Microwave enhanced stabilization of heavy metal sludge.
A microwave process can be utilized to stabilize the copper ions in heavy metal sludge. The effects of microwave processing on stabilization of heavy metal sludge were studied as a function of additive, power, process time, reaction atmosphere, cooling gas, organic substance, and temperature. Copper leach resistance increased with addition of aluminum metal powder, with increased microwave power, increased processing time, and using a gaseous environment of nitrogen for processing and air for cooling [N2/air]. The organic in the sludge affected stabilization, whether or not the organic smoldered. During heating in conventional ovens, exothermic oxidation of the organic resulted in sludge temperatures of about 500 degrees C for oven control temperatures of 200-500 degrees C. After microwave heating dried the sludge, the sludge temperature rose to 500 degrees C. The reaction between copper ions and metal aluminum in the dried sludge should be regarded as a solid phase reaction. Adding aluminum metal powder and reaction temperature were the key parameters in stabilizing copper in the heavy metal sludge, whether heated by microwave radiation or conventional oven. The mass balance indicates insignificant volatization of the copper during heating.
Hsieh
Ching-Hong
CH
Research Center for Environmental Pollution Prevention and Control Technology, Graduate Institute of Environmental Engineering, National Taiwan University, 71 Chou-Shan Road, Taipei 106, Taiwan, ROC.
Lo
Shang-Lien
SL
Chiueh
Pei-Te
PT
Kuan
Wen-Hui
WH
Chen
Ching-Lung
CL
D000535:Aluminum / Q000737:chemistry; D000537:Aluminum Oxide; D005740:Gases; D019216:Metals, Heavy / Q000737:chemistry*; D008872:Microwaves; D009930:Organic Chemicals / Q000737:chemistry; D012722:Sewage / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
D005740:Gases; D019216:Metals, Heavy; D009930:Organic Chemicals; D012722:Sewage; D000535:Aluminum; D000537:Aluminum Oxide