生活垃圾堆肥工艺条件及其反应动力学研究

为了改善堆肥微环境 ,提高生活垃圾堆肥速率 ,研究堆肥工艺条件及其反应动力学是非常必要的。通过控制堆肥工艺条件 ,如初始温度、含水率、C/N比及堆料颗粒大小 ,研究生活垃圾堆肥过程中生物、化学及物理因素的变化。试验结果表明 ,生活垃圾堆肥反应符合一级反应动力学 ;合理控制堆肥初始反应条件 ,能明显提高堆肥效率。     

我国长江中下游平原典型稻田含碳温室气体通量变化特性

近年来关于碳排放研究的内容越来越受到重视,我国提出了在2030年实现碳达峰的战略目标,因此对我国温室气体排放监测的研究显得非常重要.基于涡度相关法对我国长江中下游区域典型稻田生长季的CO2和CH4通量进行监测分析,结果发现整个观测阶段稻田CO2通量呈"U"型曲线,整体表现为汇,分蘖期开始出现负值,抽穗期降到最低,通量平...     

Fe3O4@SA/Ce微球的表征及对染料的吸附特性

以天然高分子化合物海藻酸钠(sodium alginate,SA)为骨架,结合磁性Fe₃O₄和稀土铈离子Ce(Ⅲ)通过溶液反应制备出一种新型的磁性海藻酸铈复合微球(Fe₃O₄@SA;Ce).采用X射线衍射(XRD)、孔结构比表面积分析(BET)、扫描电子显微镜(SEM)、红外光谱(FT-IR)及振动样品强磁计(VSM)对Fe₃O₄@SA;Ce的结构进行了表征,并以直接桃红12B(direct red 12B,DR 12B)和直接橙S(direct orange S,DO S)两种染料为吸附对象,探讨了Fe₃O₄@SA;Ce的吸附剂性能、吸附动力学和热力学.结果表明,Fe₃O₄@SA;Ce对室温下自然pH染料溶液中DR 12B和DO S均表现出良好的吸附效果,吸附量分别可达464 mg·g^-1和730 mg·g^-1.在不同温度下(298、313、328 K),Fe₃O₄@SA;Ce对DR 12B和DO S的吸附过程均可用拟二级吸附动力学方程准确描述.通过等温吸附研究,发现Fe₃O₄@SA;Ce对两种染料的等温吸附较好地符合Freundlich模型.各种表征结果表明,SA与Ce(Ⅲ)和Fe₃O₄交联反应后生成的Fe₃O₄@SA;Ce凝胶球表面有大量深浅不一的褶皱沟纹,形貌发生了显著变化.作为一种绿色环保、制备方法简单、可高效吸附的磁性高分子复合吸附剂,Fe₃O₄@SA;Ce对高浓度染料具有很好的吸附效果,期望能够在染料废水处理中得到广泛应用.     

The performance of nitrate-reducing Fe(II) oxidation processes under variable initial Fe/N ratios: The fate of nitrogen and iron species

•Bacterially-mediated coupled N and Fe processes examined in incubation experiments. •NO₃⁻ reduction was considerably inhibited as initial Fe/N ratio increased. •The maximum production of N₂ occurred at an initial Fe/N molar ratio of 6. •Fe minerals produced at Fe/N ratios of 1–2 were mainly easily reducible oxides. The Fe/N ratio is an important control on nitrate-reducing Fe(II) oxidation processes that occur both in the aquatic environment and in wastewater treatment systems. The response of nitrate reduction, Fe oxidation, and mineral production to different initial Fe/N molar ratios in the presence of Paracoccus denitrificans was investigated in 132 h incubation experiments. A decrease in the nitrate reduction rate at 12 h occurred as the Fe/N ratio increased. Accumulated nitrite concentration at Fe/N ratios of 2–10 peaked at 12–84 h, and then decreased continuously to less than 0.1 mmol/L at the end of incubation. N₂O emission was promoted by high Fe/N ratios. Maximum production of N₂ occurred at a Fe/N ratio of 6, in parallel with the highest mole proportion of N₂ resulting from the reduction of nitrate (81.2%). XRD analysis and sequential extraction demonstrated that the main Fe minerals obtained from Fe(II) oxidation were easily reducible oxides such as ferrihydrite (at Fe/N ratios of 1–2), and easily reducible oxides and reducible oxides (at Fe/N ratios of 3–10). The results suggest that Fe/N ratio potentially plays a critical role in regulating N₂, N₂O emissions and Fe mineral formation in nitrate-reducing Fe(II) oxidation processes.     

