Combustion and inorganic bromine emission of waste printed circuit boards in a high temperature furnace

High temperature combustion experiments of waste printed circuit boards (PCBs) were conducted using a lab-scale system featuring a continuously-fed drop tube furnace. Combustion efficiency and the occurrence of inorganic bromine (HBr and Br₂) were systematically studied by monitoring the main combustion products continuously. The influence of furnace temperature (T) was studied from 800 to 1400 °C, the excess air factor (EAF) was varied from 1.2 to 1.9 and the residence time in the high temperature zone (RT_HT) was set at 0.25, 0.5, or 0.75 s.Combustion efficiency depends on temperature, EAF and RT_HT; temperature has the most significant effect. Conversion of organic bromine from flame retardants into HBr and Br₂ depends on temperature and EAF. Temperature has crucial influence over the ratio of HBr to Br₂, whereas oxygen partial pressure plays a minor role. The two forms of inorganic bromine seem substantially to reach thermodynamic equilibrium within 0.25 s. High temperature is required to improve the combustion performance: at 1200 °C or higher, an EAF of 1.3 or more, and a RT_HT exceeding 0.75 s, combustion is quite complete, the CO concentration in flue gas and remained carbon in ash are sufficiently low, and organobrominated compounds are successfully decomposed (more than 99.9%).According to these results, incineration of waste PCBs without preliminary separation and without additives would perform very well under certain conditions; the potential precursors for brominated dioxins formation could be destroyed efficiently. Increasing temperature could decrease the volume percentage ratio of Br₂/HBr in flue gas greatly.     

垃圾焚烧飞灰物理化学性质的实验研究

应用激光粒度粒形分析仪、灰熔融性测定仪、原子吸收光谱仪和XRD等仪器手段对国内2种垃圾焚烧飞灰的密度、颗粒特性、熔点、成分和晶相结构等物理化学性质进行了详细的研究。研究发现，2种灰样颗粒直径的数量积分分布非常接近，其中基本没有超过40／μm的颗粒。由于垃圾焚烧飞灰在化学成分上存在的差异导致了其熔点有很大的不同。此外，XRD结果显示不同来源的飞灰其晶相结构存在较大的差别，这可能与垃圾的来源和焚烧工艺以及烟气处理方法有关。实验结果为飞灰无害化低温烧结工艺的选择和运行参数的制定提供了依据。     

Effect of temperature and particle size on the thermal desorption of PCBs from contaminated soil

Thermal desorption is widely used for remediation of soil contaminated with volatiles, such as solvents and distillates. In this study, a soil contaminated with semivolatile polychlorinated biphenyls (PCBs) was sampled at an interim storage point for waste PCB transformers and heated to temperatures from 300 to 600 °C in a flow of nitrogen to investigate the effect of temperature and particle size on thermal desorption. Two size fractions were tested: coarse soil of 420–841 μm and fine soil with particles <250 μm. A PCB removal efficiency of 98.0 % was attained after 1 h of thermal treatment at 600 °C. The residual amount of PCBs in this soil decreased with rising thermal treatment temperature while the amount transferred to the gas phase increased up to 550 °C; at 600 °C, destruction of PCBs became more obvious. At low temperature, the thermally treated soil still had a similar PCB homologue distribution as raw soil, indicating thermal desorption as a main mechanism in removal. Dechlorination and decomposition increasingly occurred at high temperature, since shifts in average chlorination level were observed, from 3.34 in the raw soil to 2.75 in soil treated at 600 °C. Fine soil particles showed higher removal efficiency and destruction efficiency than coarse particles, suggesting that desorption from coarse particles is influenced by mass transfer.     

污泥在CO2气氛下热解CO与CH4的生成特性

利用热重-红外(TG-FTIR)联用技术研究了典型市政污水污泥在CO2和N2气氛下的热解特性。基于TG-FTIR分析结果,采用等温模式配合法研究了CO2气氛下污泥固定床热解过程中CO和CH4的生成特性,建立了CO和CH4的生成动力学机理模型,并同传统N2气氛下污泥热解情况进行了对比,理论模型利用实际实验数据进行了验证分析。结果表明,在实验温度范围内2种气氛下CO与CH4的生成情况有着比较明显的差异,CO2气氛下CH4释放浓度在峰值和总量上都要低于N2气氛,CH4释放峰值来得更早,释放时间更为集中,释放过程也结束得更快。相反,CO的释放浓度峰值,总量以及持续时间在CO2气氛下都要远远高于N2气氛,随着温度的升高,差距越来越大,CO2的存在大大促进了CO的生成。经实验验证,理论推导所得的模型公式对于热解产物生成有着良好的预测结果。     

