利用土著微生物处理焚烧飞灰及资源化初探

利用从自然界花坛土壤中筛选的土著脲酶微生物开展了微生物诱导碳酸盐沉淀作用(MICP)处理垃圾焚烧飞灰试验,通过颗粒级配、无侧限抗压强度、重金属浸出毒性测试对固化/稳定化效果进行了评价.结果表明,在土著微生物附著剑菌(Ensifer adhaerens)的MICP作用及飞灰火山灰性的共同作用下,飞灰固化、稳定化效果明显;在较优工况下,无侧限抗压强度可达205.2kPa,弹性模量可达200MPa,主要重金属元素Cd、Cr、Pb、Zn、Cu的浸出浓度满足《地表水环境质量标准》Ⅲ类要求.在此基础上,利用有限元软件ABAQUS分析了将固化飞灰用作道路路面和路基之间填料后,对沥青路面性能的影响.结果表明:在路面碎石基层与路基之间设置固化飞灰层,可有效降低沥青路面底部拉应变,延长疲劳寿命,有效减轻车辙损伤,可作为大量消纳飞灰的处理途径之一.

Treatment of MSWI fly ash by using indigenous microorganism and the investigation of its promising utilization

The indigenous urease-producing bacterium selected from nursery soil were employed in the test of MICP treatment of MSWI fly ash. The solidification / stabilization effect of the treated fly ash was evaluated by particle size distribution, unconfined compressive strength (UCS) and heavy metal leaching toxicity. The results showed that under the combined action of MICP of Ensifer adhaerens and pozzolanic properties of fly ash, the solidification and stabilization of fly ash were obvious; under the optimal working condition, the UCS could reach 205.2kPa and the elastic modulus could reach 200MPa, and the leaching concentrations of Cd, Cr, Pb, Zn and Cu all met the class III requirements of the environmental quality standards for surface water. On this basis, the performance of asphalt pavement with the subgrade filler partly replaced by solidified fly ash was analyzed by using finite element software ABAQUS. The results showed that the reconstructive subgrade could effectively reduce the tensile strain at bottom, prolong the fatigue life and effectively reduce the rutting damage of the asphalt pavement. Therefore, the part replacement of subgrade filler is one of the promising ways for the utilization of fly ash.