海洋厌氧氨氧化菌处理含海水污水的基质抑制及其动力学特性

采用ASBR反应器通过改变单一基质浓度分别研究了NH_4~+-N和NO_2~--N对海洋厌氧氨氧化菌脱氮效能的影响及其动力学特性.结果表明,保持进水NO_2~--N为105.6 mg·L~(-1),当进水NH_4~+-N浓度提高至1 200 mg·L~(-1)时,海洋厌氧氨氧化反应器仍保持较好的脱氮能力,未受到明显的抑制作用,NO_2~--N的去除率稳定在80.70%左右;当进水NO_2~--N浓度提高至265.6mg·L~(-1)时,反应器开始受到明显的抑制作用,NH_4~+-N的去除率下降至63.01%左右,随着进水NO_2~--N浓度继续提高至305.6mg·L~(-1)时,NH_4~+-N的去除率进一步下降至43.93%左右.利用Haldane模型和Aiba模型拟合NH_4~+-N和NO_2~--N抑制作用的动力学特性,得到了NRRmax、KS、Ki这3个动力学参数及出水基质浓度与总氮容积负荷(TNRR)之间的关系,根据进一步分析可知,Haldane模型更适合描述NH_4~+-N抑制作用下的动力学特性,Aiba模型更适合描述NO_2~--N抑制作用下的动力学特性,并得到NH_4~+-N和NO_2~--N的出水抑制浓度分别为3 893.625 mg·L~(-1)和287.208 mg·L~(-1),为海洋厌氧氨氧化菌处理含海水污水提供了理论依据.     

北京地区夏冬季气溶胶变化特征分析

北京市夏季平均可吸入颗粒物质量浓度(ρ(PM₁₀))和气溶胶粒子数密度的平均日变化呈现明显的双峰结构,冬季除12:30—15:00相对较小外,其余时间都很大;夏季大气能见度的平均日变化呈单峰结构,而冬季呈双峰结构;夏季平均PM₁₀和气溶胶粒子数密度通常比冬季的小;北京市夏季平均大气能见度比冬季的小,主要原因在于夏季空气相对湿度大,半径大于1 25μm的大粒子数密度较大,夏冬季0:00—9:00各时刻的平均能见度存在较大差别,其余时间的差别不大。      

对苯二甲酸的微生物降解

从处理对苯二甲酸(PTA)生产废水的上流式厌氧生物滤床(UASB)底部活性污泥中分离到一株降解活性较高的细菌T_6.当PTA为唯一碳源时,降解率可达98％,菌体接种量的大小对降解速度有一定影响.该菌可以分别在好氧和厌氧条件下降解PTA.试验表明,降解PTA的酶为胞内酶,经鉴定,T_6菌为假单胞菌(Pseudomonas sp.).其某些特性与已知种有差异,尚待进一步确定.     

pH冲击对海洋厌氧氨氧化菌处理含海水污水脱氮效能的影响

采用ASBR反应器,研究了pH冲击对海洋厌氧氨氧化菌处理含海水污水脱氮效能的影响,并利用Andrew模型和Ratkowsky模型模拟pH冲击下海洋厌氧氨氧化菌的脱氮过程.结果表明,当pH在7~8时,反应器的脱氮效果最佳,氨氮去除负荷(NRR)稳定在(0.30±0.04)kg·(m~3·d)~(-1),总氮去除率(TNRE)在(76.73±5.74)%;当pH为8.5时,游离氨(FA)的平均浓度为14.22 mg·L~(-1),该FA浓度对NRR的影响较小,NRR仍维持在(0.30±0.02)kg·(m~3·d)~(-1)左右,但是NO_2~--N在pH的直接影响下出现了积累,不能够完全去除,此条件不利于反应器的稳定运行;当pH为6.5和9时,FA浓度分别为0.22mg·L~(-1)和37.84 mg·L~(-1),NRR分别低至(0.10±0.02)kg·(m~3·d)~(-1)和(0.15±0.02)kg·(m~3·d)~(-1),且TNRE仅为(23.04±9.88)%和(42.12±5.52)%.海洋厌氧氨氧化菌在碱性条件下的耐受性强于酸性条件.采用修正的Andrew模型进行拟合,得到了NRR与FA之间的相互关系,同时还可以得到NRR_(max)、k_S和k_I等参数,对于表征海洋厌氧氨氧化菌的脱氮过程具有实际意义.     

