The assistance of microwave process in sludge stabilization with sodium sulfide and sodium phosphate.
After industrial wastewater sludge passed through an acid-extraction process to reclaim most of the copper ions in it, the residue may still need to be treated by stabilization technologies. The common method for the stabilization of hazardous waste in Taiwan is by cement solidification. However, this method has the disadvantage of an increase in waste volume. In this study, it was tried to combine the advantages of sulfur anions and phosphate anions with the characteristics of microwave energy to offer a new method which can avoid the disadvantage of cement solidification. From the results, it was found that the assistance of heating in sludge stabilization with additives was effective. Huge amounts of additives were saved. Compared with the assistance of the traditional electrical-heating in sludge stabilization with additives, that of the microwave process saved much time and was more powerful. However, when the reaction time was longer, a re-leaching situation would occur. The hybrid microwave process, a procedure of leading an inert gas into the microwave process, could overcome the disadvantage of the microwave process with regard to the long reaction time. Finally, a modified hybrid microwave process which reduced the use of gas was performed and recommended.
Chen
Ching-Lung
CL
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
Hsieh
Ching-Hong
CH
D007220:Industrial Waste / Q000517:prevention & control; D008872:Microwaves; D010710:Phosphates / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
D007220:Industrial Waste; D010710:Phosphates; D012722:Sewage; D013440:Sulfides; C018279:sodium phosphate; C033479:sodium sulfide