离子交换树脂对高浓度氨氮废水的吸附研究

采用D707、D708两种不同类型的离子交换树脂对高浓度氨氮废水进行吸附处理研究,分析了不同的吸附条件及等温吸附模型对吸附效果的影响.静态吸附实验表明:NH+4的吸附率随树脂投加量的增大而增加,在非碱性条件下树脂对NH+4的吸附率随p H的升高而增加;恒速振荡时间达到90 min以上时两种树脂可吸附平衡,当p H为7时,D707、D708树脂对NH+4的吸附容量分别达到196.1、217.4 mg·g-1;D707、D708树脂对NH+4的吸附属吸热过程,随温度的升高树脂对NH+4的吸附率逐渐增大,在298 K温度下D707、D708树脂吸附NH+4的表观吸附活化能Ea分别为54.67和34.46 k J·mol-1,吸附过程为液膜扩散主控制;树脂对NH+4吸附符合Langmuir吸附等温式;使用2 mol·L-1H2SO4对树脂进行解吸,脱附率达到98%以上,重复实验3次吸附率基本不变.     

控氧生物膜系统对微污染水体的脱氮性能

通过控制生物膜系统溶解氧(DO)浓度分别为0.5~1 mg/L(Ⅰ)、1~2 mg/L(Ⅱ)、2~3 mg/L(Ⅲ),研究在微污染城市河道水体中实现短程硝化反硝化的可行性。研究表明,在3个系统中,化学需氧量(COD)、氨氮(NH+4-N)和总氮(TN)的平均去除率分别稳定在62.3%、38.6%和38.2%(工况Ⅰ),65.5%、59.4%和28.2%(工况Ⅱ),66.1%、77.3%和22.8%(工况Ⅲ)。系统中各形态氮素含量及其变化情况分析表明,在具有一定NH+4-N去除率前提下,控制体系处于低DO浓度(1 mg/L),亚硝酸盐氧化菌(NOB)生长及活性受到抑制,NO-2-N明显累积,经反硝化作用直接转化为氮气(N2),实现了微污染城市河道水体中的短程硝化反硝化。     

The evolution of phosphorus metabolism model in China

It is important to analyze why phosphorus metabolism is unsustainable in China's modern industrial society. In this paper, the Substance Flow Analysis (SFA) approach is used to build different models of phosphorus metabolism for the following three periods: the prehuman period, traditional agricultural period and modern industrial period. Based on these models, the evolution process of phosphorus metabolism in China is analyzed from the viewpoint of its metabolic structure and intensity. The indices of intensity analysis involve phosphorus input, phosphorus circulation and recycling efficiency, phosphorus production and production efficiency, water phosphorus emission and water emission proportion, solid waste phosphorus output and solid waste discharge proportion. Through the analysis of the evolution process, the key factors that cause the lack of sustainability of phosphorus metabolism in China are identified, which can be summarized by four aspects: the increase of soil phosphorus accumulation, the increase of water phosphorus emission, the decrease of recycling efficiency and the decrease of production efficiency in croplands. Furthermore, the specific unsustainable processes of phosphor resources utilization in China are discussed. For these unsustainable processes, the relevant solutions for the phosphor resources crisis are given.     

CO2 emissions in calcium carbide industry: An analysis of China's mitigation potential

China's calcium carbide output has dominated the global market for several years, driven by the demand for PVC (polyvinyl chloride), a fundamental polymer material and also the primary downstream product of calcium carbide in China. The fast growth of this energy-intensive industry leads to an inevitable increase in CO₂ emissions. However, there is a large reduction potential with process improvement in this industry which is currently characterized by widespread outdated facilities. In this study, we attempt to assess the reduction potential of CO₂ emissions in China's calcium carbide production, based on the analysis of CO₂ emission patterns and estimation of the emission amount. Three scenarios regarding process improvement are employed to conduct this assessment. The results imply that the cumulative CO₂ abatement in the Current Policy Scenario and in the Strengthened Policy Scenario from 2008 to 2020, compared with the Baseline Scenario, are 89.0 and 107.6 million t, respectively. The specific measures and policy implications to achieve this potential are also discussed in the article.     

Enhanced removal of ethylbenzene from gas streams in biotrickling filters by Tween-20 and Zn(II)

The effects of Tween-20 and Zn（II） on ethylbenzene removal were evaluated using two biotrickling filters（BTFs）, BTF1 and BTF2. Only BTF1 was fed with Tween-20 and Zn（II）.Results show that ethylbenzene removal decreased from 94% to 69% for BTF1 and from 74%to 54% for BTF2 with increased organic loading from 64.8 to 189.0 g ethylbenzene/（m3·hr） at EBRT of 40 sec. The effect of EBRT（60–15 sec） at a constant ethylbenzene inlet concentration was more significant than that of EBRT（30–10 sec） at a constant organic loading. Biomass accumulation rate within packing media was reduced significantly.     

A historical record of trace metal deposition in northeastern Qinghai-Tibetan Plateau for the last two centuries

Environmental Science and Pollution Research - Owing to rapid socio-economic development in China, trace metal emissions have increased and lakes even in remote areas have experienced marked...