随着我国社会经济的发展、城市化进程的加快以及人们物质生活的提高,全国城市生活垃圾年产生量已达1.5亿吨以上,并以每年8%~10%的速率增加[1-3]。城市垃圾焚烧是我国垃圾处置的重要手段,在焚烧过程中将产生大量飞灰,飞灰产量与垃圾种类、焚烧条件、焚烧炉型及烟气处理工艺有关,一般约占被焚烧垃圾量的3%~5%。
In view of treatment efficiency and stability about stabilization treatment of fly ash from municipal solid waste incineration,a stabilization technology was developed for treating heavy metals in fly ash using organic heavy metal chelator ammonium dipropyl dithiophosphate(ADD).The effect of pH on heavy metal leached amount from stabilized fly ash was studied.The contents of different forms of heavy metals in fly ash were compared before and after stabilization treatment with ADD chelator,and the stabilization effect was analyzed with different amounts of ADD chelator.The result showed that stabilization rate against Pb,Zn,and Cd of 1.5% ADD chelator reached 95.6%,85.5% and 93.4% respectively,and the amounts of Pb,Zn,and Cd in the leachate met the Pollution Control Standards for Hazardous Waste Landfill(GB 18598—2001)at pH values exceeding 3.The contents of Pb,Zn and Cd bound to carbonates in fly ash after ADD chelator treatment was significantly decreased with significantly increased contents bound to organic matter.The Pb,Zn and Cd stable form contents increased by 15.4%,17.1% and 24.3% respectively,and accordingly reduced the risk of secondary pollution of stabilized products under environment change.The stabilization effect of ADD chelator on heavy metals in fly ash was apparently better than that of inorganic stabilizing agent lime and sodium sulfide.