BAF反应器中氨化细菌的筛选与氨化特性分析

以BAF反应器中的生物膜为接种物,分离筛选得到2株氨化细菌,分别命名为A1、A2。通过形态学特征观察、生理生化特性分析及氨化性能进行表征,初步鉴定A1为变形杆菌属（Proteus）,A2为微球菌属（Micrococcus）。生态影响因子实验确定菌株氨化过程主要影响因素是温度、初始pH、投菌量。在30℃、初始pH值7．0,接种量5％的最佳运行条件下,A1、A2两株氨化细菌对有机氮分解效率分别达到86．91％、69．98％。所分离的2株氨化细菌对于高浓度有机氮工业废水的生物降解有一定的应用价值。     

MSW箱内排气压缩数值模拟与实验研究

结合有效应力原理与变形多孔介质渗流原理,给出了垃圾压缩过程的气固耦合方程,并给出了初始条件。针对封闭式垃圾压缩中转装置,提出了排气压缩原理,分析压缩机构的结构,构建垃圾压缩物理模型,应用ABAQUS数值模拟软件,探索城市固体垃圾（MSW）箱内排气压缩规律,并对传统封闭式垃圾压缩中转装置进行优化。实验表明,数值模拟与实验较吻合,优化后结构更利于提高垃圾压缩量与降低压缩能耗。     

Influence of pesticides contamination on the emission of PCDD/PCDF to the land from open burning of corn straws

Open burning of crop residues has been identified as an important emission source of PCDD/PCDF to the environment. This paper presents the first known data on the emission of PCDD/PCDF to the land considering the influence of pesticides applied in crops planting. Emission factor for PCDD/PCDF to the land from open burning of corn straw with pesticides contamination ranged from 0.07 to 0.57 ng WHO₂₀₀₅-TEQ/kg straw burned with a mean value of 0.24 ng WHO₂₀₀₅-TEQ/kg straw burned and median value of 0.20 ng WHO₂₀₀₅-TEQ/kg straw burned, respectively. The concentration was 35 to 270 times higher than that without additional pesticide contaminated. Initial observation was that emission factor for PCDD/PCDF from open burning of crop residues was overestimated in the former UNEP Dioxin Toolkit. Pesticides contamination should be considered in some hotpots where special and over dosed pesticides has been sprayed especially in developing countries.     

Tannery waste as a renewable source of nitrogen for production of multicomponent fertilizers with biostimulating properties

Environmental Science and Pollution Research - The studies presented in this work show that solid tannery waste-like shavings can be used as high-protein materials for fertilizer production...     

北京道路尘负荷分布及对大气环境影响

以北京平原地区铺装道路为研究对象,利用车载移动监测系统于2019年四季选择4个周期开展了道路尘负荷监测,分析数值分布及对大气环境影响.结果表明,道路频率在不同道路尘负荷范围内呈极显著的幂律分布,4个周期道路尘负荷小提琴图形状相似,存在部分道路数值显著高于其它道路.差道路与最清洁道路数值可相差100倍以上.各季节至少25%的道路数值在0.37 g·m^-2以内,至少50%的道路数值在0.64 g·m^-2以内,至少75%的道路数值在1.25 g·m^-2以内.核心区、中心城区、郊区、通州区道路尘负荷依次增大,且均呈现春季最高秋季最低的特征,城六区冬季高于夏季,郊区夏季高于冬季.核心区整体较低,通州区北部高值较多.道路尘负荷越高的道路类型,数据离散程度也越大.随着道路扬尘管控力度的加大,不同类型道路的尘负荷差距减小.道路扬尘排放量核心区占全市3%,中心城区占23%,郊区占74%(其中通州区13%).排放强度为核心区、中心城区、环路、国道等交通活动密集的区域高,而这些区域或道路的尘负荷低.典型道路PM2.5影响距离主要在下风向1 k...     

Photocatalytic decomposition of methanol over La/TiO<Subscript>2</Subscript> materials

Lanthanum-modified TiO₂ photocatalysts (0.2–1.5 wt% La) were investigated in the methanol decomposition in an aqueous solution. The photocatalysts were prepared by the common sol-gel method followed by calcination. The structural (X-ray diffraction, Raman, X-ray photoelectron spectroscopy), textural (N₂ physisorption), and optical properties (diffuse reflectance spectroscopy, photoelectrochemical measurements) of all synthetized nanomaterials were correlated with photocatalytic activity. Both pure TiO₂ and La-doped TiO₂ photocatalysts proved higher yields of hydrogen in comparison to photolysis. The photocatalyst with optimal amount of lanthanum (0.2 wt% La) showed almost two times higher amount of hydrogen produced at the same time as in the presence of pure TiO₂. The photocatalytic activity increased with both increasing photocurrent response and decreasing amount of lattice and surface O species. It has been shown that both direct and indirect mechanisms of methanol photocatalytic oxidation participate in the production of hydrogen. Both direct and indirect mechanisms take part in the formation of hydrogen.     