不同菌种组合对发酵残余物好氧堆肥进程及氮素变化的影响

适宜菌剂组合对于初始电导率（Electronic conductivity,EC）较高的发酵残余物二次干化腐熟效果具有重要影响。通过在发酵残余物（猪场沼渣、城市生活污泥）好氧发酵过程中添加不同菌种组合,研究堆肥腐熟指标变化,特别是不同形态氮素指标变化,以期更好提升发酵残余物的干化和腐熟程度。结果表明：F3菌剂组合处理高温期达16 d,最高温度为69.5℃,最早进入腐熟阶段,全氮损失比例最少,为8.72%;对照组在高温期（14 d、69.3℃）及全氮损失比例（9.21%）指标上仅低于F3处理组,表明自然堆体存在耐盐菌种;在促进堆肥腐熟效果方面,霉菌起着关键的作用,堆肥后期酵母菌的存在促进堆体腐熟度的提升;菌种比例和种类的合理设置对于堆体腐熟度提高的重要性要高于活菌添加量;在堆肥保氮过程中,真菌（霉菌和酵母菌）起着重要作用。F3处理（即芽孢杆菌：霉菌：酵母菌=1：2：2）,是实现发酵残余物快速高效堆肥的理想菌剂配方,其他复配菌种组合保氮效果改良侧重点各不相同。     

垃圾焚烧飞灰物理化学性质的实验研究

应用激光粒度粒形分析仪、灰熔融性测定仪、原子吸收光谱仪和XRD等仪器手段对国内2种垃圾焚烧飞灰的密度、颗粒特性、熔点、成分和晶相结构等物理化学性质进行了详细的研究。研究发现，2种灰样颗粒直径的数量积分分布非常接近，其中基本没有超过40 μm的颗粒。由于垃圾焚烧飞灰在化学成分上存在的差异导致了其熔点有很大的不同。此外，XRD结果显示不同来源的飞灰其晶相结构存在较大的差别，这可能与垃圾的来源和焚烧工艺以及烟气处理方法有关。实验结果为飞灰无害化低温烧结工艺的选择和运行参数的制定提供了依据。     

制备方法对MgAl水滑石衍生氧化物负载钯催化剂丙烷完全氧化活性的影响

以沉积沉淀法(DP)、浸渍法(IM)和共沉淀法(CP)制备MgAl水滑石衍生氧化物负载钯催化剂,用ICP、XRD、SEM、TEM、EDS、TPR以及比表面测定等手段对催化剂进行了表征.ICP和XRD数据表明用上述3种方法均可成功制备水滑石为前体载钯催化剂.SEM、TEM、EDS数据表明不同方法制备的样品具有不同的形貌以及钯在其中的分散度.综合各类表征数据可知Pd在催化剂中暴露的活性位是影响其活性的主要因素.     

中小型工业窑炉NOx废气的净化技术与应用

介绍了中小型工业窑炉生产过程中排放NOx的现状,并针对NOx的治理问题,从工程应用角度,简述了湿法和干法净化NOx的原理和化学反应过程。讨论了NOx排放特性和NOx废气中NO2/NOx比例的问题。提出了影响NOx治理的主要因素,包括吸收剂、吸附剂、催化剂和设备的部分应用参数,并结合工程实例指出工程需要注意的问题。介绍了多项采用湿法和干法净化NOx的工程应用项目,丰富了中小工业窑炉NOx废气的治理的实践经验,为中小工业窑炉排放NOx治理奠定了基础。     

表面活性剂改性4A分子筛对Cr(VI)的吸附行为

采用浸渍法对4A分子筛进行表面改性,通过引入阳离子表面活性剂,使4A分子筛表面附着季铵型阳离子,并与反离子Br-形成"阴离子交换膜",从而促使更多的Cr(VI)阴离子通过离子交换吸附到改性4A分子筛上,通过X-射线衍射(XRD)和傅里叶变换红外光谱(FTIR)对样品的物相结构和组成进行表征分析。研究表明,表面活性剂的类型和疏水碳氢链结构会影响4A分子筛的吸附能力,十八烷基三甲基溴化铵(OTAB)碳氢链长,在分子筛表面形成的双分子层密,对Cr(VI)的吸附量最大。采用准一级、准二级、Elovich和Bangham动力学模型对六价铬的吸附数据进行拟合,其中准一级动力学方程最符合十八烷基三甲基溴化铵改性分子筛的吸附行为。同时,分别从Langmuir和Redlich-Peterson等温吸附模型获得六价铬的最大吸附量为13.98 mg/g,且改性分子筛以均一表面吸附为主。     

基于CA-MAS的水域总有机碳扩散模拟研究

当前水环境污染扩散研究一般基于普通数值模型模拟,忽略了水污染扩散微观驱动力的影响。为能更真实地反映其动态扩散过程,针对水域总有机碳(TOC)扩散机理,基于CA和MAS技术,将影响TOC扩散的自然和社会经济因素抽象为微观的水流Agent、风速Agent、径流量Agent、污水排放口Agent、人工管理Agent以及农业生产地Agent,将研究水域抽象为CA元胞空间,建立了CA-MAS水域总有机碳扩散模型,对水域总有机碳的动态演化过程进行模拟,并以武汉理工大学鉴湖水域作为实验区域,借助NetLogo仿真平台完成了模型的实现与验证。模拟结果表明,该模型基本能够反映水体总有机碳的扩散规律,可以为水环境污染控制提供参考。