污泥掺烧过程中Cl/S/P交互作用对重金属迁移转化和脱除影响的机理研究

The emissions of heavy metals will cause serious harm to the environment during the sludge co-incineration process and the typical composition of chlorine, sulfur and phosphorus are the key factors induced the migration and transformation of heavy metals.. The previous study showed that the chlorine or phosphorus can promote or inhibit the volatilization of heavy metals during the sludge incineration process and which can change the heavy metals reaction and transformational process. However, under the interaction of chlorine, sulfur and phosphorus, the competition chemical reaction will occur between the heavy metals and chlorine, sulfur and phosphorus or with the interaction of heavy metals, chlorine, sulfur and phosphorus. But the effects of the competitive reaction on the transportation of heavy metals and their simultaneous removal process mechanism are unclear. The simulation incineration experiments and thermodynamic theory mutual authentication are concerned to study the migration and transformation behavior and removal control of heavy metals induced by the interaction of chlorine, sulfur and phosphorus during the sludge incineration. The sludge incineration and adsorption removal process were simulated with the tube furnace. The heavy metal distributions and their fractions were investigated with the sequential extraction method of BCR and FAAS、XRD、SEM/EDS instruments. At the same time, the intermediate chemical products and the phase transition will be tracked. The evaporation and homogeneous, non-homogeneous reaction processes of heavy metals and their compounds were quantitatively described in the incineration. Thermodynamic equilibrium model was carried out to track the chemical reaction pathways of heavy metals during the sludge incineration process and resolve the law of interaction between heavy metal, chlorine, sulfur and phosphorus. Combined the category, morphology, migration characteristics, toxicity parameters and so on, the removal control model of heavy metals was established in the sludge incineration process, which provides scientifi basis for the further control of heavy metal discharge in the sludge incineration process.

污泥掺烧中重金属的排放会对环境造成严重危害，而Cl/S/P是诱发重金属迁移转化的关键因子。本小组前期研究表明焚烧中Cl/S可改变重金属的迁移途径，而P在污泥中普遍存在。在Cl/S/P交互作用的掺烧体系中，重金属与Cl/S/P必然发生竞争化学反应，而此反应对重金属迁移转化及脱除影响的机理尚不清楚。本课题拟采用实验模拟及热力学理论计算相互验证方法，通过管式炉模拟污泥焚烧及重金属脱除过程，利用BCR法及FAAS、XRD等手段获得重金属分布及形态变化规律，并跟踪其中间产物及相变过程，定量描述重金属在交互条件下的蒸发、均相/非均相反应；采用热力学平衡模型跟踪重金属化学反应路径，解析重金属与Cl/S/P及Ca/Si/Al氧化物之间的交互作用规律，根据重金属类别、分布、形态、迁移特性、毒性等，阐明Cl/S/P交互作用对重金属迁移转化和脱除的影响，为进一步控制污泥焚烧或掺烧过程中重金属的排放提供科学依据。

污泥成分的复杂性（重金属与有机物并存）和特殊性（P含量较高）导致其焚烧过程中重金属迁移转化行为的复杂化，在特征元素Cl-S-P交互作用下，重金属与Cl/S/P两者或三者必然发生竞争化学反应，因此有必要深入研究当前污泥焚烧处理过程中Cl-S-P交互作用下诱发重金属的迁移转化规律及其污染控制。本项目针对上述问题开展了有关研究如下：（1）利用热重法深入探讨了污泥、污泥与煤混合、污泥与生物质混合样品的燃烧特性，求解了燃尽指数、着火指数、燃烧综合指数等，获得污泥掺烧的动力参数，建立了焚烧动力学模型，为污泥管式炉焚烧条件优化和污泥掺烧实施提供科学依据；（2）利用热力学平衡计算软件模拟计算了污泥焚烧外在条件对多种重金属迁移转化规律及其吸附脱除特性，获得部分重金属的产生、迁移、分布和相变过程参数；（3）利用管式炉模拟了污泥焚烧实验，探讨了不同氯化物及不同硫化物对重金属焚烧的影响，获得多种重金属在Cl-S-P交互作用下的迁移转化影响因素和机制。（4）利用管式炉模拟了污泥焚烧实验，深入研究了Cl-S-P交互作用对固体吸附剂（CaO、Al2O3、高岭土及粉煤灰）脱除Pb效果的影响；（5）利用管式炉模拟了污泥焚烧实验，深入研究了调理剂交互作用对重金属迁移转化的影响，获得各个调理剂对重金属挥发、酸性气体排放的关键数据。（6）利用管式炉模拟了污泥焚烧实验，深入研究了高S印染污泥在Cl-P影响条件下的重金属挥发行为，查明多个条件下重金属的BCR、XPS迁变过程。以本内容为基础，申报人以第一作者或者通讯作者发表论文18篇，其中SCI 8篇、EI收录论文2篇，一级学报8篇；专利2个，国家标准1个；培养研究生3名；其他联合撰写论文11篇。上述成果的获得可以为进一步控制污泥焚烧过程中重金属的排放，并可为寻求适合我国污泥焚烧后灰渣及重金属的无害化、资源化处置思路和方法提供理论依据，具有一定的现实意义和科学价值。