粉煤灰免烧陶粒制备及其重金属废水净化性能

摘要重金属废水对环境的污染已经引起科研人员的广泛关注。以粉煤灰和水泥为原料、添加活性成分FeS,制备一种免烧陶粒用于含重金属Cu2＋、Zn2＋、Pb2＋的废水处理。探讨了物料配比及蒸养时间对陶粒筒压强度及其比表面积的影响;研究了固液比、接触时间、pH、温度及初始溶液浓度等因素对Cu2＋、Zn2＋、Pb2＋离子净化效果的影响规律,并对实验结果进行了等温线拟合。XRD分析显示,免烧陶粒中存在Ca（OH）2、C—D—H、FeS等矿物相,对重金属离子具有非常好的固定化作用。该免烧陶粒对重金属离子具有很好的去除效果,具备较好的应用前景。     

Adsorption of basic dye from aqueous solution onto fly ash

The fly ash treated by H₂SO₄ was used as a low-cost adsorbent for the removal of a typical dye, methylene blue, from aqueous solution. An increase in the specific surface area and dye-adsorption capacity was observed after the acid treatment. The adsorption isotherm and kinetics of the treated fly ash were studied. The experimental results were fitted using Langmuir and Freundlich isotherms. It shows that the Freundlich isotherm is better in describing the adsorption process. Two kinetic models, pseudo-first order and pseudo-second order, were employed to analyze the kinetic data. It was found that the pseudo-second-order model is the better choice to describe the adsorption behavior. The thermodynamic study reveals that the enthalpy (ΔH⁰) value is positive (5.63 kJ/mol), suggesting an endothermic nature of the adsorption.     

垃圾焚烧飞灰处置与资源化利用研究进展

随着生活垃圾焚烧处理方式的不断推广,焚烧飞灰的产生量也不断增加。按照我国固体废物分类方法,焚烧飞灰属于危险废物,必须进一步处置才能进入填埋场或资源化利用。本文分析了飞灰物理化学特性,论述了常规处置技术（水泥固化、化学药剂稳定化、酸溶剂提取和熔融固化等）存在的问题。将原始飞灰直接应用于水泥、混凝土或路基材料,飞灰中高含量的重金属和盐类会产生新的环境问题。飞灰水洗可以高效去除其中的可溶性盐类,水洗飞灰在焙烧后重金属的浸出浓度远低于原始飞灰烧结后的相应浓度,飞灰水洗-焙烧技术具有很好的应用前景。     

Effect of unburned carbon on lead, zinc, and copper recovery from molten fly ash by chloride-induced volatilization

The present work focuses on investigation of the effective recovery of heavy metals from molten fly ash by applying chloride-induced volatilization. In particular, the effect of unburned carbon on the chloride-induced volatilization of lead, zinc, and copper from model and real molten fly ashes was investigated in the temperature range 873–1173 K under a N₂ atmosphere. As a result, almost 100% of lead and a significant proportion of zinc were volatilized from the real molten fly ash samples at 1173 K. In contrast, for the model fly ash, volatilization ratios of lead and zinc at 1173 K were only 85% and 25%, respectively. Further, the results of X-ray diffraction analysis suggested that PbO in molten fly ash was converted either to Pb₂OCl₂ or Pb by respective chlorination and reduction reactions. Meanwhile ZnO and CuO in the molten fly ash were reduced to Zn and Cu by reaction with unburned carbon. Subsequently, Pb, Zn, and Pb₂OCl₂ were volatilized, but Cu remained in the solid residue. Finally, the volatilization ratio of zinc increased with the addition of carbon, and more than 98% of zinc was volatilized at 1173 K from a fly ash with a carbon content of 20%.     

Leaching behavior of heavy metals from municipal solid waste incineration bottom ash and its geochemical modeling

With the increase in the number of municipal solid waste incineration (MSWI) plants constructed in China recently, great attention has been paid to the heavy metal leaching toxicity of MSWI residues. In this study, the effects of various parameters, including extractant, leaching time, liquid-to-solid ratio, leachate pH, and heavy metal content, on the release properties of Cd, Cr, Cu, Ni, Pb, and Zn from MSWI bottom ash were investigated. Partial least-squares analysis was employed to highlight the interrelationships between the factors and response variables. Both experimental research and geochemical modeling using Visual MINTEQ software were conducted to study the pH-dependent leaching behavior of these metals in fresh and weathered bottom ash, considering precipitation/dissolution and surface complexation reactions (adsorption by hydrous ferric oxide and amorphous aluminum oxide/hydroxide). The results showed that leachate pH was the predominant factor influencing heavy metal leachability. The leaching of Cu, Pb, and Zn was mainly controlled by precipitation/dissolution reactions, whereas surface complexation had some effect on the leaching of Cr, Cd, and Ni for certain pH ranges. The modeling results aggreed well with the experimental results. Part of this work was presented at the Fourth International Conference on Combustion, Incineration/Pyrolysis and Emission Control (i-CIPEC)     

