微生物胶凝材料固结垃圾焚烧飞灰效果及机制

Consolidation of Municipal Solid Waste Incineration Fly Ash by Microbial Cementing Material: Effect and Mechanism

针对当前利用普通硅酸盐水泥固结垃圾焚烧飞灰存在能耗大、环境污染严重等问题,采用微生物胶凝材料固结飞灰,研究其对飞灰的固结效果,并通过X射线衍射仪、扫描电子显微镜、红外光谱和原子吸收光谱等测试技术分析其固结飞灰的机制。研究结果表明,不同的拌合介质(水、上清液、微生物溶液、化学碳酸钙、微生物胶凝材料、微生物胶凝材料和上清液、微生物胶凝材料和微生物溶液)均能将松散的飞灰颗粒固结为一个整体,但其中以微生物胶凝材料和上清液为介质拌制的飞灰固结体强度和重金属离子固化效果最优(Pb离子和Cd离子的固结率分别为33%和32%)。微生物胶凝材料具有双重固结飞灰的作用,一方面它与其他介质固结飞灰相同,均是在固结体内部形成了水化产物Ca 2SiO 4·0.30H 2O;另一方面,微生物胶凝材料中的有机基质能分别与飞灰和方解石中Si-O键、C-O键的O原子作用形成大量的分子间氢键。

Using ordinary Portland cement to consolidate the municipal solid waste incineration (MSWI) fly ash brings about the problems of large energy consumption and serious environmental pollution. Aiming at relieving this problem, microbial cementing material was employed to consolidate the MSWI fly ash, and its consolidation effect was investigated. Furthermore, the consolidation mechanism of MSWI fly ash by microbial cementing material was analyzed by X-ray diffraction, scanning electron microscopy, infrared spectroscope and atomic absorption spectroscope. Research results demonstrated that the consolidation of loose MSWI fly ash particles as a whole could be achieved by various mixing media, including water, supernatant, bacterial fluid, chemical CaCO 3, microbial gelling material, microbial cementing material and supernatant fluid, microbial cementing material and bacterial fluid.While, microbial cementing material and supernatant fluid exhibited superior consolidation strength and consolidation effect of heavy metal ions of MSWI fly ash among those mixing media, presenting 33% and 32% consolidation rate for Pb and Cd, respectively. Regarding to the mechanism, there were dual effects of microbial cementing material in consolidation of MSWI fly ash. Specifically speaking, one action was the generation of the hydrated product (Ca 2SiO 4· 0.30H 2O) which was the same with other consolidation products, another action was the formation of a large number of intermolecular hydrogen bonds resulted from the interaction between the organic matrix in the microbial cementing materialand the O atom of Si-O bonds and C-O bonds in MSWI fly ash and calcite respectively.