Applicability of energy-positive net-zero water management in Alaska: technology status and case study

Challenges of water and wastewater management in Alaska include the potential need for above-grade and freeze-protected piping, high unit energy costs and, in many rural areas, low population density and median annual income. However, recently developed net-zero water (NZW), i.e., nearly closed-loop, direct potable water reuse systems, can retain the thermal energy in municipal wastewater, producing warm treated potable water without the need for substantial water re-heating, heat pumping or transfer, or additional energy conversion. Consequently, these systems are projected to be capable of saving more energy than they use in water treatment and conveyance, in the temperate USA. In this paper, NZW technology is reviewed in terms of potential applicability in Alaska by performing a hypothetical case study for the city of Fairbanks, Alaska. Results of this paper study indicate that in municipalities of Alaska with local engineering and road access, the use of NZW systems may provide an energy-efficient water service option. In particular, case study modeling suggests hot water energy savings are equivalent to five times the energy used for treatment, much greater savings than in mid-latitudes, due largely to the substantially higher energy needed for heating water from a conventional treatment system and lack of need for freeze-protected piping. Further study of the applicability of NZW technology in cold regions, with expanded evaluation in terms of system-wide lifecycle cost, is recommended.     

Adsorption of 2,4-dichlorophenoxyacetic acid and 4-chloro-2-metylphenoxyacetic acid onto activated carbons derived from various lignocellulosic materials

Adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-metylphenoxyacetic acid (MCPA) from aqueous solution onto activated carbons derived from various lignocellulosic materials including willow, miscanthus, flax, and hemp shives was investigated. The adsorption kinetic data were analyzed using two kinetic models: the pseudo-first order and pseudo-second order equations. The adsorption kinetics of both herbicides was better represented by the pseudo-second order model. The adsorption isotherms of 2,4-D and MCPA on the activated carbons were analyzed using the Freundlich and Langmuir isotherm models. The equilibrium data followed the Langmuir isotherm. The effect of pH on the adsorption was also studied. The results showed that the activated carbons prepared from the lignocellulosic materials are efficient adsorbents for the removal of 2,4-D and MCPA from aqueous solutions.     

绵阳重污染天气机动车限行对空气质量的影响研究

为应对2017年底绵阳出现的一次重污染天气,绵阳政府于2017年12月25日0时至29日12时首次实行了机动车尾号限行措施。利用2017年12月20日至2018年1月2日绵阳4个国控环境质量监测站点的CO、NO_2、SO_2、O_3、PM_(2.5)、PM_(10)的数据分析限行前后的污染物浓度变化特征,并结合气象数据进行污染成因分析。结果表明,大气颗粒物PM_(2.5)和PM_(10)是此次重污染天气的首要污染物,机动车尾号限行措施对PM_(2.5)和PM_(10)有一定的减排效果。机动车尾号限行措施对NO_2、SO_2、O_3具有明显的减排效果,而对CO几乎没有减排效果。限行前和限行期大气颗粒物主要来源于化学转化形成的二次颗粒物,而限行后则转为沙尘、扬尘等一次颗粒物。江油对绵阳大气颗粒物PM_(2.5)、PM_(10)影响很大,气流轨迹出现频率高,大气颗粒物浓度也高,有必要考虑进行区域联防联控。     

盐度和曝气时间对包埋颗粒短程硝化启动的影响及其动力学分析

针对短程硝化反应器启动时间长、效果不稳定等问题,使用水性聚氨酯(WPU)制作硝化污泥包埋颗粒,利用SBR设置盐度梯度以及不同曝气时间进行批次实验,启动短程硝化;通过控制最佳反应条件启动UASB短程硝化反应器,同时进行动力学分析。结果表明:在批次实验过程中,随着盐度的增加,氨氮去除率(η_A)及NO_2~--N积累率(R_(NAR))先上升后下降。当NaCl浓度为10 g·L~(-1)时,短程硝化效果最佳,η_A为55%,R_(NAR)为90%;不同曝气时间对短程硝化的稳定性有较大的影响,曝气时间为8 h时短程硝化效果最稳定,η_A和R_(NAR)分别达到56%和96%。控制NaCl浓度为10 g·L~(-1),HRT为8 h,成功实现了UASB短程硝化反应器的启动;包埋颗粒对氨氮的动力学特性符合Haldane基质抑制动力学模型,具有优良的动力学特性。研究可为包埋颗粒与短程硝化工艺的耦合脱氮提供参考,并为含盐废水的处理提供技术支持。