Remediation of 2,4-dichlorophenol-contaminated groundwater using nano-sized CaO2 in a two-dimensional scale tank

• Nano CaO₂ is evaluated as a remediation agent for 2,4-DCP contaminated groundwater. • 2,4-DCP degradation mechanism by different Fe²⁺ concentration was proposed. • 2,4-DCP was not degraded in the system for solution pH>10. • The 2,4-DCP degradation area is inconsistent with the nano CaO₂ distribution area. This study evaluates the applicability of nano-sized calcium peroxide (CaO₂) as a source of H₂O₂ to remediate 2,4-dichlorophenol (2,4-DCP) contaminated groundwater via the advanced oxidation process (AOP). First, the effect and mechanism of 2,4-DCP degradation by CaO₂ at different Fe concentrations were studied (Fenton reaction). We found that at high Fe concentrations, 2,4-DCP almost completely degrades via primarily the oxidation of •OH within 5 h. At low Fe concentrations, the degradation rate of 2,4-DCP decreased rapidly. The main mechanism was the combined action of •OH and O₂^•−. Without Fe, the 2,4-DCP degradation reached 13.6% in 213 h, primarily via the heterogeneous reaction on the surface of CaO₂. Besides, 2,4-DCP degradation was significantly affected by solution pH. When the solution pH was>10, the degradation was almost completely inhibited. Thus, we adopted a two-dimensional water tank experiment to study the remediation efficiency CaO₂ on the water sample. We noticed that the degradation took place mainly in regions of pH<10 (i.e., CaO₂ distribution area), both upstream and downstream of the tank. After 28 days of treatment, the average 2,4-DCP degradation level was ≈36.5%. Given the inadequacy of the results, we recommend that groundwater remediation using nano CaO₂: (1) a buffer solution should be added to retard the rapid increase in pH, and (2) the nano CaO₂ should be injected copiously in batches to reduce CaO₂ deposition.     

多手段综合分析特厚煤层分层开采覆岩破坏高度

为研究特厚煤层分层开采过程中已采工作面上覆围岩破坏高度,以老虎台矿83002已采工作面为例,分别采用EH-4物理探测、数值模拟和微震监测等多种手段进行分析论证。EH-4探测确定了垮落带和裂隙带位于油页岩层内,高阻区位于绿色页岩和砂砾岩的交界面,F1断层处出现离层空间,数值模拟和微震监测对该结果进行了验证;数值模拟和微震监测综合确定了覆岩破坏高度为400～485 m,为累计采高的6.3～7.5倍。研究成果可对下一分层83003工作面的安全开采进行指导,为类似条件矿井提供借鉴。     

羟基自由基和水合电子降解对叔丁基酚的研究

采用电子束辐照水溶液的方法产生水合电子（e_aq^-）,研究了e_aq^-与对叔丁基酚（4-t-BP）的反应,结果表明还原性的e_aq^-不能降解4-t-BP.同时,采用254nm紫外光辐照H₂O₂来产生羟基自由基（·OH）,研究了UV//H₂O₂体系对4-t-BP的降解效果,考察了4-t-BP初始浓度,H₂O₂的添加浓度,溶液初始pH值等因素对反应的影响,结果表明4-t-BP初始浓度越低,H₂O₂的浓度越高,则越有利于反应的进行;溶液pH=6时是反应的最佳pH值.采用HPLC结合GC-MS的分析方法对反应的中间产物进行了定性分析,得出对叔丁基邻苯二酚,对叔丁基酚二聚体和对苯二酚等3种主要中间产物,归纳总结了4-t-BP与·OH的反应路径.     

基于行为安全理论的化工事故统计及分析

行为安全理论是事故分析和预防的理论和方法,应用基于行为安全理论的事故致因“2-4”模型对10起化工事故的直接、间接、根本、根源原因进行分析。结果表明:该模型是化工事故分析的有效方法。10起事故的直接原因主要为一线员工在涉及高温加热工艺、带压设备、有毒有害环境和动火作业中的违规违章操作,管理人员未建立或运行安全管理体系等不安全动作及不安全物态,且不安全物态与管理人员不安全行为有关;间接原因是一线员工缺乏岗位安全操作等知识,管理人员缺乏安全管理、技术等知识,导致其安全意识薄弱,养成不良的安全习惯;根本原因是组织安全教育等管理程序缺失和执行不力;根源原因是组织成员对安全的重要度等安全文化元素缺乏理解。     

大同矿区煤的导热系数灰色关联分析及预测

为分析煤质指标及密度对导热系数的影响作用,选取了山西大同矿区的不同煤质煤样,进行导热系数测定实验,应用灰色系统理论对导热系数与影响因素进行灰色关联分析,建立导热系数与主要影响因素的GM(1,4)灰色预测模型,进行导热系数预测。结果表明:固定碳、密度和水分是影响煤导热系数的主要因素;根据得出的主要影响因素建立的GM(1,4)预测模型平均相对误差为4.5%,预测精度较高,能够用于导热系数的预测。     

硫铁填料和微电流强化再生水脱氮除磷的研究

为提高再生水质量,在不同C/N和HRT条件下,对比分析硫铁复合填料和微电流作用强化再生水深度脱氮除磷效果.结果表明,硫铁复合填料和微电流作用均能够强化氮、磷的深度去除效果,且二者结合能够使反硝化系统pH值稳定在7.2~8.5之间.系统中TN主要靠异养反硝化、氢自养反硝化和硫自养反硝化作用去除,94.04%的TP是以生成磷酸铁沉淀的形式去除.分别从填料上取生物膜,进行Miseq高通量测序,构建细菌16S rRNA基因克隆文库.结果发现,在仅有海绵铁作用系统中,同时具有异养反硝化和氢自养反硝化功能的细菌所占比例达到29.47%;硫铁复合填料和硫铁微电流作用系统中,具有硫自养反硝化功能的Thiobacillus(硫杆菌属)所占比例分别达到60.47%和40.62%.因此,硫铁复合填料和微电流作用用于强化再生水深度脱氮除磷具有明显的优势.