摘要
在一维固定燃烧炉上进行了污泥层燃模拟实验，重点研究了不同焚烧温度、停留时间、含水率及不同空气过剩系数条件下Cd的迁移和转化特征，并利用4种固体吸附剂CaO、Al2O3粉煤灰和高岭土对污泥焚烧过程中Cd的排放进行吸附去除．研究结果表明，随着焚烧温度的升高，底渣中Cd有一定的挥发，并且焚烧底渣中Cd的可氧化态和易还原态会向残渣态转化，有利于降低焚烧底渣中Cd的生物可利用性．随着焚烧时间的延长，对焚烧过程中Cd的挥发影响不大，但可使焚烧底渣中Cd的易还原态和可氧化态向残渣态转化．焚烧过程中含水率对重金属Cd的残留率影响较大，当含水率达超过75％后，底渣中Cd残留率会明显降低，并且随着含水率的增加，底渣中Cd的可氧化态会向易还原态转化，而残渣态的比例变化不大．空气过剩系数五在1～1．5之间时，焚烧底渣中Cd的含量、残留率及Cd可氧化态所占的比例变化不大，当五从1．5升至2时，底渣中Cd的含量及残留率大幅度降低，并且底渣中Cd基本上以残渣态存在．污泥焚烧过程中4种固体吸附剂的加入有利于Cd的残留并固定在焚烧底渣中，并且随着固体吸附剂添加比例的增多，Cd的残留率也逐渐增加，吸附剂粉煤灰和高岭土要优于CaO和Al2O3．
Staged incineration was carried out on laboratory-scale sewage sludge combustion. Partitioning and transformation of Cd were investigated under different combustion conditions including different incineration temperature, residence time, water content and different excess air coefficient. Four solid sorbents including CaO, Al2O3, fly ash and kaolin were added in sewage sludge combustion in order to reduce the Cd emissions. The results show that the Cd has volatilization with the increasing incineration temperature and the reducible, oxidizable fractions of Cd transformed to the residual fraction, which reduces the biologic-alavailability of Cd in the bottom ash. With the extension of furnace residence time, the volatilization of Cd becomes a little in the incineration process and the reducible, oxidizable fractions of Cd transformed to the residual fraction. The residual rate of Cd is affected great by the moisture content of the sewage sludge during the incineration process, when the water content reaches over 75% and the residual rate of Cd will be significantly reduced. With the increase of the moisture content, the oxidizable fractions of Cd transform to the reducible fraction, while the proportion of residual changes a little. Excess air ratio is between 1 and 1.5, the concentration, the residual rate and the oxidizable proportion of Cd in the bottom ash change a little. When excess air ratio is from 1.5 to 2, the concentration and the residual rate of Cd in bottom ash were significantly reduced, and Cd in bottom ash is almost in residual fraction. With the increase of the solid adsorbent ratio, the residual rate of heavy metals increase gradually in the bottom ash and the adsorbent fly ash and kaolin and are superior to Al2O3 and CaO in the controlling of Cd evaporation.
出处
《中国科学：化学》
CAS
CSCD
北大核心
2013年第1期94-103,共10页
SCIENTIA SINICA Chimica
基金
广东省高校优秀青年创新人才培养项目(LYM11059)
广东省科技计划项目及广东省部产学研结合项目(2011B090400161
2011B090400144)资助
关键词
污泥
焚烧
CD
形态
迁移
转化
municipal sludge, incineration, Cd, fraction, migration, transformation
