Monitoring gas- and particulate-phase short-chain polychlorinated paraffins in the urban air of Dalian by a self-developed passive sampler

The concentration of short-chain polychlorinated paraffins(SCCPs) in the urban air of Dalian,China was monitored from September 2016 to August 2017 with a self-developed passive sampler(PAS1) and an active high-volume sampler, simultaneously. PAS1 successfully collected the entire target SCCPs in the ambient air. Air SCCPs sampled by PAS1 were found be in the linear uptake stage during 181 days of sampling. Passive and active samples showed comparable congener profiles, and the dominant contributors of SCCPs in the two kinds of samples were similar. A significant linear correlation was observed between the total concentration of SCCPs sampled by PAS1 and active sampler in the four seasons. The passive sampling rates of the PAS1 for the gas and particulate phases of SCCPs were measured. The quantitative structure–property relationship of the sampling rate of PAS1(Rair) for gas-phase SCCPs was studied. From the molecular point of view, Rairwas mainly affected by the molecular weight and sub-cooled liquid vapor pressure of SCCPs. In general, SCCPs in the urban air of Dalian mainly existed in gas phase,lower molecular weight SCCPs primarily occurred in the gas phase, whereas higher molecular weight SCCPs were predominately adsorbed or absorbed on airborne particles. The air concentration of SCCPs in the four seasons were different, the correlation of the concentration of SCCPs in the air with the meteorology parameters was conducted. The exposure risk by intake air SCCPs of the residents around the sampling sites was evaluated according to the European risk assessment standards.     

Vehicular volatile organic compounds losses due to refueling and diurnal process in China: 2010–2050

Volatile organic compounds (VOCs) are crucial to control air pollution in major Chinese cities since VOCs are the dominant factor influencing ambient ozone level, and also an important precursor of secondary organic aerosols. Vehicular evaporative emissions have become a major and growing source of VOC emissions in China. This study consists of lab tests, technology evaluation, emissions modeling, policy projections and cost-benefit analysis to draw a roadmap for China for controlling vehicular evaporative emissions. The analysis suggests that evaporative VOC emissions from China's light-duty gasoline vehicles were approximately 185,000 ton in 2010 and would peak at 1,200,000 ton in 2040 without control. The current control strategy implemented in China, as shown in business as usual (BAU) scenario, will barely reduce the long-term growth in emissions. Even if Stage II gasoline station vapor control policies were extended national wide (BAU + extended Stage II), there would still be over 400,000 ton fuel loss in 2050. In contrast, the implementation of on-board refueling vapor recovery (ORVR) on new cars could reduce 97.5% of evaporative VOCs by 2050 (BAU + ORVR/BAU + delayed ORVR). According to the results, a combined Stage II and ORVR program is a comprehensive solution that provides both short-term and long-term benefits. The net cost to achieve the optimal total evaporative VOC control is approximately 62 billion CNY in 2025 and 149 billion CNY in 2050.     

膨化预处理玉米秸秆的还原糖酶解工艺

应用膨化技术对玉米秸秆进行预处理.在单因素实验基础上,以还原糖转化率为影响值设计正交实验,研究温度、pH、液固比、酶浓度及酶解时间五因素对纤维素酶解过程的影响.得出玉米秸秆糖化酶解最佳工艺条件为:温度48℃,pH 4.5,液固比8:1,酶浓度36.0 U/g,酶解时间25 h;在此工艺条件下还原糖转化率达到28.98％.扫描电镜表征对比观察可看出,膨化后玉米秸秆纤维素酶解充分;结合红外光谱对各组分特征基团分析表明,膨化后的玉米秸秆酶解的纤维素基团特征峰变化更为明显.     

太湖水草监管体系构建初步研究

随着太湖地区的经济发展及湖泊资源的利用,太湖水草的爆发性生长已经成为提高太湖水质、维持生态系统稳定的严重阻碍。水草枯亡后可能会导致水质异常,进而给苏州市饮用水安全带来威胁。依据4年来对太湖主要湖区水草的群落结构、分布范围、季节更替的研究,初步构建了太湖水草监管体系,为政府部门实施系统性监管提供支撑,并在全国湖泊水草监管方面发挥积极的示范作用。     

Economic analysis of atmospheric mercury emission control for coal-fired power plants in China