Heterogeneous uptake of gaseous hydrogen peroxide on mineral dust

The heterogeneous uptake processes of hydrogen peroxide on Arizona test dust and two types of authentic Chinese mineral dusts, i.e., Inner Mongolia desert dust and Xinjiang calciferous dust, were investigated using a Knudsen cell reactor coupled with a quadrupole mass spectrometer. The uptake coefficients were measured as a function of the initial concentration of H_2O_2 from 2.6 × 10~(11) to 1.2 × 10~(12)molecules/cm~3, and the temperature dependence of the uptake coefficients was investigated over a range from 253 to 313 K. The concentration of H_2O_2 showed little effect on the uptake coefficients of these heterogeneous processes. As a function of temperature, the initial uptake coefficients decrease with increasing temperature, whereas the steady state uptake coefficients of Arizona test dust and Inner Mongolia desert dust increase with increasing temperature. Implications for the understanding of the uptake processes onto mineral dust samples were also discussed.     

城市污泥-猪粪混合堆肥过程中湿度的层次效应及其动态变化

由城市污泥、猪粪混合堆肥试验表明:升温期堆体各剖面的湿度在50.82%～60.87%之间,高温期在38.7%～52.17%之间;升温期和高温期堆体中湿度的层次效应不明显,堆肥仓门、仓内壁以及堆体深度对湿度层次效应的影响较小;降温期堆体各剖面的湿度在24.54%～49.39%之间,湿度层次效应非常明显,仓门、仓内壁和堆体深度对湿度层次效应产生明显影响;后熟期堆体各剖面的湿度在19.18%～49.34%之间,湿度层次效应相对减弱,仓门和仓内壁是导致湿度层次效应减弱的重要原因.不同堆肥期堆体剖面的湿度差异由大到小为:后熟期>降温期>高温期＝升温期,堆体的湿度由大到小为:下部>中部>上部.堆肥过程中湿度随时间的变化满足二级动力学方程.     

The influence of various additives on coagulation process at different dosing point: From a perspective of structure properties

Structure properties of flocs (size, fractal dimension (D_f), etc.) have a high impact on coagulation efficiency. In this work, the influences of three different additives (ferric salt (Fe), phosphate (P), and citric acid (CA)) on coagulation process/efficiency were investigated. Results showed that a small amount of extra Fe can facilitate the growth of Al flocs by providing more ‘active sites’. Although zeta potential and D_f showed a limited change, the average floc size increased apparently and the increment was more obvious when Fe was added after the formation of the flocs. In contrast, P addition during the rapid mixing period will decrease the final average floc size, while the influence is less significant when P was added after the growth of the flocs. In terms of CA, a more striking negative effect on the growth ability of the flocs was observed compared to P. The strong complexing/coordination interactions between CA and aluminum hydroxide is the main reason behind the influence. CA also significantly decreased the D_f value of the flocs compared to P, and D_f showed a comparatively higher decrease when P or CA was added during the rapid mixing stage compared to the addition after the flocs formation. These results indicated that the addition of CA or P during the rapid mixing stage ‘inactivated’ or occupied more ‘active sites’ on the preliminarily formed Al NPs during the hydrolysis process, and therefore presented stronger impact on the morphology/size of the formed flocs.     

0.6米×0.6米跨超声速风洞噪声的分析及降噪研究

0.6米×0.6米跨超声速风洞是一座直流暂冲式风洞,风洞运行时的噪声最高达到120dB,为了降低噪声对人员和实验的影响,本文通过声学测量和理论分析噪声的特性,提出具体的降噪措施,为风洞厂房的建设提供科学依据。     

Strong ozone production at a rural site in theNorth China Plain: Mixed effects of urban plumesand biogenic emissions

Regional ozone (O₃) pollution has drawn increasing attention in China over the recent decade, but the contributions from urban pollution and biogenic emissions have not been clearly elucidated. To better understand the formation of the regional O₃ problem in the North China Plain (NCP), intensive field measurements of O₃ and related parameters were conducted at a rural site downwind of Ji'nan, the capital city of Shandong province, in the summer of 2013. Markedly severe O₃ pollution was recorded, with the O₃ mixing ratios exceeding the Chinese national ambient air quality standard on 28?days (a frequency of 78%) and with a maximum hourly value of 198 ppbv. Extensive regional transport of well-processed urban plumes to the site was identified. An observation-constrained chemical box model was deployed to evaluate in situ photochemical O₃ production on two episodes. The results show that the in situ formation accounted for approximately 46% of the observed O₃ accumulation, while the remainder (~ 54%) was contributed by regional transport of the O₃-laden urban plumes. The in situ ozone production was in a mixed controlled regime that reducing either NOx or VOCs would lead to a reduction of ozone formation. Biogenic VOCs played an important role in the local ozone formation. This study demonstrates the significant mixed effects of both anthropogenic pollution from urban zones and biogenic emission in rural areas on the regional O₃ pollution in the NCP region, and may have general applicability in facilitating the understanding of the formation of secondary pollution over China.     

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.