, we find that program participants were 38% more likely to adopt pollution prevention practices than non-participants. Program participants who adopted pollution prevention practices reduced their 33/50 releases by 52% compared to facilities that neither participated nor adopted pollution prevention. This indicates that VEPs that emphasize pollution prevention can play a complementary role in reducing toxic releases.