杉木观光木混交林群落的能量生态

对杉木观光木混交林群落能量的研究结果表明：混交林中观光木地上部分灰分含量以皮最高,而杉则以叶最高,两者GCV（干重热值）和AFCV（去灰分热值）均以叶为最高;观光木、杉木地下各部分的灰分含量均随径级的减小而增加,GCV均以粗根最高,细根最低;观光木的平均灰分含量高于杉木,但GCV和AFCV均低于杉木;从乔木层、灌木层到草本层,灰分含量依次增加,GCV和AFCV则依次降低,混交林群落的能量现存量公占群落的很小一部分,而其能量年净增量、归还量和净固定量却占有一定比重,混交林群落的太阳能转化率为1.57%,而纯林为1.44%,表明杉观混交林是一种能量生产力较高和维持地力能力较强的杉阔混交类型。同时,混交林的能量累积比大于纯林,能量流动速率则低于纯林;乔木层的能量累积比高于林下植被,能量流动速率则低于林下植被,从能量的角度看,构建合理的群落结构必须选择高能量累积比的乔木层树种,同时须促进能量流动速率快的林下植被的发育以维持和提高地力。     

秸秆焚烧对哈尔滨市灰霾天气的影响

2015年11月1—4日,哈尔滨市及周边地区发生了连续的灰霾天气,颗粒物浓度急剧升高。污染发生时,监测仪器均布设在哈尔滨市区上风向30 km处(哈尔滨市双城区)并开展了连续96 h的监测分析。综合利用气象观测资料,3D可视激光雷达监测资料及地面空气污染监测资料分析了灰霾天气发生的气象条件和污染边界层特征,根据哈尔滨市双城区大气污染物排放源谱库对主要成分进行来源解析,结合颗粒物质量浓度和气象条件研究了秸秆焚烧对灰霾天气的影响。结果表明,灰霾天气持续期间,夜间生物质燃烧源成为该地区颗粒物的第二大源;秸秆焚烧产生的大气污染物,由于地面长时间静风,污染边界层降低等原因,致使本地污染物累积、不易扩散,加剧了本次污染。     

间歇-阶段性酸雨入侵对填埋稳定化飞灰中重金属浸出行为影响

以间歇-分阶段进水方式进行了模拟酸雨柱式动态淋溶实验.结果表明,间歇-阶段性酸雨入侵会影响填埋飞灰中Pb、Zn、Cu、Cr和Ni的浸出行为;尤其间歇停滞期后的初期酸雨入侵会增加多数重金属的再浸出水平,且该部分重金属的释放主要源于前阶段酸雨侵蚀过程中所形成的非稳定性(弱酸态)重金属.各酸雨侵蚀阶段,部分重金属(如Pb-Zn)的浸出行为具有相关性,这与各重金属在飞灰基质内的赋存形态、矿物相稳定性及酸性侵蚀程度等有关.各阶段酸雨入侵会相继溶出飞灰中的可溶性(NaCl、KCl等)、难溶性氯盐(CaClOH)以及微溶性钙盐(CaSO₄),并增加CaCO₃和Ca-Al-Si-O等矿物的峰强.各阶段酸雨入侵会使初始飞灰表面的团簇状结构逐渐被酸性(H⁺)侵蚀作用破坏,并暴露出大量棒状或条形状CaCO₃晶体,且随着酸雨入侵次数的增加,CaCO₃也将逐渐被侵蚀破坏.本研究为非连续酸性降雨条件下填埋稳定化飞灰的重金属浸出行为评价及风险管控提供了科学依据.     

类水滑石对污泥焚烧飞灰浸出液中磷的纯化

采用Mg-Fe型类水滑石（LDH）吸附剂提纯污泥焚烧飞灰（ISSA）浸出液中的磷,探究了吸附剂煅烧对磷吸附效果的影响及磷吸附和脱附机理.研究发现,在高浓度磷溶液（>1000mg/L）中,未煅烧的类水滑石（LDHu）磷吸附容量高于煅烧后的类水滑石（LDHc）.LDHu具有典型的层状结构,磷的吸附与脱附主要通过磷和金属离子沉淀-溶解、静电吸附-排斥、配位作用和离子交换实现.而LDHc层状结构消失,形成双金属氧化物,不存在明显的阴离子交换作用.经LDHu或LDHc吸附和NaOH溶液脱附后,ISSA浸出液均具有良好的磷纯化效果,磷相对纯度从36%分别上升至77%和69%,磷回收率分别为84%和57%.纯化后的溶液适合制备高值含磷产物.     

Stabilization of heavy metals in MSWI fly ash using silica fume

The objective of this work was to investigate the feasibility and effectiveness of silica fume on stabilizing heavy metals in municipal solid waste incineration (MSWI) fly ash. In addition to compressive strength measurements, hydrated pastes were characterized by X-ray diffraction (XRD), thermal-analyses (DTA/TG), and MAS NMR (²⁷Al and ²⁹Si) techniques. It was found that silica fume additions could effectively reduce the leaching of toxic heavy metals. At the addition of 20% silica fume, leaching concentrations for Cu, Pb and Zn of the hydrated paste cured for 7 days decreased from 0.32 mg/L to 0.05 mg/L, 40.99 mg/L to 4.40 mg/L, and 6.96 mg/L to 0.21 mg/L compared with the MSWI fly ash. After curing for 135 days, Cd and Pb in the leachates were not detected, while Cu and Zn concentrations decreased to 0.02 mg/L and 0.03 mg/L. The speciation of Pb and Cd by the modified version of the European Community Bureau of Reference (BCR) extractions showed that these metals converted into more stable state in hydrated pastes of MSWI fly ash in the presence of silica fume. Although exchangeable and weak-acid soluble fractions of Cu and Zn increased with hydration time, silica fume addition of 10% can satisfy the requirement of detoxification for heavy metals investigated in terms of the identification standard of hazardous waste of China.