Coal combustion and mercury pollution are closely linked, and this relationship is particularly relevant in China, the world's largest coal consumer. This paper begins with a summary of recent China-specific studies on mercury removal by air pollution control technologies and then provides an economic analysis of mercury abatement from these emission control technologies at coal-fired power plants in China. This includes a cost-effectiveness analysis at the enterprise and sector level in China using 2010 as a baseline and projecting out to 2020 and 2030. Of the control technologies evaluated, the most cost-effective is a fabric filter installed upstream of the wet flue gas desulfurization system (FF + WFGD). Halogen injection (HI) is also a cost-effective mercury-specific control strategy, although it has not yet reached commercial maturity. The sector-level analysis shows that 193 tons of mercury was removed in 2010 in China's coal-fired power sector, with annualized mercury emission control costs of 2.7 billion Chinese Yuan. Under a projected 2030 Emission Control (EC) scenario with stringent mercury limits compared to Business As Usual (BAU) scenario, the increase of selective catalytic reduction systems (SCR) and the use of HI could contribute to 39 tons of mercury removal at a cost of 3.8 billion CNY. The economic analysis presented in this paper offers insights on air pollution control technologies and practices for enhancing atmospheric mercury control that can aid decision-making in policy design and private-sector investments.     

电化学辅助微电解法处理焦化废水

制备了锰粉改进的规整化微电解填料,采用电化学辅助改进微电解填料处理初始COD为6 153.6 mg/L、ρ(NH_3-N)为182.6 mg/L的焦化废水,优化了工艺条件。实验结果表明,电化学辅助微电解法处理焦化废水的最佳工艺条件为电压8 V,填料投加量20 g/L,初始废水pH 6,反应时间30 min。在此条件下废水COD去除率为75.3%,NH_3-N去除率为65.4%;在其他工艺条件相同的情况下,未通过电化学辅助的填料微电解反应的COD去除率为33.0%,NH_3-N去除率为16.2%,电化学辅助后的COD去除率和NH_3-N去除率均明显提高。     

汽车排放污染物浓度的预测

为了预测汽车排放污染物的浓度,应用简化的高斯烟团模式得到静风条件下的线源扩散预测模式。并结合高斯烟流扩散模式,建立了预测汽车污染物在任意风向下和年平均浓度的预测模式,考虑车道上存在车辆行驶的强烈机械扰动湍流和把繁忙的公路视为线源两个因素,提出了计算初始扩散参数的方法。然后,运用Turner和Pasquill扩散参数,建立了线源扩散参数的确定方法。该模式应用于预测高速公路沿途汽车污染物的浓度表明,计算值与监测值吻合较好,可用于我国公路环境影响的评价。     

双线盾构多因素引起地下管线的附加荷载研究

研究了地下管线与双线盾构垂直时地下管线附加荷载的分布规律。采用弹性力学Mindlin解,推导出双线盾构在掘进过程中多因素引起的土体附加应力计算公式。基于Winkler土体模型,推导出双线盾构施工中土体损失引起的竖向土体附加应力计算公式。算例分析结果表明:双线盾构施工中盾壳摩擦力和盾尾注浆压力引起的地下管线附加荷载较大;正面附加推力引起的附加荷载较小;土体损失是引起竖向附加荷载的主要原因;随着先行、后行盾构开挖面前后距离Q的减小,后行盾构上方管线的附加荷载变化比较明显;随着先行、后行盾构轴线水平间距L的增大,x和z方向的附加荷载峰值减小。     

Metagenomic insights into responses of microbial population and key functional genes to fulvic acid during partial nitritation

The long-term impact of fulvic acid (FA) on partial nitritation (PN) system was initially examined in this study. The obtained results revealed that the FA lower than 50 mg/L had negligible effect on the nitrite accumulation rate (NAR nearly 100%) and ammonium removal rate (ARR 56.85%), while FA over 50 mg/L decreased ARR from 56.85% to 0.7%. Sludge characteristics analysis found that appropriate FA (<50 mg/L) exposure promoted the settling performance and granulation of PN sludge by removing Bacteroidetes and accumulating Chloroflexi. The analysis of metagenomics suggested that the presence of limited FA (0-50 mg/L) stimulated the generation of NADH, which favors the denitrification and nitrite reduction. The negative impact of FA on the PN system could be divided into two stages. Initially, limited FA (50-120 mg/L) was decomposed by Anaerolineae to stimulate the growth and propagation of heterotrophic bacteria (Thauera). Increasing heterotrophs competed with AOB (Nitrosomonas) for dissolved oxygen, causing AOB to be eliminated and ARR to declined. Subsequently, when FA dosage was over 120 mg/L, Anaerolineae were inhibited and heterotrophic bacteria reduced, resulting in the abundance of AOB recovered. Nevertheless, the ammonium transformation pathway was suppressed because genes amoABC and hao were obviously reduced, leading to the deterioration of reactor performance. Overall, these results provide theoretical guidance for the practical application of PN for the treatment of FA-containing sewage.